--- /dev/null
+/*
+ * GPL HEADER START
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 only,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License version 2 for more details (a copy is included
+ * in the LICENSE file that accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License
+ * version 2 along with this program; If not, see
+ * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ * GPL HEADER END
+ */
+/*
+ * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Use is subject to license terms.
+ *
+ * Copyright (c) 2011, 2012, Intel Corporation.
+ */
+/*
+ * This file is part of Lustre, http://www.lustre.org/
+ * Lustre is a trademark of Sun Microsystems, Inc.
+ */
+#ifndef _LUSTRE_CL_OBJECT_H
+#define _LUSTRE_CL_OBJECT_H
+
+/** \defgroup clio clio
+ *
+ * Client objects implement io operations and cache pages.
+ *
+ * Examples: lov and osc are implementations of cl interface.
+ *
+ * Big Theory Statement.
+ *
+ * Layered objects.
+ *
+ * Client implementation is based on the following data-types:
+ *
+ * - cl_object
+ *
+ * - cl_page
+ *
+ * - cl_lock represents an extent lock on an object.
+ *
+ * - cl_io represents high-level i/o activity such as whole read/write
+ * system call, or write-out of pages from under the lock being
+ * canceled. cl_io has sub-ios that can be stopped and resumed
+ * independently, thus achieving high degree of transfer
+ * parallelism. Single cl_io can be advanced forward by
+ * the multiple threads (although in the most usual case of
+ * read/write system call it is associated with the single user
+ * thread, that issued the system call).
+ *
+ * - cl_req represents a collection of pages for a transfer. cl_req is
+ * constructed by req-forming engine that tries to saturate
+ * transport with large and continuous transfers.
+ *
+ * Terminology
+ *
+ * - to avoid confusion high-level I/O operation like read or write system
+ * call is referred to as "an io", whereas low-level I/O operation, like
+ * RPC, is referred to as "a transfer"
+ *
+ * - "generic code" means generic (not file system specific) code in the
+ * hosting environment. "cl-code" means code (mostly in cl_*.c files) that
+ * is not layer specific.
+ *
+ * Locking.
+ *
+ * - i_mutex
+ * - PG_locked
+ * - cl_object_header::coh_page_guard
+ * - cl_object_header::coh_lock_guard
+ * - lu_site::ls_guard
+ *
+ * See the top comment in cl_object.c for the description of overall locking and
+ * reference-counting design.
+ *
+ * See comments below for the description of i/o, page, and dlm-locking
+ * design.
+ *
+ * @{
+ */
+
+/*
+ * super-class definitions.
+ */
+#include "lu_object.h"
+#include "linux/lustre_compat25.h"
+#include <linux/mutex.h>
+#include <linux/radix-tree.h>
+
+struct inode;
+
+struct cl_device;
+struct cl_device_operations;
+
+struct cl_object;
+struct cl_object_page_operations;
+struct cl_object_lock_operations;
+
+struct cl_page;
+struct cl_page_slice;
+struct cl_lock;
+struct cl_lock_slice;
+
+struct cl_lock_operations;
+struct cl_page_operations;
+
+struct cl_io;
+struct cl_io_slice;
+
+struct cl_req;
+struct cl_req_slice;
+
+/**
+ * Operations for each data device in the client stack.
+ *
+ * \see vvp_cl_ops, lov_cl_ops, lovsub_cl_ops, osc_cl_ops
+ */
+struct cl_device_operations {
+ /**
+ * Initialize cl_req. This method is called top-to-bottom on all
+ * devices in the stack to get them a chance to allocate layer-private
+ * data, and to attach them to the cl_req by calling
+ * cl_req_slice_add().
+ *
+ * \see osc_req_init(), lov_req_init(), lovsub_req_init()
+ * \see ccc_req_init()
+ */
+ int (*cdo_req_init)(const struct lu_env *env, struct cl_device *dev,
+ struct cl_req *req);
+};
+
+/**
+ * Device in the client stack.
+ *
+ * \see ccc_device, lov_device, lovsub_device, osc_device
+ */
+struct cl_device {
+ /** Super-class. */
+ struct lu_device cd_lu_dev;
+ /** Per-layer operation vector. */
+ const struct cl_device_operations *cd_ops;
+};
+
+/** \addtogroup cl_object cl_object
+ * @{ */
+/**
+ * "Data attributes" of cl_object. Data attributes can be updated
+ * independently for a sub-object, and top-object's attributes are calculated
+ * from sub-objects' ones.
+ */
+struct cl_attr {
+ /** Object size, in bytes */
+ loff_t cat_size;
+ /**
+ * Known minimal size, in bytes.
+ *
+ * This is only valid when at least one DLM lock is held.
+ */
+ loff_t cat_kms;
+ /** Modification time. Measured in seconds since epoch. */
+ time_t cat_mtime;
+ /** Access time. Measured in seconds since epoch. */
+ time_t cat_atime;
+ /** Change time. Measured in seconds since epoch. */
+ time_t cat_ctime;
+ /**
+ * Blocks allocated to this cl_object on the server file system.
+ *
+ * \todo XXX An interface for block size is needed.
+ */
+ __u64 cat_blocks;
+ /**
+ * User identifier for quota purposes.
+ */
+ uid_t cat_uid;
+ /**
+ * Group identifier for quota purposes.
+ */
+ gid_t cat_gid;
+};
+
+/**
+ * Fields in cl_attr that are being set.
+ */
+enum cl_attr_valid {
+ CAT_SIZE = 1 << 0,
+ CAT_KMS = 1 << 1,
+ CAT_MTIME = 1 << 3,
+ CAT_ATIME = 1 << 4,
+ CAT_CTIME = 1 << 5,
+ CAT_BLOCKS = 1 << 6,
+ CAT_UID = 1 << 7,
+ CAT_GID = 1 << 8
+};
+
+/**
+ * Sub-class of lu_object with methods common for objects on the client
+ * stacks.
+ *
+ * cl_object: represents a regular file system object, both a file and a
+ * stripe. cl_object is based on lu_object: it is identified by a fid,
+ * layered, cached, hashed, and lrued. Important distinction with the server
+ * side, where md_object and dt_object are used, is that cl_object "fans out"
+ * at the lov/sns level: depending on the file layout, single file is
+ * represented as a set of "sub-objects" (stripes). At the implementation
+ * level, struct lov_object contains an array of cl_objects. Each sub-object
+ * is a full-fledged cl_object, having its fid, living in the lru and hash
+ * table.
+ *
+ * This leads to the next important difference with the server side: on the
+ * client, it's quite usual to have objects with the different sequence of
+ * layers. For example, typical top-object is composed of the following
+ * layers:
+ *
+ * - vvp
+ * - lov
+ *
+ * whereas its sub-objects are composed of
+ *
+ * - lovsub
+ * - osc
+ *
+ * layers. Here "lovsub" is a mostly dummy layer, whose purpose is to keep
+ * track of the object-subobject relationship.
+ *
+ * Sub-objects are not cached independently: when top-object is about to
+ * be discarded from the memory, all its sub-objects are torn-down and
+ * destroyed too.
+ *
+ * \see ccc_object, lov_object, lovsub_object, osc_object
+ */
+struct cl_object {
+ /** super class */
+ struct lu_object co_lu;
+ /** per-object-layer operations */
+ const struct cl_object_operations *co_ops;
+ /** offset of page slice in cl_page buffer */
+ int co_slice_off;
+};
+
+/**
+ * Description of the client object configuration. This is used for the
+ * creation of a new client object that is identified by a more state than
+ * fid.
+ */
+struct cl_object_conf {
+ /** Super-class. */
+ struct lu_object_conf coc_lu;
+ union {
+ /**
+ * Object layout. This is consumed by lov.
+ */
+ struct lustre_md *coc_md;
+ /**
+ * Description of particular stripe location in the
+ * cluster. This is consumed by osc.
+ */
+ struct lov_oinfo *coc_oinfo;
+ } u;
+ /**
+ * VFS inode. This is consumed by vvp.
+ */
+ struct inode *coc_inode;
+ /**
+ * Layout lock handle.
+ */
+ struct ldlm_lock *coc_lock;
+ /**
+ * Operation to handle layout, OBJECT_CONF_XYZ.
+ */
+ int coc_opc;
+};
+
+enum {
+ /** configure layout, set up a new stripe, must be called while
+ * holding layout lock. */
+ OBJECT_CONF_SET = 0,
+ /** invalidate the current stripe configuration due to losing
+ * layout lock. */
+ OBJECT_CONF_INVALIDATE = 1,
+ /** wait for old layout to go away so that new layout can be
+ * set up. */
+ OBJECT_CONF_WAIT = 2
+};
+
+/**
+ * Operations implemented for each cl object layer.
+ *
+ * \see vvp_ops, lov_ops, lovsub_ops, osc_ops
+ */
+struct cl_object_operations {
+ /**
+ * Initialize page slice for this layer. Called top-to-bottom through
+ * every object layer when a new cl_page is instantiated. Layer
+ * keeping private per-page data, or requiring its own page operations
+ * vector should allocate these data here, and attach then to the page
+ * by calling cl_page_slice_add(). \a vmpage is locked (in the VM
+ * sense). Optional.
+ *
+ * \retval NULL success.
+ *
+ * \retval ERR_PTR(errno) failure code.
+ *
+ * \retval valid-pointer pointer to already existing referenced page
+ * to be used instead of newly created.
+ */
+ int (*coo_page_init)(const struct lu_env *env, struct cl_object *obj,
+ struct cl_page *page, struct page *vmpage);
+ /**
+ * Initialize lock slice for this layer. Called top-to-bottom through
+ * every object layer when a new cl_lock is instantiated. Layer
+ * keeping private per-lock data, or requiring its own lock operations
+ * vector should allocate these data here, and attach then to the lock
+ * by calling cl_lock_slice_add(). Mandatory.
+ */
+ int (*coo_lock_init)(const struct lu_env *env,
+ struct cl_object *obj, struct cl_lock *lock,
+ const struct cl_io *io);
+ /**
+ * Initialize io state for a given layer.
+ *
+ * called top-to-bottom once per io existence to initialize io
+ * state. If layer wants to keep some state for this type of io, it
+ * has to embed struct cl_io_slice in lu_env::le_ses, and register
+ * slice with cl_io_slice_add(). It is guaranteed that all threads
+ * participating in this io share the same session.
+ */
+ int (*coo_io_init)(const struct lu_env *env,
+ struct cl_object *obj, struct cl_io *io);
+ /**
+ * Fill portion of \a attr that this layer controls. This method is
+ * called top-to-bottom through all object layers.
+ *
+ * \pre cl_object_header::coh_attr_guard of the top-object is locked.
+ *
+ * \return 0: to continue
+ * \return +ve: to stop iterating through layers (but 0 is returned
+ * from enclosing cl_object_attr_get())
+ * \return -ve: to signal error
+ */
+ int (*coo_attr_get)(const struct lu_env *env, struct cl_object *obj,
+ struct cl_attr *attr);
+ /**
+ * Update attributes.
+ *
+ * \a valid is a bitmask composed from enum #cl_attr_valid, and
+ * indicating what attributes are to be set.
+ *
+ * \pre cl_object_header::coh_attr_guard of the top-object is locked.
+ *
+ * \return the same convention as for
+ * cl_object_operations::coo_attr_get() is used.
+ */
+ int (*coo_attr_set)(const struct lu_env *env, struct cl_object *obj,
+ const struct cl_attr *attr, unsigned valid);
+ /**
+ * Update object configuration. Called top-to-bottom to modify object
+ * configuration.
+ *
+ * XXX error conditions and handling.
+ */
+ int (*coo_conf_set)(const struct lu_env *env, struct cl_object *obj,
+ const struct cl_object_conf *conf);
+ /**
+ * Glimpse ast. Executed when glimpse ast arrives for a lock on this
+ * object. Layers are supposed to fill parts of \a lvb that will be
+ * shipped to the glimpse originator as a glimpse result.
+ *
+ * \see ccc_object_glimpse(), lovsub_object_glimpse(),
+ * \see osc_object_glimpse()
+ */
+ int (*coo_glimpse)(const struct lu_env *env,
+ const struct cl_object *obj, struct ost_lvb *lvb);
+};
+
+/**
+ * Extended header for client object.
+ */
+struct cl_object_header {
+ /** Standard lu_object_header. cl_object::co_lu::lo_header points
+ * here. */
+ struct lu_object_header coh_lu;
+ /** \name locks
+ * \todo XXX move locks below to the separate cache-lines, they are
+ * mostly useless otherwise.
+ */
+ /** @{ */
+ /** Lock protecting page tree. */
+ spinlock_t coh_page_guard;
+ /** Lock protecting lock list. */
+ spinlock_t coh_lock_guard;
+ /** @} locks */
+ /** Radix tree of cl_page's, cached for this object. */
+ struct radix_tree_root coh_tree;
+ /** # of pages in radix tree. */
+ unsigned long coh_pages;
+ /** List of cl_lock's granted for this object. */
+ struct list_head coh_locks;
+
+ /**
+ * Parent object. It is assumed that an object has a well-defined
+ * parent, but not a well-defined child (there may be multiple
+ * sub-objects, for the same top-object). cl_object_header::coh_parent
+ * field allows certain code to be written generically, without
+ * limiting possible cl_object layouts unduly.
+ */
+ struct cl_object_header *coh_parent;
+ /**
+ * Protects consistency between cl_attr of parent object and
+ * attributes of sub-objects, that the former is calculated ("merged")
+ * from.
+ *
+ * \todo XXX this can be read/write lock if needed.
+ */
+ spinlock_t coh_attr_guard;
+ /**
+ * Size of cl_page + page slices
+ */
+ unsigned short coh_page_bufsize;
+ /**
+ * Number of objects above this one: 0 for a top-object, 1 for its
+ * sub-object, etc.
+ */
+ unsigned char coh_nesting;
+};
+
+/**
+ * Helper macro: iterate over all layers of the object \a obj, assigning every
+ * layer top-to-bottom to \a slice.
+ */
+#define cl_object_for_each(slice, obj) \
+ list_for_each_entry((slice), \
+ &(obj)->co_lu.lo_header->loh_layers, \
+ co_lu.lo_linkage)
+/**
+ * Helper macro: iterate over all layers of the object \a obj, assigning every
+ * layer bottom-to-top to \a slice.
+ */
+#define cl_object_for_each_reverse(slice, obj) \
+ list_for_each_entry_reverse((slice), \
+ &(obj)->co_lu.lo_header->loh_layers, \
+ co_lu.lo_linkage)
+/** @} cl_object */
+
+#ifndef pgoff_t
+#define pgoff_t unsigned long
+#endif
+
+#define CL_PAGE_EOF ((pgoff_t)~0ull)
+
+/** \addtogroup cl_page cl_page
+ * @{ */
+
+/** \struct cl_page
+ * Layered client page.
+ *
+ * cl_page: represents a portion of a file, cached in the memory. All pages
+ * of the given file are of the same size, and are kept in the radix tree
+ * hanging off the cl_object. cl_page doesn't fan out, but as sub-objects
+ * of the top-level file object are first class cl_objects, they have their
+ * own radix trees of pages and hence page is implemented as a sequence of
+ * struct cl_pages's, linked into double-linked list through
+ * cl_page::cp_parent and cl_page::cp_child pointers, each residing in the
+ * corresponding radix tree at the corresponding logical offset.
+ *
+ * cl_page is associated with VM page of the hosting environment (struct
+ * page in Linux kernel, for example), struct page. It is assumed, that this
+ * association is implemented by one of cl_page layers (top layer in the
+ * current design) that
+ *
+ * - intercepts per-VM-page call-backs made by the environment (e.g.,
+ * memory pressure),
+ *
+ * - translates state (page flag bits) and locking between lustre and
+ * environment.
+ *
+ * The association between cl_page and struct page is immutable and
+ * established when cl_page is created.
+ *
+ * cl_page can be "owned" by a particular cl_io (see below), guaranteeing
+ * this io an exclusive access to this page w.r.t. other io attempts and
+ * various events changing page state (such as transfer completion, or
+ * eviction of the page from the memory). Note, that in general cl_io
+ * cannot be identified with a particular thread, and page ownership is not
+ * exactly equal to the current thread holding a lock on the page. Layer
+ * implementing association between cl_page and struct page has to implement
+ * ownership on top of available synchronization mechanisms.
+ *
+ * While lustre client maintains the notion of an page ownership by io,
+ * hosting MM/VM usually has its own page concurrency control
+ * mechanisms. For example, in Linux, page access is synchronized by the
+ * per-page PG_locked bit-lock, and generic kernel code (generic_file_*())
+ * takes care to acquire and release such locks as necessary around the
+ * calls to the file system methods (->readpage(), ->prepare_write(),
+ * ->commit_write(), etc.). This leads to the situation when there are two
+ * different ways to own a page in the client:
+ *
+ * - client code explicitly and voluntary owns the page (cl_page_own());
+ *
+ * - VM locks a page and then calls the client, that has "to assume"
+ * the ownership from the VM (cl_page_assume()).
+ *
+ * Dual methods to release ownership are cl_page_disown() and
+ * cl_page_unassume().
+ *
+ * cl_page is reference counted (cl_page::cp_ref). When reference counter
+ * drops to 0, the page is returned to the cache, unless it is in
+ * cl_page_state::CPS_FREEING state, in which case it is immediately
+ * destroyed.
+ *
+ * The general logic guaranteeing the absence of "existential races" for
+ * pages is the following:
+ *
+ * - there are fixed known ways for a thread to obtain a new reference
+ * to a page:
+ *
+ * - by doing a lookup in the cl_object radix tree, protected by the
+ * spin-lock;
+ *
+ * - by starting from VM-locked struct page and following some
+ * hosting environment method (e.g., following ->private pointer in
+ * the case of Linux kernel), see cl_vmpage_page();
+ *
+ * - when the page enters cl_page_state::CPS_FREEING state, all these
+ * ways are severed with the proper synchronization
+ * (cl_page_delete());
+ *
+ * - entry into cl_page_state::CPS_FREEING is serialized by the VM page
+ * lock;
+ *
+ * - no new references to the page in cl_page_state::CPS_FREEING state
+ * are allowed (checked in cl_page_get()).
+ *
+ * Together this guarantees that when last reference to a
+ * cl_page_state::CPS_FREEING page is released, it is safe to destroy the
+ * page, as neither references to it can be acquired at that point, nor
+ * ones exist.
+ *
+ * cl_page is a state machine. States are enumerated in enum
+ * cl_page_state. Possible state transitions are enumerated in
+ * cl_page_state_set(). State transition process (i.e., actual changing of
+ * cl_page::cp_state field) is protected by the lock on the underlying VM
+ * page.
+ *
+ * Linux Kernel implementation.
+ *
+ * Binding between cl_page and struct page (which is a typedef for
+ * struct page) is implemented in the vvp layer. cl_page is attached to the
+ * ->private pointer of the struct page, together with the setting of
+ * PG_private bit in page->flags, and acquiring additional reference on the
+ * struct page (much like struct buffer_head, or any similar file system
+ * private data structures).
+ *
+ * PG_locked lock is used to implement both ownership and transfer
+ * synchronization, that is, page is VM-locked in CPS_{OWNED,PAGE{IN,OUT}}
+ * states. No additional references are acquired for the duration of the
+ * transfer.
+ *
+ * \warning *THIS IS NOT* the behavior expected by the Linux kernel, where
+ * write-out is "protected" by the special PG_writeback bit.
+ */
+
+/**
+ * States of cl_page. cl_page.c assumes particular order here.
+ *
+ * The page state machine is rather crude, as it doesn't recognize finer page
+ * states like "dirty" or "up to date". This is because such states are not
+ * always well defined for the whole stack (see, for example, the
+ * implementation of the read-ahead, that hides page up-to-dateness to track
+ * cache hits accurately). Such sub-states are maintained by the layers that
+ * are interested in them.
+ */
+enum cl_page_state {
+ /**
+ * Page is in the cache, un-owned. Page leaves cached state in the
+ * following cases:
+ *
+ * - [cl_page_state::CPS_OWNED] io comes across the page and
+ * owns it;
+ *
+ * - [cl_page_state::CPS_PAGEOUT] page is dirty, the
+ * req-formation engine decides that it wants to include this page
+ * into an cl_req being constructed, and yanks it from the cache;
+ *
+ * - [cl_page_state::CPS_FREEING] VM callback is executed to
+ * evict the page form the memory;
+ *
+ * \invariant cl_page::cp_owner == NULL && cl_page::cp_req == NULL
+ */
+ CPS_CACHED,
+ /**
+ * Page is exclusively owned by some cl_io. Page may end up in this
+ * state as a result of
+ *
+ * - io creating new page and immediately owning it;
+ *
+ * - [cl_page_state::CPS_CACHED] io finding existing cached page
+ * and owning it;
+ *
+ * - [cl_page_state::CPS_OWNED] io finding existing owned page
+ * and waiting for owner to release the page;
+ *
+ * Page leaves owned state in the following cases:
+ *
+ * - [cl_page_state::CPS_CACHED] io decides to leave the page in
+ * the cache, doing nothing;
+ *
+ * - [cl_page_state::CPS_PAGEIN] io starts read transfer for
+ * this page;
+ *
+ * - [cl_page_state::CPS_PAGEOUT] io starts immediate write
+ * transfer for this page;
+ *
+ * - [cl_page_state::CPS_FREEING] io decides to destroy this
+ * page (e.g., as part of truncate or extent lock cancellation).
+ *
+ * \invariant cl_page::cp_owner != NULL && cl_page::cp_req == NULL
+ */
+ CPS_OWNED,
+ /**
+ * Page is being written out, as a part of a transfer. This state is
+ * entered when req-formation logic decided that it wants this page to
+ * be sent through the wire _now_. Specifically, it means that once
+ * this state is achieved, transfer completion handler (with either
+ * success or failure indication) is guaranteed to be executed against
+ * this page independently of any locks and any scheduling decisions
+ * made by the hosting environment (that effectively means that the
+ * page is never put into cl_page_state::CPS_PAGEOUT state "in
+ * advance". This property is mentioned, because it is important when
+ * reasoning about possible dead-locks in the system). The page can
+ * enter this state as a result of
+ *
+ * - [cl_page_state::CPS_OWNED] an io requesting an immediate
+ * write-out of this page, or
+ *
+ * - [cl_page_state::CPS_CACHED] req-forming engine deciding
+ * that it has enough dirty pages cached to issue a "good"
+ * transfer.
+ *
+ * The page leaves cl_page_state::CPS_PAGEOUT state when the transfer
+ * is completed---it is moved into cl_page_state::CPS_CACHED state.
+ *
+ * Underlying VM page is locked for the duration of transfer.
+ *
+ * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL
+ */
+ CPS_PAGEOUT,
+ /**
+ * Page is being read in, as a part of a transfer. This is quite
+ * similar to the cl_page_state::CPS_PAGEOUT state, except that
+ * read-in is always "immediate"---there is no such thing a sudden
+ * construction of read cl_req from cached, presumably not up to date,
+ * pages.
+ *
+ * Underlying VM page is locked for the duration of transfer.
+ *
+ * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req != NULL
+ */
+ CPS_PAGEIN,
+ /**
+ * Page is being destroyed. This state is entered when client decides
+ * that page has to be deleted from its host object, as, e.g., a part
+ * of truncate.
+ *
+ * Once this state is reached, there is no way to escape it.
+ *
+ * \invariant: cl_page::cp_owner == NULL && cl_page::cp_req == NULL
+ */
+ CPS_FREEING,
+ CPS_NR
+};
+
+enum cl_page_type {
+ /** Host page, the page is from the host inode which the cl_page
+ * belongs to. */
+ CPT_CACHEABLE = 1,
+
+ /** Transient page, the transient cl_page is used to bind a cl_page
+ * to vmpage which is not belonging to the same object of cl_page.
+ * it is used in DirectIO, lockless IO and liblustre. */
+ CPT_TRANSIENT,
+};
+
+/**
+ * Flags maintained for every cl_page.
+ */
+enum cl_page_flags {
+ /**
+ * Set when pagein completes. Used for debugging (read completes at
+ * most once for a page).
+ */
+ CPF_READ_COMPLETED = 1 << 0
+};
+
+/**
+ * Fields are protected by the lock on struct page, except for atomics and
+ * immutables.
+ *
+ * \invariant Data type invariants are in cl_page_invariant(). Basically:
+ * cl_page::cp_parent and cl_page::cp_child are a well-formed double-linked
+ * list, consistent with the parent/child pointers in the cl_page::cp_obj and
+ * cl_page::cp_owner (when set).
+ */
+struct cl_page {
+ /** Reference counter. */
+ atomic_t cp_ref;
+ /** An object this page is a part of. Immutable after creation. */
+ struct cl_object *cp_obj;
+ /** Logical page index within the object. Immutable after creation. */
+ pgoff_t cp_index;
+ /** List of slices. Immutable after creation. */
+ struct list_head cp_layers;
+ /** Parent page, NULL for top-level page. Immutable after creation. */
+ struct cl_page *cp_parent;
+ /** Lower-layer page. NULL for bottommost page. Immutable after
+ * creation. */
+ struct cl_page *cp_child;
+ /**
+ * Page state. This field is const to avoid accidental update, it is
+ * modified only internally within cl_page.c. Protected by a VM lock.
+ */
+ const enum cl_page_state cp_state;
+ /** Linkage of pages within group. Protected by cl_page::cp_mutex. */
+ struct list_head cp_batch;
+ /** Mutex serializing membership of a page in a batch. */
+ struct mutex cp_mutex;
+ /** Linkage of pages within cl_req. */
+ struct list_head cp_flight;
+ /** Transfer error. */
+ int cp_error;
+
+ /**
+ * Page type. Only CPT_TRANSIENT is used so far. Immutable after
+ * creation.
+ */
+ enum cl_page_type cp_type;
+
+ /**
+ * Owning IO in cl_page_state::CPS_OWNED state. Sub-page can be owned
+ * by sub-io. Protected by a VM lock.
+ */
+ struct cl_io *cp_owner;
+ /**
+ * Debug information, the task is owning the page.
+ */
+ struct task_struct *cp_task;
+ /**
+ * Owning IO request in cl_page_state::CPS_PAGEOUT and
+ * cl_page_state::CPS_PAGEIN states. This field is maintained only in
+ * the top-level pages. Protected by a VM lock.
+ */
+ struct cl_req *cp_req;
+ /** List of references to this page, for debugging. */
+ struct lu_ref cp_reference;
+ /** Link to an object, for debugging. */
+ struct lu_ref_link cp_obj_ref;
+ /** Link to a queue, for debugging. */
+ struct lu_ref_link cp_queue_ref;
+ /** Per-page flags from enum cl_page_flags. Protected by a VM lock. */
+ unsigned cp_flags;
+ /** Assigned if doing a sync_io */
+ struct cl_sync_io *cp_sync_io;
+};
+
+/**
+ * Per-layer part of cl_page.
+ *
+ * \see ccc_page, lov_page, osc_page
+ */
+struct cl_page_slice {
+ struct cl_page *cpl_page;
+ /**
+ * Object slice corresponding to this page slice. Immutable after
+ * creation.
+ */
+ struct cl_object *cpl_obj;
+ const struct cl_page_operations *cpl_ops;
+ /** Linkage into cl_page::cp_layers. Immutable after creation. */
+ struct list_head cpl_linkage;
+};
+
+/**
+ * Lock mode. For the client extent locks.
+ *
+ * \warning: cl_lock_mode_match() assumes particular ordering here.
+ * \ingroup cl_lock
+ */
+enum cl_lock_mode {
+ /**
+ * Mode of a lock that protects no data, and exists only as a
+ * placeholder. This is used for `glimpse' requests. A phantom lock
+ * might get promoted to real lock at some point.
+ */
+ CLM_PHANTOM,
+ CLM_READ,
+ CLM_WRITE,
+ CLM_GROUP
+};
+
+/**
+ * Requested transfer type.
+ * \ingroup cl_req
+ */
+enum cl_req_type {
+ CRT_READ,
+ CRT_WRITE,
+ CRT_NR
+};
+
+/**
+ * Per-layer page operations.
+ *
+ * Methods taking an \a io argument are for the activity happening in the
+ * context of given \a io. Page is assumed to be owned by that io, except for
+ * the obvious cases (like cl_page_operations::cpo_own()).
+ *
+ * \see vvp_page_ops, lov_page_ops, osc_page_ops
+ */
+struct cl_page_operations {
+ /**
+ * cl_page<->struct page methods. Only one layer in the stack has to
+ * implement these. Current code assumes that this functionality is
+ * provided by the topmost layer, see cl_page_disown0() as an example.
+ */
+
+ /**
+ * \return the underlying VM page. Optional.
+ */
+ struct page *(*cpo_vmpage)(const struct lu_env *env,
+ const struct cl_page_slice *slice);
+ /**
+ * Called when \a io acquires this page into the exclusive
+ * ownership. When this method returns, it is guaranteed that the is
+ * not owned by other io, and no transfer is going on against
+ * it. Optional.
+ *
+ * \see cl_page_own()
+ * \see vvp_page_own(), lov_page_own()
+ */
+ int (*cpo_own)(const struct lu_env *env,
+ const struct cl_page_slice *slice,
+ struct cl_io *io, int nonblock);
+ /** Called when ownership it yielded. Optional.
+ *
+ * \see cl_page_disown()
+ * \see vvp_page_disown()
+ */
+ void (*cpo_disown)(const struct lu_env *env,
+ const struct cl_page_slice *slice, struct cl_io *io);
+ /**
+ * Called for a page that is already "owned" by \a io from VM point of
+ * view. Optional.
+ *
+ * \see cl_page_assume()
+ * \see vvp_page_assume(), lov_page_assume()
+ */
+ void (*cpo_assume)(const struct lu_env *env,
+ const struct cl_page_slice *slice, struct cl_io *io);
+ /** Dual to cl_page_operations::cpo_assume(). Optional. Called
+ * bottom-to-top when IO releases a page without actually unlocking
+ * it.
+ *
+ * \see cl_page_unassume()
+ * \see vvp_page_unassume()
+ */
+ void (*cpo_unassume)(const struct lu_env *env,
+ const struct cl_page_slice *slice,
+ struct cl_io *io);
+ /**
+ * Announces whether the page contains valid data or not by \a uptodate.
+ *
+ * \see cl_page_export()
+ * \see vvp_page_export()
+ */
+ void (*cpo_export)(const struct lu_env *env,
+ const struct cl_page_slice *slice, int uptodate);
+ /**
+ * Unmaps page from the user space (if it is mapped).
+ *
+ * \see cl_page_unmap()
+ * \see vvp_page_unmap()
+ */
+ int (*cpo_unmap)(const struct lu_env *env,
+ const struct cl_page_slice *slice, struct cl_io *io);
+ /**
+ * Checks whether underlying VM page is locked (in the suitable
+ * sense). Used for assertions.
+ *
+ * \retval -EBUSY: page is protected by a lock of a given mode;
+ * \retval -ENODATA: page is not protected by a lock;
+ * \retval 0: this layer cannot decide. (Should never happen.)
+ */
+ int (*cpo_is_vmlocked)(const struct lu_env *env,
+ const struct cl_page_slice *slice);
+ /**
+ * Page destruction.
+ */
+
+ /**
+ * Called when page is truncated from the object. Optional.
+ *
+ * \see cl_page_discard()
+ * \see vvp_page_discard(), osc_page_discard()
+ */
+ void (*cpo_discard)(const struct lu_env *env,
+ const struct cl_page_slice *slice,
+ struct cl_io *io);
+ /**
+ * Called when page is removed from the cache, and is about to being
+ * destroyed. Optional.
+ *
+ * \see cl_page_delete()
+ * \see vvp_page_delete(), osc_page_delete()
+ */
+ void (*cpo_delete)(const struct lu_env *env,
+ const struct cl_page_slice *slice);
+ /** Destructor. Frees resources and slice itself. */
+ void (*cpo_fini)(const struct lu_env *env,
+ struct cl_page_slice *slice);
+
+ /**
+ * Checks whether the page is protected by a cl_lock. This is a
+ * per-layer method, because certain layers have ways to check for the
+ * lock much more efficiently than through the generic locks scan, or
+ * implement locking mechanisms separate from cl_lock, e.g.,
+ * LL_FILE_GROUP_LOCKED in vvp. If \a pending is true, check for locks
+ * being canceled, or scheduled for cancellation as soon as the last
+ * user goes away, too.
+ *
+ * \retval -EBUSY: page is protected by a lock of a given mode;
+ * \retval -ENODATA: page is not protected by a lock;
+ * \retval 0: this layer cannot decide.
+ *
+ * \see cl_page_is_under_lock()
+ */
+ int (*cpo_is_under_lock)(const struct lu_env *env,
+ const struct cl_page_slice *slice,
+ struct cl_io *io);
+
+ /**
+ * Optional debugging helper. Prints given page slice.
+ *
+ * \see cl_page_print()
+ */
+ int (*cpo_print)(const struct lu_env *env,
+ const struct cl_page_slice *slice,
+ void *cookie, lu_printer_t p);
+ /**
+ * \name transfer
+ *
+ * Transfer methods. See comment on cl_req for a description of
+ * transfer formation and life-cycle.
+ *
+ * @{
+ */
+ /**
+ * Request type dependent vector of operations.
+ *
+ * Transfer operations depend on transfer mode (cl_req_type). To avoid
+ * passing transfer mode to each and every of these methods, and to
+ * avoid branching on request type inside of the methods, separate
+ * methods for cl_req_type:CRT_READ and cl_req_type:CRT_WRITE are
+ * provided. That is, method invocation usually looks like
+ *
+ * slice->cp_ops.io[req->crq_type].cpo_method(env, slice, ...);
+ */
+ struct {
+ /**
+ * Called when a page is submitted for a transfer as a part of
+ * cl_page_list.
+ *
+ * \return 0 : page is eligible for submission;
+ * \return -EALREADY : skip this page;
+ * \return -ve : error.
+ *
+ * \see cl_page_prep()
+ */
+ int (*cpo_prep)(const struct lu_env *env,
+ const struct cl_page_slice *slice,
+ struct cl_io *io);
+ /**
+ * Completion handler. This is guaranteed to be eventually
+ * fired after cl_page_operations::cpo_prep() or
+ * cl_page_operations::cpo_make_ready() call.
+ *
+ * This method can be called in a non-blocking context. It is
+ * guaranteed however, that the page involved and its object
+ * are pinned in memory (and, hence, calling cl_page_put() is
+ * safe).
+ *
+ * \see cl_page_completion()
+ */
+ void (*cpo_completion)(const struct lu_env *env,
+ const struct cl_page_slice *slice,
+ int ioret);
+ /**
+ * Called when cached page is about to be added to the
+ * cl_req as a part of req formation.
+ *
+ * \return 0 : proceed with this page;
+ * \return -EAGAIN : skip this page;
+ * \return -ve : error.
+ *
+ * \see cl_page_make_ready()
+ */
+ int (*cpo_make_ready)(const struct lu_env *env,
+ const struct cl_page_slice *slice);
+ /**
+ * Announce that this page is to be written out
+ * opportunistically, that is, page is dirty, it is not
+ * necessary to start write-out transfer right now, but
+ * eventually page has to be written out.
+ *
+ * Main caller of this is the write path (see
+ * vvp_io_commit_write()), using this method to build a
+ * "transfer cache" from which large transfers are then
+ * constructed by the req-formation engine.
+ *
+ * \todo XXX it would make sense to add page-age tracking
+ * semantics here, and to oblige the req-formation engine to
+ * send the page out not later than it is too old.
+ *
+ * \see cl_page_cache_add()
+ */
+ int (*cpo_cache_add)(const struct lu_env *env,
+ const struct cl_page_slice *slice,
+ struct cl_io *io);
+ } io[CRT_NR];
+ /**
+ * Tell transfer engine that only [to, from] part of a page should be
+ * transmitted.
+ *
+ * This is used for immediate transfers.
+ *
+ * \todo XXX this is not very good interface. It would be much better
+ * if all transfer parameters were supplied as arguments to
+ * cl_io_operations::cio_submit() call, but it is not clear how to do
+ * this for page queues.
+ *
+ * \see cl_page_clip()
+ */
+ void (*cpo_clip)(const struct lu_env *env,
+ const struct cl_page_slice *slice,
+ int from, int to);
+ /**
+ * \pre the page was queued for transferring.
+ * \post page is removed from client's pending list, or -EBUSY
+ * is returned if it has already been in transferring.
+ *
+ * This is one of seldom page operation which is:
+ * 0. called from top level;
+ * 1. don't have vmpage locked;
+ * 2. every layer should synchronize execution of its ->cpo_cancel()
+ * with completion handlers. Osc uses client obd lock for this
+ * purpose. Based on there is no vvp_page_cancel and
+ * lov_page_cancel(), cpo_cancel is defacto protected by client lock.
+ *
+ * \see osc_page_cancel().
+ */
+ int (*cpo_cancel)(const struct lu_env *env,
+ const struct cl_page_slice *slice);
+ /**
+ * Write out a page by kernel. This is only called by ll_writepage
+ * right now.
+ *
+ * \see cl_page_flush()
+ */
+ int (*cpo_flush)(const struct lu_env *env,
+ const struct cl_page_slice *slice,
+ struct cl_io *io);
+ /** @} transfer */
+};
+
+/**
+ * Helper macro, dumping detailed information about \a page into a log.
+ */
+#define CL_PAGE_DEBUG(mask, env, page, format, ...) \
+do { \
+ LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
+ \
+ if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
+ cl_page_print(env, &msgdata, lu_cdebug_printer, page); \
+ CDEBUG(mask, format , ## __VA_ARGS__); \
+ } \
+} while (0)
+
+/**
+ * Helper macro, dumping shorter information about \a page into a log.
+ */
+#define CL_PAGE_HEADER(mask, env, page, format, ...) \
+do { \
+ LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
+ \
+ if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
+ cl_page_header_print(env, &msgdata, lu_cdebug_printer, page); \
+ CDEBUG(mask, format , ## __VA_ARGS__); \
+ } \
+} while (0)
+
+static inline int __page_in_use(const struct cl_page *page, int refc)
+{
+ if (page->cp_type == CPT_CACHEABLE)
+ ++refc;
+ LASSERT(atomic_read(&page->cp_ref) > 0);
+ return (atomic_read(&page->cp_ref) > refc);
+}
+#define cl_page_in_use(pg) __page_in_use(pg, 1)
+#define cl_page_in_use_noref(pg) __page_in_use(pg, 0)
+
+/** @} cl_page */
+
+/** \addtogroup cl_lock cl_lock
+ * @{ */
+/** \struct cl_lock
+ *
+ * Extent locking on the client.
+ *
+ * LAYERING
+ *
+ * The locking model of the new client code is built around
+ *
+ * struct cl_lock
+ *
+ * data-type representing an extent lock on a regular file. cl_lock is a
+ * layered object (much like cl_object and cl_page), it consists of a header
+ * (struct cl_lock) and a list of layers (struct cl_lock_slice), linked to
+ * cl_lock::cll_layers list through cl_lock_slice::cls_linkage.
+ *
+ * All locks for a given object are linked into cl_object_header::coh_locks
+ * list (protected by cl_object_header::coh_lock_guard spin-lock) through
+ * cl_lock::cll_linkage. Currently this list is not sorted in any way. We can
+ * sort it in starting lock offset, or use altogether different data structure
+ * like a tree.
+ *
+ * Typical cl_lock consists of the two layers:
+ *
+ * - vvp_lock (vvp specific data), and
+ * - lov_lock (lov specific data).
+ *
+ * lov_lock contains an array of sub-locks. Each of these sub-locks is a
+ * normal cl_lock: it has a header (struct cl_lock) and a list of layers:
+ *
+ * - lovsub_lock, and
+ * - osc_lock
+ *
+ * Each sub-lock is associated with a cl_object (representing stripe
+ * sub-object or the file to which top-level cl_lock is associated to), and is
+ * linked into that cl_object::coh_locks. In this respect cl_lock is similar to
+ * cl_object (that at lov layer also fans out into multiple sub-objects), and
+ * is different from cl_page, that doesn't fan out (there is usually exactly
+ * one osc_page for every vvp_page). We shall call vvp-lov portion of the lock
+ * a "top-lock" and its lovsub-osc portion a "sub-lock".
+ *
+ * LIFE CYCLE
+ *
+ * cl_lock is reference counted. When reference counter drops to 0, lock is
+ * placed in the cache, except when lock is in CLS_FREEING state. CLS_FREEING
+ * lock is destroyed when last reference is released. Referencing between
+ * top-lock and its sub-locks is described in the lov documentation module.
+ *
+ * STATE MACHINE
+ *
+ * Also, cl_lock is a state machine. This requires some clarification. One of
+ * the goals of client IO re-write was to make IO path non-blocking, or at
+ * least to make it easier to make it non-blocking in the future. Here
+ * `non-blocking' means that when a system call (read, write, truncate)
+ * reaches a situation where it has to wait for a communication with the
+ * server, it should --instead of waiting-- remember its current state and
+ * switch to some other work. E.g,. instead of waiting for a lock enqueue,
+ * client should proceed doing IO on the next stripe, etc. Obviously this is
+ * rather radical redesign, and it is not planned to be fully implemented at
+ * this time, instead we are putting some infrastructure in place, that would
+ * make it easier to do asynchronous non-blocking IO easier in the
+ * future. Specifically, where old locking code goes to sleep (waiting for
+ * enqueue, for example), new code returns cl_lock_transition::CLO_WAIT. When
+ * enqueue reply comes, its completion handler signals that lock state-machine
+ * is ready to transit to the next state. There is some generic code in
+ * cl_lock.c that sleeps, waiting for these signals. As a result, for users of
+ * this cl_lock.c code, it looks like locking is done in normal blocking
+ * fashion, and it the same time it is possible to switch to the non-blocking
+ * locking (simply by returning cl_lock_transition::CLO_WAIT from cl_lock.c
+ * functions).
+ *
+ * For a description of state machine states and transitions see enum
+ * cl_lock_state.
+ *
+ * There are two ways to restrict a set of states which lock might move to:
+ *
+ * - placing a "hold" on a lock guarantees that lock will not be moved
+ * into cl_lock_state::CLS_FREEING state until hold is released. Hold
+ * can be only acquired on a lock that is not in
+ * cl_lock_state::CLS_FREEING. All holds on a lock are counted in
+ * cl_lock::cll_holds. Hold protects lock from cancellation and
+ * destruction. Requests to cancel and destroy a lock on hold will be
+ * recorded, but only honored when last hold on a lock is released;
+ *
+ * - placing a "user" on a lock guarantees that lock will not leave
+ * cl_lock_state::CLS_NEW, cl_lock_state::CLS_QUEUING,
+ * cl_lock_state::CLS_ENQUEUED and cl_lock_state::CLS_HELD set of
+ * states, once it enters this set. That is, if a user is added onto a
+ * lock in a state not from this set, it doesn't immediately enforce
+ * lock to move to this set, but once lock enters this set it will
+ * remain there until all users are removed. Lock users are counted in
+ * cl_lock::cll_users.
+ *
+ * User is used to assure that lock is not canceled or destroyed while
+ * it is being enqueued, or actively used by some IO.
+ *
+ * Currently, a user always comes with a hold (cl_lock_invariant()
+ * checks that a number of holds is not less than a number of users).
+ *
+ * CONCURRENCY
+ *
+ * This is how lock state-machine operates. struct cl_lock contains a mutex
+ * cl_lock::cll_guard that protects struct fields.
+ *
+ * - mutex is taken, and cl_lock::cll_state is examined.
+ *
+ * - for every state there are possible target states where lock can move
+ * into. They are tried in order. Attempts to move into next state are
+ * done by _try() functions in cl_lock.c:cl_{enqueue,unlock,wait}_try().
+ *
+ * - if the transition can be performed immediately, state is changed,
+ * and mutex is released.
+ *
+ * - if the transition requires blocking, _try() function returns
+ * cl_lock_transition::CLO_WAIT. Caller unlocks mutex and goes to
+ * sleep, waiting for possibility of lock state change. It is woken
+ * up when some event occurs, that makes lock state change possible
+ * (e.g., the reception of the reply from the server), and repeats
+ * the loop.
+ *
+ * Top-lock and sub-lock has separate mutexes and the latter has to be taken
+ * first to avoid dead-lock.
+ *
+ * To see an example of interaction of all these issues, take a look at the
+ * lov_cl.c:lov_lock_enqueue() function. It is called as a part of
+ * cl_enqueue_try(), and tries to advance top-lock to ENQUEUED state, by
+ * advancing state-machines of its sub-locks (lov_lock_enqueue_one()). Note
+ * also, that it uses trylock to grab sub-lock mutex to avoid dead-lock. It
+ * also has to handle CEF_ASYNC enqueue, when sub-locks enqueues have to be
+ * done in parallel, rather than one after another (this is used for glimpse
+ * locks, that cannot dead-lock).
+ *
+ * INTERFACE AND USAGE
+ *
+ * struct cl_lock_operations provide a number of call-backs that are invoked
+ * when events of interest occurs. Layers can intercept and handle glimpse,
+ * blocking, cancel ASTs and a reception of the reply from the server.
+ *
+ * One important difference with the old client locking model is that new
+ * client has a representation for the top-lock, whereas in the old code only
+ * sub-locks existed as real data structures and file-level locks are
+ * represented by "request sets" that are created and destroyed on each and
+ * every lock creation.
+ *
+ * Top-locks are cached, and can be found in the cache by the system calls. It
+ * is possible that top-lock is in cache, but some of its sub-locks were
+ * canceled and destroyed. In that case top-lock has to be enqueued again
+ * before it can be used.
+ *
+ * Overall process of the locking during IO operation is as following:
+ *
+ * - once parameters for IO are setup in cl_io, cl_io_operations::cio_lock()
+ * is called on each layer. Responsibility of this method is to add locks,
+ * needed by a given layer into cl_io.ci_lockset.
+ *
+ * - once locks for all layers were collected, they are sorted to avoid
+ * dead-locks (cl_io_locks_sort()), and enqueued.
+ *
+ * - when all locks are acquired, IO is performed;
+ *
+ * - locks are released into cache.
+ *
+ * Striping introduces major additional complexity into locking. The
+ * fundamental problem is that it is generally unsafe to actively use (hold)
+ * two locks on the different OST servers at the same time, as this introduces
+ * inter-server dependency and can lead to cascading evictions.
+ *
+ * Basic solution is to sub-divide large read/write IOs into smaller pieces so
+ * that no multi-stripe locks are taken (note that this design abandons POSIX
+ * read/write semantics). Such pieces ideally can be executed concurrently. At
+ * the same time, certain types of IO cannot be sub-divived, without
+ * sacrificing correctness. This includes:
+ *
+ * - O_APPEND write, where [0, EOF] lock has to be taken, to guarantee
+ * atomicity;
+ *
+ * - ftruncate(fd, offset), where [offset, EOF] lock has to be taken.
+ *
+ * Also, in the case of read(fd, buf, count) or write(fd, buf, count), where
+ * buf is a part of memory mapped Lustre file, a lock or locks protecting buf
+ * has to be held together with the usual lock on [offset, offset + count].
+ *
+ * As multi-stripe locks have to be allowed, it makes sense to cache them, so
+ * that, for example, a sequence of O_APPEND writes can proceed quickly
+ * without going down to the individual stripes to do lock matching. On the
+ * other hand, multi-stripe locks shouldn't be used by normal read/write
+ * calls. To achieve this, every layer can implement ->clo_fits_into() method,
+ * that is called by lock matching code (cl_lock_lookup()), and that can be
+ * used to selectively disable matching of certain locks for certain IOs. For
+ * example, lov layer implements lov_lock_fits_into() that allow multi-stripe
+ * locks to be matched only for truncates and O_APPEND writes.
+ *
+ * Interaction with DLM
+ *
+ * In the expected setup, cl_lock is ultimately backed up by a collection of
+ * DLM locks (struct ldlm_lock). Association between cl_lock and DLM lock is
+ * implemented in osc layer, that also matches DLM events (ASTs, cancellation,
+ * etc.) into cl_lock_operation calls. See struct osc_lock for a more detailed
+ * description of interaction with DLM.
+ */
+
+/**
+ * Lock description.
+ */
+struct cl_lock_descr {
+ /** Object this lock is granted for. */
+ struct cl_object *cld_obj;
+ /** Index of the first page protected by this lock. */
+ pgoff_t cld_start;
+ /** Index of the last page (inclusive) protected by this lock. */
+ pgoff_t cld_end;
+ /** Group ID, for group lock */
+ __u64 cld_gid;
+ /** Lock mode. */
+ enum cl_lock_mode cld_mode;
+ /**
+ * flags to enqueue lock. A combination of bit-flags from
+ * enum cl_enq_flags.
+ */
+ __u32 cld_enq_flags;
+};
+
+#define DDESCR "%s(%d):[%lu, %lu]"
+#define PDESCR(descr) \
+ cl_lock_mode_name((descr)->cld_mode), (descr)->cld_mode, \
+ (descr)->cld_start, (descr)->cld_end
+
+const char *cl_lock_mode_name(const enum cl_lock_mode mode);
+
+/**
+ * Lock state-machine states.
+ *
+ * \htmlonly
+ * <pre>
+ *
+ * Possible state transitions:
+ *
+ * +------------------>NEW
+ * | |
+ * | | cl_enqueue_try()
+ * | |
+ * | cl_unuse_try() V
+ * | +--------------QUEUING (*)
+ * | | |
+ * | | | cl_enqueue_try()
+ * | | |
+ * | | cl_unuse_try() V
+ * sub-lock | +-------------ENQUEUED (*)
+ * canceled | | |
+ * | | | cl_wait_try()
+ * | | |
+ * | | (R)
+ * | | |
+ * | | V
+ * | | HELD<---------+
+ * | | | |
+ * | | | | cl_use_try()
+ * | | cl_unuse_try() | |
+ * | | | |
+ * | | V ---+
+ * | +------------>INTRANSIT (D) <--+
+ * | | |
+ * | cl_unuse_try() | | cached lock found
+ * | | | cl_use_try()
+ * | | |
+ * | V |
+ * +------------------CACHED---------+
+ * |
+ * (C)
+ * |
+ * V
+ * FREEING
+ *
+ * Legend:
+ *
+ * In states marked with (*) transition to the same state (i.e., a loop
+ * in the diagram) is possible.
+ *
+ * (R) is the point where Receive call-back is invoked: it allows layers
+ * to handle arrival of lock reply.
+ *
+ * (C) is the point where Cancellation call-back is invoked.
+ *
+ * (D) is the transit state which means the lock is changing.
+ *
+ * Transition to FREEING state is possible from any other state in the
+ * diagram in case of unrecoverable error.
+ * </pre>
+ * \endhtmlonly
+ *
+ * These states are for individual cl_lock object. Top-lock and its sub-locks
+ * can be in the different states. Another way to say this is that we have
+ * nested state-machines.
+ *
+ * Separate QUEUING and ENQUEUED states are needed to support non-blocking
+ * operation for locks with multiple sub-locks. Imagine lock on a file F, that
+ * intersects 3 stripes S0, S1, and S2. To enqueue F client has to send
+ * enqueue to S0, wait for its completion, then send enqueue for S1, wait for
+ * its completion and at last enqueue lock for S2, and wait for its
+ * completion. In that case, top-lock is in QUEUING state while S0, S1 are
+ * handled, and is in ENQUEUED state after enqueue to S2 has been sent (note
+ * that in this case, sub-locks move from state to state, and top-lock remains
+ * in the same state).
+ */
+enum cl_lock_state {
+ /**
+ * Lock that wasn't yet enqueued
+ */
+ CLS_NEW,
+ /**
+ * Enqueue is in progress, blocking for some intermediate interaction
+ * with the other side.
+ */
+ CLS_QUEUING,
+ /**
+ * Lock is fully enqueued, waiting for server to reply when it is
+ * granted.
+ */
+ CLS_ENQUEUED,
+ /**
+ * Lock granted, actively used by some IO.
+ */
+ CLS_HELD,
+ /**
+ * This state is used to mark the lock is being used, or unused.
+ * We need this state because the lock may have several sublocks,
+ * so it's impossible to have an atomic way to bring all sublocks
+ * into CLS_HELD state at use case, or all sublocks to CLS_CACHED
+ * at unuse case.
+ * If a thread is referring to a lock, and it sees the lock is in this
+ * state, it must wait for the lock.
+ * See state diagram for details.
+ */
+ CLS_INTRANSIT,
+ /**
+ * Lock granted, not used.
+ */
+ CLS_CACHED,
+ /**
+ * Lock is being destroyed.
+ */
+ CLS_FREEING,
+ CLS_NR
+};
+
+enum cl_lock_flags {
+ /**
+ * lock has been cancelled. This flag is never cleared once set (by
+ * cl_lock_cancel0()).
+ */
+ CLF_CANCELLED = 1 << 0,
+ /** cancellation is pending for this lock. */
+ CLF_CANCELPEND = 1 << 1,
+ /** destruction is pending for this lock. */
+ CLF_DOOMED = 1 << 2,
+ /** from enqueue RPC reply upcall. */
+ CLF_FROM_UPCALL= 1 << 3,
+};
+
+/**
+ * Lock closure.
+ *
+ * Lock closure is a collection of locks (both top-locks and sub-locks) that
+ * might be updated in a result of an operation on a certain lock (which lock
+ * this is a closure of).
+ *
+ * Closures are needed to guarantee dead-lock freedom in the presence of
+ *
+ * - nested state-machines (top-lock state-machine composed of sub-lock
+ * state-machines), and
+ *
+ * - shared sub-locks.
+ *
+ * Specifically, many operations, such as lock enqueue, wait, unlock,
+ * etc. start from a top-lock, and then operate on a sub-locks of this
+ * top-lock, holding a top-lock mutex. When sub-lock state changes as a result
+ * of such operation, this change has to be propagated to all top-locks that
+ * share this sub-lock. Obviously, no natural lock ordering (e.g.,
+ * top-to-bottom or bottom-to-top) captures this scenario, so try-locking has
+ * to be used. Lock closure systematizes this try-and-repeat logic.
+ */
+struct cl_lock_closure {
+ /**
+ * Lock that is mutexed when closure construction is started. When
+ * closure in is `wait' mode (cl_lock_closure::clc_wait), mutex on
+ * origin is released before waiting.
+ */
+ struct cl_lock *clc_origin;
+ /**
+ * List of enclosed locks, so far. Locks are linked here through
+ * cl_lock::cll_inclosure.
+ */
+ struct list_head clc_list;
+ /**
+ * True iff closure is in a `wait' mode. This determines what
+ * cl_lock_enclosure() does when a lock L to be added to the closure
+ * is currently mutexed by some other thread.
+ *
+ * If cl_lock_closure::clc_wait is not set, then closure construction
+ * fails with CLO_REPEAT immediately.
+ *
+ * In wait mode, cl_lock_enclosure() waits until next attempt to build
+ * a closure might succeed. To this end it releases an origin mutex
+ * (cl_lock_closure::clc_origin), that has to be the only lock mutex
+ * owned by the current thread, and then waits on L mutex (by grabbing
+ * it and immediately releasing), before returning CLO_REPEAT to the
+ * caller.
+ */
+ int clc_wait;
+ /** Number of locks in the closure. */
+ int clc_nr;
+};
+
+/**
+ * Layered client lock.
+ */
+struct cl_lock {
+ /** Reference counter. */
+ atomic_t cll_ref;
+ /** List of slices. Immutable after creation. */
+ struct list_head cll_layers;
+ /**
+ * Linkage into cl_lock::cll_descr::cld_obj::coh_locks list. Protected
+ * by cl_lock::cll_descr::cld_obj::coh_lock_guard.
+ */
+ struct list_head cll_linkage;
+ /**
+ * Parameters of this lock. Protected by
+ * cl_lock::cll_descr::cld_obj::coh_lock_guard nested within
+ * cl_lock::cll_guard. Modified only on lock creation and in
+ * cl_lock_modify().
+ */
+ struct cl_lock_descr cll_descr;
+ /** Protected by cl_lock::cll_guard. */
+ enum cl_lock_state cll_state;
+ /** signals state changes. */
+ wait_queue_head_t cll_wq;
+ /**
+ * Recursive lock, most fields in cl_lock{} are protected by this.
+ *
+ * Locking rules: this mutex is never held across network
+ * communication, except when lock is being canceled.
+ *
+ * Lock ordering: a mutex of a sub-lock is taken first, then a mutex
+ * on a top-lock. Other direction is implemented through a
+ * try-lock-repeat loop. Mutices of unrelated locks can be taken only
+ * by try-locking.
+ *
+ * \see osc_lock_enqueue_wait(), lov_lock_cancel(), lov_sublock_wait().
+ */
+ struct mutex cll_guard;
+ struct task_struct *cll_guarder;
+ int cll_depth;
+
+ /**
+ * the owner for INTRANSIT state
+ */
+ struct task_struct *cll_intransit_owner;
+ int cll_error;
+ /**
+ * Number of holds on a lock. A hold prevents a lock from being
+ * canceled and destroyed. Protected by cl_lock::cll_guard.
+ *
+ * \see cl_lock_hold(), cl_lock_unhold(), cl_lock_release()
+ */
+ int cll_holds;
+ /**
+ * Number of lock users. Valid in cl_lock_state::CLS_HELD state
+ * only. Lock user pins lock in CLS_HELD state. Protected by
+ * cl_lock::cll_guard.
+ *
+ * \see cl_wait(), cl_unuse().
+ */
+ int cll_users;
+ /**
+ * Flag bit-mask. Values from enum cl_lock_flags. Updates are
+ * protected by cl_lock::cll_guard.
+ */
+ unsigned long cll_flags;
+ /**
+ * A linkage into a list of locks in a closure.
+ *
+ * \see cl_lock_closure
+ */
+ struct list_head cll_inclosure;
+ /**
+ * Confict lock at queuing time.
+ */
+ struct cl_lock *cll_conflict;
+ /**
+ * A list of references to this lock, for debugging.
+ */
+ struct lu_ref cll_reference;
+ /**
+ * A list of holds on this lock, for debugging.
+ */
+ struct lu_ref cll_holders;
+ /**
+ * A reference for cl_lock::cll_descr::cld_obj. For debugging.
+ */
+ struct lu_ref_link cll_obj_ref;
+#ifdef CONFIG_LOCKDEP
+ /* "dep_map" name is assumed by lockdep.h macros. */
+ struct lockdep_map dep_map;
+#endif
+};
+
+/**
+ * Per-layer part of cl_lock
+ *
+ * \see ccc_lock, lov_lock, lovsub_lock, osc_lock
+ */
+struct cl_lock_slice {
+ struct cl_lock *cls_lock;
+ /** Object slice corresponding to this lock slice. Immutable after
+ * creation. */
+ struct cl_object *cls_obj;
+ const struct cl_lock_operations *cls_ops;
+ /** Linkage into cl_lock::cll_layers. Immutable after creation. */
+ struct list_head cls_linkage;
+};
+
+/**
+ * Possible (non-error) return values of ->clo_{enqueue,wait,unlock}().
+ *
+ * NOTE: lov_subresult() depends on ordering here.
+ */
+enum cl_lock_transition {
+ /** operation cannot be completed immediately. Wait for state change. */
+ CLO_WAIT = 1,
+ /** operation had to release lock mutex, restart. */
+ CLO_REPEAT = 2,
+ /** lower layer re-enqueued. */
+ CLO_REENQUEUED = 3,
+};
+
+/**
+ *
+ * \see vvp_lock_ops, lov_lock_ops, lovsub_lock_ops, osc_lock_ops
+ */
+struct cl_lock_operations {
+ /**
+ * \name statemachine
+ *
+ * State machine transitions. These 3 methods are called to transfer
+ * lock from one state to another, as described in the commentary
+ * above enum #cl_lock_state.
+ *
+ * \retval 0 this layer has nothing more to do to before
+ * transition to the target state happens;
+ *
+ * \retval CLO_REPEAT method had to release and re-acquire cl_lock
+ * mutex, repeat invocation of transition method
+ * across all layers;
+ *
+ * \retval CLO_WAIT this layer cannot move to the target state
+ * immediately, as it has to wait for certain event
+ * (e.g., the communication with the server). It
+ * is guaranteed, that when the state transfer
+ * becomes possible, cl_lock::cll_wq wait-queue
+ * is signaled. Caller can wait for this event by
+ * calling cl_lock_state_wait();
+ *
+ * \retval -ve failure, abort state transition, move the lock
+ * into cl_lock_state::CLS_FREEING state, and set
+ * cl_lock::cll_error.
+ *
+ * Once all layers voted to agree to transition (by returning 0), lock
+ * is moved into corresponding target state. All state transition
+ * methods are optional.
+ */
+ /** @{ */
+ /**
+ * Attempts to enqueue the lock. Called top-to-bottom.
+ *
+ * \see ccc_lock_enqueue(), lov_lock_enqueue(), lovsub_lock_enqueue(),
+ * \see osc_lock_enqueue()
+ */
+ int (*clo_enqueue)(const struct lu_env *env,
+ const struct cl_lock_slice *slice,
+ struct cl_io *io, __u32 enqflags);
+ /**
+ * Attempts to wait for enqueue result. Called top-to-bottom.
+ *
+ * \see ccc_lock_wait(), lov_lock_wait(), osc_lock_wait()
+ */
+ int (*clo_wait)(const struct lu_env *env,
+ const struct cl_lock_slice *slice);
+ /**
+ * Attempts to unlock the lock. Called bottom-to-top. In addition to
+ * usual return values of lock state-machine methods, this can return
+ * -ESTALE to indicate that lock cannot be returned to the cache, and
+ * has to be re-initialized.
+ * unuse is a one-shot operation, so it must NOT return CLO_WAIT.
+ *
+ * \see ccc_lock_unuse(), lov_lock_unuse(), osc_lock_unuse()
+ */
+ int (*clo_unuse)(const struct lu_env *env,
+ const struct cl_lock_slice *slice);
+ /**
+ * Notifies layer that cached lock is started being used.
+ *
+ * \pre lock->cll_state == CLS_CACHED
+ *
+ * \see lov_lock_use(), osc_lock_use()
+ */
+ int (*clo_use)(const struct lu_env *env,
+ const struct cl_lock_slice *slice);
+ /** @} statemachine */
+ /**
+ * A method invoked when lock state is changed (as a result of state
+ * transition). This is used, for example, to track when the state of
+ * a sub-lock changes, to propagate this change to the corresponding
+ * top-lock. Optional
+ *
+ * \see lovsub_lock_state()
+ */
+ void (*clo_state)(const struct lu_env *env,
+ const struct cl_lock_slice *slice,
+ enum cl_lock_state st);
+ /**
+ * Returns true, iff given lock is suitable for the given io, idea
+ * being, that there are certain "unsafe" locks, e.g., ones acquired
+ * for O_APPEND writes, that we don't want to re-use for a normal
+ * write, to avoid the danger of cascading evictions. Optional. Runs
+ * under cl_object_header::coh_lock_guard.
+ *
+ * XXX this should take more information about lock needed by
+ * io. Probably lock description or something similar.
+ *
+ * \see lov_fits_into()
+ */
+ int (*clo_fits_into)(const struct lu_env *env,
+ const struct cl_lock_slice *slice,
+ const struct cl_lock_descr *need,
+ const struct cl_io *io);
+ /**
+ * \name ast
+ * Asynchronous System Traps. All of then are optional, all are
+ * executed bottom-to-top.
+ */
+ /** @{ */
+
+ /**
+ * Cancellation callback. Cancel a lock voluntarily, or under
+ * the request of server.
+ */
+ void (*clo_cancel)(const struct lu_env *env,
+ const struct cl_lock_slice *slice);
+ /**
+ * Lock weighting ast. Executed to estimate how precious this lock
+ * is. The sum of results across all layers is used to determine
+ * whether lock worth keeping in cache given present memory usage.
+ *
+ * \see osc_lock_weigh(), vvp_lock_weigh(), lovsub_lock_weigh().
+ */
+ unsigned long (*clo_weigh)(const struct lu_env *env,
+ const struct cl_lock_slice *slice);
+ /** @} ast */
+
+ /**
+ * \see lovsub_lock_closure()
+ */
+ int (*clo_closure)(const struct lu_env *env,
+ const struct cl_lock_slice *slice,
+ struct cl_lock_closure *closure);
+ /**
+ * Executed bottom-to-top when lock description changes (e.g., as a
+ * result of server granting more generous lock than was requested).
+ *
+ * \see lovsub_lock_modify()
+ */
+ int (*clo_modify)(const struct lu_env *env,
+ const struct cl_lock_slice *slice,
+ const struct cl_lock_descr *updated);
+ /**
+ * Notifies layers (bottom-to-top) that lock is going to be
+ * destroyed. Responsibility of layers is to prevent new references on
+ * this lock from being acquired once this method returns.
+ *
+ * This can be called multiple times due to the races.
+ *
+ * \see cl_lock_delete()
+ * \see osc_lock_delete(), lovsub_lock_delete()
+ */
+ void (*clo_delete)(const struct lu_env *env,
+ const struct cl_lock_slice *slice);
+ /**
+ * Destructor. Frees resources and the slice.
+ *
+ * \see ccc_lock_fini(), lov_lock_fini(), lovsub_lock_fini(),
+ * \see osc_lock_fini()
+ */
+ void (*clo_fini)(const struct lu_env *env, struct cl_lock_slice *slice);
+ /**
+ * Optional debugging helper. Prints given lock slice.
+ */
+ int (*clo_print)(const struct lu_env *env,
+ void *cookie, lu_printer_t p,
+ const struct cl_lock_slice *slice);
+};
+
+#define CL_LOCK_DEBUG(mask, env, lock, format, ...) \
+do { \
+ LIBCFS_DEBUG_MSG_DATA_DECL(msgdata, mask, NULL); \
+ \
+ if (cfs_cdebug_show(mask, DEBUG_SUBSYSTEM)) { \
+ cl_lock_print(env, &msgdata, lu_cdebug_printer, lock); \
+ CDEBUG(mask, format , ## __VA_ARGS__); \
+ } \
+} while (0)
+
+#define CL_LOCK_ASSERT(expr, env, lock) do { \
+ if (likely(expr)) \
+ break; \
+ \
+ CL_LOCK_DEBUG(D_ERROR, env, lock, "failed at %s.\n", #expr); \
+ LBUG(); \
+} while (0)
+
+/** @} cl_lock */
+
+/** \addtogroup cl_page_list cl_page_list
+ * Page list used to perform collective operations on a group of pages.
+ *
+ * Pages are added to the list one by one. cl_page_list acquires a reference
+ * for every page in it. Page list is used to perform collective operations on
+ * pages:
+ *
+ * - submit pages for an immediate transfer,
+ *
+ * - own pages on behalf of certain io (waiting for each page in turn),
+ *
+ * - discard pages.
+ *
+ * When list is finalized, it releases references on all pages it still has.
+ *
+ * \todo XXX concurrency control.
+ *
+ * @{
+ */
+struct cl_page_list {
+ unsigned pl_nr;
+ struct list_head pl_pages;
+ struct task_struct *pl_owner;
+};
+
+/**
+ * A 2-queue of pages. A convenience data-type for common use case, 2-queue
+ * contains an incoming page list and an outgoing page list.
+ */
+struct cl_2queue {
+ struct cl_page_list c2_qin;
+ struct cl_page_list c2_qout;
+};
+
+/** @} cl_page_list */
+
+/** \addtogroup cl_io cl_io
+ * @{ */
+/** \struct cl_io
+ * I/O
+ *
+ * cl_io represents a high level I/O activity like
+ * read(2)/write(2)/truncate(2) system call, or cancellation of an extent
+ * lock.
+ *
+ * cl_io is a layered object, much like cl_{object,page,lock} but with one
+ * important distinction. We want to minimize number of calls to the allocator
+ * in the fast path, e.g., in the case of read(2) when everything is cached:
+ * client already owns the lock over region being read, and data are cached
+ * due to read-ahead. To avoid allocation of cl_io layers in such situations,
+ * per-layer io state is stored in the session, associated with the io, see
+ * struct {vvp,lov,osc}_io for example. Sessions allocation is amortized
+ * by using free-lists, see cl_env_get().
+ *
+ * There is a small predefined number of possible io types, enumerated in enum
+ * cl_io_type.
+ *
+ * cl_io is a state machine, that can be advanced concurrently by the multiple
+ * threads. It is up to these threads to control the concurrency and,
+ * specifically, to detect when io is done, and its state can be safely
+ * released.
+ *
+ * For read/write io overall execution plan is as following:
+ *
+ * (0) initialize io state through all layers;
+ *
+ * (1) loop: prepare chunk of work to do
+ *
+ * (2) call all layers to collect locks they need to process current chunk
+ *
+ * (3) sort all locks to avoid dead-locks, and acquire them
+ *
+ * (4) process the chunk: call per-page methods
+ * (cl_io_operations::cio_read_page() for read,
+ * cl_io_operations::cio_prepare_write(),
+ * cl_io_operations::cio_commit_write() for write)
+ *
+ * (5) release locks
+ *
+ * (6) repeat loop.
+ *
+ * To implement the "parallel IO mode", lov layer creates sub-io's (lazily to
+ * address allocation efficiency issues mentioned above), and returns with the
+ * special error condition from per-page method when current sub-io has to
+ * block. This causes io loop to be repeated, and lov switches to the next
+ * sub-io in its cl_io_operations::cio_iter_init() implementation.
+ */
+
+/** IO types */
+enum cl_io_type {
+ /** read system call */
+ CIT_READ,
+ /** write system call */
+ CIT_WRITE,
+ /** truncate, utime system calls */
+ CIT_SETATTR,
+ /**
+ * page fault handling
+ */
+ CIT_FAULT,
+ /**
+ * fsync system call handling
+ * To write out a range of file
+ */
+ CIT_FSYNC,
+ /**
+ * Miscellaneous io. This is used for occasional io activity that
+ * doesn't fit into other types. Currently this is used for:
+ *
+ * - cancellation of an extent lock. This io exists as a context
+ * to write dirty pages from under the lock being canceled back
+ * to the server;
+ *
+ * - VM induced page write-out. An io context for writing page out
+ * for memory cleansing;
+ *
+ * - glimpse. An io context to acquire glimpse lock.
+ *
+ * - grouplock. An io context to acquire group lock.
+ *
+ * CIT_MISC io is used simply as a context in which locks and pages
+ * are manipulated. Such io has no internal "process", that is,
+ * cl_io_loop() is never called for it.
+ */
+ CIT_MISC,
+ CIT_OP_NR
+};
+
+/**
+ * States of cl_io state machine
+ */
+enum cl_io_state {
+ /** Not initialized. */
+ CIS_ZERO,
+ /** Initialized. */
+ CIS_INIT,
+ /** IO iteration started. */
+ CIS_IT_STARTED,
+ /** Locks taken. */
+ CIS_LOCKED,
+ /** Actual IO is in progress. */
+ CIS_IO_GOING,
+ /** IO for the current iteration finished. */
+ CIS_IO_FINISHED,
+ /** Locks released. */
+ CIS_UNLOCKED,
+ /** Iteration completed. */
+ CIS_IT_ENDED,
+ /** cl_io finalized. */
+ CIS_FINI
+};
+
+/**
+ * IO state private for a layer.
+ *
+ * This is usually embedded into layer session data, rather than allocated
+ * dynamically.
+ *
+ * \see vvp_io, lov_io, osc_io, ccc_io
+ */
+struct cl_io_slice {
+ struct cl_io *cis_io;
+ /** corresponding object slice. Immutable after creation. */
+ struct cl_object *cis_obj;
+ /** io operations. Immutable after creation. */
+ const struct cl_io_operations *cis_iop;
+ /**
+ * linkage into a list of all slices for a given cl_io, hanging off
+ * cl_io::ci_layers. Immutable after creation.
+ */
+ struct list_head cis_linkage;
+};
+
+
+/**
+ * Per-layer io operations.
+ * \see vvp_io_ops, lov_io_ops, lovsub_io_ops, osc_io_ops
+ */
+struct cl_io_operations {
+ /**
+ * Vector of io state transition methods for every io type.
+ *
+ * \see cl_page_operations::io
+ */
+ struct {
+ /**
+ * Prepare io iteration at a given layer.
+ *
+ * Called top-to-bottom at the beginning of each iteration of
+ * "io loop" (if it makes sense for this type of io). Here
+ * layer selects what work it will do during this iteration.
+ *
+ * \see cl_io_operations::cio_iter_fini()
+ */
+ int (*cio_iter_init) (const struct lu_env *env,
+ const struct cl_io_slice *slice);
+ /**
+ * Finalize io iteration.
+ *
+ * Called bottom-to-top at the end of each iteration of "io
+ * loop". Here layers can decide whether IO has to be
+ * continued.
+ *
+ * \see cl_io_operations::cio_iter_init()
+ */
+ void (*cio_iter_fini) (const struct lu_env *env,
+ const struct cl_io_slice *slice);
+ /**
+ * Collect locks for the current iteration of io.
+ *
+ * Called top-to-bottom to collect all locks necessary for
+ * this iteration. This methods shouldn't actually enqueue
+ * anything, instead it should post a lock through
+ * cl_io_lock_add(). Once all locks are collected, they are
+ * sorted and enqueued in the proper order.
+ */
+ int (*cio_lock) (const struct lu_env *env,
+ const struct cl_io_slice *slice);
+ /**
+ * Finalize unlocking.
+ *
+ * Called bottom-to-top to finish layer specific unlocking
+ * functionality, after generic code released all locks
+ * acquired by cl_io_operations::cio_lock().
+ */
+ void (*cio_unlock)(const struct lu_env *env,
+ const struct cl_io_slice *slice);
+ /**
+ * Start io iteration.
+ *
+ * Once all locks are acquired, called top-to-bottom to
+ * commence actual IO. In the current implementation,
+ * top-level vvp_io_{read,write}_start() does all the work
+ * synchronously by calling generic_file_*(), so other layers
+ * are called when everything is done.
+ */
+ int (*cio_start)(const struct lu_env *env,
+ const struct cl_io_slice *slice);
+ /**
+ * Called top-to-bottom at the end of io loop. Here layer
+ * might wait for an unfinished asynchronous io.
+ */
+ void (*cio_end) (const struct lu_env *env,
+ const struct cl_io_slice *slice);
+ /**
+ * Called bottom-to-top to notify layers that read/write IO
+ * iteration finished, with \a nob bytes transferred.
+ */
+ void (*cio_advance)(const struct lu_env *env,
+ const struct cl_io_slice *slice,
+ size_t nob);
+ /**
+ * Called once per io, bottom-to-top to release io resources.
+ */
+ void (*cio_fini) (const struct lu_env *env,
+ const struct cl_io_slice *slice);
+ } op[CIT_OP_NR];
+ struct {
+ /**
+ * Submit pages from \a queue->c2_qin for IO, and move
+ * successfully submitted pages into \a queue->c2_qout. Return
+ * non-zero if failed to submit even the single page. If
+ * submission failed after some pages were moved into \a
+ * queue->c2_qout, completion callback with non-zero ioret is
+ * executed on them.
+ */
+ int (*cio_submit)(const struct lu_env *env,
+ const struct cl_io_slice *slice,
+ enum cl_req_type crt,
+ struct cl_2queue *queue);
+ } req_op[CRT_NR];
+ /**
+ * Read missing page.
+ *
+ * Called by a top-level cl_io_operations::op[CIT_READ]::cio_start()
+ * method, when it hits not-up-to-date page in the range. Optional.
+ *
+ * \pre io->ci_type == CIT_READ
+ */
+ int (*cio_read_page)(const struct lu_env *env,
+ const struct cl_io_slice *slice,
+ const struct cl_page_slice *page);
+ /**
+ * Prepare write of a \a page. Called bottom-to-top by a top-level
+ * cl_io_operations::op[CIT_WRITE]::cio_start() to prepare page for
+ * get data from user-level buffer.
+ *
+ * \pre io->ci_type == CIT_WRITE
+ *
+ * \see vvp_io_prepare_write(), lov_io_prepare_write(),
+ * osc_io_prepare_write().
+ */
+ int (*cio_prepare_write)(const struct lu_env *env,
+ const struct cl_io_slice *slice,
+ const struct cl_page_slice *page,
+ unsigned from, unsigned to);
+ /**
+ *
+ * \pre io->ci_type == CIT_WRITE
+ *
+ * \see vvp_io_commit_write(), lov_io_commit_write(),
+ * osc_io_commit_write().
+ */
+ int (*cio_commit_write)(const struct lu_env *env,
+ const struct cl_io_slice *slice,
+ const struct cl_page_slice *page,
+ unsigned from, unsigned to);
+ /**
+ * Optional debugging helper. Print given io slice.
+ */
+ int (*cio_print)(const struct lu_env *env, void *cookie,
+ lu_printer_t p, const struct cl_io_slice *slice);
+};
+
+/**
+ * Flags to lock enqueue procedure.
+ * \ingroup cl_lock
+ */
+enum cl_enq_flags {
+ /**
+ * instruct server to not block, if conflicting lock is found. Instead
+ * -EWOULDBLOCK is returned immediately.
+ */
+ CEF_NONBLOCK = 0x00000001,
+ /**
+ * take lock asynchronously (out of order), as it cannot
+ * deadlock. This is for LDLM_FL_HAS_INTENT locks used for glimpsing.
+ */
+ CEF_ASYNC = 0x00000002,
+ /**
+ * tell the server to instruct (though a flag in the blocking ast) an
+ * owner of the conflicting lock, that it can drop dirty pages
+ * protected by this lock, without sending them to the server.
+ */
+ CEF_DISCARD_DATA = 0x00000004,
+ /**
+ * tell the sub layers that it must be a `real' lock. This is used for
+ * mmapped-buffer locks and glimpse locks that must be never converted
+ * into lockless mode.
+ *
+ * \see vvp_mmap_locks(), cl_glimpse_lock().
+ */
+ CEF_MUST = 0x00000008,
+ /**
+ * tell the sub layers that never request a `real' lock. This flag is
+ * not used currently.
+ *
+ * cl_io::ci_lockreq and CEF_{MUST,NEVER} flags specify lockless
+ * conversion policy: ci_lockreq describes generic information of lock
+ * requirement for this IO, especially for locks which belong to the
+ * object doing IO; however, lock itself may have precise requirements
+ * that are described by the enqueue flags.
+ */
+ CEF_NEVER = 0x00000010,
+ /**
+ * for async glimpse lock.
+ */
+ CEF_AGL = 0x00000020,
+ /**
+ * mask of enq_flags.
+ */
+ CEF_MASK = 0x0000003f,
+};
+
+/**
+ * Link between lock and io. Intermediate structure is needed, because the
+ * same lock can be part of multiple io's simultaneously.
+ */
+struct cl_io_lock_link {
+ /** linkage into one of cl_lockset lists. */
+ struct list_head cill_linkage;
+ struct cl_lock_descr cill_descr;
+ struct cl_lock *cill_lock;
+ /** optional destructor */
+ void (*cill_fini)(const struct lu_env *env,
+ struct cl_io_lock_link *link);
+};
+
+/**
+ * Lock-set represents a collection of locks, that io needs at a
+ * time. Generally speaking, client tries to avoid holding multiple locks when
+ * possible, because
+ *
+ * - holding extent locks over multiple ost's introduces the danger of
+ * "cascading timeouts";
+ *
+ * - holding multiple locks over the same ost is still dead-lock prone,
+ * see comment in osc_lock_enqueue(),
+ *
+ * but there are certain situations where this is unavoidable:
+ *
+ * - O_APPEND writes have to take [0, EOF] lock for correctness;
+ *
+ * - truncate has to take [new-size, EOF] lock for correctness;
+ *
+ * - SNS has to take locks across full stripe for correctness;
+ *
+ * - in the case when user level buffer, supplied to {read,write}(file0),
+ * is a part of a memory mapped lustre file, client has to take a dlm
+ * locks on file0, and all files that back up the buffer (or a part of
+ * the buffer, that is being processed in the current chunk, in any
+ * case, there are situations where at least 2 locks are necessary).
+ *
+ * In such cases we at least try to take locks in the same consistent
+ * order. To this end, all locks are first collected, then sorted, and then
+ * enqueued.
+ */
+struct cl_lockset {
+ /** locks to be acquired. */
+ struct list_head cls_todo;
+ /** locks currently being processed. */
+ struct list_head cls_curr;
+ /** locks acquired. */
+ struct list_head cls_done;
+};
+
+/**
+ * Lock requirements(demand) for IO. It should be cl_io_lock_req,
+ * but 'req' is always to be thought as 'request' :-)
+ */
+enum cl_io_lock_dmd {
+ /** Always lock data (e.g., O_APPEND). */
+ CILR_MANDATORY = 0,
+ /** Layers are free to decide between local and global locking. */
+ CILR_MAYBE,
+ /** Never lock: there is no cache (e.g., liblustre). */
+ CILR_NEVER
+};
+
+enum cl_fsync_mode {
+ /** start writeback, do not wait for them to finish */
+ CL_FSYNC_NONE = 0,
+ /** start writeback and wait for them to finish */
+ CL_FSYNC_LOCAL = 1,
+ /** discard all of dirty pages in a specific file range */
+ CL_FSYNC_DISCARD = 2,
+ /** start writeback and make sure they have reached storage before
+ * return. OST_SYNC RPC must be issued and finished */
+ CL_FSYNC_ALL = 3
+};
+
+struct cl_io_rw_common {
+ loff_t crw_pos;
+ size_t crw_count;
+ int crw_nonblock;
+};
+
+
+/**
+ * State for io.
+ *
+ * cl_io is shared by all threads participating in this IO (in current
+ * implementation only one thread advances IO, but parallel IO design and
+ * concurrent copy_*_user() require multiple threads acting on the same IO. It
+ * is up to these threads to serialize their activities, including updates to
+ * mutable cl_io fields.
+ */
+struct cl_io {
+ /** type of this IO. Immutable after creation. */
+ enum cl_io_type ci_type;
+ /** current state of cl_io state machine. */
+ enum cl_io_state ci_state;
+ /** main object this io is against. Immutable after creation. */
+ struct cl_object *ci_obj;
+ /**
+ * Upper layer io, of which this io is a part of. Immutable after
+ * creation.
+ */
+ struct cl_io *ci_parent;
+ /** List of slices. Immutable after creation. */
+ struct list_head ci_layers;
+ /** list of locks (to be) acquired by this io. */
+ struct cl_lockset ci_lockset;
+ /** lock requirements, this is just a help info for sublayers. */
+ enum cl_io_lock_dmd ci_lockreq;
+ union {
+ struct cl_rd_io {
+ struct cl_io_rw_common rd;
+ } ci_rd;
+ struct cl_wr_io {
+ struct cl_io_rw_common wr;
+ int wr_append;
+ int wr_sync;
+ } ci_wr;
+ struct cl_io_rw_common ci_rw;
+ struct cl_setattr_io {
+ struct ost_lvb sa_attr;
+ unsigned int sa_valid;
+ struct obd_capa *sa_capa;
+ } ci_setattr;
+ struct cl_fault_io {
+ /** page index within file. */
+ pgoff_t ft_index;
+ /** bytes valid byte on a faulted page. */
+ int ft_nob;
+ /** writable page? for nopage() only */
+ int ft_writable;
+ /** page of an executable? */
+ int ft_executable;
+ /** page_mkwrite() */
+ int ft_mkwrite;
+ /** resulting page */
+ struct cl_page *ft_page;
+ } ci_fault;
+ struct cl_fsync_io {
+ loff_t fi_start;
+ loff_t fi_end;
+ struct obd_capa *fi_capa;
+ /** file system level fid */
+ struct lu_fid *fi_fid;
+ enum cl_fsync_mode fi_mode;
+ /* how many pages were written/discarded */
+ unsigned int fi_nr_written;
+ } ci_fsync;
+ } u;
+ struct cl_2queue ci_queue;
+ size_t ci_nob;
+ int ci_result;
+ unsigned int ci_continue:1,
+ /**
+ * This io has held grouplock, to inform sublayers that
+ * don't do lockless i/o.
+ */
+ ci_no_srvlock:1,
+ /**
+ * The whole IO need to be restarted because layout has been changed
+ */
+ ci_need_restart:1,
+ /**
+ * to not refresh layout - the IO issuer knows that the layout won't
+ * change(page operations, layout change causes all page to be
+ * discarded), or it doesn't matter if it changes(sync).
+ */
+ ci_ignore_layout:1,
+ /**
+ * Check if layout changed after the IO finishes. Mainly for HSM
+ * requirement. If IO occurs to openning files, it doesn't need to
+ * verify layout because HSM won't release openning files.
+ * Right now, only two operations need to verify layout: glimpse
+ * and setattr.
+ */
+ ci_verify_layout:1,
+ /**
+ * file is released, restore has to to be triggered by vvp layer
+ */
+ ci_restore_needed:1,
+ /**
+ * O_NOATIME
+ */
+ ci_noatime:1;
+ /**
+ * Number of pages owned by this IO. For invariant checking.
+ */
+ unsigned ci_owned_nr;
+};
+
+/** @} cl_io */
+
+/** \addtogroup cl_req cl_req
+ * @{ */
+/** \struct cl_req
+ * Transfer.
+ *
+ * There are two possible modes of transfer initiation on the client:
+ *
+ * - immediate transfer: this is started when a high level io wants a page
+ * or a collection of pages to be transferred right away. Examples:
+ * read-ahead, synchronous read in the case of non-page aligned write,
+ * page write-out as a part of extent lock cancellation, page write-out
+ * as a part of memory cleansing. Immediate transfer can be both
+ * cl_req_type::CRT_READ and cl_req_type::CRT_WRITE;
+ *
+ * - opportunistic transfer (cl_req_type::CRT_WRITE only), that happens
+ * when io wants to transfer a page to the server some time later, when
+ * it can be done efficiently. Example: pages dirtied by the write(2)
+ * path.
+ *
+ * In any case, transfer takes place in the form of a cl_req, which is a
+ * representation for a network RPC.
+ *
+ * Pages queued for an opportunistic transfer are cached until it is decided
+ * that efficient RPC can be composed of them. This decision is made by "a
+ * req-formation engine", currently implemented as a part of osc
+ * layer. Req-formation depends on many factors: the size of the resulting
+ * RPC, whether or not multi-object RPCs are supported by the server,
+ * max-rpc-in-flight limitations, size of the dirty cache, etc.
+ *
+ * For the immediate transfer io submits a cl_page_list, that req-formation
+ * engine slices into cl_req's, possibly adding cached pages to some of
+ * the resulting req's.
+ *
+ * Whenever a page from cl_page_list is added to a newly constructed req, its
+ * cl_page_operations::cpo_prep() layer methods are called. At that moment,
+ * page state is atomically changed from cl_page_state::CPS_OWNED to
+ * cl_page_state::CPS_PAGEOUT or cl_page_state::CPS_PAGEIN, cl_page::cp_owner
+ * is zeroed, and cl_page::cp_req is set to the
+ * req. cl_page_operations::cpo_prep() method at the particular layer might
+ * return -EALREADY to indicate that it does not need to submit this page
+ * at all. This is possible, for example, if page, submitted for read,
+ * became up-to-date in the meantime; and for write, the page don't have
+ * dirty bit marked. \see cl_io_submit_rw()
+ *
+ * Whenever a cached page is added to a newly constructed req, its
+ * cl_page_operations::cpo_make_ready() layer methods are called. At that
+ * moment, page state is atomically changed from cl_page_state::CPS_CACHED to
+ * cl_page_state::CPS_PAGEOUT, and cl_page::cp_req is set to
+ * req. cl_page_operations::cpo_make_ready() method at the particular layer
+ * might return -EAGAIN to indicate that this page is not eligible for the
+ * transfer right now.
+ *
+ * FUTURE
+ *
+ * Plan is to divide transfers into "priority bands" (indicated when
+ * submitting cl_page_list, and queuing a page for the opportunistic transfer)
+ * and allow glueing of cached pages to immediate transfers only within single
+ * band. This would make high priority transfers (like lock cancellation or
+ * memory pressure induced write-out) really high priority.
+ *
+ */
+
+/**
+ * Per-transfer attributes.
+ */
+struct cl_req_attr {
+ /** Generic attributes for the server consumption. */
+ struct obdo *cra_oa;
+ /** Capability. */
+ struct obd_capa *cra_capa;
+ /** Jobid */
+ char cra_jobid[JOBSTATS_JOBID_SIZE];
+};
+
+/**
+ * Transfer request operations definable at every layer.
+ *
+ * Concurrency: transfer formation engine synchronizes calls to all transfer
+ * methods.
+ */
+struct cl_req_operations {
+ /**
+ * Invoked top-to-bottom by cl_req_prep() when transfer formation is
+ * complete (all pages are added).
+ *
+ * \see osc_req_prep()
+ */
+ int (*cro_prep)(const struct lu_env *env,
+ const struct cl_req_slice *slice);
+ /**
+ * Called top-to-bottom to fill in \a oa fields. This is called twice
+ * with different flags, see bug 10150 and osc_build_req().
+ *
+ * \param obj an object from cl_req which attributes are to be set in
+ * \a oa.
+ *
+ * \param oa struct obdo where attributes are placed
+ *
+ * \param flags \a oa fields to be filled.
+ */
+ void (*cro_attr_set)(const struct lu_env *env,
+ const struct cl_req_slice *slice,
+ const struct cl_object *obj,
+ struct cl_req_attr *attr, u64 flags);
+ /**
+ * Called top-to-bottom from cl_req_completion() to notify layers that
+ * transfer completed. Has to free all state allocated by
+ * cl_device_operations::cdo_req_init().
+ */
+ void (*cro_completion)(const struct lu_env *env,
+ const struct cl_req_slice *slice, int ioret);
+};
+
+/**
+ * A per-object state that (potentially multi-object) transfer request keeps.
+ */
+struct cl_req_obj {
+ /** object itself */
+ struct cl_object *ro_obj;
+ /** reference to cl_req_obj::ro_obj. For debugging. */
+ struct lu_ref_link ro_obj_ref;
+ /* something else? Number of pages for a given object? */
+};
+
+/**
+ * Transfer request.
+ *
+ * Transfer requests are not reference counted, because IO sub-system owns
+ * them exclusively and knows when to free them.
+ *
+ * Life cycle.
+ *
+ * cl_req is created by cl_req_alloc() that calls
+ * cl_device_operations::cdo_req_init() device methods to allocate per-req
+ * state in every layer.
+ *
+ * Then pages are added (cl_req_page_add()), req keeps track of all objects it
+ * contains pages for.
+ *
+ * Once all pages were collected, cl_page_operations::cpo_prep() method is
+ * called top-to-bottom. At that point layers can modify req, let it pass, or
+ * deny it completely. This is to support things like SNS that have transfer
+ * ordering requirements invisible to the individual req-formation engine.
+ *
+ * On transfer completion (or transfer timeout, or failure to initiate the
+ * transfer of an allocated req), cl_req_operations::cro_completion() method
+ * is called, after execution of cl_page_operations::cpo_completion() of all
+ * req's pages.
+ */
+struct cl_req {
+ enum cl_req_type crq_type;
+ /** A list of pages being transferred */
+ struct list_head crq_pages;
+ /** Number of pages in cl_req::crq_pages */
+ unsigned crq_nrpages;
+ /** An array of objects which pages are in ->crq_pages */
+ struct cl_req_obj *crq_o;
+ /** Number of elements in cl_req::crq_objs[] */
+ unsigned crq_nrobjs;
+ struct list_head crq_layers;
+};
+
+/**
+ * Per-layer state for request.
+ */
+struct cl_req_slice {
+ struct cl_req *crs_req;
+ struct cl_device *crs_dev;
+ struct list_head crs_linkage;
+ const struct cl_req_operations *crs_ops;
+};
+
+/* @} cl_req */
+
+enum cache_stats_item {
+ /** how many cache lookups were performed */
+ CS_lookup = 0,
+ /** how many times cache lookup resulted in a hit */
+ CS_hit,
+ /** how many entities are in the cache right now */
+ CS_total,
+ /** how many entities in the cache are actively used (and cannot be
+ * evicted) right now */
+ CS_busy,
+ /** how many entities were created at all */
+ CS_create,
+ CS_NR
+};
+
+#define CS_NAMES { "lookup", "hit", "total", "busy", "create" }
+
+/**
+ * Stats for a generic cache (similar to inode, lu_object, etc. caches).
+ */
+struct cache_stats {
+ const char *cs_name;
+ atomic_t cs_stats[CS_NR];
+};
+
+/** These are not exported so far */
+void cache_stats_init (struct cache_stats *cs, const char *name);
+
+/**
+ * Client-side site. This represents particular client stack. "Global"
+ * variables should (directly or indirectly) be added here to allow multiple
+ * clients to co-exist in the single address space.
+ */
+struct cl_site {
+ struct lu_site cs_lu;
+ /**
+ * Statistical counters. Atomics do not scale, something better like
+ * per-cpu counters is needed.
+ *
+ * These are exported as /proc/fs/lustre/llite/.../site
+ *
+ * When interpreting keep in mind that both sub-locks (and sub-pages)
+ * and top-locks (and top-pages) are accounted here.
+ */
+ struct cache_stats cs_pages;
+ struct cache_stats cs_locks;
+ atomic_t cs_pages_state[CPS_NR];
+ atomic_t cs_locks_state[CLS_NR];
+};
+
+int cl_site_init (struct cl_site *s, struct cl_device *top);
+void cl_site_fini (struct cl_site *s);
+void cl_stack_fini(const struct lu_env *env, struct cl_device *cl);
+
+/**
+ * Output client site statistical counters into a buffer. Suitable for
+ * ll_rd_*()-style functions.
+ */
+int cl_site_stats_print(const struct cl_site *site, struct seq_file *m);
+
+/**
+ * \name helpers
+ *
+ * Type conversion and accessory functions.
+ */
+/** @{ */
+
+static inline struct cl_site *lu2cl_site(const struct lu_site *site)
+{
+ return container_of(site, struct cl_site, cs_lu);
+}
+
+static inline int lu_device_is_cl(const struct lu_device *d)
+{
+ return d->ld_type->ldt_tags & LU_DEVICE_CL;
+}
+
+static inline struct cl_device *lu2cl_dev(const struct lu_device *d)
+{
+ LASSERT(d == NULL || IS_ERR(d) || lu_device_is_cl(d));
+ return container_of0(d, struct cl_device, cd_lu_dev);
+}
+
+static inline struct lu_device *cl2lu_dev(struct cl_device *d)
+{
+ return &d->cd_lu_dev;
+}
+
+static inline struct cl_object *lu2cl(const struct lu_object *o)
+{
+ LASSERT(o == NULL || IS_ERR(o) || lu_device_is_cl(o->lo_dev));
+ return container_of0(o, struct cl_object, co_lu);
+}
+
+static inline const struct cl_object_conf *
+lu2cl_conf(const struct lu_object_conf *conf)
+{
+ return container_of0(conf, struct cl_object_conf, coc_lu);
+}
+
+static inline struct cl_object *cl_object_next(const struct cl_object *obj)
+{
+ return obj ? lu2cl(lu_object_next(&obj->co_lu)) : NULL;
+}
+
+static inline struct cl_device *cl_object_device(const struct cl_object *o)
+{
+ LASSERT(o == NULL || IS_ERR(o) || lu_device_is_cl(o->co_lu.lo_dev));
+ return container_of0(o->co_lu.lo_dev, struct cl_device, cd_lu_dev);
+}
+
+static inline struct cl_object_header *luh2coh(const struct lu_object_header *h)
+{
+ return container_of0(h, struct cl_object_header, coh_lu);
+}
+
+static inline struct cl_site *cl_object_site(const struct cl_object *obj)
+{
+ return lu2cl_site(obj->co_lu.lo_dev->ld_site);
+}
+
+static inline
+struct cl_object_header *cl_object_header(const struct cl_object *obj)
+{
+ return luh2coh(obj->co_lu.lo_header);
+}
+
+static inline int cl_device_init(struct cl_device *d, struct lu_device_type *t)
+{
+ return lu_device_init(&d->cd_lu_dev, t);
+}
+
+static inline void cl_device_fini(struct cl_device *d)
+{
+ lu_device_fini(&d->cd_lu_dev);
+}
+
+void cl_page_slice_add(struct cl_page *page, struct cl_page_slice *slice,
+ struct cl_object *obj,
+ const struct cl_page_operations *ops);
+void cl_lock_slice_add(struct cl_lock *lock, struct cl_lock_slice *slice,
+ struct cl_object *obj,
+ const struct cl_lock_operations *ops);
+void cl_io_slice_add(struct cl_io *io, struct cl_io_slice *slice,
+ struct cl_object *obj, const struct cl_io_operations *ops);
+void cl_req_slice_add(struct cl_req *req, struct cl_req_slice *slice,
+ struct cl_device *dev,
+ const struct cl_req_operations *ops);
+/** @} helpers */
+
+/** \defgroup cl_object cl_object
+ * @{ */
+struct cl_object *cl_object_top (struct cl_object *o);
+struct cl_object *cl_object_find(const struct lu_env *env, struct cl_device *cd,
+ const struct lu_fid *fid,
+ const struct cl_object_conf *c);
+
+int cl_object_header_init(struct cl_object_header *h);
+void cl_object_header_fini(struct cl_object_header *h);
+void cl_object_put (const struct lu_env *env, struct cl_object *o);
+void cl_object_get (struct cl_object *o);
+void cl_object_attr_lock (struct cl_object *o);
+void cl_object_attr_unlock(struct cl_object *o);
+int cl_object_attr_get (const struct lu_env *env, struct cl_object *obj,
+ struct cl_attr *attr);
+int cl_object_attr_set (const struct lu_env *env, struct cl_object *obj,
+ const struct cl_attr *attr, unsigned valid);
+int cl_object_glimpse (const struct lu_env *env, struct cl_object *obj,
+ struct ost_lvb *lvb);
+int cl_conf_set (const struct lu_env *env, struct cl_object *obj,
+ const struct cl_object_conf *conf);
+void cl_object_prune (const struct lu_env *env, struct cl_object *obj);
+void cl_object_kill (const struct lu_env *env, struct cl_object *obj);
+int cl_object_has_locks (struct cl_object *obj);
+
+/**
+ * Returns true, iff \a o0 and \a o1 are slices of the same object.
+ */
+static inline int cl_object_same(struct cl_object *o0, struct cl_object *o1)
+{
+ return cl_object_header(o0) == cl_object_header(o1);
+}
+
+static inline void cl_object_page_init(struct cl_object *clob, int size)
+{
+ clob->co_slice_off = cl_object_header(clob)->coh_page_bufsize;
+ cl_object_header(clob)->coh_page_bufsize += ALIGN(size, 8);
+}
+
+static inline void *cl_object_page_slice(struct cl_object *clob,
+ struct cl_page *page)
+{
+ return (void *)((char *)page + clob->co_slice_off);
+}
+
+/** @} cl_object */
+
+/** \defgroup cl_page cl_page
+ * @{ */
+enum {
+ CLP_GANG_OKAY = 0,
+ CLP_GANG_RESCHED,
+ CLP_GANG_AGAIN,
+ CLP_GANG_ABORT
+};
+
+/* callback of cl_page_gang_lookup() */
+typedef int (*cl_page_gang_cb_t) (const struct lu_env *, struct cl_io *,
+ struct cl_page *, void *);
+int cl_page_gang_lookup (const struct lu_env *env,
+ struct cl_object *obj,
+ struct cl_io *io,
+ pgoff_t start, pgoff_t end,
+ cl_page_gang_cb_t cb, void *cbdata);
+struct cl_page *cl_page_lookup (struct cl_object_header *hdr,
+ pgoff_t index);
+struct cl_page *cl_page_find (const struct lu_env *env,
+ struct cl_object *obj,
+ pgoff_t idx, struct page *vmpage,
+ enum cl_page_type type);
+struct cl_page *cl_page_find_sub (const struct lu_env *env,
+ struct cl_object *obj,
+ pgoff_t idx, struct page *vmpage,
+ struct cl_page *parent);
+void cl_page_get (struct cl_page *page);
+void cl_page_put (const struct lu_env *env,
+ struct cl_page *page);
+void cl_page_print (const struct lu_env *env, void *cookie,
+ lu_printer_t printer,
+ const struct cl_page *pg);
+void cl_page_header_print(const struct lu_env *env, void *cookie,
+ lu_printer_t printer,
+ const struct cl_page *pg);
+struct page *cl_page_vmpage (const struct lu_env *env,
+ struct cl_page *page);
+struct cl_page *cl_vmpage_page (struct page *vmpage, struct cl_object *obj);
+struct cl_page *cl_page_top (struct cl_page *page);
+
+const struct cl_page_slice *cl_page_at(const struct cl_page *page,
+ const struct lu_device_type *dtype);
+
+/**
+ * \name ownership
+ *
+ * Functions dealing with the ownership of page by io.
+ */
+/** @{ */
+
+int cl_page_own (const struct lu_env *env,
+ struct cl_io *io, struct cl_page *page);
+int cl_page_own_try (const struct lu_env *env,
+ struct cl_io *io, struct cl_page *page);
+void cl_page_assume (const struct lu_env *env,
+ struct cl_io *io, struct cl_page *page);
+void cl_page_unassume (const struct lu_env *env,
+ struct cl_io *io, struct cl_page *pg);
+void cl_page_disown (const struct lu_env *env,
+ struct cl_io *io, struct cl_page *page);
+int cl_page_is_owned (const struct cl_page *pg, const struct cl_io *io);
+
+/** @} ownership */
+
+/**
+ * \name transfer
+ *
+ * Functions dealing with the preparation of a page for a transfer, and
+ * tracking transfer state.
+ */
+/** @{ */
+int cl_page_prep (const struct lu_env *env, struct cl_io *io,
+ struct cl_page *pg, enum cl_req_type crt);
+void cl_page_completion (const struct lu_env *env,
+ struct cl_page *pg, enum cl_req_type crt, int ioret);
+int cl_page_make_ready (const struct lu_env *env, struct cl_page *pg,
+ enum cl_req_type crt);
+int cl_page_cache_add (const struct lu_env *env, struct cl_io *io,
+ struct cl_page *pg, enum cl_req_type crt);
+void cl_page_clip (const struct lu_env *env, struct cl_page *pg,
+ int from, int to);
+int cl_page_cancel (const struct lu_env *env, struct cl_page *page);
+int cl_page_flush (const struct lu_env *env, struct cl_io *io,
+ struct cl_page *pg);
+
+/** @} transfer */
+
+
+/**
+ * \name helper routines
+ * Functions to discard, delete and export a cl_page.
+ */
+/** @{ */
+void cl_page_discard (const struct lu_env *env, struct cl_io *io,
+ struct cl_page *pg);
+void cl_page_delete (const struct lu_env *env, struct cl_page *pg);
+int cl_page_unmap (const struct lu_env *env, struct cl_io *io,
+ struct cl_page *pg);
+int cl_page_is_vmlocked (const struct lu_env *env,
+ const struct cl_page *pg);
+void cl_page_export (const struct lu_env *env,
+ struct cl_page *pg, int uptodate);
+int cl_page_is_under_lock(const struct lu_env *env, struct cl_io *io,
+ struct cl_page *page);
+loff_t cl_offset (const struct cl_object *obj, pgoff_t idx);
+pgoff_t cl_index (const struct cl_object *obj, loff_t offset);
+int cl_page_size (const struct cl_object *obj);
+int cl_pages_prune (const struct lu_env *env, struct cl_object *obj);
+
+void cl_lock_print (const struct lu_env *env, void *cookie,
+ lu_printer_t printer, const struct cl_lock *lock);
+void cl_lock_descr_print(const struct lu_env *env, void *cookie,
+ lu_printer_t printer,
+ const struct cl_lock_descr *descr);
+/* @} helper */
+
+/** @} cl_page */
+
+/** \defgroup cl_lock cl_lock
+ * @{ */
+
+struct cl_lock *cl_lock_hold(const struct lu_env *env, const struct cl_io *io,
+ const struct cl_lock_descr *need,
+ const char *scope, const void *source);
+struct cl_lock *cl_lock_peek(const struct lu_env *env, const struct cl_io *io,
+ const struct cl_lock_descr *need,
+ const char *scope, const void *source);
+struct cl_lock *cl_lock_request(const struct lu_env *env, struct cl_io *io,
+ const struct cl_lock_descr *need,
+ const char *scope, const void *source);
+struct cl_lock *cl_lock_at_pgoff(const struct lu_env *env,
+ struct cl_object *obj, pgoff_t index,
+ struct cl_lock *except, int pending,
+ int canceld);
+static inline struct cl_lock *cl_lock_at_page(const struct lu_env *env,
+ struct cl_object *obj,
+ struct cl_page *page,
+ struct cl_lock *except,
+ int pending, int canceld)
+{
+ LASSERT(cl_object_header(obj) == cl_object_header(page->cp_obj));
+ return cl_lock_at_pgoff(env, obj, page->cp_index, except,
+ pending, canceld);
+}
+
+const struct cl_lock_slice *cl_lock_at(const struct cl_lock *lock,
+ const struct lu_device_type *dtype);
+
+void cl_lock_get (struct cl_lock *lock);
+void cl_lock_get_trust (struct cl_lock *lock);
+void cl_lock_put (const struct lu_env *env, struct cl_lock *lock);
+void cl_lock_hold_add (const struct lu_env *env, struct cl_lock *lock,
+ const char *scope, const void *source);
+void cl_lock_hold_release(const struct lu_env *env, struct cl_lock *lock,
+ const char *scope, const void *source);
+void cl_lock_unhold (const struct lu_env *env, struct cl_lock *lock,
+ const char *scope, const void *source);
+void cl_lock_release (const struct lu_env *env, struct cl_lock *lock,
+ const char *scope, const void *source);
+void cl_lock_user_add (const struct lu_env *env, struct cl_lock *lock);
+void cl_lock_user_del (const struct lu_env *env, struct cl_lock *lock);
+
+enum cl_lock_state cl_lock_intransit(const struct lu_env *env,
+ struct cl_lock *lock);
+void cl_lock_extransit(const struct lu_env *env, struct cl_lock *lock,
+ enum cl_lock_state state);
+int cl_lock_is_intransit(struct cl_lock *lock);
+
+int cl_lock_enqueue_wait(const struct lu_env *env, struct cl_lock *lock,
+ int keep_mutex);
+
+/** \name statemachine statemachine
+ * Interface to lock state machine consists of 3 parts:
+ *
+ * - "try" functions that attempt to effect a state transition. If state
+ * transition is not possible right now (e.g., if it has to wait for some
+ * asynchronous event to occur), these functions return
+ * cl_lock_transition::CLO_WAIT.
+ *
+ * - "non-try" functions that implement synchronous blocking interface on
+ * top of non-blocking "try" functions. These functions repeatedly call
+ * corresponding "try" versions, and if state transition is not possible
+ * immediately, wait for lock state change.
+ *
+ * - methods from cl_lock_operations, called by "try" functions. Lock can
+ * be advanced to the target state only when all layers voted that they
+ * are ready for this transition. "Try" functions call methods under lock
+ * mutex. If a layer had to release a mutex, it re-acquires it and returns
+ * cl_lock_transition::CLO_REPEAT, causing "try" function to call all
+ * layers again.
+ *
+ * TRY NON-TRY METHOD FINAL STATE
+ *
+ * cl_enqueue_try() cl_enqueue() cl_lock_operations::clo_enqueue() CLS_ENQUEUED
+ *
+ * cl_wait_try() cl_wait() cl_lock_operations::clo_wait() CLS_HELD
+ *
+ * cl_unuse_try() cl_unuse() cl_lock_operations::clo_unuse() CLS_CACHED
+ *
+ * cl_use_try() NONE cl_lock_operations::clo_use() CLS_HELD
+ *
+ * @{ */
+
+int cl_enqueue (const struct lu_env *env, struct cl_lock *lock,
+ struct cl_io *io, __u32 flags);
+int cl_wait (const struct lu_env *env, struct cl_lock *lock);
+void cl_unuse (const struct lu_env *env, struct cl_lock *lock);
+int cl_enqueue_try(const struct lu_env *env, struct cl_lock *lock,
+ struct cl_io *io, __u32 flags);
+int cl_unuse_try (const struct lu_env *env, struct cl_lock *lock);
+int cl_wait_try (const struct lu_env *env, struct cl_lock *lock);
+int cl_use_try (const struct lu_env *env, struct cl_lock *lock, int atomic);
+
+/** @} statemachine */
+
+void cl_lock_signal (const struct lu_env *env, struct cl_lock *lock);
+int cl_lock_state_wait (const struct lu_env *env, struct cl_lock *lock);
+void cl_lock_state_set (const struct lu_env *env, struct cl_lock *lock,
+ enum cl_lock_state state);
+int cl_queue_match (const struct list_head *queue,
+ const struct cl_lock_descr *need);
+
+void cl_lock_mutex_get (const struct lu_env *env, struct cl_lock *lock);
+int cl_lock_mutex_try (const struct lu_env *env, struct cl_lock *lock);
+void cl_lock_mutex_put (const struct lu_env *env, struct cl_lock *lock);
+int cl_lock_is_mutexed (struct cl_lock *lock);
+int cl_lock_nr_mutexed (const struct lu_env *env);
+int cl_lock_discard_pages(const struct lu_env *env, struct cl_lock *lock);
+int cl_lock_ext_match (const struct cl_lock_descr *has,
+ const struct cl_lock_descr *need);
+int cl_lock_descr_match(const struct cl_lock_descr *has,
+ const struct cl_lock_descr *need);
+int cl_lock_mode_match (enum cl_lock_mode has, enum cl_lock_mode need);
+int cl_lock_modify (const struct lu_env *env, struct cl_lock *lock,
+ const struct cl_lock_descr *desc);
+
+void cl_lock_closure_init (const struct lu_env *env,
+ struct cl_lock_closure *closure,
+ struct cl_lock *origin, int wait);
+void cl_lock_closure_fini (struct cl_lock_closure *closure);
+int cl_lock_closure_build(const struct lu_env *env, struct cl_lock *lock,
+ struct cl_lock_closure *closure);
+void cl_lock_disclosure (const struct lu_env *env,
+ struct cl_lock_closure *closure);
+int cl_lock_enclosure (const struct lu_env *env, struct cl_lock *lock,
+ struct cl_lock_closure *closure);
+
+void cl_lock_cancel(const struct lu_env *env, struct cl_lock *lock);
+void cl_lock_delete(const struct lu_env *env, struct cl_lock *lock);
+void cl_lock_error (const struct lu_env *env, struct cl_lock *lock, int error);
+void cl_locks_prune(const struct lu_env *env, struct cl_object *obj, int wait);
+
+unsigned long cl_lock_weigh(const struct lu_env *env, struct cl_lock *lock);
+
+/** @} cl_lock */
+
+/** \defgroup cl_io cl_io
+ * @{ */
+
+int cl_io_init (const struct lu_env *env, struct cl_io *io,
+ enum cl_io_type iot, struct cl_object *obj);
+int cl_io_sub_init (const struct lu_env *env, struct cl_io *io,
+ enum cl_io_type iot, struct cl_object *obj);
+int cl_io_rw_init (const struct lu_env *env, struct cl_io *io,
+ enum cl_io_type iot, loff_t pos, size_t count);
+int cl_io_loop (const struct lu_env *env, struct cl_io *io);
+
+void cl_io_fini (const struct lu_env *env, struct cl_io *io);
+int cl_io_iter_init (const struct lu_env *env, struct cl_io *io);
+void cl_io_iter_fini (const struct lu_env *env, struct cl_io *io);
+int cl_io_lock (const struct lu_env *env, struct cl_io *io);
+void cl_io_unlock (const struct lu_env *env, struct cl_io *io);
+int cl_io_start (const struct lu_env *env, struct cl_io *io);
+void cl_io_end (const struct lu_env *env, struct cl_io *io);
+int cl_io_lock_add (const struct lu_env *env, struct cl_io *io,
+ struct cl_io_lock_link *link);
+int cl_io_lock_alloc_add(const struct lu_env *env, struct cl_io *io,
+ struct cl_lock_descr *descr);
+int cl_io_read_page (const struct lu_env *env, struct cl_io *io,
+ struct cl_page *page);
+int cl_io_prepare_write(const struct lu_env *env, struct cl_io *io,
+ struct cl_page *page, unsigned from, unsigned to);
+int cl_io_commit_write (const struct lu_env *env, struct cl_io *io,
+ struct cl_page *page, unsigned from, unsigned to);
+int cl_io_submit_rw (const struct lu_env *env, struct cl_io *io,
+ enum cl_req_type iot, struct cl_2queue *queue);
+int cl_io_submit_sync (const struct lu_env *env, struct cl_io *io,
+ enum cl_req_type iot, struct cl_2queue *queue,
+ long timeout);
+void cl_io_rw_advance (const struct lu_env *env, struct cl_io *io,
+ size_t nob);
+int cl_io_cancel (const struct lu_env *env, struct cl_io *io,
+ struct cl_page_list *queue);
+int cl_io_is_going (const struct lu_env *env);
+
+/**
+ * True, iff \a io is an O_APPEND write(2).
+ */
+static inline int cl_io_is_append(const struct cl_io *io)
+{
+ return io->ci_type == CIT_WRITE && io->u.ci_wr.wr_append;
+}
+
+static inline int cl_io_is_sync_write(const struct cl_io *io)
+{
+ return io->ci_type == CIT_WRITE && io->u.ci_wr.wr_sync;
+}
+
+static inline int cl_io_is_mkwrite(const struct cl_io *io)
+{
+ return io->ci_type == CIT_FAULT && io->u.ci_fault.ft_mkwrite;
+}
+
+/**
+ * True, iff \a io is a truncate(2).
+ */
+static inline int cl_io_is_trunc(const struct cl_io *io)
+{
+ return io->ci_type == CIT_SETATTR &&
+ (io->u.ci_setattr.sa_valid & ATTR_SIZE);
+}
+
+struct cl_io *cl_io_top(struct cl_io *io);
+
+void cl_io_print(const struct lu_env *env, void *cookie,
+ lu_printer_t printer, const struct cl_io *io);
+
+#define CL_IO_SLICE_CLEAN(foo_io, base) \
+do { \
+ typeof(foo_io) __foo_io = (foo_io); \
+ \
+ CLASSERT(offsetof(typeof(*__foo_io), base) == 0); \
+ memset(&__foo_io->base + 1, 0, \
+ sizeof(*__foo_io) - sizeof(__foo_io->base)); \
+} while (0)
+
+/** @} cl_io */
+
+/** \defgroup cl_page_list cl_page_list
+ * @{ */
+
+/**
+ * Last page in the page list.
+ */
+static inline struct cl_page *cl_page_list_last(struct cl_page_list *plist)
+{
+ LASSERT(plist->pl_nr > 0);
+ return list_entry(plist->pl_pages.prev, struct cl_page, cp_batch);
+}
+
+/**
+ * Iterate over pages in a page list.
+ */
+#define cl_page_list_for_each(page, list) \
+ list_for_each_entry((page), &(list)->pl_pages, cp_batch)
+
+/**
+ * Iterate over pages in a page list, taking possible removals into account.
+ */
+#define cl_page_list_for_each_safe(page, temp, list) \
+ list_for_each_entry_safe((page), (temp), &(list)->pl_pages, cp_batch)
+
+void cl_page_list_init (struct cl_page_list *plist);
+void cl_page_list_add (struct cl_page_list *plist, struct cl_page *page);
+void cl_page_list_move (struct cl_page_list *dst, struct cl_page_list *src,
+ struct cl_page *page);
+void cl_page_list_splice (struct cl_page_list *list,
+ struct cl_page_list *head);
+void cl_page_list_del (const struct lu_env *env,
+ struct cl_page_list *plist, struct cl_page *page);
+void cl_page_list_disown (const struct lu_env *env,
+ struct cl_io *io, struct cl_page_list *plist);
+int cl_page_list_own (const struct lu_env *env,
+ struct cl_io *io, struct cl_page_list *plist);
+void cl_page_list_assume (const struct lu_env *env,
+ struct cl_io *io, struct cl_page_list *plist);
+void cl_page_list_discard(const struct lu_env *env,
+ struct cl_io *io, struct cl_page_list *plist);
+int cl_page_list_unmap (const struct lu_env *env,
+ struct cl_io *io, struct cl_page_list *plist);
+void cl_page_list_fini (const struct lu_env *env, struct cl_page_list *plist);
+
+void cl_2queue_init (struct cl_2queue *queue);
+void cl_2queue_add (struct cl_2queue *queue, struct cl_page *page);
+void cl_2queue_disown (const struct lu_env *env,
+ struct cl_io *io, struct cl_2queue *queue);
+void cl_2queue_assume (const struct lu_env *env,
+ struct cl_io *io, struct cl_2queue *queue);
+void cl_2queue_discard (const struct lu_env *env,
+ struct cl_io *io, struct cl_2queue *queue);
+void cl_2queue_fini (const struct lu_env *env, struct cl_2queue *queue);
+void cl_2queue_init_page(struct cl_2queue *queue, struct cl_page *page);
+
+/** @} cl_page_list */
+
+/** \defgroup cl_req cl_req
+ * @{ */
+struct cl_req *cl_req_alloc(const struct lu_env *env, struct cl_page *page,
+ enum cl_req_type crt, int nr_objects);
+
+void cl_req_page_add (const struct lu_env *env, struct cl_req *req,
+ struct cl_page *page);
+void cl_req_page_done (const struct lu_env *env, struct cl_page *page);
+int cl_req_prep (const struct lu_env *env, struct cl_req *req);
+void cl_req_attr_set (const struct lu_env *env, struct cl_req *req,
+ struct cl_req_attr *attr, u64 flags);
+void cl_req_completion(const struct lu_env *env, struct cl_req *req, int ioret);
+
+/** \defgroup cl_sync_io cl_sync_io
+ * @{ */
+
+/**
+ * Anchor for synchronous transfer. This is allocated on a stack by thread
+ * doing synchronous transfer, and a pointer to this structure is set up in
+ * every page submitted for transfer. Transfer completion routine updates
+ * anchor and wakes up waiting thread when transfer is complete.
+ */
+struct cl_sync_io {
+ /** number of pages yet to be transferred. */
+ atomic_t csi_sync_nr;
+ /** error code. */
+ int csi_sync_rc;
+ /** barrier of destroy this structure */
+ atomic_t csi_barrier;
+ /** completion to be signaled when transfer is complete. */
+ wait_queue_head_t csi_waitq;
+};
+
+void cl_sync_io_init(struct cl_sync_io *anchor, int nrpages);
+int cl_sync_io_wait(const struct lu_env *env, struct cl_io *io,
+ struct cl_page_list *queue, struct cl_sync_io *anchor,
+ long timeout);
+void cl_sync_io_note(struct cl_sync_io *anchor, int ioret);
+
+/** @} cl_sync_io */
+
+/** @} cl_req */
+
+/** \defgroup cl_env cl_env
+ *
+ * lu_env handling for a client.
+ *
+ * lu_env is an environment within which lustre code executes. Its major part
+ * is lu_context---a fast memory allocation mechanism that is used to conserve
+ * precious kernel stack space. Originally lu_env was designed for a server,
+ * where
+ *
+ * - there is a (mostly) fixed number of threads, and
+ *
+ * - call chains have no non-lustre portions inserted between lustre code.
+ *
+ * On a client both these assumption fails, because every user thread can
+ * potentially execute lustre code as part of a system call, and lustre calls
+ * into VFS or MM that call back into lustre.
+ *
+ * To deal with that, cl_env wrapper functions implement the following
+ * optimizations:
+ *
+ * - allocation and destruction of environment is amortized by caching no
+ * longer used environments instead of destroying them;
+ *
+ * - there is a notion of "current" environment, attached to the kernel
+ * data structure representing current thread Top-level lustre code
+ * allocates an environment and makes it current, then calls into
+ * non-lustre code, that in turn calls lustre back. Low-level lustre
+ * code thus called can fetch environment created by the top-level code
+ * and reuse it, avoiding additional environment allocation.
+ * Right now, three interfaces can attach the cl_env to running thread:
+ * - cl_env_get
+ * - cl_env_implant
+ * - cl_env_reexit(cl_env_reenter had to be called priorly)
+ *
+ * \see lu_env, lu_context, lu_context_key
+ * @{ */
+
+struct cl_env_nest {
+ int cen_refcheck;
+ void *cen_cookie;
+};
+
+struct lu_env *cl_env_peek (int *refcheck);
+struct lu_env *cl_env_get (int *refcheck);
+struct lu_env *cl_env_alloc (int *refcheck, __u32 tags);
+struct lu_env *cl_env_nested_get (struct cl_env_nest *nest);
+void cl_env_put (struct lu_env *env, int *refcheck);
+void cl_env_nested_put (struct cl_env_nest *nest, struct lu_env *env);
+void *cl_env_reenter (void);
+void cl_env_reexit (void *cookie);
+void cl_env_implant (struct lu_env *env, int *refcheck);
+void cl_env_unplant (struct lu_env *env, int *refcheck);
+
+/** @} cl_env */
+
+/*
+ * Misc
+ */
+void cl_attr2lvb(struct ost_lvb *lvb, const struct cl_attr *attr);
+void cl_lvb2attr(struct cl_attr *attr, const struct ost_lvb *lvb);
+
+struct cl_device *cl_type_setup(const struct lu_env *env, struct lu_site *site,
+ struct lu_device_type *ldt,
+ struct lu_device *next);
+/** @} clio */
+
+int cl_global_init(void);
+void cl_global_fini(void);
+
+#endif /* _LINUX_CL_OBJECT_H */
Code Review / kvmfornfv.git / blobdiff