kernel/drivers/staging/lustre/lustre/lclient/glimpse.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2011, 2012, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * glimpse code shared between vvp and liblustre (and other Lustre clients in
  37  * the future).
  38  *
  39  *   Author: Nikita Danilov <nikita.danilov@sun.com>
  40  *   Author: Oleg Drokin <oleg.drokin@sun.com>
  41  */
  42
  43 #include "../../include/linux/libcfs/libcfs.h"
  44 #include "../include/obd_class.h"
  45 #include "../include/obd_support.h"
  46 #include "../include/obd.h"
  47
  48 #include "../include/lustre_dlm.h"
  49 #include "../include/lustre_lite.h"
  50 #include "../include/lustre_mdc.h"
  51 #include <linux/pagemap.h>
  52 #include <linux/file.h>
  53
  54 #include "../include/cl_object.h"
  55 #include "../include/lclient.h"
  56 #include "../llite/llite_internal.h"
  57
  58 static const struct cl_lock_descr whole_file = {
  59         .cld_start = 0,
  60         .cld_end   = CL_PAGE_EOF,
  61         .cld_mode  = CLM_READ
  62 };
  63
  64 /*
  65  * Check whether file has possible unwriten pages.
  66  *
  67  * \retval 1    file is mmap-ed or has dirty pages
  68  *       0    otherwise
  69  */
  70 blkcnt_t dirty_cnt(struct inode *inode)
  71 {
  72         blkcnt_t cnt = 0;
  73         struct ccc_object *vob = cl_inode2ccc(inode);
  74         void          *results[1];
  75
  76         if (inode->i_mapping != NULL)
  77                 cnt += radix_tree_gang_lookup_tag(&inode->i_mapping->page_tree,
  78                                                   results, 0, 1,
  79                                                   PAGECACHE_TAG_DIRTY);
  80         if (cnt == 0 && atomic_read(&vob->cob_mmap_cnt) > 0)
  81                 cnt = 1;
  82
  83         return (cnt > 0) ? 1 : 0;
  84 }
  85
  86 int cl_glimpse_lock(const struct lu_env *env, struct cl_io *io,
  87                     struct inode *inode, struct cl_object *clob, int agl)
  88 {
  89         struct cl_lock_descr *descr = &ccc_env_info(env)->cti_descr;
  90         struct cl_inode_info *lli   = cl_i2info(inode);
  91         const struct lu_fid  *fid   = lu_object_fid(&clob->co_lu);
  92         struct ccc_io   *cio   = ccc_env_io(env);
  93         struct cl_lock       *lock;
  94         int result;
  95
  96         result = 0;
  97         if (!(lli->lli_flags & LLIF_MDS_SIZE_LOCK)) {
  98                 CDEBUG(D_DLMTRACE, "Glimpsing inode "DFID"\n", PFID(fid));
  99                 if (lli->lli_has_smd) {
 100                         /* NOTE: this looks like DLM lock request, but it may
 101                          *       not be one. Due to CEF_ASYNC flag (translated
 102                          *       to LDLM_FL_HAS_INTENT by osc), this is
 103                          *       glimpse request, that won't revoke any
 104                          *       conflicting DLM locks held. Instead,
 105                          *       ll_glimpse_callback() will be called on each
 106                          *       client holding a DLM lock against this file,
 107                          *       and resulting size will be returned for each
 108                          *       stripe. DLM lock on [0, EOF] is acquired only
 109                          *       if there were no conflicting locks. If there
 110                          *       were conflicting locks, enqueuing or waiting
 111                          *       fails with -ENAVAIL, but valid inode
 112                          *       attributes are returned anyway. */
 113                         *descr = whole_file;
 114                         descr->cld_obj   = clob;
 115                         descr->cld_mode  = CLM_PHANTOM;
 116                         descr->cld_enq_flags = CEF_ASYNC | CEF_MUST;
 117                         if (agl)
 118                                 descr->cld_enq_flags |= CEF_AGL;
 119                         cio->cui_glimpse = 1;
 120                         /*
 121                          * CEF_ASYNC is used because glimpse sub-locks cannot
 122                          * deadlock (because they never conflict with other
 123                          * locks) and, hence, can be enqueued out-of-order.
 124                          *
 125                          * CEF_MUST protects glimpse lock from conversion into
 126                          * a lockless mode.
 127                          */
 128                         lock = cl_lock_request(env, io, descr, "glimpse",
 129                                                current);
 130                         cio->cui_glimpse = 0;
 131
 132                         if (lock == NULL)
 133                                 return 0;
 134
 135                         if (IS_ERR(lock))
 136                                 return PTR_ERR(lock);
 137
 138                         LASSERT(agl == 0);
 139                         result = cl_wait(env, lock);
 140                         if (result == 0) {
 141                                 cl_merge_lvb(env, inode);
 142                                 if (cl_isize_read(inode) > 0 &&
 143                                     inode->i_blocks == 0) {
 144                                         /*
 145                                          * LU-417: Add dirty pages block count
 146                                          * lest i_blocks reports 0, some "cp" or
 147                                          * "tar" may think it's a completely
 148                                          * sparse file and skip it.
 149                                          */
 150                                         inode->i_blocks = dirty_cnt(inode);
 151                                 }
 152                                 cl_unuse(env, lock);
 153                         }
 154                         cl_lock_release(env, lock, "glimpse", current);
 155                 } else {
 156                         CDEBUG(D_DLMTRACE, "No objects for inode\n");
 157                         cl_merge_lvb(env, inode);
 158                 }
 159         }
 160
 161         return result;
 162 }
 163
 164 static int cl_io_get(struct inode *inode, struct lu_env **envout,
 165                      struct cl_io **ioout, int *refcheck)
 166 {
 167         struct lu_env     *env;
 168         struct cl_io       *io;
 169         struct cl_inode_info   *lli = cl_i2info(inode);
 170         struct cl_object       *clob = lli->lli_clob;
 171         int result;
 172
 173         if (S_ISREG(cl_inode_mode(inode))) {
 174                 env = cl_env_get(refcheck);
 175                 if (!IS_ERR(env)) {
 176                         io = ccc_env_thread_io(env);
 177                         io->ci_obj = clob;
 178                         *envout = env;
 179                         *ioout  = io;
 180                         result = 1;
 181                 } else
 182                         result = PTR_ERR(env);
 183         } else
 184                 result = 0;
 185         return result;
 186 }
 187
 188 int cl_glimpse_size0(struct inode *inode, int agl)
 189 {
 190         /*
 191          * We don't need ast_flags argument to cl_glimpse_size(), because
 192          * osc_lock_enqueue() takes care of the possible deadlock that said
 193          * argument was introduced to avoid.
 194          */
 195         /*
 196          * XXX but note that ll_file_seek() passes LDLM_FL_BLOCK_NOWAIT to
 197          * cl_glimpse_size(), which doesn't make sense: glimpse locks are not
 198          * blocking anyway.
 199          */
 200         struct lu_env     *env = NULL;
 201         struct cl_io       *io  = NULL;
 202         int                  result;
 203         int                  refcheck;
 204
 205         result = cl_io_get(inode, &env, &io, &refcheck);
 206         if (result > 0) {
 207 again:
 208                 io->ci_verify_layout = 1;
 209                 result = cl_io_init(env, io, CIT_MISC, io->ci_obj);
 210                 if (result > 0)
 211                         /*
 212                          * nothing to do for this io. This currently happens
 213                          * when stripe sub-object's are not yet created.
 214                          */
 215                         result = io->ci_result;
 216                 else if (result == 0)
 217                         result = cl_glimpse_lock(env, io, inode, io->ci_obj,
 218                                                  agl);
 219
 220                 OBD_FAIL_TIMEOUT(OBD_FAIL_GLIMPSE_DELAY, 2);
 221                 cl_io_fini(env, io);
 222                 if (unlikely(io->ci_need_restart))
 223                         goto again;
 224                 cl_env_put(env, &refcheck);
 225         }
 226         return result;
 227 }
 228
 229 int cl_local_size(struct inode *inode)
 230 {
 231         struct lu_env      *env = NULL;
 232         struct cl_io        *io  = NULL;
 233         struct ccc_thread_info  *cti;
 234         struct cl_object        *clob;
 235         struct cl_lock_descr    *descr;
 236         struct cl_lock    *lock;
 237         int                   result;
 238         int                   refcheck;
 239
 240         if (!cl_i2info(inode)->lli_has_smd)
 241                 return 0;
 242
 243         result = cl_io_get(inode, &env, &io, &refcheck);
 244         if (result <= 0)
 245                 return result;
 246
 247         clob = io->ci_obj;
 248         result = cl_io_init(env, io, CIT_MISC, clob);
 249         if (result > 0)
 250                 result = io->ci_result;
 251         else if (result == 0) {
 252                 cti = ccc_env_info(env);
 253                 descr = &cti->cti_descr;
 254
 255                 *descr = whole_file;
 256                 descr->cld_obj = clob;
 257                 lock = cl_lock_peek(env, io, descr, "localsize", current);
 258                 if (lock != NULL) {
 259                         cl_merge_lvb(env, inode);
 260                         cl_unuse(env, lock);
 261                         cl_lock_release(env, lock, "localsize", current);
 262                         result = 0;
 263                 } else
 264                         result = -ENODATA;
 265         }
 266         cl_io_fini(env, io);
 267         cl_env_put(env, &refcheck);
 268         return result;
 269 }