--- /dev/null
+/*
+ * linux/fs/lockd/svclock.c
+ *
+ * Handling of server-side locks, mostly of the blocked variety.
+ * This is the ugliest part of lockd because we tread on very thin ice.
+ * GRANT and CANCEL calls may get stuck, meet in mid-flight, etc.
+ * IMNSHO introducing the grant callback into the NLM protocol was one
+ * of the worst ideas Sun ever had. Except maybe for the idea of doing
+ * NFS file locking at all.
+ *
+ * I'm trying hard to avoid race conditions by protecting most accesses
+ * to a file's list of blocked locks through a semaphore. The global
+ * list of blocked locks is not protected in this fashion however.
+ * Therefore, some functions (such as the RPC callback for the async grant
+ * call) move blocked locks towards the head of the list *while some other
+ * process might be traversing it*. This should not be a problem in
+ * practice, because this will only cause functions traversing the list
+ * to visit some blocks twice.
+ *
+ * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
+ */
+
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/svc_xprt.h>
+#include <linux/lockd/nlm.h>
+#include <linux/lockd/lockd.h>
+#include <linux/kthread.h>
+
+#define NLMDBG_FACILITY NLMDBG_SVCLOCK
+
+#ifdef CONFIG_LOCKD_V4
+#define nlm_deadlock nlm4_deadlock
+#else
+#define nlm_deadlock nlm_lck_denied
+#endif
+
+static void nlmsvc_release_block(struct nlm_block *block);
+static void nlmsvc_insert_block(struct nlm_block *block, unsigned long);
+static void nlmsvc_remove_block(struct nlm_block *block);
+
+static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
+static void nlmsvc_freegrantargs(struct nlm_rqst *call);
+static const struct rpc_call_ops nlmsvc_grant_ops;
+
+/*
+ * The list of blocked locks to retry
+ */
+static LIST_HEAD(nlm_blocked);
+static DEFINE_SPINLOCK(nlm_blocked_lock);
+
+#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
+static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
+{
+ /*
+ * We can get away with a static buffer because this is only called
+ * from lockd, which is single-threaded.
+ */
+ static char buf[2*NLM_MAXCOOKIELEN+1];
+ unsigned int i, len = sizeof(buf);
+ char *p = buf;
+
+ len--; /* allow for trailing \0 */
+ if (len < 3)
+ return "???";
+ for (i = 0 ; i < cookie->len ; i++) {
+ if (len < 2) {
+ strcpy(p-3, "...");
+ break;
+ }
+ sprintf(p, "%02x", cookie->data[i]);
+ p += 2;
+ len -= 2;
+ }
+ *p = '\0';
+
+ return buf;
+}
+#endif
+
+/*
+ * Insert a blocked lock into the global list
+ */
+static void
+nlmsvc_insert_block_locked(struct nlm_block *block, unsigned long when)
+{
+ struct nlm_block *b;
+ struct list_head *pos;
+
+ dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
+ if (list_empty(&block->b_list)) {
+ kref_get(&block->b_count);
+ } else {
+ list_del_init(&block->b_list);
+ }
+
+ pos = &nlm_blocked;
+ if (when != NLM_NEVER) {
+ if ((when += jiffies) == NLM_NEVER)
+ when ++;
+ list_for_each(pos, &nlm_blocked) {
+ b = list_entry(pos, struct nlm_block, b_list);
+ if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
+ break;
+ }
+ /* On normal exit from the loop, pos == &nlm_blocked,
+ * so we will be adding to the end of the list - good
+ */
+ }
+
+ list_add_tail(&block->b_list, pos);
+ block->b_when = when;
+}
+
+static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
+{
+ spin_lock(&nlm_blocked_lock);
+ nlmsvc_insert_block_locked(block, when);
+ spin_unlock(&nlm_blocked_lock);
+}
+
+/*
+ * Remove a block from the global list
+ */
+static inline void
+nlmsvc_remove_block(struct nlm_block *block)
+{
+ if (!list_empty(&block->b_list)) {
+ spin_lock(&nlm_blocked_lock);
+ list_del_init(&block->b_list);
+ spin_unlock(&nlm_blocked_lock);
+ nlmsvc_release_block(block);
+ }
+}
+
+/*
+ * Find a block for a given lock
+ */
+static struct nlm_block *
+nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
+{
+ struct nlm_block *block;
+ struct file_lock *fl;
+
+ dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
+ file, lock->fl.fl_pid,
+ (long long)lock->fl.fl_start,
+ (long long)lock->fl.fl_end, lock->fl.fl_type);
+ list_for_each_entry(block, &nlm_blocked, b_list) {
+ fl = &block->b_call->a_args.lock.fl;
+ dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
+ block->b_file, fl->fl_pid,
+ (long long)fl->fl_start,
+ (long long)fl->fl_end, fl->fl_type,
+ nlmdbg_cookie2a(&block->b_call->a_args.cookie));
+ if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
+ kref_get(&block->b_count);
+ return block;
+ }
+ }
+
+ return NULL;
+}
+
+static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
+{
+ if (a->len != b->len)
+ return 0;
+ if (memcmp(a->data, b->data, a->len))
+ return 0;
+ return 1;
+}
+
+/*
+ * Find a block with a given NLM cookie.
+ */
+static inline struct nlm_block *
+nlmsvc_find_block(struct nlm_cookie *cookie)
+{
+ struct nlm_block *block;
+
+ list_for_each_entry(block, &nlm_blocked, b_list) {
+ if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
+ goto found;
+ }
+
+ return NULL;
+
+found:
+ dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
+ kref_get(&block->b_count);
+ return block;
+}
+
+/*
+ * Create a block and initialize it.
+ *
+ * Note: we explicitly set the cookie of the grant reply to that of
+ * the blocked lock request. The spec explicitly mentions that the client
+ * should _not_ rely on the callback containing the same cookie as the
+ * request, but (as I found out later) that's because some implementations
+ * do just this. Never mind the standards comittees, they support our
+ * logging industries.
+ *
+ * 10 years later: I hope we can safely ignore these old and broken
+ * clients by now. Let's fix this so we can uniquely identify an incoming
+ * GRANTED_RES message by cookie, without having to rely on the client's IP
+ * address. --okir
+ */
+static struct nlm_block *
+nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
+ struct nlm_file *file, struct nlm_lock *lock,
+ struct nlm_cookie *cookie)
+{
+ struct nlm_block *block;
+ struct nlm_rqst *call = NULL;
+
+ call = nlm_alloc_call(host);
+ if (call == NULL)
+ return NULL;
+
+ /* Allocate memory for block, and initialize arguments */
+ block = kzalloc(sizeof(*block), GFP_KERNEL);
+ if (block == NULL)
+ goto failed;
+ kref_init(&block->b_count);
+ INIT_LIST_HEAD(&block->b_list);
+ INIT_LIST_HEAD(&block->b_flist);
+
+ if (!nlmsvc_setgrantargs(call, lock))
+ goto failed_free;
+
+ /* Set notifier function for VFS, and init args */
+ call->a_args.lock.fl.fl_flags |= FL_SLEEP;
+ call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
+ nlmclnt_next_cookie(&call->a_args.cookie);
+
+ dprintk("lockd: created block %p...\n", block);
+
+ /* Create and initialize the block */
+ block->b_daemon = rqstp->rq_server;
+ block->b_host = host;
+ block->b_file = file;
+ file->f_count++;
+
+ /* Add to file's list of blocks */
+ list_add(&block->b_flist, &file->f_blocks);
+
+ /* Set up RPC arguments for callback */
+ block->b_call = call;
+ call->a_flags = RPC_TASK_ASYNC;
+ call->a_block = block;
+
+ return block;
+
+failed_free:
+ kfree(block);
+failed:
+ nlmsvc_release_call(call);
+ return NULL;
+}
+
+/*
+ * Delete a block.
+ * It is the caller's responsibility to check whether the file
+ * can be closed hereafter.
+ */
+static int nlmsvc_unlink_block(struct nlm_block *block)
+{
+ int status;
+ dprintk("lockd: unlinking block %p...\n", block);
+
+ /* Remove block from list */
+ status = posix_unblock_lock(&block->b_call->a_args.lock.fl);
+ nlmsvc_remove_block(block);
+ return status;
+}
+
+static void nlmsvc_free_block(struct kref *kref)
+{
+ struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
+ struct nlm_file *file = block->b_file;
+
+ dprintk("lockd: freeing block %p...\n", block);
+
+ /* Remove block from file's list of blocks */
+ list_del_init(&block->b_flist);
+ mutex_unlock(&file->f_mutex);
+
+ nlmsvc_freegrantargs(block->b_call);
+ nlmsvc_release_call(block->b_call);
+ nlm_release_file(block->b_file);
+ kfree(block);
+}
+
+static void nlmsvc_release_block(struct nlm_block *block)
+{
+ if (block != NULL)
+ kref_put_mutex(&block->b_count, nlmsvc_free_block, &block->b_file->f_mutex);
+}
+
+/*
+ * Loop over all blocks and delete blocks held by
+ * a matching host.
+ */
+void nlmsvc_traverse_blocks(struct nlm_host *host,
+ struct nlm_file *file,
+ nlm_host_match_fn_t match)
+{
+ struct nlm_block *block, *next;
+
+restart:
+ mutex_lock(&file->f_mutex);
+ list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
+ if (!match(block->b_host, host))
+ continue;
+ /* Do not destroy blocks that are not on
+ * the global retry list - why? */
+ if (list_empty(&block->b_list))
+ continue;
+ kref_get(&block->b_count);
+ mutex_unlock(&file->f_mutex);
+ nlmsvc_unlink_block(block);
+ nlmsvc_release_block(block);
+ goto restart;
+ }
+ mutex_unlock(&file->f_mutex);
+}
+
+/*
+ * Initialize arguments for GRANTED call. The nlm_rqst structure
+ * has been cleared already.
+ */
+static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
+{
+ locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
+ memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
+ call->a_args.lock.caller = utsname()->nodename;
+ call->a_args.lock.oh.len = lock->oh.len;
+
+ /* set default data area */
+ call->a_args.lock.oh.data = call->a_owner;
+ call->a_args.lock.svid = lock->fl.fl_pid;
+
+ if (lock->oh.len > NLMCLNT_OHSIZE) {
+ void *data = kmalloc(lock->oh.len, GFP_KERNEL);
+ if (!data)
+ return 0;
+ call->a_args.lock.oh.data = (u8 *) data;
+ }
+
+ memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
+ return 1;
+}
+
+static void nlmsvc_freegrantargs(struct nlm_rqst *call)
+{
+ if (call->a_args.lock.oh.data != call->a_owner)
+ kfree(call->a_args.lock.oh.data);
+
+ locks_release_private(&call->a_args.lock.fl);
+}
+
+/*
+ * Deferred lock request handling for non-blocking lock
+ */
+static __be32
+nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
+{
+ __be32 status = nlm_lck_denied_nolocks;
+
+ block->b_flags |= B_QUEUED;
+
+ nlmsvc_insert_block(block, NLM_TIMEOUT);
+
+ block->b_cache_req = &rqstp->rq_chandle;
+ if (rqstp->rq_chandle.defer) {
+ block->b_deferred_req =
+ rqstp->rq_chandle.defer(block->b_cache_req);
+ if (block->b_deferred_req != NULL)
+ status = nlm_drop_reply;
+ }
+ dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
+ block, block->b_flags, ntohl(status));
+
+ return status;
+}
+
+/*
+ * Attempt to establish a lock, and if it can't be granted, block it
+ * if required.
+ */
+__be32
+nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
+ struct nlm_host *host, struct nlm_lock *lock, int wait,
+ struct nlm_cookie *cookie, int reclaim)
+{
+ struct nlm_block *block = NULL;
+ int error;
+ __be32 ret;
+
+ dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
+ file_inode(file->f_file)->i_sb->s_id,
+ file_inode(file->f_file)->i_ino,
+ lock->fl.fl_type, lock->fl.fl_pid,
+ (long long)lock->fl.fl_start,
+ (long long)lock->fl.fl_end,
+ wait);
+
+ /* Lock file against concurrent access */
+ mutex_lock(&file->f_mutex);
+ /* Get existing block (in case client is busy-waiting)
+ * or create new block
+ */
+ block = nlmsvc_lookup_block(file, lock);
+ if (block == NULL) {
+ block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
+ ret = nlm_lck_denied_nolocks;
+ if (block == NULL)
+ goto out;
+ lock = &block->b_call->a_args.lock;
+ } else
+ lock->fl.fl_flags &= ~FL_SLEEP;
+
+ if (block->b_flags & B_QUEUED) {
+ dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
+ block, block->b_flags);
+ if (block->b_granted) {
+ nlmsvc_unlink_block(block);
+ ret = nlm_granted;
+ goto out;
+ }
+ if (block->b_flags & B_TIMED_OUT) {
+ nlmsvc_unlink_block(block);
+ ret = nlm_lck_denied;
+ goto out;
+ }
+ ret = nlm_drop_reply;
+ goto out;
+ }
+
+ if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
+ ret = nlm_lck_denied_grace_period;
+ goto out;
+ }
+ if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
+ ret = nlm_lck_denied_grace_period;
+ goto out;
+ }
+
+ if (!wait)
+ lock->fl.fl_flags &= ~FL_SLEEP;
+ error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
+ lock->fl.fl_flags &= ~FL_SLEEP;
+
+ dprintk("lockd: vfs_lock_file returned %d\n", error);
+ switch (error) {
+ case 0:
+ ret = nlm_granted;
+ goto out;
+ case -EAGAIN:
+ /*
+ * If this is a blocking request for an
+ * already pending lock request then we need
+ * to put it back on lockd's block list
+ */
+ if (wait)
+ break;
+ ret = nlm_lck_denied;
+ goto out;
+ case FILE_LOCK_DEFERRED:
+ if (wait)
+ break;
+ /* Filesystem lock operation is in progress
+ Add it to the queue waiting for callback */
+ ret = nlmsvc_defer_lock_rqst(rqstp, block);
+ goto out;
+ case -EDEADLK:
+ ret = nlm_deadlock;
+ goto out;
+ default: /* includes ENOLCK */
+ ret = nlm_lck_denied_nolocks;
+ goto out;
+ }
+
+ ret = nlm_lck_blocked;
+
+ /* Append to list of blocked */
+ nlmsvc_insert_block(block, NLM_NEVER);
+out:
+ mutex_unlock(&file->f_mutex);
+ nlmsvc_release_block(block);
+ dprintk("lockd: nlmsvc_lock returned %u\n", ret);
+ return ret;
+}
+
+/*
+ * Test for presence of a conflicting lock.
+ */
+__be32
+nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
+ struct nlm_host *host, struct nlm_lock *lock,
+ struct nlm_lock *conflock, struct nlm_cookie *cookie)
+{
+ int error;
+ __be32 ret;
+
+ dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
+ file_inode(file->f_file)->i_sb->s_id,
+ file_inode(file->f_file)->i_ino,
+ lock->fl.fl_type,
+ (long long)lock->fl.fl_start,
+ (long long)lock->fl.fl_end);
+
+ if (locks_in_grace(SVC_NET(rqstp))) {
+ ret = nlm_lck_denied_grace_period;
+ goto out;
+ }
+
+ error = vfs_test_lock(file->f_file, &lock->fl);
+ if (error) {
+ /* We can't currently deal with deferred test requests */
+ if (error == FILE_LOCK_DEFERRED)
+ WARN_ON_ONCE(1);
+
+ ret = nlm_lck_denied_nolocks;
+ goto out;
+ }
+
+ if (lock->fl.fl_type == F_UNLCK) {
+ ret = nlm_granted;
+ goto out;
+ }
+
+ dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
+ lock->fl.fl_type, (long long)lock->fl.fl_start,
+ (long long)lock->fl.fl_end);
+ conflock->caller = "somehost"; /* FIXME */
+ conflock->len = strlen(conflock->caller);
+ conflock->oh.len = 0; /* don't return OH info */
+ conflock->svid = lock->fl.fl_pid;
+ conflock->fl.fl_type = lock->fl.fl_type;
+ conflock->fl.fl_start = lock->fl.fl_start;
+ conflock->fl.fl_end = lock->fl.fl_end;
+ locks_release_private(&lock->fl);
+ ret = nlm_lck_denied;
+out:
+ return ret;
+}
+
+/*
+ * Remove a lock.
+ * This implies a CANCEL call: We send a GRANT_MSG, the client replies
+ * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
+ * afterwards. In this case the block will still be there, and hence
+ * must be removed.
+ */
+__be32
+nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
+{
+ int error;
+
+ dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
+ file_inode(file->f_file)->i_sb->s_id,
+ file_inode(file->f_file)->i_ino,
+ lock->fl.fl_pid,
+ (long long)lock->fl.fl_start,
+ (long long)lock->fl.fl_end);
+
+ /* First, cancel any lock that might be there */
+ nlmsvc_cancel_blocked(net, file, lock);
+
+ lock->fl.fl_type = F_UNLCK;
+ error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
+
+ return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
+}
+
+/*
+ * Cancel a previously blocked request.
+ *
+ * A cancel request always overrides any grant that may currently
+ * be in progress.
+ * The calling procedure must check whether the file can be closed.
+ */
+__be32
+nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
+{
+ struct nlm_block *block;
+ int status = 0;
+
+ dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
+ file_inode(file->f_file)->i_sb->s_id,
+ file_inode(file->f_file)->i_ino,
+ lock->fl.fl_pid,
+ (long long)lock->fl.fl_start,
+ (long long)lock->fl.fl_end);
+
+ if (locks_in_grace(net))
+ return nlm_lck_denied_grace_period;
+
+ mutex_lock(&file->f_mutex);
+ block = nlmsvc_lookup_block(file, lock);
+ mutex_unlock(&file->f_mutex);
+ if (block != NULL) {
+ vfs_cancel_lock(block->b_file->f_file,
+ &block->b_call->a_args.lock.fl);
+ status = nlmsvc_unlink_block(block);
+ nlmsvc_release_block(block);
+ }
+ return status ? nlm_lck_denied : nlm_granted;
+}
+
+/*
+ * This is a callback from the filesystem for VFS file lock requests.
+ * It will be used if lm_grant is defined and the filesystem can not
+ * respond to the request immediately.
+ * For SETLK or SETLKW request it will get the local posix lock.
+ * In all cases it will move the block to the head of nlm_blocked q where
+ * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
+ * deferred rpc for GETLK and SETLK.
+ */
+static void
+nlmsvc_update_deferred_block(struct nlm_block *block, int result)
+{
+ block->b_flags |= B_GOT_CALLBACK;
+ if (result == 0)
+ block->b_granted = 1;
+ else
+ block->b_flags |= B_TIMED_OUT;
+}
+
+static int nlmsvc_grant_deferred(struct file_lock *fl, int result)
+{
+ struct nlm_block *block;
+ int rc = -ENOENT;
+
+ spin_lock(&nlm_blocked_lock);
+ list_for_each_entry(block, &nlm_blocked, b_list) {
+ if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
+ dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
+ block, block->b_flags);
+ if (block->b_flags & B_QUEUED) {
+ if (block->b_flags & B_TIMED_OUT) {
+ rc = -ENOLCK;
+ break;
+ }
+ nlmsvc_update_deferred_block(block, result);
+ } else if (result == 0)
+ block->b_granted = 1;
+
+ nlmsvc_insert_block_locked(block, 0);
+ svc_wake_up(block->b_daemon);
+ rc = 0;
+ break;
+ }
+ }
+ spin_unlock(&nlm_blocked_lock);
+ if (rc == -ENOENT)
+ printk(KERN_WARNING "lockd: grant for unknown block\n");
+ return rc;
+}
+
+/*
+ * Unblock a blocked lock request. This is a callback invoked from the
+ * VFS layer when a lock on which we blocked is removed.
+ *
+ * This function doesn't grant the blocked lock instantly, but rather moves
+ * the block to the head of nlm_blocked where it can be picked up by lockd.
+ */
+static void
+nlmsvc_notify_blocked(struct file_lock *fl)
+{
+ struct nlm_block *block;
+
+ dprintk("lockd: VFS unblock notification for block %p\n", fl);
+ spin_lock(&nlm_blocked_lock);
+ list_for_each_entry(block, &nlm_blocked, b_list) {
+ if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
+ nlmsvc_insert_block_locked(block, 0);
+ spin_unlock(&nlm_blocked_lock);
+ svc_wake_up(block->b_daemon);
+ return;
+ }
+ }
+ spin_unlock(&nlm_blocked_lock);
+ printk(KERN_WARNING "lockd: notification for unknown block!\n");
+}
+
+static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
+{
+ return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
+}
+
+/*
+ * Since NLM uses two "keys" for tracking locks, we need to hash them down
+ * to one for the blocked_hash. Here, we're just xor'ing the host address
+ * with the pid in order to create a key value for picking a hash bucket.
+ */
+static unsigned long
+nlmsvc_owner_key(struct file_lock *fl)
+{
+ return (unsigned long)fl->fl_owner ^ (unsigned long)fl->fl_pid;
+}
+
+const struct lock_manager_operations nlmsvc_lock_operations = {
+ .lm_compare_owner = nlmsvc_same_owner,
+ .lm_owner_key = nlmsvc_owner_key,
+ .lm_notify = nlmsvc_notify_blocked,
+ .lm_grant = nlmsvc_grant_deferred,
+};
+
+/*
+ * Try to claim a lock that was previously blocked.
+ *
+ * Note that we use both the RPC_GRANTED_MSG call _and_ an async
+ * RPC thread when notifying the client. This seems like overkill...
+ * Here's why:
+ * - we don't want to use a synchronous RPC thread, otherwise
+ * we might find ourselves hanging on a dead portmapper.
+ * - Some lockd implementations (e.g. HP) don't react to
+ * RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
+ */
+static void
+nlmsvc_grant_blocked(struct nlm_block *block)
+{
+ struct nlm_file *file = block->b_file;
+ struct nlm_lock *lock = &block->b_call->a_args.lock;
+ int error;
+ loff_t fl_start, fl_end;
+
+ dprintk("lockd: grant blocked lock %p\n", block);
+
+ kref_get(&block->b_count);
+
+ /* Unlink block request from list */
+ nlmsvc_unlink_block(block);
+
+ /* If b_granted is true this means we've been here before.
+ * Just retry the grant callback, possibly refreshing the RPC
+ * binding */
+ if (block->b_granted) {
+ nlm_rebind_host(block->b_host);
+ goto callback;
+ }
+
+ /* Try the lock operation again */
+ /* vfs_lock_file() can mangle fl_start and fl_end, but we need
+ * them unchanged for the GRANT_MSG
+ */
+ lock->fl.fl_flags |= FL_SLEEP;
+ fl_start = lock->fl.fl_start;
+ fl_end = lock->fl.fl_end;
+ error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
+ lock->fl.fl_flags &= ~FL_SLEEP;
+ lock->fl.fl_start = fl_start;
+ lock->fl.fl_end = fl_end;
+
+ switch (error) {
+ case 0:
+ break;
+ case FILE_LOCK_DEFERRED:
+ dprintk("lockd: lock still blocked error %d\n", error);
+ nlmsvc_insert_block(block, NLM_NEVER);
+ nlmsvc_release_block(block);
+ return;
+ default:
+ printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
+ -error, __func__);
+ nlmsvc_insert_block(block, 10 * HZ);
+ nlmsvc_release_block(block);
+ return;
+ }
+
+callback:
+ /* Lock was granted by VFS. */
+ dprintk("lockd: GRANTing blocked lock.\n");
+ block->b_granted = 1;
+
+ /* keep block on the list, but don't reattempt until the RPC
+ * completes or the submission fails
+ */
+ nlmsvc_insert_block(block, NLM_NEVER);
+
+ /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
+ * will queue up a new one if this one times out
+ */
+ error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
+ &nlmsvc_grant_ops);
+
+ /* RPC submission failed, wait a bit and retry */
+ if (error < 0)
+ nlmsvc_insert_block(block, 10 * HZ);
+}
+
+/*
+ * This is the callback from the RPC layer when the NLM_GRANTED_MSG
+ * RPC call has succeeded or timed out.
+ * Like all RPC callbacks, it is invoked by the rpciod process, so it
+ * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
+ * chain once more in order to have it removed by lockd itself (which can
+ * then sleep on the file semaphore without disrupting e.g. the nfs client).
+ */
+static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
+{
+ struct nlm_rqst *call = data;
+ struct nlm_block *block = call->a_block;
+ unsigned long timeout;
+
+ dprintk("lockd: GRANT_MSG RPC callback\n");
+
+ spin_lock(&nlm_blocked_lock);
+ /* if the block is not on a list at this point then it has
+ * been invalidated. Don't try to requeue it.
+ *
+ * FIXME: it's possible that the block is removed from the list
+ * after this check but before the nlmsvc_insert_block. In that
+ * case it will be added back. Perhaps we need better locking
+ * for nlm_blocked?
+ */
+ if (list_empty(&block->b_list))
+ goto out;
+
+ /* Technically, we should down the file semaphore here. Since we
+ * move the block towards the head of the queue only, no harm
+ * can be done, though. */
+ if (task->tk_status < 0) {
+ /* RPC error: Re-insert for retransmission */
+ timeout = 10 * HZ;
+ } else {
+ /* Call was successful, now wait for client callback */
+ timeout = 60 * HZ;
+ }
+ nlmsvc_insert_block_locked(block, timeout);
+ svc_wake_up(block->b_daemon);
+out:
+ spin_unlock(&nlm_blocked_lock);
+}
+
+/*
+ * FIXME: nlmsvc_release_block() grabs a mutex. This is not allowed for an
+ * .rpc_release rpc_call_op
+ */
+static void nlmsvc_grant_release(void *data)
+{
+ struct nlm_rqst *call = data;
+ nlmsvc_release_block(call->a_block);
+}
+
+static const struct rpc_call_ops nlmsvc_grant_ops = {
+ .rpc_call_done = nlmsvc_grant_callback,
+ .rpc_release = nlmsvc_grant_release,
+};
+
+/*
+ * We received a GRANT_RES callback. Try to find the corresponding
+ * block.
+ */
+void
+nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
+{
+ struct nlm_block *block;
+
+ dprintk("grant_reply: looking for cookie %x, s=%d \n",
+ *(unsigned int *)(cookie->data), status);
+ if (!(block = nlmsvc_find_block(cookie)))
+ return;
+
+ if (block) {
+ if (status == nlm_lck_denied_grace_period) {
+ /* Try again in a couple of seconds */
+ nlmsvc_insert_block(block, 10 * HZ);
+ } else {
+ /* Lock is now held by client, or has been rejected.
+ * In both cases, the block should be removed. */
+ nlmsvc_unlink_block(block);
+ }
+ }
+ nlmsvc_release_block(block);
+}
+
+/* Helper function to handle retry of a deferred block.
+ * If it is a blocking lock, call grant_blocked.
+ * For a non-blocking lock or test lock, revisit the request.
+ */
+static void
+retry_deferred_block(struct nlm_block *block)
+{
+ if (!(block->b_flags & B_GOT_CALLBACK))
+ block->b_flags |= B_TIMED_OUT;
+ nlmsvc_insert_block(block, NLM_TIMEOUT);
+ dprintk("revisit block %p flags %d\n", block, block->b_flags);
+ if (block->b_deferred_req) {
+ block->b_deferred_req->revisit(block->b_deferred_req, 0);
+ block->b_deferred_req = NULL;
+ }
+}
+
+/*
+ * Retry all blocked locks that have been notified. This is where lockd
+ * picks up locks that can be granted, or grant notifications that must
+ * be retransmitted.
+ */
+unsigned long
+nlmsvc_retry_blocked(void)
+{
+ unsigned long timeout = MAX_SCHEDULE_TIMEOUT;
+ struct nlm_block *block;
+
+ spin_lock(&nlm_blocked_lock);
+ while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
+ block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
+
+ if (block->b_when == NLM_NEVER)
+ break;
+ if (time_after(block->b_when, jiffies)) {
+ timeout = block->b_when - jiffies;
+ break;
+ }
+ spin_unlock(&nlm_blocked_lock);
+
+ dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
+ block, block->b_when);
+ if (block->b_flags & B_QUEUED) {
+ dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
+ block, block->b_granted, block->b_flags);
+ retry_deferred_block(block);
+ } else
+ nlmsvc_grant_blocked(block);
+ spin_lock(&nlm_blocked_lock);
+ }
+ spin_unlock(&nlm_blocked_lock);
+
+ return timeout;
+}
Code Review / kvmfornfv.git / blobdiff