// SPDX-License-Identifier: GPL-2.0 /* * 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 = locks_delete_block(&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); } static struct nlm_lockowner * nlmsvc_get_lockowner(struct nlm_lockowner *lockowner) { refcount_inc(&lockowner->count); return lockowner; } static void nlmsvc_put_lockowner(struct nlm_lockowner *lockowner) { if (!refcount_dec_and_lock(&lockowner->count, &lockowner->host->h_lock)) return; list_del(&lockowner->list); spin_unlock(&lockowner->host->h_lock); nlmsvc_release_host(lockowner->host); kfree(lockowner); } static struct nlm_lockowner *__nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid) { struct nlm_lockowner *lockowner; list_for_each_entry(lockowner, &host->h_lockowners, list) { if (lockowner->pid != pid) continue; return nlmsvc_get_lockowner(lockowner); } return NULL; } static struct nlm_lockowner *nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid) { struct nlm_lockowner *res, *new = NULL; spin_lock(&host->h_lock); res = __nlmsvc_find_lockowner(host, pid); if (res == NULL) { spin_unlock(&host->h_lock); new = kmalloc(sizeof(*res), GFP_KERNEL); spin_lock(&host->h_lock); res = __nlmsvc_find_lockowner(host, pid); if (res == NULL && new != NULL) { res = new; /* fs/locks.c will manage the refcount through lock_ops */ refcount_set(&new->count, 1); new->pid = pid; new->host = nlm_get_host(host); list_add(&new->list, &host->h_lockowners); new = NULL; } } spin_unlock(&host->h_lock); kfree(new); return res; } void nlmsvc_release_lockowner(struct nlm_lock *lock) { if (lock->fl.fl_owner) nlmsvc_put_lockowner(lock->fl.fl_owner); } static void nlmsvc_locks_copy_lock(struct file_lock *new, struct file_lock *fl) { struct nlm_lockowner *nlm_lo = (struct nlm_lockowner *)fl->fl_owner; new->fl_owner = nlmsvc_get_lockowner(nlm_lo); } static void nlmsvc_locks_release_private(struct file_lock *fl) { nlmsvc_put_lockowner((struct nlm_lockowner *)fl->fl_owner); } static const struct file_lock_operations nlmsvc_lock_ops = { .fl_copy_lock = nlmsvc_locks_copy_lock, .fl_release_private = nlmsvc_locks_release_private, }; void nlmsvc_locks_init_private(struct file_lock *fl, struct nlm_host *host, pid_t pid) { fl->fl_owner = nlmsvc_find_lockowner(host, pid); if (fl->fl_owner != NULL) fl->fl_ops = &nlmsvc_lock_ops; } /* * 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 = ((struct nlm_lockowner *)lock->fl.fl_owner)->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", locks_inode(file->f_file)->i_sb->s_id, locks_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; struct nlm_lockowner *test_owner; dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n", locks_inode(file->f_file)->i_sb->s_id, locks_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; } /* If there's a conflicting lock, remember to clean up the test lock */ test_owner = (struct nlm_lockowner *)lock->fl.fl_owner; 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 = ((struct nlm_lockowner *)lock->fl.fl_owner)->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); /* Clean up the test lock */ lock->fl.fl_owner = NULL; nlmsvc_put_lockowner(test_owner); 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", locks_inode(file->f_file)->i_sb->s_id, locks_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", locks_inode(file->f_file)->i_sb->s_id, locks_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"); } const struct lock_manager_operations nlmsvc_lock_operations = { .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 (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; }