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- // 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);
- }
- void nlmsvc_locks_init_private(struct file_lock *fl, struct nlm_host *host,
- pid_t pid)
- {
- fl->fl_owner = nlmsvc_find_lockowner(host, pid);
- }
- /*
- * 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 = 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);
- /* 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");
- }
- static fl_owner_t nlmsvc_get_owner(fl_owner_t owner)
- {
- return nlmsvc_get_lockowner(owner);
- }
- static void nlmsvc_put_owner(fl_owner_t owner)
- {
- nlmsvc_put_lockowner(owner);
- }
- const struct lock_manager_operations nlmsvc_lock_operations = {
- .lm_notify = nlmsvc_notify_blocked,
- .lm_grant = nlmsvc_grant_deferred,
- .lm_get_owner = nlmsvc_get_owner,
- .lm_put_owner = nlmsvc_put_owner,
- };
- /*
- * 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;
- }
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