From 64a318ee2af9000df482d7a125c3b3e1f1007404 Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Tue, 3 Jan 2006 09:55:46 +0100 Subject: [PATCH] NLM: Further cancel fixes If the server receives an NLM cancel call and finds no waiting lock to cancel, then chances are the lock has already been applied, and the client just hadn't yet processed the NLM granted callback before it sent the cancel. The Open Group text, for example, perimts a server to return either success (LCK_GRANTED) or failure (LCK_DENIED) in this case. But returning an error seems more helpful; the client may be able to use it to recognize that a race has occurred and to recover from the race. So, modify the relevant functions to return an error in this case. Signed-off-by: J. Bruce Fields Signed-off-by: Trond Myklebust --- fs/lockd/svclock.c | 15 ++++++++++----- fs/locks.c | 7 ++++++- include/linux/fs.h | 2 +- 3 files changed, 17 insertions(+), 7 deletions(-) diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c index b56d439bad..9cfced65d4 100644 --- a/fs/lockd/svclock.c +++ b/fs/lockd/svclock.c @@ -227,25 +227,27 @@ failed: * It is the caller's responsibility to check whether the file * can be closed hereafter. */ -static void +static int nlmsvc_delete_block(struct nlm_block *block, int unlock) { struct file_lock *fl = &block->b_call.a_args.lock.fl; struct nlm_file *file = block->b_file; struct nlm_block **bp; + int status = 0; dprintk("lockd: deleting block %p...\n", block); /* Remove block from list */ nlmsvc_remove_block(block); - posix_unblock_lock(file->f_file, fl); + if (unlock) + status = posix_unblock_lock(file->f_file, fl); /* If the block is in the middle of a GRANT callback, * don't kill it yet. */ if (block->b_incall) { nlmsvc_insert_block(block, NLM_NEVER); block->b_done = 1; - return; + return status; } /* Remove block from file's list of blocks */ @@ -260,6 +262,7 @@ nlmsvc_delete_block(struct nlm_block *block, int unlock) nlm_release_host(block->b_host); nlmclnt_freegrantargs(&block->b_call); kfree(block); + return status; } /* @@ -270,6 +273,7 @@ int nlmsvc_traverse_blocks(struct nlm_host *host, struct nlm_file *file, int action) { struct nlm_block *block, *next; + /* XXX: Will everything get cleaned up if we don't unlock here? */ down(&file->f_sema); for (block = file->f_blocks; block; block = next) { @@ -439,6 +443,7 @@ u32 nlmsvc_cancel_blocked(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->f_file->f_dentry->d_inode->i_sb->s_id, @@ -449,9 +454,9 @@ nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock) down(&file->f_sema); if ((block = nlmsvc_lookup_block(file, lock, 1)) != NULL) - nlmsvc_delete_block(block, 1); + status = nlmsvc_delete_block(block, 1); up(&file->f_sema); - return nlm_granted; + return status ? nlm_lck_denied : nlm_granted; } /* diff --git a/fs/locks.c b/fs/locks.c index 75650d52fe..fb32d6218e 100644 --- a/fs/locks.c +++ b/fs/locks.c @@ -1958,13 +1958,18 @@ EXPORT_SYMBOL(posix_block_lock); * * lockd needs to block waiting for locks. */ -void +int posix_unblock_lock(struct file *filp, struct file_lock *waiter) { + int status = 0; + lock_kernel(); if (waiter->fl_next) __locks_delete_block(waiter); + else + status = -ENOENT; unlock_kernel(); + return status; } EXPORT_SYMBOL(posix_unblock_lock); diff --git a/include/linux/fs.h b/include/linux/fs.h index 115e72be25..2c9c48d656 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -760,7 +760,7 @@ extern struct file_lock *posix_test_lock(struct file *, struct file_lock *); extern int posix_lock_file(struct file *, struct file_lock *); extern int posix_lock_file_wait(struct file *, struct file_lock *); extern void posix_block_lock(struct file_lock *, struct file_lock *); -extern void posix_unblock_lock(struct file *, struct file_lock *); +extern int posix_unblock_lock(struct file *, struct file_lock *); extern int posix_locks_deadlock(struct file_lock *, struct file_lock *); extern int flock_lock_file_wait(struct file *filp, struct file_lock *fl); extern int __break_lease(struct inode *inode, unsigned int flags); -- 2.39.5