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Commit f8120480 authored by Marc Eshel's avatar Marc Eshel Committed by J. Bruce Fields
Browse files

lockd: always preallocate block in nlmsvc_lock() 



Normally we could skip ever having to allocate a block in the case where
the client asks for a non-blocking lock, or asks for a blocking lock that
succeeds immediately.

However we're going to want to always look up a block first in order to
check whether we're revisiting a deferred lock call, and to be prepared to
handle the case where the filesystem returns -EINPROGRESS--in that case we
want to make sure the lock we've given the filesystem is the one embedded
in the block that we'll use to track the deferred request.

Signed-off-by: default avatarMarc Eshel <eshel@almaden.ibm.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
parent 5ea0d750

fs/lockd/svclock.c

+11 −23
Original line number Diff line number Diff line
@@ -365,7 +365,7 @@ __be32 
nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,

			struct nlm_lock *lock, int wait, struct nlm_cookie *cookie)

{

	struct nlm_block	*block, *newblock = NULL;

	struct nlm_block	*block = NULL;

	int			error;

	__be32			ret;
@@ -378,17 +378,20 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, 
				wait);





	lock->fl.fl_flags &= ~FL_SLEEP;

again:

	/* Lock file against concurrent access */

	mutex_lock(&file->f_mutex);

	/* Get existing block (in case client is busy-waiting) */

	/* Get existing block (in case client is busy-waiting)

	 * or create new block

	 */

	block = nlmsvc_lookup_block(file, lock);

	if (block == NULL) {

		if (newblock != NULL)

			lock = &newblock->b_call->a_args.lock;

	} else

		block = nlmsvc_create_block(rqstp, 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;



	error = posix_lock_file(file->f_file, &lock->fl, NULL);

	lock->fl.fl_flags &= ~FL_SLEEP;
@@ -414,26 +417,11 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, 
		goto out;



	ret = nlm_lck_blocked;

	if (block != NULL)

		goto out;



	/* If we don't have a block, create and initialize it. Then

	 * retry because we may have slept in kmalloc. */

	/* We have to release f_mutex as nlmsvc_create_block may try to

	 * to claim it while doing host garbage collection */

	if (newblock == NULL) {

		mutex_unlock(&file->f_mutex);

		dprintk("lockd: blocking on this lock (allocating).\n");

		if (!(newblock = nlmsvc_create_block(rqstp, file, lock, cookie)))

			return nlm_lck_denied_nolocks;

		goto again;

	}



	/* Append to list of blocked */

	nlmsvc_insert_block(newblock, NLM_NEVER);

	nlmsvc_insert_block(block, NLM_NEVER);

out:

	mutex_unlock(&file->f_mutex);

	nlmsvc_release_block(newblock);

	nlmsvc_release_block(block);

	dprintk("lockd: nlmsvc_lock returned %u\n", ret);

	return ret;