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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: Marc Eshel <eshel@almaden.ibm.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
This commit is contained in:
Marc Eshel 2006-12-05 23:48:10 -05:00 committed by J. Bruce Fields
parent 5ea0d75037
commit f812048020
1 changed files with 11 additions and 23 deletions
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34
fs/lockd/svclock.c
View File

@ -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 @@ again:
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;