Commit eb76b3fd authored by Andy Adamson's avatar Andy Adamson Committed by Linus Torvalds
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[PATCH] NFSD4: return conflict lock without races 



Update the NFSv4 server to use the new posix_lock_file_conf() interface.
Remove unnecessary (and race-prone) posix_test_file() calls.

Signed-off-by: default avatarAndy Adamson <andros@citi.umich.edu>
Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 5842add2

fs/nfsd/nfs4state.c

+16 −22
Original line number Diff line number Diff line
@@ -2750,37 +2750,31 @@ nfsd4_lock(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_lock 
	* Note: locks.c uses the BKL to protect the inode's lock list.

	*/



	status = posix_lock_file(filp, &file_lock);

	dprintk("NFSD: nfsd4_lock: posix_lock_file status %d\n",status);

	/* XXX?: Just to divert the locks_release_private at the start of

	 * locks_copy_lock: */

	conflock.fl_ops = NULL;

	conflock.fl_lmops = NULL;

	status = posix_lock_file_conf(filp, &file_lock, &conflock);

	dprintk("NFSD: nfsd4_lock: posix_lock_file_conf status %d\n",status);

	switch (-status) {

	case 0: /* success! */

		update_stateid(&lock_stp->st_stateid);

		memcpy(&lock->lk_resp_stateid, &lock_stp->st_stateid, 

				sizeof(stateid_t));

		goto out;

	case (EAGAIN):

		goto conflicting_lock;

		break;

	case (EAGAIN):		/* conflock holds conflicting lock */

		status = nfserr_denied;

		dprintk("NFSD: nfsd4_lock: conflicting lock found!\n");

		nfs4_set_lock_denied(&conflock, &lock->lk_denied);

		break;

	case (EDEADLK):

		status = nfserr_deadlock;

		dprintk("NFSD: nfsd4_lock: posix_lock_file() failed! status %d\n",status);

		goto out;

		break;

	default:        

		status = nfserrno(status);

		dprintk("NFSD: nfsd4_lock: posix_lock_file() failed! status %d\n",status);

		goto out;

	}



conflicting_lock:

	dprintk("NFSD: nfsd4_lock: conflicting lock found!\n");

	status = nfserr_denied;

	/* XXX There is a race here. Future patch needed to provide 

	 * an atomic posix_lock_and_test_file

	 */

	if (!posix_test_lock(filp, &file_lock, &conflock)) {

		status = nfserr_serverfault;

		goto out;

		dprintk("NFSD: nfsd4_lock: posix_lock_file_conf() failed! status %d\n",status);

		status = nfserr_resource;

		break;

	}

	nfs4_set_lock_denied(&conflock, &lock->lk_denied);

out:

	if (status && lock->lk_is_new && lock_sop)

		release_stateowner(lock_sop);