[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: Andy Adamson <andros@citi.umich.edu>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 16 insertions, 22 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index c7b87e92f91b..47ec112b266c 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -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);