[PATCH] NLM: Fix the NLM_GRANTED callback checks

If 2 threads attached to the same process are blocking on different locks on
different files (maybe even on different servers) but have the same lock
arguments (i.e.  same offset+length - actually quite common, since most
processes try to lock the entire file) then the first GRANTED call that wakes
one up will also wake the other.

Currently when the NLM_GRANTED callback comes in, lockd walks the list of
blocked locks in search of a match to the lock that the NLM server has
granted.  Although it checks the lock pid, start and end, it fails to check
the filehandle and the server address.

By checking the filehandle and server IP address, we ensure that this only
happens if the locks truly are referencing the same file.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/lockd/clntlock.c

@@ -111,9 +111,10 @@ long nlmclnt_block(struct nlm_rqst *req, long timeout)
 /*
  * The server lockd has called us back to tell us the lock was granted
  */
-u32
-nlmclnt_grant(struct nlm_lock *lock)
+u32 nlmclnt_grant(const struct sockaddr_in *addr, const struct nlm_lock *lock)
 {
+	const struct file_lock *fl = &lock->fl;
+	const struct nfs_fh *fh = &lock->fh;
 	struct nlm_wait	*block;
 	u32 res = nlm_lck_denied;
 
@@ -122,14 +123,20 @@ nlmclnt_grant(struct nlm_lock *lock)
 	 * Warning: must not use cookie to match it!
 	 */
 	list_for_each_entry(block, &nlm_blocked, b_list) {
-		if (nlm_compare_locks(block->b_lock, &lock->fl)) {
-			/* Alright, we found a lock. Set the return status
-			 * and wake up the caller
-			 */
-			block->b_status = NLM_LCK_GRANTED;
-			wake_up(&block->b_wait);
-			res = nlm_granted;
-		}
+		struct file_lock *fl_blocked = block->b_lock;
+
+		if (!nlm_compare_locks(fl_blocked, fl))
+			continue;
+		if (!nlm_cmp_addr(&block->b_host->h_addr, addr))
+			continue;
+		if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_dentry->d_inode) ,fh) != 0)
+			continue;
+		/* Alright, we found a lock. Set the return status
+		 * and wake up the caller
+		 */
+		block->b_status = NLM_LCK_GRANTED;
+		wake_up(&block->b_wait);
+		res = nlm_granted;
 	}
 	return res;
 }

fs/lockd/svc4proc.c

@@ -228,7 +228,7 @@ nlm4svc_proc_granted(struct svc_rqst *rqstp, struct nlm_args *argp,
 	resp->cookie = argp->cookie;
 
 	dprintk("lockd: GRANTED       called\n");
-	resp->status = nlmclnt_grant(&argp->lock);
+	resp->status = nlmclnt_grant(&rqstp->rq_addr, &argp->lock);
 	dprintk("lockd: GRANTED       status %d\n", ntohl(resp->status));
 	return rpc_success;
 }

fs/lockd/svcproc.c

@@ -256,7 +256,7 @@ nlmsvc_proc_granted(struct svc_rqst *rqstp, struct nlm_args *argp,
 	resp->cookie = argp->cookie;
 
 	dprintk("lockd: GRANTED       called\n");
-	resp->status = nlmclnt_grant(&argp->lock);
+	resp->status = nlmclnt_grant(&rqstp->rq_addr, &argp->lock);
 	dprintk("lockd: GRANTED       status %d\n", ntohl(resp->status));
 	return rpc_success;
 }

include/linux/lockd/lockd.h

@@ -149,7 +149,7 @@ struct nlm_rqst * nlmclnt_alloc_call(void);
 int		  nlmclnt_prepare_block(struct nlm_rqst *req, struct nlm_host *host, struct file_lock *fl);
 void		  nlmclnt_finish_block(struct nlm_rqst *req);
 long		  nlmclnt_block(struct nlm_rqst *req, long timeout);
-u32		  nlmclnt_grant(struct nlm_lock *);
+u32		  nlmclnt_grant(const struct sockaddr_in *addr, const struct nlm_lock *);
 void		  nlmclnt_recovery(struct nlm_host *, u32);
 int		  nlmclnt_reclaim(struct nlm_host *, struct file_lock *);
 int		  nlmclnt_setgrantargs(struct nlm_rqst *, struct nlm_lock *);
@@ -204,7 +204,7 @@ nlmsvc_file_inode(struct nlm_file *file)
  * Compare two host addresses (needs modifying for ipv6)
  */
 static __inline__ int
-nlm_cmp_addr(struct sockaddr_in *sin1, struct sockaddr_in *sin2)
+nlm_cmp_addr(const struct sockaddr_in *sin1, const struct sockaddr_in *sin2)
 {
 	return sin1->sin_addr.s_addr == sin2->sin_addr.s_addr;
 }
@@ -214,7 +214,7 @@ nlm_cmp_addr(struct sockaddr_in *sin1, struct sockaddr_in *sin2)
  * When the second lock is of type F_UNLCK, this acts like a wildcard.
  */
 static __inline__ int
-nlm_compare_locks(struct file_lock *fl1, struct file_lock *fl2)
+nlm_compare_locks(const struct file_lock *fl1, const struct file_lock *fl2)
 {
 	return	fl1->fl_pid   == fl2->fl_pid
 	     && fl1->fl_start == fl2->fl_start