[Cluster-devel] [PATCH v1 06/11] locks: convert to i_lock to protect i_flock list

[Jeff Layton <jlayton@redhat.com>]

Having a global lock that protects all of this code is a clear
scalability problem. Instead of doing that, move most of the code to be
protected by the i_lock instead.

The exceptions are the global lists that file_lock->fl_link sits on.
Those still need a global lock of some sort, so wrap just those accesses
in the file_lock_lock().

Note that this requires a small change to the /proc/locks code. Instead
of walking the fl_block list to look for locks blocked on the current
lock, we must instead walk the global blocker list and skip any that
aren't blocked on the current lock. Otherwise, we'd need to take the
i_lock on each inode as we go and that would create a lock inversion
problem.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
---
 Documentation/filesystems/Locking |   23 +++++--
 fs/afs/flock.c                    |    5 +-
 fs/ceph/locks.c                   |    2 +-
 fs/ceph/mds_client.c              |    8 +-
 fs/cifs/cifsfs.c                  |    2 +-
 fs/cifs/file.c                    |   13 ++--
 fs/gfs2/file.c                    |    2 +-
 fs/lockd/svcsubs.c                |   12 ++--
 fs/locks.c                        |  121 ++++++++++++++++++++-----------------
 fs/nfs/delegation.c               |   11 ++--
 fs/nfs/nfs4state.c                |    8 +-
 fs/nfsd/nfs4state.c               |    8 +-
 include/linux/fs.h                |   11 ----
 13 files changed, 119 insertions(+), 107 deletions(-)

diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 0706d32..13f91ab 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -344,7 +344,7 @@ prototypes:
 
 
 locking rules:
-			file_lock_lock	may block
+			inode->i_lock	may block
 fl_copy_lock:		yes		no
 fl_release_private:	maybe		no
 
@@ -357,12 +357,21 @@ prototypes:
 	int (*lm_change)(struct file_lock **, int);
 
 locking rules:
-			file_lock_lock	may block
-lm_compare_owner:	yes		no
-lm_notify:		yes		no
-lm_grant:		no		no
-lm_break:		yes		no
-lm_change		yes		no
+
+			inode->i_lock	file_lock_lock	may block
+lm_compare_owner:	yes		maybe		no
+lm_notify:		yes		no		no
+lm_grant:		no		no		no
+lm_break:		yes		no		no
+lm_change		yes		no		no
+
+	->lm_compare_owner is generally called with *an* inode->i_lock
+held. It may not be the i_lock of the inode for either file_lock being
+compared! This is the case with deadlock detection, since the code has
+to chase down the owners of locks that may be entirely unrelated to the
+one on which the lock is being acquired. For deadlock detection however,
+the file_lock_lock is also held. The locks primarily ensure that neither
+file_lock disappear out from under you while doing the comparison.
 
 --------------------------- buffer_head -----------------------------------
 prototypes:
diff --git a/fs/afs/flock.c b/fs/afs/flock.c
index 2497bf3..03fc0d1 100644
--- a/fs/afs/flock.c
+++ b/fs/afs/flock.c
@@ -252,6 +252,7 @@ static void afs_defer_unlock(struct afs_vnode *vnode, struct key *key)
  */
 static int afs_do_setlk(struct file *file, struct file_lock *fl)
 {
+	struct inode = file_inode(file);
 	struct afs_vnode *vnode = AFS_FS_I(file->f_mapping->host);
 	afs_lock_type_t type;
 	struct key *key = file->private_data;
@@ -273,7 +274,7 @@ static int afs_do_setlk(struct file *file, struct file_lock *fl)
 
 	type = (fl->fl_type == F_RDLCK) ? AFS_LOCK_READ : AFS_LOCK_WRITE;
 
-	lock_flocks();
+	spin_lock(&inode->i_lock);
 
 	/* make sure we've got a callback on this file and that our view of the
 	 * data version is up to date */
@@ -420,7 +421,7 @@ given_lock:
 	afs_vnode_fetch_status(vnode, NULL, key);
 
 error:
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 	_leave(" = %d", ret);
 	return ret;
 
diff --git a/fs/ceph/locks.c b/fs/ceph/locks.c
index 202dd3d..cd0a664 100644
--- a/fs/ceph/locks.c
+++ b/fs/ceph/locks.c
@@ -194,7 +194,7 @@ void ceph_count_locks(struct inode *inode, int *fcntl_count, int *flock_count)
  * Encode the flock and fcntl locks for the given inode into the pagelist.
  * Format is: #fcntl locks, sequential fcntl locks, #flock locks,
  * sequential flock locks.
- * Must be called with lock_flocks() already held.
+ * Must be called with inode->i_lock already held.
  * If we encounter more of a specific lock type than expected,
  * we return the value 1.
  */
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 4f22671..ae621b5 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -2482,13 +2482,13 @@ static int encode_caps_cb(struct inode *inode, struct ceph_cap *cap,
 
 		ceph_pagelist_set_cursor(pagelist, &trunc_point);
 		do {
-			lock_flocks();
+			spin_lock(&inode->i_lock);
 			ceph_count_locks(inode, &num_fcntl_locks,
 					 &num_flock_locks);
 			rec.v2.flock_len = (2*sizeof(u32) +
 					    (num_fcntl_locks+num_flock_locks) *
 					    sizeof(struct ceph_filelock));
-			unlock_flocks();
+			spin_unlock(&inode->i_lock);
 
 			/* pre-alloc pagelist */
 			ceph_pagelist_truncate(pagelist, &trunc_point);
@@ -2499,12 +2499,12 @@ static int encode_caps_cb(struct inode *inode, struct ceph_cap *cap,
 
 			/* encode locks */
 			if (!err) {
-				lock_flocks();
+				spin_lock(&inode->i_lock);
 				err = ceph_encode_locks(inode,
 							pagelist,
 							num_fcntl_locks,
 							num_flock_locks);
-				unlock_flocks();
+				spin_unlock(&inode->i_lock);
 			}
 		} while (err == -ENOSPC);
 	} else {
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 72e4efe..29952d5 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -768,7 +768,7 @@ static loff_t cifs_llseek(struct file *file, loff_t offset, int whence)
 
 static int cifs_setlease(struct file *file, long arg, struct file_lock **lease)
 {
-	/* note that this is called by vfs setlease with lock_flocks held
+	/* note that this is called by vfs setlease with i_lock held
 	   to protect *lease from going away */
 	struct inode *inode = file_inode(file);
 	struct cifsFileInfo *cfile = file->private_data;
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 44a4f18..0dd10cd 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1092,6 +1092,7 @@ struct lock_to_push {
 static int
 cifs_push_posix_locks(struct cifsFileInfo *cfile)
 {
+	struct inode *inode = cfile->dentry->d_inode;
 	struct cifs_tcon *tcon = tlink_tcon(cfile->tlink);
 	struct file_lock *flock, **before;
 	unsigned int count = 0, i = 0;
@@ -1102,12 +1103,12 @@ cifs_push_posix_locks(struct cifsFileInfo *cfile)
 
 	xid = get_xid();
 
-	lock_flocks();
-	cifs_for_each_lock(cfile->dentry->d_inode, before) {
+	spin_lock(&inode->i_lock);
+	cifs_for_each_lock(inode, before) {
 		if ((*before)->fl_flags & FL_POSIX)
 			count++;
 	}
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 
 	INIT_LIST_HEAD(&locks_to_send);
 
@@ -1126,8 +1127,8 @@ cifs_push_posix_locks(struct cifsFileInfo *cfile)
 	}
 
 	el = locks_to_send.next;
-	lock_flocks();
-	cifs_for_each_lock(cfile->dentry->d_inode, before) {
+	spin_lock(&inode->i_lock);
+	cifs_for_each_lock(inode, before) {
 		flock = *before;
 		if ((flock->fl_flags & FL_POSIX) == 0)
 			continue;
@@ -1152,7 +1153,7 @@ cifs_push_posix_locks(struct cifsFileInfo *cfile)
 		lck->offset = flock->fl_start;
 		el = el->next;
 	}
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 
 	list_for_each_entry_safe(lck, tmp, &locks_to_send, llist) {
 		int stored_rc;
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index acd1676..9e634e0 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -889,7 +889,7 @@ out_uninit:
  * cluster; until we do, disable leases (by just returning -EINVAL),
  * unless the administrator has requested purely local locking.
  *
- * Locking: called under lock_flocks
+ * Locking: called under i_lock
  *
  * Returns: errno
  */
diff --git a/fs/lockd/svcsubs.c b/fs/lockd/svcsubs.c
index 97e8741..dc5c759 100644
--- a/fs/lockd/svcsubs.c
+++ b/fs/lockd/svcsubs.c
@@ -169,7 +169,7 @@ nlm_traverse_locks(struct nlm_host *host, struct nlm_file *file,
 
 again:
 	file->f_locks = 0;
-	lock_flocks(); /* protects i_flock list */
+	spin_lock(&inode->i_lock);
 	for (fl = inode->i_flock; fl; fl = fl->fl_next) {
 		if (fl->fl_lmops != &nlmsvc_lock_operations)
 			continue;
@@ -181,7 +181,7 @@ again:
 		if (match(lockhost, host)) {
 			struct file_lock lock = *fl;
 
-			unlock_flocks();
+			spin_unlock(&inode->i_lock);
 			lock.fl_type  = F_UNLCK;
 			lock.fl_start = 0;
 			lock.fl_end   = OFFSET_MAX;
@@ -193,7 +193,7 @@ again:
 			goto again;
 		}
 	}
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 
 	return 0;
 }
@@ -228,14 +228,14 @@ nlm_file_inuse(struct nlm_file *file)
 	if (file->f_count || !list_empty(&file->f_blocks) || file->f_shares)
 		return 1;
 
-	lock_flocks();
+	spin_lock(&inode->i_lock);
 	for (fl = inode->i_flock; fl; fl = fl->fl_next) {
 		if (fl->fl_lmops == &nlmsvc_lock_operations) {
-			unlock_flocks();
+			spin_unlock(&inode->i_lock);
 			return 1;
 		}
 	}
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 	file->f_locks = 0;
 	return 0;
 }
diff --git a/fs/locks.c b/fs/locks.c
index caca466..055c06c 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -165,22 +165,9 @@ int lease_break_time = 45;
 
 static LIST_HEAD(file_lock_list);
 static LIST_HEAD(blocked_list);
-static DEFINE_SPINLOCK(file_lock_lock);
-
-/*
- * Protects the two list heads above, plus the inode->i_flock list
- */
-void lock_flocks(void)
-{
-	spin_lock(&file_lock_lock);
-}
-EXPORT_SYMBOL_GPL(lock_flocks);
 
-void unlock_flocks(void)
-{
-	spin_unlock(&file_lock_lock);
-}
-EXPORT_SYMBOL_GPL(unlock_flocks);
+/* Protects the two list heads above */
+static DEFINE_SPINLOCK(file_lock_lock);
 
 static struct kmem_cache *filelock_cache __read_mostly;
 
@@ -498,25 +485,33 @@ static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 static inline void
 locks_insert_global_blocked(struct file_lock *waiter)
 {
+	spin_lock(&file_lock_lock);
 	list_add(&waiter->fl_link, &blocked_list);
+	spin_unlock(&file_lock_lock);
 }
 
 static inline void
 locks_delete_global_blocked(struct file_lock *waiter)
 {
+	spin_lock(&file_lock_lock);
 	list_del_init(&waiter->fl_link);
+	spin_unlock(&file_lock_lock);
 }
 
 static inline void
 locks_insert_global_locks(struct file_lock *waiter)
 {
+	spin_lock(&file_lock_lock);
 	list_add_tail(&waiter->fl_link, &file_lock_list);
+	spin_unlock(&file_lock_lock);
 }
 
 static inline void
 locks_delete_global_locks(struct file_lock *waiter)
 {
+	spin_lock(&file_lock_lock);
 	list_del_init(&waiter->fl_link);
+	spin_unlock(&file_lock_lock);
 }
 
 /* Remove waiter from blocker's block list.
@@ -533,9 +528,11 @@ static void __locks_delete_block(struct file_lock *waiter)
  */
 static void locks_delete_block(struct file_lock *waiter)
 {
-	lock_flocks();
+	struct inode *inode = file_inode(waiter->fl_file);
+
+	spin_lock(&inode->i_lock);
 	__locks_delete_block(waiter);
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 }
 
 /* Insert waiter into blocker's block list.
@@ -657,8 +654,9 @@ void
 posix_test_lock(struct file *filp, struct file_lock *fl)
 {
 	struct file_lock *cfl;
+	struct inode *inode = file_inode(filp);
 
-	lock_flocks();
+	spin_lock(&inode->i_lock);
 	for (cfl = file_inode(filp)->i_flock; cfl; cfl = cfl->fl_next) {
 		if (!IS_POSIX(cfl))
 			continue;
@@ -671,7 +669,7 @@ posix_test_lock(struct file *filp, struct file_lock *fl)
 			fl->fl_pid = pid_vnr(cfl->fl_nspid);
 	} else
 		fl->fl_type = F_UNLCK;
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 	return;
 }
 EXPORT_SYMBOL(posix_test_lock);
@@ -719,14 +717,19 @@ static int posix_locks_deadlock(struct file_lock *caller_fl,
 				struct file_lock *block_fl)
 {
 	int i = 0;
+	int ret = 0;
 
+	spin_lock(&file_lock_lock);
 	while ((block_fl = what_owner_is_waiting_for(block_fl))) {
 		if (i++ > MAX_DEADLK_ITERATIONS)
-			return 0;
-		if (posix_same_owner(caller_fl, block_fl))
-			return 1;
+			break;
+		if (posix_same_owner(caller_fl, block_fl)) {
+			++ret;
+			break;
+		}
 	}
-	return 0;
+	spin_unlock(&file_lock_lock);
+	return ret;
 }
 
 /* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
@@ -750,7 +753,7 @@ static int flock_lock_file(struct file *filp, struct file_lock *request)
 			return -ENOMEM;
 	}
 
-	lock_flocks();
+	spin_lock(&inode->i_lock);
 	if (request->fl_flags & FL_ACCESS)
 		goto find_conflict;
 
@@ -780,9 +783,9 @@ static int flock_lock_file(struct file *filp, struct file_lock *request)
 	 * give it the opportunity to lock the file.
 	 */
 	if (found) {
-		unlock_flocks();
+		spin_unlock(&inode->i_lock);
 		cond_resched();
-		lock_flocks();
+		spin_lock(&inode->i_lock);
 	}
 
 find_conflict:
@@ -809,7 +812,7 @@ find_conflict:
 	error = 0;
 
 out:
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 	if (new_fl)
 		locks_free_lock(new_fl);
 	return error;
@@ -839,7 +842,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
 		new_fl2 = locks_alloc_lock();
 	}
 
-	lock_flocks();
+	spin_lock(&inode->i_lock);
 	/*
 	 * New lock request. Walk all POSIX locks and look for conflicts. If
 	 * there are any, either return -EAGAIN or put the request on the
@@ -1012,7 +1015,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
 		locks_wake_up_blocks(left);
 	}
  out:
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 	/*
 	 * Free any unused locks.
 	 */
@@ -1087,14 +1090,14 @@ int locks_mandatory_locked(struct inode *inode)
 	/*
 	 * Search the lock list for this inode for any POSIX locks.
 	 */
-	lock_flocks();
+	spin_lock(&inode->i_lock);
 	for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
 		if (!IS_POSIX(fl))
 			continue;
 		if (fl->fl_owner != owner)
 			break;
 	}
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 	return fl ? -EAGAIN : 0;
 }
 
@@ -1237,7 +1240,7 @@ int __break_lease(struct inode *inode, unsigned int mode)
 	if (IS_ERR(new_fl))
 		return PTR_ERR(new_fl);
 
-	lock_flocks();
+	spin_lock(&inode->i_lock);
 
 	time_out_leases(inode);
 
@@ -1287,10 +1290,10 @@ restart:
 			break_time++;
 	}
 	locks_insert_block(flock, new_fl);
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 	error = wait_event_interruptible_timeout(new_fl->fl_wait,
 						!new_fl->fl_next, break_time);
-	lock_flocks();
+	spin_lock(&inode->i_lock);
 	__locks_delete_block(new_fl);
 	if (error >= 0) {
 		if (error == 0)
@@ -1308,7 +1311,7 @@ restart:
 	}
 
 out:
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 	locks_free_lock(new_fl);
 	return error;
 }
@@ -1361,9 +1364,10 @@ EXPORT_SYMBOL(lease_get_mtime);
 int fcntl_getlease(struct file *filp)
 {
 	struct file_lock *fl;
+	struct inode *inode = file_inode(filp);
 	int type = F_UNLCK;
 
-	lock_flocks();
+	spin_lock(&inode->i_lock);
 	time_out_leases(file_inode(filp));
 	for (fl = file_inode(filp)->i_flock; fl && IS_LEASE(fl);
 			fl = fl->fl_next) {
@@ -1372,7 +1376,7 @@ int fcntl_getlease(struct file *filp)
 			break;
 		}
 	}
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 	return type;
 }
 
@@ -1466,7 +1470,7 @@ static int generic_delete_lease(struct file *filp, struct file_lock **flp)
  *	The (input) flp->fl_lmops->lm_break function is required
  *	by break_lease().
  *
- *	Called with file_lock_lock held.
+ *	Called with inode->i_lock held.
  */
 int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
 {
@@ -1535,11 +1539,12 @@ static int __vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
 
 int vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
 {
+	struct inode *inode = file_inode(filp);
 	int error;
 
-	lock_flocks();
+	spin_lock(&inode->i_lock);
 	error = __vfs_setlease(filp, arg, lease);
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 
 	return error;
 }
@@ -1557,6 +1562,7 @@ static int do_fcntl_delete_lease(struct file *filp)
 static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
 {
 	struct file_lock *fl, *ret;
+	struct inode *inode = file_inode(filp);
 	struct fasync_struct *new;
 	int error;
 
@@ -1570,10 +1576,10 @@ static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
 		return -ENOMEM;
 	}
 	ret = fl;
-	lock_flocks();
+	spin_lock(&inode->i_lock);
 	error = __vfs_setlease(filp, arg, &ret);
 	if (error) {
-		unlock_flocks();
+		spin_unlock(&inode->i_lock);
 		locks_free_lock(fl);
 		goto out_free_fasync;
 	}
@@ -1590,7 +1596,7 @@ static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
 		new = NULL;
 
 	error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 
 out_free_fasync:
 	if (new)
@@ -2114,7 +2120,7 @@ void locks_remove_flock(struct file *filp)
 			fl.fl_ops->fl_release_private(&fl);
 	}
 
-	lock_flocks();
+	spin_lock(&inode->i_lock);
 	before = &inode->i_flock;
 
 	while ((fl = *before) != NULL) {
@@ -2132,7 +2138,7 @@ void locks_remove_flock(struct file *filp)
  		}
 		before = &fl->fl_next;
 	}
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 }
 
 /**
@@ -2145,14 +2151,15 @@ void locks_remove_flock(struct file *filp)
 int
 posix_unblock_lock(struct file *filp, struct file_lock *waiter)
 {
+	struct inode *inode = file_inode(filp);
 	int status = 0;
 
-	lock_flocks();
+	spin_lock(&inode->i_lock);
 	if (waiter->fl_next)
 		__locks_delete_block(waiter);
 	else
 		status = -ENOENT;
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 	return status;
 }
 
@@ -2257,8 +2264,10 @@ static int locks_show(struct seq_file *f, void *v)
 
 	lock_get_status(f, fl, *((loff_t *)f->private), "");
 
-	list_for_each_entry(bfl, &fl->fl_block, fl_block)
-		lock_get_status(f, bfl, *((loff_t *)f->private), " ->");
+	list_for_each_entry(bfl, &blocked_list, fl_link) {
+		if (bfl->fl_next == fl)
+			lock_get_status(f, bfl, *((loff_t *)f->private), " ->");
+	}
 
 	return 0;
 }
@@ -2267,7 +2276,7 @@ static void *locks_start(struct seq_file *f, loff_t *pos)
 {
 	loff_t *p = f->private;
 
-	lock_flocks();
+	spin_lock(&file_lock_lock);
 	*p = (*pos + 1);
 	return seq_list_start(&file_lock_list, *pos);
 }
@@ -2281,7 +2290,7 @@ static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
 
 static void locks_stop(struct seq_file *f, void *v)
 {
-	unlock_flocks();
+	spin_unlock(&file_lock_lock);
 }
 
 static const struct seq_operations locks_seq_operations = {
@@ -2328,7 +2337,8 @@ int lock_may_read(struct inode *inode, loff_t start, unsigned long len)
 {
 	struct file_lock *fl;
 	int result = 1;
-	lock_flocks();
+
+	spin_lock(&inode->i_lock);
 	for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
 		if (IS_POSIX(fl)) {
 			if (fl->fl_type == F_RDLCK)
@@ -2345,7 +2355,7 @@ int lock_may_read(struct inode *inode, loff_t start, unsigned long len)
 		result = 0;
 		break;
 	}
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 	return result;
 }
 
@@ -2368,7 +2378,8 @@ int lock_may_write(struct inode *inode, loff_t start, unsigned long len)
 {
 	struct file_lock *fl;
 	int result = 1;
-	lock_flocks();
+
+	spin_lock(&inode->i_lock);
 	for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
 		if (IS_POSIX(fl)) {
 			if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
@@ -2383,7 +2394,7 @@ int lock_may_write(struct inode *inode, loff_t start, unsigned long len)
 		result = 0;
 		break;
 	}
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 	return result;
 }
 
diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 57db324..43ee7f9 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -73,20 +73,21 @@ static int nfs_delegation_claim_locks(struct nfs_open_context *ctx, struct nfs4_
 	if (inode->i_flock == NULL)
 		goto out;
 
-	/* Protect inode->i_flock using the file locks lock */
-	lock_flocks();
+	/* Protect inode->i_flock using the i_lock */
+	spin_lock(&inode->i_lock);
 	for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
 		if (!(fl->fl_flags & (FL_POSIX|FL_FLOCK)))
 			continue;
 		if (nfs_file_open_context(fl->fl_file) != ctx)
 			continue;
-		unlock_flocks();
+		/* FIXME: safe to drop lock here while walking list? */
+		spin_unlock(&inode->i_lock);
 		status = nfs4_lock_delegation_recall(fl, state, stateid);
 		if (status < 0)
 			goto out;
-		lock_flocks();
+		spin_lock(&inode->i_lock);
 	}
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 out:
 	return status;
 }
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 1fab140..ff10b4a 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -1373,13 +1373,13 @@ static int nfs4_reclaim_locks(struct nfs4_state *state, const struct nfs4_state_
 	/* Guard against delegation returns and new lock/unlock calls */
 	down_write(&nfsi->rwsem);
 	/* Protect inode->i_flock using the BKL */
-	lock_flocks();
+	spin_lock(&inode->i_lock);
 	for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
 		if (!(fl->fl_flags & (FL_POSIX|FL_FLOCK)))
 			continue;
 		if (nfs_file_open_context(fl->fl_file)->state != state)
 			continue;
-		unlock_flocks();
+		spin_unlock(&inode->i_lock);
 		status = ops->recover_lock(state, fl);
 		switch (status) {
 			case 0:
@@ -1406,9 +1406,9 @@ static int nfs4_reclaim_locks(struct nfs4_state *state, const struct nfs4_state_
 				/* kill_proc(fl->fl_pid, SIGLOST, 1); */
 				status = 0;
 		}
-		lock_flocks();
+		spin_lock(&inode->i_lock);
 	}
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 out:
 	up_write(&nfsi->rwsem);
 	return status;
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 316ec84..f170518 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2645,13 +2645,13 @@ static void nfsd_break_one_deleg(struct nfs4_delegation *dp)
 
 	list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru);
 
-	/* only place dl_time is set. protected by lock_flocks*/
+	/* Only place dl_time is set; protected by i_lock: */
 	dp->dl_time = get_seconds();
 
 	nfsd4_cb_recall(dp);
 }
 
-/* Called from break_lease() with lock_flocks() held. */
+/* Called from break_lease() with i_lock held. */
 static void nfsd_break_deleg_cb(struct file_lock *fl)
 {
 	struct nfs4_file *fp = (struct nfs4_file *)fl->fl_owner;
@@ -4520,7 +4520,7 @@ check_for_locks(struct nfs4_file *filp, struct nfs4_lockowner *lowner)
 	struct inode *inode = filp->fi_inode;
 	int status = 0;
 
-	lock_flocks();
+	spin_lock(&inode->i_lock);
 	for (flpp = &inode->i_flock; *flpp != NULL; flpp = &(*flpp)->fl_next) {
 		if ((*flpp)->fl_owner == (fl_owner_t)lowner) {
 			status = 1;
@@ -4528,7 +4528,7 @@ check_for_locks(struct nfs4_file *filp, struct nfs4_lockowner *lowner)
 		}
 	}
 out:
-	unlock_flocks();
+	spin_unlock(&inode->i_lock);
 	return status;
 }
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ae377e9..ccb44ea 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1012,8 +1012,6 @@ extern int vfs_setlease(struct file *, long, struct file_lock **);
 extern int lease_modify(struct file_lock **, int);
 extern int lock_may_read(struct inode *, loff_t start, unsigned long count);
 extern int lock_may_write(struct inode *, loff_t start, unsigned long count);
-extern void lock_flocks(void);
-extern void unlock_flocks(void);
 #else /* !CONFIG_FILE_LOCKING */
 static inline int fcntl_getlk(struct file *file, struct flock __user *user)
 {
@@ -1155,15 +1153,6 @@ static inline int lock_may_write(struct inode *inode, loff_t start,
 {
 	return 1;
 }
-
-static inline void lock_flocks(void)
-{
-}
-
-static inline void unlock_flocks(void)
-{
-}
-
 #endif /* !CONFIG_FILE_LOCKING */
 
 
-- 
1.7.1