remove the XFS iolock, V2

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* remove the XFS iolock, V2
@ 2016-10-21 16:50 Christoph Hellwig
  2016-10-21 16:50 ` [PATCH 1/2] locking/lockdep: Provide a type check for lock_is_held Christoph Hellwig
  2016-10-21 16:50 ` [PATCH 2/2] xfs: remove i_iolock and use i_rwsem in the VFS inode instead Christoph Hellwig
  0 siblings, 2 replies; 3+ messages in thread
From: Christoph Hellwig @ 2016-10-21 16:50 UTC (permalink / raw)
  To: linux-xfs; +Cc: peterz

Hi all,

this series remove the per-inode iolock in XFS which has historically
been used to serialize I/O.  But now that the VFS i_mutex has been
replaced with a rw_semaphore called i_rwsem there is no need to keep
the XFS lock - by relying on the VFS i_rwsem we unify the locking
constraints between difference file systems, reduce the XFS inode size
and reduce the amount of atomic instruction we do with every read
or write call.

Note that Dave asked to kill the XFS mrlock first the last time this
series was posted - while that seems desirable it's not easily possible
due to the way XFS may offload allocator work to a workqueues, and how
lockdep doesn't recognize that.  As removing mrlocks entirely would
be just a cleanup without an affect on locking hierchies or inode
size reduction (except for debug builds) I would prefer to get this
series to remove the iolock in first, and then see what we can do about
the two remaining mrlocks later.

^ permalink raw reply	[flat|nested] 3+ messages in thread

* [PATCH 1/2] locking/lockdep: Provide a type check for lock_is_held
  2016-10-21 16:50 remove the XFS iolock, V2 Christoph Hellwig
@ 2016-10-21 16:50 ` Christoph Hellwig
  2016-10-21 16:50 ` [PATCH 2/2] xfs: remove i_iolock and use i_rwsem in the VFS inode instead Christoph Hellwig
  1 sibling, 0 replies; 3+ messages in thread
From: Christoph Hellwig @ 2016-10-21 16:50 UTC (permalink / raw)
  To: linux-xfs; +Cc: peterz

From: Peter Zijlstra <peterz@infradead.org>

Christoph requested lockdep_assert_held() variants that distinguish
between held-for-read or held-for-write.

Provide:

  int lock_is_held_type(struct lockdep_map *lock, int read)

which takes the same argument as lock_acquire(.read) and matches it to
the held_lock instance.

Use of this function should be gated by the debug_locks variable. When
that is 0 the return value of the lock_is_held_type() function is
undefined. This is done to allow both negative and positive tests for
holding locks.

By default we provide (positive) lockdep_assert_held{,_exclusive,_read}()
macros.

Requested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 include/linux/lockdep.h  | 23 +++++++++++++++++++++--
 kernel/locking/lockdep.c | 20 ++++++++++++--------
 2 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index c1458fe..5b46871 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -338,9 +338,18 @@ extern void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 extern void lock_release(struct lockdep_map *lock, int nested,
 			 unsigned long ip);
 
-#define lockdep_is_held(lock)	lock_is_held(&(lock)->dep_map)
+/*
+ * Same "read" as for lock_acquire(), except -1 means any.
+ */
+extern int lock_is_held_type(struct lockdep_map *lock, int read);
+
+static inline int lock_is_held(struct lockdep_map *lock)
+{
+	return lock_is_held_type(lock, -1);
+}
 
-extern int lock_is_held(struct lockdep_map *lock);
+#define lockdep_is_held(lock)		lock_is_held(&(lock)->dep_map)
+#define lockdep_is_held_type(lock, r)	lock_is_held_type(&(lock)->dep_map, (r))
 
 extern void lock_set_class(struct lockdep_map *lock, const char *name,
 			   struct lock_class_key *key, unsigned int subclass,
@@ -372,6 +381,14 @@ extern void lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie);
 		WARN_ON(debug_locks && !lockdep_is_held(l));	\
 	} while (0)
 
+#define lockdep_assert_held_exclusive(l)	do {			\
+		WARN_ON(debug_locks && !lockdep_is_held_type(l, 0));	\
+	} while (0)
+
+#define lockdep_assert_held_read(l)	do {				\
+		WARN_ON(debug_locks && !lockdep_is_held_type(l, 1));	\
+	} while (0)
+
 #define lockdep_assert_held_once(l)	do {				\
 		WARN_ON_ONCE(debug_locks && !lockdep_is_held(l));	\
 	} while (0)
@@ -429,6 +446,8 @@ struct lock_class_key { };
 #define lockdep_depth(tsk)	(0)
 
 #define lockdep_assert_held(l)			do { (void)(l); } while (0)
+#define lockdep_assert_held_exclusive(l)	do { (void)(l); } while (0)
+#define lockdep_assert_held_read(l)		do { (void)(l); } while (0)
 #define lockdep_assert_held_once(l)		do { (void)(l); } while (0)
 
 #define lockdep_recursing(tsk)			(0)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 589d763..cff580a 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3188,7 +3188,7 @@ print_lock_nested_lock_not_held(struct task_struct *curr,
 	return 0;
 }
 
-static int __lock_is_held(struct lockdep_map *lock);
+static int __lock_is_held(struct lockdep_map *lock, int read);
 
 /*
  * This gets called for every mutex_lock*()/spin_lock*() operation.
@@ -3329,7 +3329,7 @@ static int __lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 	}
 	chain_key = iterate_chain_key(chain_key, class_idx);
 
-	if (nest_lock && !__lock_is_held(nest_lock))
+	if (nest_lock && !__lock_is_held(nest_lock, -1))
 		return print_lock_nested_lock_not_held(curr, hlock, ip);
 
 	if (!validate_chain(curr, lock, hlock, chain_head, chain_key))
@@ -3576,7 +3576,7 @@ __lock_release(struct lockdep_map *lock, int nested, unsigned long ip)
 	return 1;
 }
 
-static int __lock_is_held(struct lockdep_map *lock)
+static int __lock_is_held(struct lockdep_map *lock, int read)
 {
 	struct task_struct *curr = current;
 	int i;
@@ -3584,8 +3584,12 @@ static int __lock_is_held(struct lockdep_map *lock)
 	for (i = 0; i < curr->lockdep_depth; i++) {
 		struct held_lock *hlock = curr->held_locks + i;
 
-		if (match_held_lock(hlock, lock))
-			return 1;
+		if (match_held_lock(hlock, lock)) {
+			if (read == -1 || hlock->read == read)
+				return 1;
+
+			return 0;
+		}
 	}
 
 	return 0;
@@ -3769,7 +3773,7 @@ void lock_release(struct lockdep_map *lock, int nested,
 }
 EXPORT_SYMBOL_GPL(lock_release);
 
-int lock_is_held(struct lockdep_map *lock)
+int lock_is_held_type(struct lockdep_map *lock, int read)
 {
 	unsigned long flags;
 	int ret = 0;
@@ -3781,13 +3785,13 @@ int lock_is_held(struct lockdep_map *lock)
 	check_flags(flags);
 
 	current->lockdep_recursion = 1;
-	ret = __lock_is_held(lock);
+	ret = __lock_is_held(lock, read);
 	current->lockdep_recursion = 0;
 	raw_local_irq_restore(flags);
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(lock_is_held);
+EXPORT_SYMBOL_GPL(lock_is_held_type);
 
 struct pin_cookie lock_pin_lock(struct lockdep_map *lock)
 {
-- 
2.1.4


^ permalink raw reply related	[flat|nested] 3+ messages in thread

* [PATCH 2/2] xfs: remove i_iolock and use i_rwsem in the VFS inode instead
  2016-10-21 16:50 remove the XFS iolock, V2 Christoph Hellwig
  2016-10-21 16:50 ` [PATCH 1/2] locking/lockdep: Provide a type check for lock_is_held Christoph Hellwig
@ 2016-10-21 16:50 ` Christoph Hellwig
  1 sibling, 0 replies; 3+ messages in thread
From: Christoph Hellwig @ 2016-10-21 16:50 UTC (permalink / raw)
  To: linux-xfs; +Cc: peterz

This patch drops the XFS-own i_iolock and uses the VFS i_rwsem which
recently replaced i_mutex instead.  This means we only have to take
one looks instead of two in many fast path operations, and we can
also shrink the xfs_inode structure.  Thanks to the xfs_ilock family
there is very little churn, the only thing of note is that we need
to switch to use the lock_two_directory helper for taking the i_rwsem
on two inodes in a few places to make sure our lock order matches
the one used in the VFS.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_aops.c         |  7 ++--
 fs/xfs/xfs_bmap_util.c    | 12 +++----
 fs/xfs/xfs_dir2_readdir.c |  2 --
 fs/xfs/xfs_file.c         | 79 +++++++++++++--------------------------------
 fs/xfs/xfs_icache.c       |  6 ++--
 fs/xfs/xfs_inode.c        | 82 +++++++++++++++++++----------------------------
 fs/xfs/xfs_inode.h        |  7 ++--
 fs/xfs/xfs_ioctl.c        |  2 +-
 fs/xfs/xfs_iops.c         | 14 ++++----
 fs/xfs/xfs_pnfs.c         |  7 +---
 fs/xfs/xfs_pnfs.h         |  4 +--
 fs/xfs/xfs_reflink.c      | 14 +++-----
 fs/xfs/xfs_super.c        |  2 +-
 fs/xfs/xfs_symlink.c      |  7 ++--
 14 files changed, 86 insertions(+), 159 deletions(-)

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 3e57a56..d5a09b7 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -1583,7 +1583,6 @@ xfs_vm_bmap(
 	struct xfs_inode	*ip = XFS_I(inode);
 
 	trace_xfs_vm_bmap(XFS_I(inode));
-	xfs_ilock(ip, XFS_IOLOCK_SHARED);
 
 	/*
 	 * The swap code (ab-)uses ->bmap to get a block mapping and then
@@ -1591,12 +1590,10 @@ xfs_vm_bmap(
 	 * that on reflinks inodes, so we have to skip out here.  And yes,
 	 * 0 is the magic code for a bmap error..
 	 */
-	if (xfs_is_reflink_inode(ip)) {
-		xfs_iunlock(ip, XFS_IOLOCK_SHARED);
+	if (xfs_is_reflink_inode(ip))
 		return 0;
-	}
+
 	filemap_write_and_wait(mapping);
-	xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 	return generic_block_bmap(mapping, block, xfs_get_blocks);
 }
 
diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index 552465e..4f31756 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -1938,8 +1938,8 @@ xfs_swap_extents(
 	 * page cache safely. Once we have done this we can take the ilocks and
 	 * do the rest of the checks.
 	 */
-	lock_flags = XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL;
-	xfs_lock_two_inodes(ip, tip, XFS_IOLOCK_EXCL);
+	lock_two_nondirectories(VFS_I(ip), VFS_I(tip));
+	lock_flags = XFS_MMAPLOCK_EXCL;
 	xfs_lock_two_inodes(ip, tip, XFS_MMAPLOCK_EXCL);
 
 	/* Verify that both files have the same format */
@@ -2079,15 +2079,13 @@ xfs_swap_extents(
 	trace_xfs_swap_extent_after(ip, 0);
 	trace_xfs_swap_extent_after(tip, 1);
 
+out_unlock:
 	xfs_iunlock(ip, lock_flags);
 	xfs_iunlock(tip, lock_flags);
+	unlock_two_nondirectories(VFS_I(ip), VFS_I(tip));
 	return error;
 
 out_trans_cancel:
 	xfs_trans_cancel(tp);
-
-out_unlock:
-	xfs_iunlock(ip, lock_flags);
-	xfs_iunlock(tip, lock_flags);
-	return error;
+	goto out_unlock;
 }
diff --git a/fs/xfs/xfs_dir2_readdir.c b/fs/xfs/xfs_dir2_readdir.c
index 2981698..003a99b 100644
--- a/fs/xfs/xfs_dir2_readdir.c
+++ b/fs/xfs/xfs_dir2_readdir.c
@@ -677,7 +677,6 @@ xfs_readdir(
 	args.dp = dp;
 	args.geo = dp->i_mount->m_dir_geo;
 
-	xfs_ilock(dp, XFS_IOLOCK_SHARED);
 	if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
 		rval = xfs_dir2_sf_getdents(&args, ctx);
 	else if ((rval = xfs_dir2_isblock(&args, &v)))
@@ -686,7 +685,6 @@ xfs_readdir(
 		rval = xfs_dir2_block_getdents(&args, ctx);
 	else
 		rval = xfs_dir2_leaf_getdents(&args, ctx, bufsize);
-	xfs_iunlock(dp, XFS_IOLOCK_SHARED);
 
 	return rval;
 }
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 6e4f7f9..8830223 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -48,40 +48,6 @@
 static const struct vm_operations_struct xfs_file_vm_ops;
 
 /*
- * Locking primitives for read and write IO paths to ensure we consistently use
- * and order the inode->i_mutex, ip->i_lock and ip->i_iolock.
- */
-static inline void
-xfs_rw_ilock(
-	struct xfs_inode	*ip,
-	int			type)
-{
-	if (type & XFS_IOLOCK_EXCL)
-		inode_lock(VFS_I(ip));
-	xfs_ilock(ip, type);
-}
-
-static inline void
-xfs_rw_iunlock(
-	struct xfs_inode	*ip,
-	int			type)
-{
-	xfs_iunlock(ip, type);
-	if (type & XFS_IOLOCK_EXCL)
-		inode_unlock(VFS_I(ip));
-}
-
-static inline void
-xfs_rw_ilock_demote(
-	struct xfs_inode	*ip,
-	int			type)
-{
-	xfs_ilock_demote(ip, type);
-	if (type & XFS_IOLOCK_EXCL)
-		inode_unlock(VFS_I(ip));
-}
-
-/*
  * Clear the specified ranges to zero through either the pagecache or DAX.
  * Holes and unwritten extents will be left as-is as they already are zeroed.
  */
@@ -273,7 +239,7 @@ xfs_file_dio_aio_read(
 
 	file_accessed(iocb->ki_filp);
 
-	xfs_rw_ilock(ip, XFS_IOLOCK_SHARED);
+	xfs_ilock(ip, XFS_IOLOCK_SHARED);
 	if (mapping->nrpages) {
 		ret = filemap_write_and_wait_range(mapping, iocb->ki_pos, end);
 		if (ret)
@@ -299,7 +265,7 @@ xfs_file_dio_aio_read(
 	}
 
 out_unlock:
-	xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
+	xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 	return ret;
 }
 
@@ -317,9 +283,9 @@ xfs_file_dax_read(
 	if (!count)
 		return 0; /* skip atime */
 
-	xfs_rw_ilock(ip, XFS_IOLOCK_SHARED);
+	xfs_ilock(ip, XFS_IOLOCK_SHARED);
 	ret = iomap_dax_rw(iocb, to, &xfs_iomap_ops);
-	xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
+	xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 
 	file_accessed(iocb->ki_filp);
 	return ret;
@@ -335,9 +301,9 @@ xfs_file_buffered_aio_read(
 
 	trace_xfs_file_buffered_read(ip, iov_iter_count(to), iocb->ki_pos);
 
-	xfs_rw_ilock(ip, XFS_IOLOCK_SHARED);
+	xfs_ilock(ip, XFS_IOLOCK_SHARED);
 	ret = generic_file_read_iter(iocb, to);
-	xfs_rw_iunlock(ip, XFS_IOLOCK_SHARED);
+	xfs_iunlock(ip, XFS_IOLOCK_SHARED);
 
 	return ret;
 }
@@ -418,15 +384,18 @@ xfs_file_aio_write_checks(
 	if (error <= 0)
 		return error;
 
-	error = xfs_break_layouts(inode, iolock, true);
+	error = xfs_break_layouts(inode, iolock);
 	if (error)
 		return error;
 
-	/* For changing security info in file_remove_privs() we need i_mutex */
+	/*
+	 * For changing security info in file_remove_privs() we need i_rwsem
+	 * exclusively.
+	 */
 	if (*iolock == XFS_IOLOCK_SHARED && !IS_NOSEC(inode)) {
-		xfs_rw_iunlock(ip, *iolock);
+		xfs_iunlock(ip, *iolock);
 		*iolock = XFS_IOLOCK_EXCL;
-		xfs_rw_ilock(ip, *iolock);
+		xfs_ilock(ip, *iolock);
 		goto restart;
 	}
 	/*
@@ -451,9 +420,9 @@ xfs_file_aio_write_checks(
 		spin_unlock(&ip->i_flags_lock);
 		if (!drained_dio) {
 			if (*iolock == XFS_IOLOCK_SHARED) {
-				xfs_rw_iunlock(ip, *iolock);
+				xfs_iunlock(ip, *iolock);
 				*iolock = XFS_IOLOCK_EXCL;
-				xfs_rw_ilock(ip, *iolock);
+				xfs_ilock(ip, *iolock);
 				iov_iter_reexpand(from, count);
 			}
 			/*
@@ -559,7 +528,7 @@ xfs_file_dio_aio_write(
 		iolock = XFS_IOLOCK_SHARED;
 	}
 
-	xfs_rw_ilock(ip, iolock);
+	xfs_ilock(ip, iolock);
 
 	ret = xfs_file_aio_write_checks(iocb, from, &iolock);
 	if (ret)
@@ -591,7 +560,7 @@ xfs_file_dio_aio_write(
 	if (unaligned_io)
 		inode_dio_wait(inode);
 	else if (iolock == XFS_IOLOCK_EXCL) {
-		xfs_rw_ilock_demote(ip, XFS_IOLOCK_EXCL);
+		xfs_ilock_demote(ip, XFS_IOLOCK_EXCL);
 		iolock = XFS_IOLOCK_SHARED;
 	}
 
@@ -621,7 +590,7 @@ xfs_file_dio_aio_write(
 		iov_iter_advance(from, ret);
 	}
 out:
-	xfs_rw_iunlock(ip, iolock);
+	xfs_iunlock(ip, iolock);
 
 	/*
 	 * No fallback to buffered IO on errors for XFS, direct IO will either
@@ -643,7 +612,7 @@ xfs_file_dax_write(
 	size_t			count;
 	loff_t			pos;
 
-	xfs_rw_ilock(ip, iolock);
+	xfs_ilock(ip, iolock);
 	ret = xfs_file_aio_write_checks(iocb, from, &iolock);
 	if (ret)
 		goto out;
@@ -652,15 +621,13 @@ xfs_file_dax_write(
 	count = iov_iter_count(from);
 
 	trace_xfs_file_dax_write(ip, count, pos);
-
 	ret = iomap_dax_rw(iocb, from, &xfs_iomap_ops);
 	if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
 		i_size_write(inode, iocb->ki_pos);
 		error = xfs_setfilesize(ip, pos, ret);
 	}
-
 out:
-	xfs_rw_iunlock(ip, iolock);
+	xfs_iunlock(ip, iolock);
 	return error ? error : ret;
 }
 
@@ -677,7 +644,7 @@ xfs_file_buffered_aio_write(
 	int			enospc = 0;
 	int			iolock = XFS_IOLOCK_EXCL;
 
-	xfs_rw_ilock(ip, iolock);
+	xfs_ilock(ip, iolock);
 
 	ret = xfs_file_aio_write_checks(iocb, from, &iolock);
 	if (ret)
@@ -721,7 +688,7 @@ xfs_file_buffered_aio_write(
 
 	current->backing_dev_info = NULL;
 out:
-	xfs_rw_iunlock(ip, iolock);
+	xfs_iunlock(ip, iolock);
 	return ret;
 }
 
@@ -797,7 +764,7 @@ xfs_file_fallocate(
 		return -EOPNOTSUPP;
 
 	xfs_ilock(ip, iolock);
-	error = xfs_break_layouts(inode, &iolock, false);
+	error = xfs_break_layouts(inode, &iolock);
 	if (error)
 		goto out_unlock;
 
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index 14796b7..0806877 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -70,8 +70,6 @@ xfs_inode_alloc(
 	ASSERT(!xfs_isiflocked(ip));
 	ASSERT(ip->i_ino == 0);
 
-	mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);
-
 	/* initialise the xfs inode */
 	ip->i_ino = ino;
 	ip->i_mount = mp;
@@ -393,8 +391,8 @@ xfs_iget_cache_hit(
 		xfs_inode_clear_reclaim_tag(pag, ip->i_ino);
 		inode->i_state = I_NEW;
 
-		ASSERT(!rwsem_is_locked(&ip->i_iolock.mr_lock));
-		mrlock_init(&ip->i_iolock, MRLOCK_BARRIER, "xfsio", ip->i_ino);
+		ASSERT(!rwsem_is_locked(&inode->i_rwsem));
+		init_rwsem(&inode->i_rwsem);
 
 		spin_unlock(&ip->i_flags_lock);
 		spin_unlock(&pag->pag_ici_lock);
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 4e560e6..e9ab42d 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -142,31 +142,31 @@ xfs_ilock_attr_map_shared(
 }
 
 /*
- * The xfs inode contains 3 multi-reader locks: the i_iolock the i_mmap_lock and
- * the i_lock.  This routine allows various combinations of the locks to be
- * obtained.
+ * In addition to i_rwsem in the VFS inode, the xfs inode contains 2
+ * multi-reader locks: i_mmap_lock and the i_lock.  This routine allows
+ * various combinations of the locks to be obtained.
  *
  * The 3 locks should always be ordered so that the IO lock is obtained first,
  * the mmap lock second and the ilock last in order to prevent deadlock.
  *
  * Basic locking order:
  *
- * i_iolock -> i_mmap_lock -> page_lock -> i_ilock
+ * i_rwsem -> i_mmap_lock -> page_lock -> i_ilock
  *
  * mmap_sem locking order:
  *
- * i_iolock -> page lock -> mmap_sem
+ * i_rwsem -> page lock -> mmap_sem
  * mmap_sem -> i_mmap_lock -> page_lock
  *
  * The difference in mmap_sem locking order mean that we cannot hold the
  * i_mmap_lock over syscall based read(2)/write(2) based IO. These IO paths can
  * fault in pages during copy in/out (for buffered IO) or require the mmap_sem
  * in get_user_pages() to map the user pages into the kernel address space for
- * direct IO. Similarly the i_iolock cannot be taken inside a page fault because
+ * direct IO. Similarly the i_rwsem cannot be taken inside a page fault because
  * page faults already hold the mmap_sem.
  *
  * Hence to serialise fully against both syscall and mmap based IO, we need to
- * take both the i_iolock and the i_mmap_lock. These locks should *only* be both
+ * take both the i_rwsem and the i_mmap_lock. These locks should *only* be both
  * taken in places where we need to invalidate the page cache in a race
  * free manner (e.g. truncate, hole punch and other extent manipulation
  * functions).
@@ -191,10 +191,13 @@ xfs_ilock(
 	       (XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
 	ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_SUBCLASS_MASK)) == 0);
 
-	if (lock_flags & XFS_IOLOCK_EXCL)
-		mrupdate_nested(&ip->i_iolock, XFS_IOLOCK_DEP(lock_flags));
-	else if (lock_flags & XFS_IOLOCK_SHARED)
-		mraccess_nested(&ip->i_iolock, XFS_IOLOCK_DEP(lock_flags));
+	if (lock_flags & XFS_IOLOCK_EXCL) {
+		down_write_nested(&VFS_I(ip)->i_rwsem,
+				  XFS_IOLOCK_DEP(lock_flags));
+	} else if (lock_flags & XFS_IOLOCK_SHARED) {
+		down_read_nested(&VFS_I(ip)->i_rwsem,
+				 XFS_IOLOCK_DEP(lock_flags));
+	}
 
 	if (lock_flags & XFS_MMAPLOCK_EXCL)
 		mrupdate_nested(&ip->i_mmaplock, XFS_MMAPLOCK_DEP(lock_flags));
@@ -240,10 +243,10 @@ xfs_ilock_nowait(
 	ASSERT((lock_flags & ~(XFS_LOCK_MASK | XFS_LOCK_SUBCLASS_MASK)) == 0);
 
 	if (lock_flags & XFS_IOLOCK_EXCL) {
-		if (!mrtryupdate(&ip->i_iolock))
+		if (!down_write_trylock(&VFS_I(ip)->i_rwsem))
 			goto out;
 	} else if (lock_flags & XFS_IOLOCK_SHARED) {
-		if (!mrtryaccess(&ip->i_iolock))
+		if (!down_read_trylock(&VFS_I(ip)->i_rwsem))
 			goto out;
 	}
 
@@ -271,9 +274,9 @@ xfs_ilock_nowait(
 		mrunlock_shared(&ip->i_mmaplock);
 out_undo_iolock:
 	if (lock_flags & XFS_IOLOCK_EXCL)
-		mrunlock_excl(&ip->i_iolock);
+		up_write(&VFS_I(ip)->i_rwsem);
 	else if (lock_flags & XFS_IOLOCK_SHARED)
-		mrunlock_shared(&ip->i_iolock);
+		up_read(&VFS_I(ip)->i_rwsem);
 out:
 	return 0;
 }
@@ -310,9 +313,9 @@ xfs_iunlock(
 	ASSERT(lock_flags != 0);
 
 	if (lock_flags & XFS_IOLOCK_EXCL)
-		mrunlock_excl(&ip->i_iolock);
+		up_write(&VFS_I(ip)->i_rwsem);
 	else if (lock_flags & XFS_IOLOCK_SHARED)
-		mrunlock_shared(&ip->i_iolock);
+		up_read(&VFS_I(ip)->i_rwsem);
 
 	if (lock_flags & XFS_MMAPLOCK_EXCL)
 		mrunlock_excl(&ip->i_mmaplock);
@@ -345,7 +348,7 @@ xfs_ilock_demote(
 	if (lock_flags & XFS_MMAPLOCK_EXCL)
 		mrdemote(&ip->i_mmaplock);
 	if (lock_flags & XFS_IOLOCK_EXCL)
-		mrdemote(&ip->i_iolock);
+		downgrade_write(&VFS_I(ip)->i_rwsem);
 
 	trace_xfs_ilock_demote(ip, lock_flags, _RET_IP_);
 }
@@ -370,8 +373,9 @@ xfs_isilocked(
 
 	if (lock_flags & (XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED)) {
 		if (!(lock_flags & XFS_IOLOCK_SHARED))
-			return !!ip->i_iolock.mr_writer;
-		return rwsem_is_locked(&ip->i_iolock.mr_lock);
+			return !debug_locks ||
+				lockdep_is_held_type(&VFS_I(ip)->i_rwsem, 0);
+		return rwsem_is_locked(&VFS_I(ip)->i_rwsem);
 	}
 
 	ASSERT(0);
@@ -421,11 +425,7 @@ xfs_lock_inumorder(int lock_mode, int subclass)
 
 	if (lock_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)) {
 		ASSERT(subclass <= XFS_IOLOCK_MAX_SUBCLASS);
-		ASSERT(xfs_lockdep_subclass_ok(subclass +
-						XFS_IOLOCK_PARENT_VAL));
 		class += subclass << XFS_IOLOCK_SHIFT;
-		if (lock_mode & XFS_IOLOCK_PARENT)
-			class += XFS_IOLOCK_PARENT_VAL << XFS_IOLOCK_SHIFT;
 	}
 
 	if (lock_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)) {
@@ -477,8 +477,6 @@ xfs_lock_inodes(
 			    XFS_ILOCK_EXCL));
 	ASSERT(!(lock_mode & (XFS_IOLOCK_SHARED | XFS_MMAPLOCK_SHARED |
 			      XFS_ILOCK_SHARED)));
-	ASSERT(!(lock_mode & XFS_IOLOCK_EXCL) ||
-		inodes <= XFS_IOLOCK_MAX_SUBCLASS + 1);
 	ASSERT(!(lock_mode & XFS_MMAPLOCK_EXCL) ||
 		inodes <= XFS_MMAPLOCK_MAX_SUBCLASS + 1);
 	ASSERT(!(lock_mode & XFS_ILOCK_EXCL) ||
@@ -581,10 +579,8 @@ xfs_lock_two_inodes(
 	int			attempts = 0;
 	xfs_log_item_t		*lp;
 
-	if (lock_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)) {
-		ASSERT(!(lock_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL)));
-		ASSERT(!(lock_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
-	} else if (lock_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL))
+	ASSERT(!(lock_mode & (XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)));
+	if (lock_mode & (XFS_MMAPLOCK_SHARED|XFS_MMAPLOCK_EXCL))
 		ASSERT(!(lock_mode & (XFS_ILOCK_SHARED|XFS_ILOCK_EXCL)));
 
 	ASSERT(ip0->i_ino != ip1->i_ino);
@@ -715,7 +711,6 @@ xfs_lookup(
 	if (XFS_FORCED_SHUTDOWN(dp->i_mount))
 		return -EIO;
 
-	xfs_ilock(dp, XFS_IOLOCK_SHARED);
 	error = xfs_dir_lookup(NULL, dp, name, &inum, ci_name);
 	if (error)
 		goto out_unlock;
@@ -724,14 +719,12 @@ xfs_lookup(
 	if (error)
 		goto out_free_name;
 
-	xfs_iunlock(dp, XFS_IOLOCK_SHARED);
 	return 0;
 
 out_free_name:
 	if (ci_name)
 		kmem_free(ci_name->name);
 out_unlock:
-	xfs_iunlock(dp, XFS_IOLOCK_SHARED);
 	*ipp = NULL;
 	return error;
 }
@@ -1215,8 +1208,7 @@ xfs_create(
 	if (error)
 		goto out_release_inode;
 
-	xfs_ilock(dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL |
-		      XFS_IOLOCK_PARENT | XFS_ILOCK_PARENT);
+	xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
 	unlock_dp_on_error = true;
 
 	xfs_defer_init(&dfops, &first_block);
@@ -1252,7 +1244,7 @@ xfs_create(
 	 * the transaction cancel unlocking dp so don't do it explicitly in the
 	 * error path.
 	 */
-	xfs_trans_ijoin(tp, dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
+	xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
 	unlock_dp_on_error = false;
 
 	error = xfs_dir_createname(tp, dp, name, ip->i_ino,
@@ -1325,7 +1317,7 @@ xfs_create(
 	xfs_qm_dqrele(pdqp);
 
 	if (unlock_dp_on_error)
-		xfs_iunlock(dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
+		xfs_iunlock(dp, XFS_ILOCK_EXCL);
 	return error;
 }
 
@@ -1466,11 +1458,10 @@ xfs_link(
 	if (error)
 		goto std_return;
 
-	xfs_ilock(tdp, XFS_IOLOCK_EXCL | XFS_IOLOCK_PARENT);
 	xfs_lock_two_inodes(sip, tdp, XFS_ILOCK_EXCL);
 
 	xfs_trans_ijoin(tp, sip, XFS_ILOCK_EXCL);
-	xfs_trans_ijoin(tp, tdp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
+	xfs_trans_ijoin(tp, tdp, XFS_ILOCK_EXCL);
 
 	/*
 	 * If we are using project inheritance, we only allow hard link
@@ -2579,10 +2570,9 @@ xfs_remove(
 		goto std_return;
 	}
 
-	xfs_ilock(dp, XFS_IOLOCK_EXCL | XFS_IOLOCK_PARENT);
 	xfs_lock_two_inodes(dp, ip, XFS_ILOCK_EXCL);
 
-	xfs_trans_ijoin(tp, dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
+	xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
 	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 
 	/*
@@ -2963,12 +2953,6 @@ xfs_rename(
 	 * whether the target directory is the same as the source
 	 * directory, we can lock from 2 to 4 inodes.
 	 */
-	if (!new_parent)
-		xfs_ilock(src_dp, XFS_IOLOCK_EXCL | XFS_IOLOCK_PARENT);
-	else
-		xfs_lock_two_inodes(src_dp, target_dp,
-				    XFS_IOLOCK_EXCL | XFS_IOLOCK_PARENT);
-
 	xfs_lock_inodes(inodes, num_inodes, XFS_ILOCK_EXCL);
 
 	/*
@@ -2976,9 +2960,9 @@ xfs_rename(
 	 * we can rely on either trans_commit or trans_cancel to unlock
 	 * them.
 	 */
-	xfs_trans_ijoin(tp, src_dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
+	xfs_trans_ijoin(tp, src_dp, XFS_ILOCK_EXCL);
 	if (new_parent)
-		xfs_trans_ijoin(tp, target_dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
+		xfs_trans_ijoin(tp, target_dp, XFS_ILOCK_EXCL);
 	xfs_trans_ijoin(tp, src_ip, XFS_ILOCK_EXCL);
 	if (target_ip)
 		xfs_trans_ijoin(tp, target_ip, XFS_ILOCK_EXCL);
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index f14c1de..1e14a6cd 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -56,7 +56,6 @@ typedef struct xfs_inode {
 	/* Transaction and locking information. */
 	struct xfs_inode_log_item *i_itemp;	/* logging information */
 	mrlock_t		i_lock;		/* inode lock */
-	mrlock_t		i_iolock;	/* inode IO lock */
 	mrlock_t		i_mmaplock;	/* inode mmap IO lock */
 	atomic_t		i_pincount;	/* inode pin count */
 	spinlock_t		i_flags_lock;	/* inode i_flags lock */
@@ -332,7 +331,7 @@ static inline int xfs_isiflocked(struct xfs_inode *ip)
  * IOLOCK values
  *
  * 0-3		subclass value
- * 4-7		PARENT subclass values
+ * 4-7		unused
  *
  * MMAPLOCK values
  *
@@ -347,10 +346,8 @@ static inline int xfs_isiflocked(struct xfs_inode *ip)
  * 
  */
 #define XFS_IOLOCK_SHIFT		16
-#define XFS_IOLOCK_PARENT_VAL		4
-#define XFS_IOLOCK_MAX_SUBCLASS		(XFS_IOLOCK_PARENT_VAL - 1)
+#define XFS_IOLOCK_MAX_SUBCLASS		3
 #define XFS_IOLOCK_DEP_MASK		0x000f0000
-#define	XFS_IOLOCK_PARENT		(XFS_IOLOCK_PARENT_VAL << XFS_IOLOCK_SHIFT)
 
 #define XFS_MMAPLOCK_SHIFT		20
 #define XFS_MMAPLOCK_NUMORDER		0
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index c245bed..94a2448 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -639,7 +639,7 @@ xfs_ioc_space(
 		return error;
 
 	xfs_ilock(ip, iolock);
-	error = xfs_break_layouts(inode, &iolock, false);
+	error = xfs_break_layouts(inode, &iolock);
 	if (error)
 		goto out_unlock;
 
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 405a65c..c962999 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -983,15 +983,13 @@ xfs_vn_setattr(
 		struct xfs_inode	*ip = XFS_I(d_inode(dentry));
 		uint			iolock = XFS_IOLOCK_EXCL;
 
-		xfs_ilock(ip, iolock);
-		error = xfs_break_layouts(d_inode(dentry), &iolock, true);
-		if (!error) {
-			xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
-			iolock |= XFS_MMAPLOCK_EXCL;
+		error = xfs_break_layouts(d_inode(dentry), &iolock);
+		if (error)
+			return error;
 
-			error = xfs_vn_setattr_size(dentry, iattr);
-		}
-		xfs_iunlock(ip, iolock);
+		xfs_ilock(ip, XFS_MMAPLOCK_EXCL);
+		error = xfs_setattr_size(ip, iattr);
+		xfs_iunlock(ip, XFS_MMAPLOCK_EXCL);
 	} else {
 		error = xfs_vn_setattr_nonsize(dentry, iattr);
 	}
diff --git a/fs/xfs/xfs_pnfs.c b/fs/xfs/xfs_pnfs.c
index 93a7aaf..2f2dc3c 100644
--- a/fs/xfs/xfs_pnfs.c
+++ b/fs/xfs/xfs_pnfs.c
@@ -32,8 +32,7 @@
 int
 xfs_break_layouts(
 	struct inode		*inode,
-	uint			*iolock,
-	bool			with_imutex)
+	uint			*iolock)
 {
 	struct xfs_inode	*ip = XFS_I(inode);
 	int			error;
@@ -42,12 +41,8 @@ xfs_break_layouts(
 
 	while ((error = break_layout(inode, false) == -EWOULDBLOCK)) {
 		xfs_iunlock(ip, *iolock);
-		if (with_imutex && (*iolock & XFS_IOLOCK_EXCL))
-			inode_unlock(inode);
 		error = break_layout(inode, true);
 		*iolock = XFS_IOLOCK_EXCL;
-		if (with_imutex)
-			inode_lock(inode);
 		xfs_ilock(ip, *iolock);
 	}
 
diff --git a/fs/xfs/xfs_pnfs.h b/fs/xfs/xfs_pnfs.h
index e8339f7..b587cb9 100644
--- a/fs/xfs/xfs_pnfs.h
+++ b/fs/xfs/xfs_pnfs.h
@@ -8,10 +8,10 @@ int xfs_fs_map_blocks(struct inode *inode, loff_t offset, u64 length,
 int xfs_fs_commit_blocks(struct inode *inode, struct iomap *maps, int nr_maps,
 		struct iattr *iattr);
 
-int xfs_break_layouts(struct inode *inode, uint *iolock, bool with_imutex);
+int xfs_break_layouts(struct inode *inode, uint *iolock);
 #else
 static inline int
-xfs_break_layouts(struct inode *inode, uint *iolock, bool with_imutex)
+xfs_break_layouts(struct inode *inode, uint *iolock)
 {
 	return 0;
 }
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index cd308f1..e1144d7 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1298,13 +1298,11 @@ xfs_reflink_remap_range(
 		return -EIO;
 
 	/* Lock both files against IO */
-	if (same_inode) {
-		xfs_ilock(src, XFS_IOLOCK_EXCL);
+	lock_two_nondirectories(inode_in, inode_out);
+	if (same_inode)
 		xfs_ilock(src, XFS_MMAPLOCK_EXCL);
-	} else {
-		xfs_lock_two_inodes(src, dest, XFS_IOLOCK_EXCL);
+	else
 		xfs_lock_two_inodes(src, dest, XFS_MMAPLOCK_EXCL);
-	}
 
 	/* Don't touch certain kinds of inodes */
 	ret = -EPERM;
@@ -1443,11 +1441,9 @@ xfs_reflink_remap_range(
 
 out_unlock:
 	xfs_iunlock(src, XFS_MMAPLOCK_EXCL);
-	xfs_iunlock(src, XFS_IOLOCK_EXCL);
-	if (src->i_ino != dest->i_ino) {
+	if (!same_inode)
 		xfs_iunlock(dest, XFS_MMAPLOCK_EXCL);
-		xfs_iunlock(dest, XFS_IOLOCK_EXCL);
-	}
+	unlock_two_nondirectories(inode_in, inode_out);
 	if (ret)
 		trace_xfs_reflink_remap_range_error(dest, ret, _RET_IP_);
 	return ret;
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index ade4691..563d1d1 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -943,7 +943,7 @@ xfs_fs_destroy_inode(
 
 	trace_xfs_destroy_inode(ip);
 
-	ASSERT(!rwsem_is_locked(&ip->i_iolock.mr_lock));
+	ASSERT(!rwsem_is_locked(&inode->i_rwsem));
 	XFS_STATS_INC(ip->i_mount, vn_rele);
 	XFS_STATS_INC(ip->i_mount, vn_remove);
 
diff --git a/fs/xfs/xfs_symlink.c b/fs/xfs/xfs_symlink.c
index 58142ae..f2cb45e 100644
--- a/fs/xfs/xfs_symlink.c
+++ b/fs/xfs/xfs_symlink.c
@@ -238,8 +238,7 @@ xfs_symlink(
 	if (error)
 		goto out_release_inode;
 
-	xfs_ilock(dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL |
-		      XFS_IOLOCK_PARENT | XFS_ILOCK_PARENT);
+	xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
 	unlock_dp_on_error = true;
 
 	/*
@@ -287,7 +286,7 @@ xfs_symlink(
 	 * the transaction cancel unlocking dp so don't do it explicitly in the
 	 * error path.
 	 */
-	xfs_trans_ijoin(tp, dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
+	xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
 	unlock_dp_on_error = false;
 
 	/*
@@ -412,7 +411,7 @@ xfs_symlink(
 	xfs_qm_dqrele(pdqp);
 
 	if (unlock_dp_on_error)
-		xfs_iunlock(dp, XFS_IOLOCK_EXCL | XFS_ILOCK_EXCL);
+		xfs_iunlock(dp, XFS_ILOCK_EXCL);
 	return error;
 }
 
-- 
2.1.4


^ permalink raw reply related	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2016-10-21 16:50 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2016-10-21 16:50 remove the XFS iolock, V2 Christoph Hellwig
2016-10-21 16:50 ` [PATCH 1/2] locking/lockdep: Provide a type check for lock_is_held Christoph Hellwig
2016-10-21 16:50 ` [PATCH 2/2] xfs: remove i_iolock and use i_rwsem in the VFS inode instead Christoph Hellwig

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