[PATCH 04/13] xfs: move RT inode locking out of __xfs_bunmapi

[Christoph Hellwig <hch@lst.de>]

__xfs_bunmapi is a bit of an odd place to lock the rtbitmap and rtsummary
inodes given that it is very high level code.  While this only looks ugly
right now, it will become a problem when supporting delayed allocations
for RT inodes as __xfs_bunmapi might end up deleting only delalloc extents
and thus never unlock the rt inodes.

Move the locking into xfs_bmap_del_extent_real just before the call to
xfs_rtfree_blocks instead and use a new flag in the transaction to ensure
that the locking happens only once.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_bmap.c   | 15 ++++++++-------
 fs/xfs/libxfs/xfs_shared.h |  3 +++
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 282b44deb9f864..e5e199d325982f 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -5305,6 +5305,14 @@ xfs_bmap_del_extent_real(
 		if (xfs_is_reflink_inode(ip) && whichfork == XFS_DATA_FORK) {
 			xfs_refcount_decrease_extent(tp, del);
 		} else if (xfs_ifork_is_realtime(ip, whichfork)) {
+			/*
+			 * Ensure the bitmap and summary inodes are locked
+			 * and joined to the transaction before modifying them.
+			 */
+			if (!(tp->t_flags & XFS_TRANS_RTBITMAP_LOCKED)) {
+				tp->t_flags |= XFS_TRANS_RTBITMAP_LOCKED;
+				xfs_rtbitmap_lock(tp, mp);
+			}
 			error = xfs_rtfree_blocks(tp, del->br_startblock,
 					del->br_blockcount);
 		} else {
@@ -5406,13 +5414,6 @@ __xfs_bunmapi(
 	} else
 		cur = NULL;
 
-	if (isrt) {
-		/*
-		 * Synchronize by locking the realtime bitmap.
-		 */
-		xfs_rtbitmap_lock(tp, mp);
-	}
-
 	extno = 0;
 	while (end != (xfs_fileoff_t)-1 && end >= start &&
 	       (nexts == 0 || extno < nexts)) {
diff --git a/fs/xfs/libxfs/xfs_shared.h b/fs/xfs/libxfs/xfs_shared.h
index f35640ad3e7fe4..34f104ed372c09 100644
--- a/fs/xfs/libxfs/xfs_shared.h
+++ b/fs/xfs/libxfs/xfs_shared.h
@@ -137,6 +137,9 @@ void	xfs_log_get_max_trans_res(struct xfs_mount *mp,
  */
 #define XFS_TRANS_LOWMODE		(1u << 8)
 
+/* Transaction has locked the rtbitmap and rtsum inodes */
+#define XFS_TRANS_RTBITMAP_LOCKED	(1u << 9)
+
 /*
  * Field values for xfs_trans_mod_sb.
  */
-- 
2.39.2