[PATCH 02/10] 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_rtfree_blocks instead (where it will also be
helpful once we support extfree items for RT allocations), and use a new
flag in the transaction to ensure they aren't locked twice.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_bmap.c     | 10 ----------
 fs/xfs/libxfs/xfs_rtbitmap.c | 14 ++++++++++++++
 fs/xfs/libxfs/xfs_shared.h   |  3 +++
 3 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index b525524a2da4ef..f8cc7c510d7bd5 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -5321,16 +5321,6 @@ __xfs_bunmapi(
 	} else
 		cur = NULL;
 
-	if (isrt) {
-		/*
-		 * Synchronize by locking the bitmap inode.
-		 */
-		xfs_ilock(mp->m_rbmip, XFS_ILOCK_EXCL|XFS_ILOCK_RTBITMAP);
-		xfs_trans_ijoin(tp, mp->m_rbmip, XFS_ILOCK_EXCL);
-		xfs_ilock(mp->m_rsumip, XFS_ILOCK_EXCL|XFS_ILOCK_RTSUM);
-		xfs_trans_ijoin(tp, mp->m_rsumip, XFS_ILOCK_EXCL);
-	}
-
 	extno = 0;
 	while (end != (xfs_fileoff_t)-1 && end >= start &&
 	       (nexts == 0 || extno < nexts)) {
diff --git a/fs/xfs/libxfs/xfs_rtbitmap.c b/fs/xfs/libxfs/xfs_rtbitmap.c
index e31663cb7b4349..2759c48390241d 100644
--- a/fs/xfs/libxfs/xfs_rtbitmap.c
+++ b/fs/xfs/libxfs/xfs_rtbitmap.c
@@ -1001,6 +1001,20 @@ xfs_rtfree_blocks(
 		return -EIO;
 	}
 
+	/*
+	 * Ensure the bitmap and summary inodes are locked before modifying
+	 * them.  We can get called multiples times per transaction, so record
+	 * the fact that they are locked in the transaction.
+	 */
+	if (!(tp->t_flags & XFS_TRANS_RTBITMAP_LOCKED)) {
+		tp->t_flags |= XFS_TRANS_RTBITMAP_LOCKED;
+
+		xfs_ilock(mp->m_rbmip, XFS_ILOCK_EXCL|XFS_ILOCK_RTBITMAP);
+		xfs_trans_ijoin(tp, mp->m_rbmip, XFS_ILOCK_EXCL);
+		xfs_ilock(mp->m_rsumip, XFS_ILOCK_EXCL|XFS_ILOCK_RTSUM);
+		xfs_trans_ijoin(tp, mp->m_rsumip, XFS_ILOCK_EXCL);
+	}
+
 	return xfs_rtfree_extent(tp, start, len);
 }
 
diff --git a/fs/xfs/libxfs/xfs_shared.h b/fs/xfs/libxfs/xfs_shared.h
index 6f1cedb850eb39..1598ff00f6805f 100644
--- a/fs/xfs/libxfs/xfs_shared.h
+++ b/fs/xfs/libxfs/xfs_shared.h
@@ -83,6 +83,9 @@ 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