[PATCH 24/33] xfs: convert xfs_zoned_end_io to rolling transactions

[Dave Chinner <dgc@kernel.org>]

Convert xfs_zoned_end_io() from per-extent transaction allocation
to a single rolling transaction that keeps the ILOCK held across
the entire extent mapping loop.

The rolling transaction keeps the ILOCK held throughout, making the
zoned IO completion operation atomic with respect to other concurrent
extent manipulations. XFS_TRANS_RENEW_BLKRES is set so that the
block reservation is automatically renewed by xfs_defer_finish()
after each iteration's deferred operations are processed.

Assisted-by: LLM
Signed-off-by: Dave Chinner <dgc@kernel.org>
---
 fs/xfs/xfs_zone_alloc.c | 40 +++++++++++++++++++++++++++-------------
 1 file changed, 27 insertions(+), 13 deletions(-)

diff --git a/fs/xfs/xfs_zone_alloc.c b/fs/xfs/xfs_zone_alloc.c
index 7e3456ca28ac..d24afffe255f 100644
--- a/fs/xfs/xfs_zone_alloc.c
+++ b/fs/xfs/xfs_zone_alloc.c
@@ -13,6 +13,7 @@
 #include "xfs_inode.h"
 #include "xfs_iomap.h"
 #include "xfs_trans.h"
+#include "xfs_defer.h"
 #include "xfs_alloc.h"
 #include "xfs_bmap.h"
 #include "xfs_bmap_btree.h"
@@ -314,6 +315,13 @@ xfs_zoned_map_extent(
 	return 0;
 }
 
+/*
+ * Map written extents into the data fork after zoned IO completion.
+ *
+ * The rolling transaction keeps the ILOCK held across the entire mapping
+ * loop, making the operation atomic with respect to other concurrent
+ * extent manipulations.
+ */
 int
 xfs_zoned_end_io(
 	struct xfs_inode	*ip,
@@ -337,24 +345,23 @@ xfs_zoned_end_io(
 	if (xfs_is_shutdown(mp))
 		return -EIO;
 
+	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0,
+			XFS_TRANS_RESERVE | XFS_TRANS_RENEW_BLKRES, &tp);
+	if (error)
+		return error;
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	xfs_trans_ijoin(tp, ip, 0);
+
 	while (new.br_startoff < end_fsb) {
 		new.br_blockcount = end_fsb - new.br_startoff;
 
-		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0,
-				XFS_TRANS_RESERVE, &tp);
-		if (error)
-			return error;
-		xfs_ilock(ip, XFS_ILOCK_EXCL);
-		xfs_trans_ijoin(tp, ip, 0);
-
 		error = xfs_zoned_map_extent(tp, ip, &new, oz, old_startblock);
 		if (error)
-			xfs_trans_cancel(tp);
-		else
-			error = xfs_trans_commit(tp);
-		xfs_iunlock(ip, XFS_ILOCK_EXCL);
+			goto out_cancel;
+
+		error = xfs_defer_finish(&tp);
 		if (error)
-			return error;
+			goto out_cancel;
 
 		new.br_startoff += new.br_blockcount;
 		new.br_startblock += new.br_blockcount;
@@ -362,7 +369,14 @@ xfs_zoned_end_io(
 			old_startblock += new.br_blockcount;
 	}
 
-	return 0;
+	error = xfs_trans_commit(tp);
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	return error;
+
+out_cancel:
+	xfs_trans_cancel(tp);
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	return error;
 }
 
 /*
-- 
2.55.0