1 files changed, 47 insertions, 6 deletions

diff --git a/fs/xfs/libxfs/xfs_trans_inode.c b/fs/xfs/libxfs/xfs_trans_inode.c
index c66d9d1dd58b..ad5974365c58 100644
--- a/fs/xfs/libxfs/xfs_trans_inode.c
+++ b/fs/xfs/libxfs/xfs_trans_inode.c
@@ -8,6 +8,8 @@
 #include "xfs_shared.h"
 #include "xfs_format.h"
 #include "xfs_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
 #include "xfs_inode.h"
 #include "xfs_trans.h"
 #include "xfs_trans_priv.h"
@@ -72,13 +74,19 @@ xfs_trans_ichgtime(
 }
 
 /*
- * This is called to mark the fields indicated in fieldmask as needing
- * to be logged when the transaction is committed.  The inode must
- * already be associated with the given transaction.
+ * This is called to mark the fields indicated in fieldmask as needing to be
+ * logged when the transaction is committed.  The inode must already be
+ * associated with the given transaction.
  *
- * The values for fieldmask are defined in xfs_inode_item.h.  We always
- * log all of the core inode if any of it has changed, and we always log
- * all of the inline data/extents/b-tree root if any of them has changed.
+ * The values for fieldmask are defined in xfs_inode_item.h.  We always log all
+ * of the core inode if any of it has changed, and we always log all of the
+ * inline data/extents/b-tree root if any of them has changed.
+ *
+ * Grab and pin the cluster buffer associated with this inode to avoid RMW
+ * cycles at inode writeback time. Avoid the need to add error handling to every
+ * xfs_trans_log_inode() call by shutting down on read error.  This will cause
+ * transactions to fail and everything to error out, just like if we return a
+ * read error in a dirty transaction and cancel it.
  */
 void
 xfs_trans_log_inode(
@@ -131,6 +139,39 @@ xfs_trans_log_inode(
 	spin_lock(&iip->ili_lock);
 	iip->ili_fsync_fields |= flags;
 
+	if (!iip->ili_item.li_buf) {
+		struct xfs_buf	*bp;
+		int		error;
+
+		/*
+		 * We hold the ILOCK here, so this inode is not going to be
+		 * flushed while we are here. Further, because there is no
+		 * buffer attached to the item, we know that there is no IO in
+		 * progress, so nothing will clear the ili_fields while we read
+		 * in the buffer. Hence we can safely drop the spin lock and
+		 * read the buffer knowing that the state will not change from
+		 * here.
+		 */
+		spin_unlock(&iip->ili_lock);
+		error = xfs_imap_to_bp(ip->i_mount, tp, &ip->i_imap, NULL,
+					&bp, 0);
+		if (error) {
+			xfs_force_shutdown(ip->i_mount, SHUTDOWN_META_IO_ERROR);
+			return;
+		}
+
+		/*
+		 * We need an explicit buffer reference for the log item but
+		 * don't want the buffer to remain attached to the transaction.
+		 * Hold the buffer but release the transaction reference.
+		 */
+		xfs_buf_hold(bp);
+		xfs_trans_brelse(tp, bp);
+
+		spin_lock(&iip->ili_lock);
+		iip->ili_item.li_buf = bp;
+	}
+
 	/*
 	 * Always OR in the bits from the ili_last_fields field.  This is to
 	 * coordinate with the xfs_iflush() and xfs_iflush_done() routines in