From: Darrick J. Wong <darrick.wong@oracle.com>
Date: Mon, 11 Dec 2017 02:03:55 +0000 (-0800)
Subject: xfs: avoid infinite loop when cancelling CoW blocks after writeback failure
X-Git-Tag: v4.15-rc5~5^2~8
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=9d40fba8b2056773b9744a95df9ddd6cc33a4f83;p=linux.git

xfs: avoid infinite loop when cancelling CoW blocks after writeback failure

When we're cancelling a cow range, we don't always delete each extent
that we iterate, so we have to move icur backwards in the list to avoid
an infinite loop.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---

diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 99c5852f9fe7..6931b0c79cac 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -611,6 +611,9 @@ xfs_reflink_cancel_cow_blocks(
 
 			/* Remove the mapping from the CoW fork. */
 			xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
+		} else {
+			/* Didn't do anything, push cursor back. */
+			xfs_iext_prev(ifp, &icur);
 		}
 next_extent:
 		if (!xfs_iext_get_extent(ifp, &icur, &got))