From 4df0f7f145f2ac143039e2c569d17a25354f411d Mon Sep 17 00:00:00 2001
From: Dave Chinner <dchinner@redhat.com>
Date: Tue, 6 Mar 2018 17:07:22 -0800
Subject: [PATCH] xfs: fix transaction allocation deadlock in IO path
Git-commit: 4df0f7f145f2ac143039e2c569d17a25354f411d
Patch-mainline: v4.17-rc1
References: bsc#1090535

xfs_trans_alloc() does GFP_KERNEL allocation, and we can call it
while holding pages locked for writeback in the ->writepages path.
The memory allocation is allowed to wait on pages under writeback,
and so can wait on pages that are tagged as writeback by the
caller.

This affects both pre-IO submission and post-IO submission paths.
Hence xfs_setsize_trans_alloc(), xfs_reflink_end_cow(),
xfs_iomap_write_unwritten() and xfs_reflink_cancel_cow_range().
xfs_iomap_write_unwritten() already does the right thing, but the
others don't. Fix them.

Signed-Off-By: Dave Chinner <dchinner@redhat.com>
Fixes: 281627df3eb5 ("xfs: log file size updates at I/O completion time")
Fixes: 43caeb187deb9 ("xfs: move mappings from cow fork to data fork after copy-write)"
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>
---
 fs/xfs/xfs_aops.c    | 3 ++-
 fs/xfs/xfs_reflink.c | 4 ++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 9c6a830da0ee..a0afb6411417 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -209,7 +209,8 @@ xfs_setfilesize_trans_alloc(
 	struct xfs_trans	*tp;
 	int			error;
 
-	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp);
+	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0,
+				XFS_TRANS_NOFS, &tp);
 	if (error)
 		return error;
 
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 270246943a06..8c16177b33d4 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -668,7 +668,7 @@ xfs_reflink_cancel_cow_range(
 
 	/* Start a rolling transaction to remove the mappings */
 	error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,
-			0, 0, 0, &tp);
+			0, 0, XFS_TRANS_NOFS, &tp);
 	if (error)
 		goto out;
 
@@ -741,7 +741,7 @@ xfs_reflink_end_cow(
 			(unsigned int)(end_fsb - offset_fsb),
 			XFS_DATA_FORK);
 	error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_write,
-			resblks, 0, XFS_TRANS_RESERVE, &tp);
+			resblks, 0, XFS_TRANS_RESERVE | XFS_TRANS_NOFS, &tp);
 	if (error)
 		goto out;
 
-- 
2.16.3