[PATCH 4/8] xfs: avoid memory allocation failures in xfs_getbmap

[Dave Chinner]

From: Dave Chinner <dchinner at redhat.com>

From: Dave Chinner <dchinner at redhat.com>

xfs_getbmap uses for a large buffer for extents, which is kmalloc'd.
This can fail after the system has been running for some time as it
is a high order allocation. Add a fallback to vmalloc so that it
doesn't require contiguous memory and so won't randomly fail on
files with large extent lists.

Signed-off-by: Dave Chinner <dchinner at redhat.com>
---
 fs/xfs/xfs_bmap.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
index 188ef2f..d1ab08d 100644
--- a/fs/xfs/xfs_bmap.c
+++ b/fs/xfs/xfs_bmap.c
@@ -5536,8 +5536,12 @@ xfs_getbmap(
 	if (bmv->bmv_count > ULONG_MAX / sizeof(struct getbmapx))
 		return XFS_ERROR(ENOMEM);
 	out = kmem_zalloc(bmv->bmv_count * sizeof(struct getbmapx), KM_MAYFAIL);
-	if (!out)
-		return XFS_ERROR(ENOMEM);
+	if (!out) {
+		out = kmem_zalloc_large(bmv->bmv_count *
+					sizeof(struct getbmapx));
+		if (!out)
+			return XFS_ERROR(ENOMEM);
+	}
 
 	xfs_ilock(ip, XFS_IOLOCK_SHARED);
 	if (whichfork == XFS_DATA_FORK && !(iflags & BMV_IF_DELALLOC)) {
-- 
1.7.9