xfs: fallback to vmalloc for large buffers in xfs_getbmap

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@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 10 insertions, 3 deletions

diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
index 188ef2fbd628..3548c6f75593 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)) {
@@ -5661,7 +5665,10 @@ xfs_getbmap(
                         break;
         }
 
-        kmem_free(out);
+        if (is_vmalloc_addr(out))
+                kmem_free_large(out);
+        else
+                kmem_free(out);
         return error;
 }