Btrfs: use larger limit for translation of logical to inode

This is the change of the kernel side.

Translation of logical to inode used to have an upper limit 4k on
inode container's size, but the limit is not large enough for a data
with a great many of refs, so when resolving logical address,
we can end up with
"ioctl ret=0, bytes_left=0, bytes_missing=19944, cnt=510, missed=2493"

This changes to regard 64k as the upper limit and use vmalloc instead of
kmalloc to get memory more easily.

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>

fs/btrfs/backref.c

@@ -16,6 +16,7 @@
  * Boston, MA 021110-1307, USA.
  */
 
+#include <linux/vmalloc.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "backref.h"
@@ -1584,7 +1585,7 @@ struct btrfs_data_container *init_data_container(u32 total_bytes)
 	size_t alloc_bytes;
 
 	alloc_bytes = max_t(size_t, total_bytes, sizeof(*data));
-	data = kmalloc(alloc_bytes, GFP_NOFS);
+	data = vmalloc(alloc_bytes);
 	if (!data)
 		return ERR_PTR(-ENOMEM);
 
@@ -1635,6 +1636,6 @@ void free_ipath(struct inode_fs_paths *ipath)
 {
 	if (!ipath)
 		return;
-	kfree(ipath->fspath);
+	vfree(ipath->fspath);
 	kfree(ipath);
 }

fs/btrfs/ioctl.c

@@ -3230,7 +3230,7 @@ static long btrfs_ioctl_logical_to_ino(struct btrfs_root *root,
 		goto out;
 	}
 
-	size = min_t(u32, loi->size, 4096);
+	size = min_t(u32, loi->size, 64 * 1024);
 	inodes = init_data_container(size);
 	if (IS_ERR(inodes)) {
 		ret = PTR_ERR(inodes);
@@ -3252,7 +3252,7 @@ static long btrfs_ioctl_logical_to_ino(struct btrfs_root *root,
 
 out:
 	btrfs_free_path(path);
-	kfree(inodes);
+	vfree(inodes);
 	kfree(loi);
 
 	return ret;