Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit de2491fd authored by David Sterba's avatar David Sterba
Browse files

btrfs: scrub: add memalloc_nofs protection around init_ipath 



init_ipath is called from a safe ioctl context and from scrub when
printing an error.  The protection is added for three reasons:

* init_data_container calls vmalloc and this does not work as expected
  in the GFP_NOFS context, so this silently does GFP_KERNEL and might
  deadlock in some cases
* keep the context constraint of GFP_NOFS, used by scrub
* we want to use GFP_KERNEL unconditionally inside init_ipath or its
  callees

Reviewed-by: default avatarAnand Jain <anand.jain@oracle.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent f11f7441

fs/btrfs/scrub.c

+9 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 


#include <linux/blkdev.h>

#include <linux/ratelimit.h>

#include <linux/sched/mm.h>

#include "ctree.h"

#include "volumes.h"

#include "disk-io.h"
@@ -733,6 +734,7 @@ static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root, 
	u32 nlink;

	int ret;

	int i;

	unsigned nofs_flag;

	struct extent_buffer *eb;

	struct btrfs_inode_item *inode_item;

	struct scrub_warning *swarn = warn_ctx;
@@ -771,7 +773,14 @@ static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root, 
	nlink = btrfs_inode_nlink(eb, inode_item);

	btrfs_release_path(swarn->path);



	/*

	 * init_path might indirectly call vmalloc, or use GFP_KERNEL. Scrub

	 * uses GFP_NOFS in this context, so we keep it consistent but it does

	 * not seem to be strictly necessary.

	 */

	nofs_flag = memalloc_nofs_save();

	ipath = init_ipath(4096, local_root, swarn->path);

	memalloc_nofs_restore(nofs_flag);

	if (IS_ERR(ipath)) {

		ret = PTR_ERR(ipath);

		ipath = NULL;