btrfs: scrub: add memalloc_nofs protection around init_ipath (de2491fd) · Commits · 戴 / test

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:

Anand Jain <anand.jain@oracle.com> Signed-off-by:

David Sterba <dsterba@suse.com>

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;

Admin message