Commit 81e87a73 authored by Filipe Manana's avatar Filipe Manana
Browse files

Btrfs: fix unprotected assignment of the left cursor for device replace 



We were assigning new values to fields of the device replace object
without holding the respective lock after processing each device extent.
This is important for the left cursor field which can be accessed by a
concurrent task running __btrfs_map_block (which, correctly, takes the
device replace lock).
So change these fields while holding the device replace lock.

Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Reviewed-by: default avatarJosef Bacik <jbacik@fb.com>
parent f0e9b7d6

fs/btrfs/scrub.c

+4 −0
Original line number Original line Diff line number Diff line
@@ -3642,9 +3642,11 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx, 
			break;

			break;

		}

		}





		btrfs_dev_replace_lock(&fs_info->dev_replace, 1);

		dev_replace->cursor_right = found_key.offset + length;

		dev_replace->cursor_right = found_key.offset + length;

		dev_replace->cursor_left = found_key.offset;

		dev_replace->cursor_left = found_key.offset;

		dev_replace->item_needs_writeback = 1;

		dev_replace->item_needs_writeback = 1;

		btrfs_dev_replace_unlock(&fs_info->dev_replace, 1);

		ret = scrub_chunk(sctx, scrub_dev, chunk_offset, length,

		ret = scrub_chunk(sctx, scrub_dev, chunk_offset, length,

				  found_key.offset, cache, is_dev_replace);

				  found_key.offset, cache, is_dev_replace);
@@ -3718,8 +3720,10 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx, 
			break;

			break;

		}

		}





		btrfs_dev_replace_lock(&fs_info->dev_replace, 1);

		dev_replace->cursor_left = dev_replace->cursor_right;

		dev_replace->cursor_left = dev_replace->cursor_right;

		dev_replace->item_needs_writeback = 1;

		dev_replace->item_needs_writeback = 1;

		btrfs_dev_replace_unlock(&fs_info->dev_replace, 1);

skip:

skip:

		key.offset = found_key.offset + length;

		key.offset = found_key.offset + length;

		btrfs_release_path(path);

		btrfs_release_path(path);

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