From: Filipe Manana Date: Sat, 14 May 2016 15:32:35 +0000 (+0100) Subject: Btrfs: fix unprotected assignment of the left cursor for device replace X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=81e87a736c5581e83f52dc054b368993ec7f16d7;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git 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: Filipe Manana Reviewed-by: Josef Bacik --- diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index 1611572d47bd..19a1eda70361 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -3642,9 +3642,11 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx, break; } + btrfs_dev_replace_lock(&fs_info->dev_replace, 1); dev_replace->cursor_right = found_key.offset + length; dev_replace->cursor_left = found_key.offset; dev_replace->item_needs_writeback = 1; + btrfs_dev_replace_unlock(&fs_info->dev_replace, 1); ret = scrub_chunk(sctx, scrub_dev, chunk_offset, length, found_key.offset, cache, is_dev_replace); @@ -3718,8 +3720,10 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx, break; } + btrfs_dev_replace_lock(&fs_info->dev_replace, 1); dev_replace->cursor_left = dev_replace->cursor_right; dev_replace->item_needs_writeback = 1; + btrfs_dev_replace_unlock(&fs_info->dev_replace, 1); skip: key.offset = found_key.offset + length; btrfs_release_path(path);