From 3fd6a73da159049bade087487256af9030423975 Mon Sep 17 00:00:00 2001 From: Liu Bo Date: Wed, 31 Jan 2018 17:09:13 -0700 Subject: [PATCH] Btrfs: fix unexpected cow in run_delalloc_nocow commit 5811375325420052fcadd944792a416a43072b7f upstream. Fstests generic/475 provides a way to fail metadata reads while checking if checksum exists for the inode inside run_delalloc_nocow(), and csum_exist_in_range() interprets error (-EIO) as inode having checksum and makes its caller enter the cow path. In case of free space inode, this ends up with a warning in cow_file_range(). The same problem applies to btrfs_cross_ref_exist() since it may also read metadata in between. With this, run_delalloc_nocow() bails out when errors occur at the two places. cc: v2.6.28+ Fixes: 17d217fe970d ("Btrfs: fix nodatasum handling in balancing code") Signed-off-by: Liu Bo Signed-off-by: David Sterba Signed-off-by: Sudip Mukherjee Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/inode.c | 33 ++++++++++++++++++++++++++++++--- 1 file changed, 30 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 23ffe27..bd03655 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1230,6 +1230,8 @@ static noinline int csum_exist_in_range(struct btrfs_root *root, list_del(&sums->list); kfree(sums); } + if (ret < 0) + return ret; return 1; } @@ -1381,10 +1383,23 @@ next_slot: goto out_check; if (btrfs_extent_readonly(root, disk_bytenr)) goto out_check; - if (btrfs_cross_ref_exist(trans, root, ino, + ret = btrfs_cross_ref_exist(trans, root, ino, found_key.offset - - extent_offset, disk_bytenr)) + extent_offset, disk_bytenr); + if (ret) { + /* + * ret could be -EIO if the above fails to read + * metadata. + */ + if (ret < 0) { + if (cow_start != (u64)-1) + cur_offset = cow_start; + goto error; + } + + WARN_ON_ONCE(nolock); goto out_check; + } disk_bytenr += extent_offset; disk_bytenr += cur_offset - found_key.offset; num_bytes = min(end + 1, extent_end) - cur_offset; @@ -1402,8 +1417,20 @@ next_slot: * this ensure that csum for a given extent are * either valid or do not exist. */ - if (csum_exist_in_range(root, disk_bytenr, num_bytes)) + ret = csum_exist_in_range(root, disk_bytenr, num_bytes); + if (ret) { + /* + * ret could be -EIO if the above fails to read + * metadata. + */ + if (ret < 0) { + if (cow_start != (u64)-1) + cur_offset = cow_start; + goto error; + } + WARN_ON_ONCE(nolock); goto out_check; + } if (!btrfs_inc_nocow_writers(root->fs_info, disk_bytenr)) goto out_check; -- 2.7.4