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btrfs: abort the transaction if we fail to inc ref in btrfs_copy_root 

While testing my error handling patches, I added a error injection site
at btrfs_inc_extent_ref, to validate the error handling I added was
doing the correct thing.  However I hit a pretty ugly corruption while
doing this check, with the following error injection stack trace:

btrfs_inc_extent_ref
  btrfs_copy_root
    create_reloc_root
      btrfs_init_reloc_root
	btrfs_record_root_in_trans
	  btrfs_start_transaction
	    btrfs_update_inode
	      btrfs_update_time
		touch_atime
		  file_accessed
		    btrfs_file_mmap

This is because we do not catch the error from btrfs_inc_extent_ref,
which in practice would be ENOMEM, which means we lose the extent
references for a root that has already been allocated and inserted,
which is the problem.  Fix this by aborting the transaction if we fail
to do the reference modification.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Josef Bacik 2021-01-14 14:02:46 -05:00 committed by David Sterba
parent eddda68d97
commit 867ed321f9
1 changed files with 3 additions and 2 deletions
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5
fs/btrfs/ctree.c
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@ -221,9 +221,10 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
ret = btrfs_inc_ref(trans, root, cow, 1); ret = btrfs_inc_ref(trans, root, cow, 1);
else else
ret = btrfs_inc_ref(trans, root, cow, 0); ret = btrfs_inc_ref(trans, root, cow, 0);
if (ret) {
if (ret) btrfs_abort_transaction(trans, ret);
return ret; return ret;
}
btrfs_mark_buffer_dirty(cow); btrfs_mark_buffer_dirty(cow);
*cow_ret = cow; *cow_ret = cow;