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Commit 918c2ee1 authored by Mark Fasheh's avatar Mark Fasheh Committed by David Sterba
Browse files

btrfs: handle non-fatal errors in btrfs_qgroup_inherit() 



create_pending_snapshot() will go readonly on _any_ error return from
btrfs_qgroup_inherit(). If qgroups are enabled, a user can crash their fs by
just making a snapshot and asking it to inherit from an invalid qgroup. For
example:

$ btrfs sub snap -i 1/10 /btrfs/ /btrfs/foo

Will cause a transaction abort.

Fix this by only throwing errors in btrfs_qgroup_inherit() when we know
going readonly is acceptable.

The following xfstests test case reproduces this bug:

  seq=`basename $0`
  seqres=$RESULT_DIR/$seq
  echo "QA output created by $seq"

  here=`pwd`
  tmp=/tmp/$$
  status=1	# failure is the default!
  trap "_cleanup; exit \$status" 0 1 2 3 15

  _cleanup()
  {
  	cd /
  	rm -f $tmp.*
  }

  # get standard environment, filters and checks
  . ./common/rc
  . ./common/filter

  # remove previous $seqres.full before test
  rm -f $seqres.full

  # real QA test starts here
  _supported_fs btrfs
  _supported_os Linux
  _require_scratch

  rm -f $seqres.full

  _scratch_mkfs
  _scratch_mount
  _run_btrfs_util_prog quota enable $SCRATCH_MNT
  # The qgroup '1/10' does not exist and should be silently ignored
  _run_btrfs_util_prog subvolume snapshot -i 1/10 $SCRATCH_MNT $SCRATCH_MNT/snap1

  _scratch_unmount

  echo "Silence is golden"

  status=0
  exit

Signed-off-by: default avatarMark Fasheh <mfasheh@suse.de>
Reviewed-by: default avatarQu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 0305bc27

fs/btrfs/qgroup.c

+32 −22
Original line number Diff line number Diff line
@@ -1842,8 +1842,10 @@ int btrfs_run_qgroups(struct btrfs_trans_handle *trans, 
}



/*

 * copy the acounting information between qgroups. This is necessary when a

 * snapshot or a subvolume is created

 * Copy the acounting information between qgroups. This is necessary

 * when a snapshot or a subvolume is created. Throwing an error will

 * cause a transaction abort so we take extra care here to only error

 * when a readonly fs is a reasonable outcome.

 */

int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans,

			 struct btrfs_fs_info *fs_info, u64 srcid, u64 objectid,
@@ -1873,15 +1875,15 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, 
		       2 * inherit->num_excl_copies;

		for (i = 0; i < nums; ++i) {

			srcgroup = find_qgroup_rb(fs_info, *i_qgroups);

			if (!srcgroup) {

				ret = -EINVAL;

				goto out;

			}



			if ((srcgroup->qgroupid >> 48) <= (objectid >> 48)) {

				ret = -EINVAL;

				goto out;

			}

			/*

			 * Zero out invalid groups so we can ignore

			 * them later.

			 */

			if (!srcgroup ||

			    ((srcgroup->qgroupid >> 48) <= (objectid >> 48)))

				*i_qgroups = 0ULL;



			++i_qgroups;

		}

	}
@@ -1916,17 +1918,19 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, 
	 */

	if (inherit) {

		i_qgroups = (u64 *)(inherit + 1);

		for (i = 0; i < inherit->num_qgroups; ++i) {

		for (i = 0; i < inherit->num_qgroups; ++i, ++i_qgroups) {

			if (*i_qgroups == 0)

				continue;

			ret = add_qgroup_relation_item(trans, quota_root,

						       objectid, *i_qgroups);

			if (ret)

			if (ret && ret != -EEXIST)

				goto out;

			ret = add_qgroup_relation_item(trans, quota_root,

						       *i_qgroups, objectid);

			if (ret)

			if (ret && ret != -EEXIST)

				goto out;

			++i_qgroups;

		}

		ret = 0;

	}
@@ -1987,17 +1991,22 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, 


	i_qgroups = (u64 *)(inherit + 1);

	for (i = 0; i < inherit->num_qgroups; ++i) {

		if (*i_qgroups) {

			ret = add_relation_rb(quota_root->fs_info, objectid,

					      *i_qgroups);

			if (ret)

				goto unlock;

		}

		++i_qgroups;

	}



	for (i = 0; i <  inherit->num_ref_copies; ++i) {

	for (i = 0; i <  inherit->num_ref_copies; ++i, i_qgroups += 2) {

		struct btrfs_qgroup *src;

		struct btrfs_qgroup *dst;



		if (!i_qgroups[0] || !i_qgroups[1])

			continue;



		src = find_qgroup_rb(fs_info, i_qgroups[0]);

		dst = find_qgroup_rb(fs_info, i_qgroups[1]);
@@ -2008,12 +2017,14 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, 


		dst->rfer = src->rfer - level_size;

		dst->rfer_cmpr = src->rfer_cmpr - level_size;

		i_qgroups += 2;

	}

	for (i = 0; i <  inherit->num_excl_copies; ++i) {

	for (i = 0; i <  inherit->num_excl_copies; ++i, i_qgroups += 2) {

		struct btrfs_qgroup *src;

		struct btrfs_qgroup *dst;



		if (!i_qgroups[0] || !i_qgroups[1])

			continue;



		src = find_qgroup_rb(fs_info, i_qgroups[0]);

		dst = find_qgroup_rb(fs_info, i_qgroups[1]);
@@ -2024,7 +2035,6 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, 


		dst->excl = src->excl + level_size;

		dst->excl_cmpr = src->excl_cmpr + level_size;

		i_qgroups += 2;

	}



unlock: