[PATCH] btrfs: Add qgroup_auto_cleanup mount flag to automatically cleanup qgroups

[PATCH] btrfs: Add qgroup_auto_cleanup mount flag to automatically cleanup qgroups

[Sargun Dhillon]

This patch introduces a new mount option - qgroup_auto_cleanup.
The purpose of this mount option is to cause btrfs to automatically
delete qgroups on subvolume deletion. This only cleans up the
associated level-0 qgroup, and not qgroups that are above it.

Since this behaviour is API-changing it is opt-in. Existing software,
and scripts may be doing qgroup cleanup on subvolume deletion explicitly,
and the absence of a qgroup may cause failure.

Signed-off-by: Sargun Dhillon <sargun@sargun.me>
---
 fs/btrfs/ctree.h |  1 +
 fs/btrfs/ioctl.c | 15 +++++++++++++++
 fs/btrfs/super.c | 15 ++++++++++++++-
 3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 5bdd3666..b3d54e4 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1336,6 +1336,7 @@ static inline u32 BTRFS_MAX_XATTR_SIZE(const struct btrfs_fs_info *info)
 #define BTRFS_MOUNT_FRAGMENT_METADATA	(1 << 25)
 #define BTRFS_MOUNT_FREE_SPACE_TREE	(1 << 26)
 #define BTRFS_MOUNT_NOLOGREPLAY		(1 << 27)
+#define BTRFS_MOUNT_QGROUP_AUTO_CLEANUP	(1 << 28)
 
 #define BTRFS_DEFAULT_COMMIT_INTERVAL	(30)
 #define BTRFS_DEFAULT_MAX_INLINE	(2048)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index fa1b78c..e9901c4 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2546,6 +2546,21 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
 			goto out_end_trans;
 		}
 	}
+	/*
+	 * Attempt to automatically remove the automatically attached qgroup
+	 * setup in btrfs_qgroup_inherit. As a matter of convention, the id
+	 * is the same as the subvolume id.
+	 *
+	 * This can fail non-fatally for level 0 qgroups, therefore we do
+	 * not abort the transaction if this fails, nor return an error.
+	 */
+	if (btrfs_test_opt(fs_info, QGROUP_AUTO_CLEANUP)) {
+		ret = btrfs_remove_qgroup(trans, fs_info,
+					  dest->root_key.objectid, 0);
+		if (ret && ret != -ENOENT)
+			btrfs_warn(fs_info,
+				   "Failed to cleanup qgroup. err: %d", ret);
+	}
 
 out_end_trans:
 	trans->block_rsv = NULL;
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 74e4779..d83c841 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -321,7 +321,8 @@ enum {
 	Opt_commit_interval, Opt_barrier, Opt_nodefrag, Opt_nodiscard,
 	Opt_noenospc_debug, Opt_noflushoncommit, Opt_acl, Opt_datacow,
 	Opt_datasum, Opt_treelog, Opt_noinode_cache, Opt_usebackuproot,
-	Opt_nologreplay, Opt_norecovery,
+	Opt_nologreplay, Opt_norecovery, Opt_qgroup_auto_cleanup,
+	Opt_no_qgroup_auto_cleanup,
 #ifdef CONFIG_BTRFS_DEBUG
 	Opt_fragment_data, Opt_fragment_metadata, Opt_fragment_all,
 #endif
@@ -381,6 +382,8 @@ static const match_table_t tokens = {
 	{Opt_rescan_uuid_tree, "rescan_uuid_tree"},
 	{Opt_fatal_errors, "fatal_errors=%s"},
 	{Opt_commit_interval, "commit=%d"},
+	{Opt_qgroup_auto_cleanup, "qgroup_auto_cleanup"},
+	{Opt_no_qgroup_auto_cleanup, "no_qgroup_auto_cleanup"},
 #ifdef CONFIG_BTRFS_DEBUG
 	{Opt_fragment_data, "fragment=data"},
 	{Opt_fragment_metadata, "fragment=metadata"},
@@ -798,6 +801,14 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
 				info->commit_interval = BTRFS_DEFAULT_COMMIT_INTERVAL;
 			}
 			break;
+		case Opt_qgroup_auto_cleanup:
+			 btrfs_set_and_info(info, QGROUP_AUTO_CLEANUP,
+					    "enabling qgroup auto cleanup");
+			break;
+		case Opt_no_qgroup_auto_cleanup:
+			btrfs_clear_and_info(info, QGROUP_AUTO_CLEANUP,
+					     "disabling qgroup auto cleanup");
+			break;
 #ifdef CONFIG_BTRFS_DEBUG
 		case Opt_fragment_all:
 			btrfs_info(info, "fragmenting all space");
@@ -1287,6 +1298,8 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
 		seq_puts(seq, ",fatal_errors=panic");
 	if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL)
 		seq_printf(seq, ",commit=%d", info->commit_interval);
+	if (btrfs_test_opt(info, QGROUP_AUTO_CLEANUP))
+		seq_puts(seq, ",qgroup_auto_cleanup");
 #ifdef CONFIG_BTRFS_DEBUG
 	if (btrfs_test_opt(info, FRAGMENT_DATA))
 		seq_puts(seq, ",fragment=data");
-- 
2.9.3

Re: [PATCH] btrfs: Add qgroup_auto_cleanup mount flag to automatically cleanup qgroups

[kbuild test robot]

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Hi Sargun,

[auto build test ERROR on v4.12-rc7]
[also build test ERROR on next-20170630]
[cannot apply to btrfs/next]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Sargun-Dhillon/btrfs-Add-qgroup_auto_cleanup-mount-flag-to-automatically-cleanup-qgroups/20170701-102114
config: x86_64-randconfig-x015-201726 (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

   fs//btrfs/ioctl.c: In function 'btrfs_ioctl_snap_destroy':
>> fs//btrfs/ioctl.c:2555:9: error: too many arguments to function 'btrfs_remove_qgroup'
      ret = btrfs_remove_qgroup(trans, fs_info,
            ^~~~~~~~~~~~~~~~~~~
   In file included from fs//btrfs/ioctl.c:60:0:
   fs//btrfs/qgroup.h:129:5: note: declared here
    int btrfs_remove_qgroup(struct btrfs_trans_handle *trans,
        ^~~~~~~~~~~~~~~~~~~

vim +/btrfs_remove_qgroup +2555 fs//btrfs/ioctl.c

  2549		 * is the same as the subvolume id.
  2550		 *
  2551		 * This can fail non-fatally for level 0 qgroups, therefore we do
  2552		 * not abort the transaction if this fails, nor return an error.
  2553		 */
  2554		if (btrfs_test_opt(fs_info, QGROUP_AUTO_CLEANUP)) {
> 2555			ret = btrfs_remove_qgroup(trans, fs_info,
  2556						  dest->root_key.objectid, 0);
  2557			if (ret && ret != -ENOENT)
  2558				btrfs_warn(fs_info,

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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