btrfs: qgroup: Avoid calling qgroup functions if qgroup is not enabled

Some qgroup trace events like btrfs_qgroup_release_data() and
btrfs_qgroup_free_delayed_ref() can still be triggered even if qgroup is
not enabled.

This is caused by the lack of qgroup status check before calling some
qgroup functions.  Thankfully the functions can handle quota disabled
case well and just do nothing for qgroup disabled case.

This patch will do earlier check before triggering related trace events.

And for enabled <-> disabled race case:

1) For enabled->disabled case
   Disable will wipe out all qgroups data including reservation and
   excl/rfer. Even if we leak some reservation or numbers, it will
   still be cleared, so nothing will go wrong.

2) For disabled -> enabled case
   Current btrfs_qgroup_release_data() will use extent_io tree to ensure
   we won't underflow reservation. And for delayed_ref we use
   head->qgroup_reserved to record the reserved space, so in that case
   head->qgroup_reserved should be 0 and we won't underflow.

CC: stable@vger.kernel.org # 4.14+
Reported-by: Chris Murphy <lists@colorremedies.com>
Link: https://lore.kernel.org/linux-btrfs/CAJCQCtQau7DtuUUeycCkZ36qjbKuxNzsgqJ7+sJ6W0dK_NLE3w@mail.gmail.com/
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index ac9690f36a94b34084f116b352530fdbdd952ef3..27f517315388b7de8827c3f9d1c516c185ee5c5a 100644 (file)
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -3521,6 +3521,10 @@ static int __btrfs_qgroup_release_data(struct inode *inode,
        int trace_op = QGROUP_RELEASE;
        int ret;
 
+       if (!test_bit(BTRFS_FS_QUOTA_ENABLED,
+                     &BTRFS_I(inode)->root->fs_info->flags))
+               return 0;
+
        /* In release case, we shouldn't have @reserved */
        WARN_ON(!free && reserved);
        if (free && reserved)

diff --git a/fs/btrfs/qgroup.h b/fs/btrfs/qgroup.h
index 80ebeb3ab5ba01ac274e63e4cf7dd2e7c75427b3..d8f78f5ab854a08a7ea673b9a7df031a37b96633 100644 (file)
--- a/fs/btrfs/qgroup.h
+++ b/fs/btrfs/qgroup.h
@@ -255,6 +255,8 @@ void btrfs_qgroup_free_refroot(struct btrfs_fs_info *fs_info,
 static inline void btrfs_qgroup_free_delayed_ref(struct btrfs_fs_info *fs_info,
                                                 u64 ref_root, u64 num_bytes)
 {
+       if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))
+               return;
        trace_btrfs_qgroup_free_delayed_ref(fs_info, ref_root, num_bytes);
        btrfs_qgroup_free_refroot(fs_info, ref_root, num_bytes,
                                  BTRFS_QGROUP_RSV_DATA);