Hi Wang,
On Thu, March 28, 2013 at 11:53 (+0100), Wang Shilong wrote:
> From: Wang Shilong <wangsl-fnst@xxxxxxxxxxxxxx>
>
> This patch introduces mutex lock 'quota_lock', and makes
> all the user change for quota protected by quota_lock.
Can you please add a few lines why this lock is needed? I.e., which ioctls fail
without that kind of synchronization?
> Signed-off-by: Wang Shilong <wangsl-fnst@xxxxxxxxxxxxxx>
> Reviewed-by: Miao Xie <miaox@xxxxxxxxxxxxxx>
> ---
> fs/btrfs/ctree.h | 3 +++
> fs/btrfs/disk-io.c | 1 +
> fs/btrfs/ioctl.c | 16 ++++++++++++----
> 3 files changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 6e81860..a11a8ed 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -1584,6 +1584,9 @@ struct btrfs_fs_info {
> struct rb_root qgroup_tree;
> spinlock_t qgroup_lock;
>
> + /* protect user change operations for quota */
> + struct mutex quota_lock;
Having fs_info->qgroup_lock and fs_info->quota_lock going to be a major source
of confusion. I'd call the new one qgroup_ioctl_lock or ioctl_qgroup_lock instead.
Furthermore, the term "quota" was intentionally left unused to leave room for
other quota implementations later (user quota).
And, please, use --thread with git send-email for related patches to get correct
headers.
Thanks,
-Jan
> [snip]
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