btrfs: enumerate the type of exclusive operation in progress

Instead of using a flag bit for exclusive operation, use a variable to
store which exclusive operation is being performed.  Introduce an API
to start and finish an exclusive operation.

This would enable another way for tools to check which operation is
running on why starting an exclusive operation failed. The followup
patch adds a sysfs_notify() to alert userspace when the state changes, so
userspace can perform select() on it to get notified of the change.

This would enable us to enqueue a command which will wait for current
exclusive operation to complete before issuing the next exclusive
operation. This has been done synchronously as opposed to a background
process, or else error collection (if any) will become difficult.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update comments ]
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Goldwyn Rodrigues 2020-08-25 10:02:32 -05:00 committed by David Sterba
parent ca10845a56
commit c3e1f96c37
5 changed files with 65 additions and 41 deletions

View file

@ -1025,7 +1025,7 @@ int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
* should never allow both to start and pause. We don't want to allow
* dev-replace to start anyway.
*/
if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_DEV_REPLACE)) {
down_write(&dev_replace->rwsem);
dev_replace->replace_state =
BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
@ -1062,7 +1062,7 @@ static int btrfs_dev_replace_kthread(void *data)
ret = btrfs_dev_replace_finishing(fs_info, ret);
WARN_ON(ret && ret != -ECANCELED);
clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
btrfs_exclop_finish(fs_info);
return 0;
}