Adds comments about BTRFS_FS_EXCL_OP to existing comments about the device locks.
Signed-off-by: Anand Jain <anand.j...@oracle.com> --- v1->v2: add more clarity to the comments added. fs/btrfs/volumes.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 3a3912a9dec9..6d7f10729713 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -202,6 +202,38 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, * device_list_mutex * chunk_mutex * balance_mutex + * + * BTRFS_FS_EXCL_OP + * ---------------- + * Maintains the exclusivity of the following device operations. + * + * - Balance (*) + * - Device add + * - Device remove + * - Device Replace (*) + * - Resize + * + * The device operations (as above) can be in one of the following states. + * + * - Running state + * - Paused state + * - Completed state + * + * Only device operations marked with (*) can go into the Paused state for the + * following reasons. + * + * - Ioctl (only Balance can be Paused through Ioctl) + * - FS re-mounted as read-only + * - FS un-mounted and mounted as read-only + * - System power-recycle and mounted as read-only + * - FS or device errors leading to read-only FS + * + * BTRFS_FS_EXCL_OP flag is set and cleared using atomic functions. + * During the course of Paused state, the BTRFS_FS_EXCL_OP remains set. + * A device operation in Paused or Running state can be canceled or resumed + * either by Ioctl (Balance only) or when re-mounted as read-write FS. + * BTRFS_FS_EXCL_OP flag is cleared when the device operation is canceled or + * completed. */ DEFINE_MUTEX(uuid_mutex); -- 2.15.0 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
