Btrfs: allow for pausing restriper

Implement an ioctl for pausing restriper.  This pauses the relocation,
but balance is still considered to be "in progress": balance item is
not deleted, other volume operations cannot be started, etc.  If paused
in the middle of profile changing operation we will continue making
allocations with the target profile.

Add a hook to close_ctree() to pause restriper and free its data
structures on unmount.  (It's safe to unmount when restriper is in
"paused" state, we will resume with the same parameters on the next
mount)

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index c8b37d2c0d77..e972e11a8d77 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -109,6 +109,9 @@ struct btrfs_ioctl_fs_info_args {
         __u64 reserved[124];                    /* pad to 1k */
 };
 
+/* balance control ioctl modes */
+#define BTRFS_BALANCE_CTL_PAUSE         1
+
 /*
  * this is packed, because it should be exactly the same as its disk
  * byte order counterpart (struct btrfs_disk_balance_args)
@@ -137,6 +140,9 @@ struct btrfs_balance_progress {
         __u64 completed;        /* # of chunks relocated so far */
 };
 
+#define BTRFS_BALANCE_STATE_RUNNING     (1ULL << 0)
+#define BTRFS_BALANCE_STATE_PAUSE_REQ   (1ULL << 1)
+
 struct btrfs_ioctl_balance_args {
         __u64 flags;                            /* in/out */
         __u64 state;                            /* out */
@@ -315,6 +321,7 @@ struct btrfs_ioctl_logical_ino_args {
                                struct btrfs_ioctl_fs_info_args)
 #define BTRFS_IOC_BALANCE_V2 _IOWR(BTRFS_IOCTL_MAGIC, 32, \
                                    struct btrfs_ioctl_balance_args)
+#define BTRFS_IOC_BALANCE_CTL _IOW(BTRFS_IOCTL_MAGIC, 33, int)
 #define BTRFS_IOC_INO_PATHS _IOWR(BTRFS_IOCTL_MAGIC, 35, \
                                         struct btrfs_ioctl_ino_path_args)
 #define BTRFS_IOC_LOGICAL_INO _IOWR(BTRFS_IOCTL_MAGIC, 36, \