Btrfs: allow for canceling restriper

Implement an ioctl for canceling restriper.  Currently we wait until
relocation of the current block group is finished, in future this can be
done by triggering a commit.  Balance item is deleted and no memory
about the interrupted balance is kept.

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

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 1afda75..dfc136c 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1216,6 +1216,7 @@ struct btrfs_fs_info {
        struct mutex balance_mutex;
        atomic_t balance_running;
        atomic_t balance_pause_req;
+       atomic_t balance_cancel_req;
        struct btrfs_balance_control *balance_ctl;
        wait_queue_head_t balance_wait_q;
 

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 8ce8374..c23b82d 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2006,6 +2006,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
        mutex_init(&fs_info->balance_mutex);
        atomic_set(&fs_info->balance_running, 0);
        atomic_set(&fs_info->balance_pause_req, 0);
+       atomic_set(&fs_info->balance_cancel_req, 0);
        fs_info->balance_ctl = NULL;
        init_waitqueue_head(&fs_info->balance_wait_q);
 

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index f572c53..6085221 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3076,6 +3076,8 @@ void update_ioctl_balance_args(struct btrfs_fs_info *fs_info,
                bargs->state |= BTRFS_BALANCE_STATE_RUNNING;
        if (atomic_read(&fs_info->balance_pause_req))
                bargs->state |= BTRFS_BALANCE_STATE_PAUSE_REQ;
+       if (atomic_read(&fs_info->balance_cancel_req))
+               bargs->state |= BTRFS_BALANCE_STATE_CANCEL_REQ;
 
        memcpy(&bargs->data, &bctl->data, sizeof(bargs->data));
        memcpy(&bargs->meta, &bctl->meta, sizeof(bargs->meta));
@@ -3157,6 +3159,8 @@ static long btrfs_ioctl_balance_ctl(struct btrfs_root *root, int cmd)
        switch (cmd) {
        case BTRFS_BALANCE_CTL_PAUSE:
                return btrfs_pause_balance(root->fs_info);
+       case BTRFS_BALANCE_CTL_CANCEL:
+               return btrfs_cancel_balance(root->fs_info);
        }
 
        return -EINVAL;

diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index e972e11..cd19d10 100644 (file)
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -111,6 +111,7 @@ struct btrfs_ioctl_fs_info_args {
 
 /* balance control ioctl modes */
 #define BTRFS_BALANCE_CTL_PAUSE                1
+#define BTRFS_BALANCE_CTL_CANCEL       2
 
 /*
  * this is packed, because it should be exactly the same as its disk
@@ -142,6 +143,7 @@ struct btrfs_balance_progress {
 
 #define BTRFS_BALANCE_STATE_RUNNING    (1ULL << 0)
 #define BTRFS_BALANCE_STATE_PAUSE_REQ  (1ULL << 1)
+#define BTRFS_BALANCE_STATE_CANCEL_REQ (1ULL << 2)
 
 struct btrfs_ioctl_balance_args {
        __u64 flags;                            /* in/out */

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index d32660c..c326673 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2492,7 +2492,8 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info)
        key.type = BTRFS_CHUNK_ITEM_KEY;
 
        while (1) {
-               if (atomic_read(&fs_info->balance_pause_req)) {
+               if (atomic_read(&fs_info->balance_pause_req) ||
+                   atomic_read(&fs_info->balance_cancel_req)) {
                        ret = -ECANCELED;
                        goto error;
                }
@@ -2560,7 +2561,10 @@ error:
 
 static inline int balance_need_close(struct btrfs_fs_info *fs_info)
 {
-       return atomic_read(&fs_info->balance_pause_req) == 0;
+       /* cancel requested || normal exit path */
+       return atomic_read(&fs_info->balance_cancel_req) ||
+               (atomic_read(&fs_info->balance_pause_req) == 0 &&
+                atomic_read(&fs_info->balance_cancel_req) == 0);
 }
 
 static void __cancel_balance(struct btrfs_fs_info *fs_info)
@@ -2586,7 +2590,8 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
        int ret;
 
        if (btrfs_fs_closing(fs_info) ||
-           atomic_read(&fs_info->balance_pause_req)) {
+           atomic_read(&fs_info->balance_pause_req) ||
+           atomic_read(&fs_info->balance_cancel_req)) {
                ret = -EINVAL;
                goto out;
        }
@@ -2832,6 +2837,42 @@ int btrfs_pause_balance(struct btrfs_fs_info *fs_info)
        return ret;
 }
 
+int btrfs_cancel_balance(struct btrfs_fs_info *fs_info)
+{
+       mutex_lock(&fs_info->balance_mutex);
+       if (!fs_info->balance_ctl) {
+               mutex_unlock(&fs_info->balance_mutex);
+               return -ENOTCONN;
+       }
+
+       atomic_inc(&fs_info->balance_cancel_req);
+       /*
+        * if we are running just wait and return, balance item is
+        * deleted in btrfs_balance in this case
+        */
+       if (atomic_read(&fs_info->balance_running)) {
+               mutex_unlock(&fs_info->balance_mutex);
+               wait_event(fs_info->balance_wait_q,
+                          atomic_read(&fs_info->balance_running) == 0);
+               mutex_lock(&fs_info->balance_mutex);
+       } else {
+               /* __cancel_balance needs volume_mutex */
+               mutex_unlock(&fs_info->balance_mutex);
+               mutex_lock(&fs_info->volume_mutex);
+               mutex_lock(&fs_info->balance_mutex);
+
+               if (fs_info->balance_ctl)
+                       __cancel_balance(fs_info);
+
+               mutex_unlock(&fs_info->volume_mutex);
+       }
+
+       BUG_ON(fs_info->balance_ctl || atomic_read(&fs_info->balance_running));
+       atomic_dec(&fs_info->balance_cancel_req);
+       mutex_unlock(&fs_info->balance_mutex);
+       return 0;
+}
+
 /*
  * shrinking a device means finding all of the device extents past
  * the new size, and then following the back refs to the chunks.

diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 80953af..caa9abd 100644 (file)
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -274,6 +274,7 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
                  struct btrfs_ioctl_balance_args *bargs);
 int btrfs_recover_balance(struct btrfs_root *tree_root);
 int btrfs_pause_balance(struct btrfs_fs_info *fs_info);
+int btrfs_cancel_balance(struct btrfs_fs_info *fs_info);
 int btrfs_chunk_readonly(struct btrfs_root *root, u64 chunk_offset);
 int find_free_dev_extent(struct btrfs_trans_handle *trans,
                         struct btrfs_device *device, u64 num_bytes,