Btrfs: fix wrong send_in_progress accounting

Steps to reproduce:
 # mkfs.btrfs -f /dev/sda8
 # mount /dev/sda8 /mnt
 # btrfs sub snapshot -r /mnt /mnt/snap1
 # btrfs sub snapshot -r /mnt /mnt/snap2
 # btrfs send /mnt/snap1 -p /mnt/snap2 -f /mnt/1
 # dmesg

The problem is that we will sort clone roots(include @send_root), it
might push @send_root before thus @send_root's @send_in_progress will
be decreased twice.

Cc: David Sterba <dsterba@suse.cz>
Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 13 insertions, 3 deletions

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index bff0b1ac3be7..5b6978516461 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -4752,6 +4752,7 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_)
         u32 i;
         u64 *clone_sources_tmp = NULL;
         int clone_sources_to_rollback = 0;
+        int sort_clone_roots = 0;
 
         if (!capable(CAP_SYS_ADMIN))
                 return -EPERM;
@@ -4942,6 +4943,7 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_)
         sort(sctx->clone_roots, sctx->clone_roots_cnt,
                         sizeof(*sctx->clone_roots), __clone_root_cmp_sort,
                         NULL);
+        sort_clone_roots = 1;
 
         ret = send_subvol(sctx);
         if (ret < 0)
@@ -4957,11 +4959,19 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_)
         }
 
 out:
-        for (i = 0; sctx && i < clone_sources_to_rollback; i++)
-                btrfs_root_dec_send_in_progress(sctx->clone_roots[i].root);
+        if (sort_clone_roots) {
+                for (i = 0; i < sctx->clone_roots_cnt; i++)
+                        btrfs_root_dec_send_in_progress(
+                                        sctx->clone_roots[i].root);
+        } else {
+                for (i = 0; sctx && i < clone_sources_to_rollback; i++)
+                        btrfs_root_dec_send_in_progress(
+                                        sctx->clone_roots[i].root);
+
+                btrfs_root_dec_send_in_progress(send_root);
+        }
         if (sctx && !IS_ERR_OR_NULL(sctx->parent_root))
                 btrfs_root_dec_send_in_progress(sctx->parent_root);
-        btrfs_root_dec_send_in_progress(send_root);
 
         kfree(arg);
         vfree(clone_sources_tmp);