2 files changed, 16 insertions, 0 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index bd70c2852ba0..064315990f8a 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2508,6 +2508,13 @@ retry_root_backup:
         }
         fs_info->num_tolerated_disk_barrier_failures =
                 btrfs_calc_num_tolerated_disk_barrier_failures(fs_info);
+        if (fs_info->fs_devices->missing_devices >
+             fs_info->num_tolerated_disk_barrier_failures &&
+            !(sb->s_flags & MS_RDONLY)) {
+                printk(KERN_WARNING
+                       "Btrfs: too many missing devices, writeable mount is not allowed\n");
+                goto fail_block_groups;
+        }
 
         fs_info->cleaner_kthread = kthread_run(cleaner_kthread, tree_root,
                                                "btrfs-cleaner");
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 915ac14c2064..acd2df85bed5 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1226,6 +1226,15 @@ static int btrfs_remount(struct super_block *sb, int *flags, char *data)
                         goto restore;
                 }
 
+                if (fs_info->fs_devices->missing_devices >
+                     fs_info->num_tolerated_disk_barrier_failures &&
+                    !(*flags & MS_RDONLY)) {
+                        printk(KERN_WARNING
+                               "Btrfs: too many missing devices, writeable remount is not allowed\n");
+                        ret = -EACCES;
+                        goto restore;
+                }
+
                 if (btrfs_super_log_root(fs_info->super_copy) != 0) {
                         ret = -EINVAL;
                         goto restore;