btrfs: s_bdev is not null after missing replace

Yauhen reported in the ML that s_bdev is null at mount, and
s_bdev gets updated to some device when missing device is
replaced, as because bdev is null for missing device, things
gets matched up. Fix this by checking if s_bdev is set. I
didn't want to completely remove updating s_bdev because
the future multi device support at vfs layer may need it.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reported-by: Yauhen Kharuzhy <yauhen.kharuzhy@zavadatar.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 5aebedf..c93eec9 100644 (file)
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -569,7 +569,8 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
        ASSERT(list_empty(&src_device->resized_list));
        tgt_device->commit_total_bytes = src_device->commit_total_bytes;
        tgt_device->commit_bytes_used = src_device->bytes_used;
-       if (fs_info->sb->s_bdev == src_device->bdev)
+       if (fs_info->sb->s_bdev &&
+               (fs_info->sb->s_bdev == src_device->bdev))
                fs_info->sb->s_bdev = tgt_device->bdev;
        if (fs_info->fs_devices->latest_bdev == src_device->bdev)
                fs_info->fs_devices->latest_bdev = tgt_device->bdev;

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index e43b01e..41bc384 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1848,7 +1848,8 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path, u64 devid)
 
        next_device = list_entry(root->fs_info->fs_devices->devices.next,
                                 struct btrfs_device, dev_list);
-       if (device->bdev == root->fs_info->sb->s_bdev)
+       if (root->fs_info->sb->s_bdev &&
+               (root->fs_info->sb->s_bdev == device->bdev))
                root->fs_info->sb->s_bdev = next_device->bdev;
        if (device->bdev == root->fs_info->fs_devices->latest_bdev)
                root->fs_info->fs_devices->latest_bdev = next_device->bdev;
@@ -1996,7 +1997,8 @@ void btrfs_destroy_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 
        next_device = list_entry(fs_info->fs_devices->devices.next,
                                 struct btrfs_device, dev_list);
-       if (tgtdev->bdev == fs_info->sb->s_bdev)
+       if (fs_info->sb->s_bdev &&
+               (tgtdev->bdev == fs_info->sb->s_bdev))
                fs_info->sb->s_bdev = next_device->bdev;
        if (tgtdev->bdev == fs_info->fs_devices->latest_bdev)
                fs_info->fs_devices->latest_bdev = next_device->bdev;