Btrfs: fix unprotected assignment of the target device

We didn't protect the assignment of the target device, it might cause the
problem that the super block update was skipped because we might find wrong
size of the target device during the assignment. Fix it by moving the
assignment sentences into the initialization function of the target device.
And there is another merit that we can check if the target device is suitable
more early.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 10dfb41f4c224c3bd70c2aace46bbe79573dbc63..72dc02e829455d4ba299c49fa41cd12be75647a6 100644 (file)
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -330,29 +330,19 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
                return -EINVAL;
 
        mutex_lock(&fs_info->volume_mutex);
-       ret = btrfs_init_dev_replace_tgtdev(root, args->start.tgtdev_name,
-                                           &tgt_device);
-       if (ret) {
-               btrfs_err(fs_info, "target device %s is invalid!",
-                      args->start.tgtdev_name);
-               mutex_unlock(&fs_info->volume_mutex);
-               return -EINVAL;
-       }
-
        ret = btrfs_dev_replace_find_srcdev(root, args->start.srcdevid,
                                            args->start.srcdev_name,
                                            &src_device);
-       mutex_unlock(&fs_info->volume_mutex);
        if (ret) {
-               ret = -EINVAL;
-               goto leave_no_lock;
+               mutex_unlock(&fs_info->volume_mutex);
+               return ret;
        }
 
-       if (tgt_device->total_bytes < src_device->total_bytes) {
-               btrfs_err(fs_info, "target device is smaller than source device!");
-               ret = -EINVAL;
-               goto leave_no_lock;
-       }
+       ret = btrfs_init_dev_replace_tgtdev(root, args->start.tgtdev_name,
+                                           src_device, &tgt_device);
+       mutex_unlock(&fs_info->volume_mutex);
+       if (ret)
+               return ret;
 
        btrfs_dev_replace_lock(dev_replace);
        switch (dev_replace->replace_state) {
@@ -380,10 +370,6 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
                      src_device->devid,
                      rcu_str_deref(tgt_device->name));
 
-       tgt_device->total_bytes = src_device->total_bytes;
-       tgt_device->disk_total_bytes = src_device->disk_total_bytes;
-       tgt_device->bytes_used = src_device->bytes_used;
-
        /*
         * from now on, the writes to the srcdev are all duplicated to
         * go to the tgtdev as well (refer to btrfs_map_block()).
@@ -426,9 +412,7 @@ leave:
        dev_replace->srcdev = NULL;
        dev_replace->tgtdev = NULL;
        btrfs_dev_replace_unlock(dev_replace);
-leave_no_lock:
-       if (tgt_device)
-               btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
+       btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
        return ret;
 }
 

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 483fc6d45299c7074c1b9734eebcc07e6303f0d6..1646659f2800b06310f0b0637b4ebfea4dffad0c 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2295,6 +2295,7 @@ error:
 }
 
 int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,
+                                 struct btrfs_device *srcdev,
                                  struct btrfs_device **device_out)
 {
        struct request_queue *q;
@@ -2307,24 +2308,37 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,
        int ret = 0;
 
        *device_out = NULL;
-       if (fs_info->fs_devices->seeding)
+       if (fs_info->fs_devices->seeding) {
+               btrfs_err(fs_info, "the filesystem is a seed filesystem!");
                return -EINVAL;
+       }
 
        bdev = blkdev_get_by_path(device_path, FMODE_WRITE | FMODE_EXCL,
                                  fs_info->bdev_holder);
-       if (IS_ERR(bdev))
+       if (IS_ERR(bdev)) {
+               btrfs_err(fs_info, "target device %s is invalid!", device_path);
                return PTR_ERR(bdev);
+       }
 
        filemap_write_and_wait(bdev->bd_inode->i_mapping);
 
        devices = &fs_info->fs_devices->devices;
        list_for_each_entry(device, devices, dev_list) {
                if (device->bdev == bdev) {
+                       btrfs_err(fs_info, "target device is in the filesystem!");
                        ret = -EEXIST;
                        goto error;
                }
        }
 
+
+       if (i_size_read(bdev->bd_inode) < srcdev->total_bytes) {
+               btrfs_err(fs_info, "target device is smaller than source device!");
+               ret = -EINVAL;
+               goto error;
+       }
+
+
        device = btrfs_alloc_device(NULL, &devid, NULL);
        if (IS_ERR(device)) {
                ret = PTR_ERR(device);
@@ -2348,8 +2362,9 @@ int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,
        device->io_width = root->sectorsize;
        device->io_align = root->sectorsize;
        device->sector_size = root->sectorsize;
-       device->total_bytes = i_size_read(bdev->bd_inode);
-       device->disk_total_bytes = device->total_bytes;
+       device->total_bytes = srcdev->total_bytes;
+       device->disk_total_bytes = srcdev->disk_total_bytes;
+       device->bytes_used = srcdev->bytes_used;
        device->dev_root = fs_info->dev_root;
        device->bdev = bdev;
        device->in_fs_metadata = 1;

diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 37f8bff97df119cbbceaed964d93861f3448873d..e15f2886d33eb3d21dc02c0b702fcd99125d2f2f 100644 (file)
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -322,6 +322,7 @@ struct btrfs_device *btrfs_find_device(struct btrfs_fs_info *fs_info, u64 devid,
 int btrfs_shrink_device(struct btrfs_device *device, u64 new_size);
 int btrfs_init_new_device(struct btrfs_root *root, char *path);
 int btrfs_init_dev_replace_tgtdev(struct btrfs_root *root, char *device_path,
+                                 struct btrfs_device *srcdev,
                                  struct btrfs_device **device_out);
 int btrfs_balance(struct btrfs_balance_control *bctl,
                  struct btrfs_ioctl_balance_args *bargs);