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-rw-r--r--fs/btrfs/disk-io.c29
1 files changed, 19 insertions, 10 deletions
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 40152458e..5756edb37 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1643,12 +1643,12 @@ void btrfs_free_fs_info(struct btrfs_fs_info *fs_info)
*
* @objectid: root id
* @anon_dev: preallocated anonymous block device number for new roots,
- * pass 0 for new allocation.
+ * pass NULL for a new allocation.
* @check_ref: whether to check root item references, If true, return -ENOENT
* for orphan roots
*/
static struct btrfs_root *btrfs_get_root_ref(struct btrfs_fs_info *fs_info,
- u64 objectid, dev_t anon_dev,
+ u64 objectid, dev_t *anon_dev,
bool check_ref)
{
struct btrfs_root *root;
@@ -1662,8 +1662,17 @@ static struct btrfs_root *btrfs_get_root_ref(struct btrfs_fs_info *fs_info,
again:
root = btrfs_lookup_fs_root(fs_info, objectid);
if (root) {
- /* Shouldn't get preallocated anon_dev for cached roots */
- ASSERT(!anon_dev);
+ /*
+ * Some other caller may have read out the newly inserted
+ * subvolume already (for things like backref walk etc). Not
+ * that common but still possible. In that case, we just need
+ * to free the anon_dev.
+ */
+ if (unlikely(anon_dev && *anon_dev)) {
+ free_anon_bdev(*anon_dev);
+ *anon_dev = 0;
+ }
+
if (check_ref && btrfs_root_refs(&root->root_item) == 0) {
btrfs_put_root(root);
return ERR_PTR(-ENOENT);
@@ -1683,7 +1692,7 @@ again:
goto fail;
}
- ret = btrfs_init_fs_root(root, anon_dev);
+ ret = btrfs_init_fs_root(root, anon_dev ? *anon_dev : 0);
if (ret)
goto fail;
@@ -1719,7 +1728,7 @@ fail:
* root's anon_dev to 0 to avoid a double free, once by btrfs_put_root()
* and once again by our caller.
*/
- if (anon_dev)
+ if (anon_dev && *anon_dev)
root->anon_dev = 0;
btrfs_put_root(root);
return ERR_PTR(ret);
@@ -1735,7 +1744,7 @@ fail:
struct btrfs_root *btrfs_get_fs_root(struct btrfs_fs_info *fs_info,
u64 objectid, bool check_ref)
{
- return btrfs_get_root_ref(fs_info, objectid, 0, check_ref);
+ return btrfs_get_root_ref(fs_info, objectid, NULL, check_ref);
}
/*
@@ -1743,11 +1752,11 @@ struct btrfs_root *btrfs_get_fs_root(struct btrfs_fs_info *fs_info,
* the anonymous block device id
*
* @objectid: tree objectid
- * @anon_dev: if zero, allocate a new anonymous block device or use the
- * parameter value
+ * @anon_dev: if NULL, allocate a new anonymous block device or use the
+ * parameter value if not NULL
*/
struct btrfs_root *btrfs_get_new_fs_root(struct btrfs_fs_info *fs_info,
- u64 objectid, dev_t anon_dev)
+ u64 objectid, dev_t *anon_dev)
{
return btrfs_get_root_ref(fs_info, objectid, anon_dev, true);
}