If we are doing an incremental send and the base snapshot has a
directory with name X that doesn't exist anymore in the second
snapshot and a new subvolume/snapshot exists in the second snapshot
that has the same name as the directory (name X), the incremental
send would fail with -ENOENT error. This is because it attempts
to lookup for an inode with a number matching the objectid of a
root, which doesn't exist.

Steps to reproduce:

    mkfs.btrfs -f /dev/sdd
    mount /dev/sdd /mnt

    mkdir /mnt/testdir
    btrfs subvolume snapshot -r /mnt /mnt/mysnap1

    rmdir /mnt/testdir
    btrfs subvolume create /mnt/testdir
    btrfs subvolume snapshot -r /mnt /mnt/mysnap2

    btrfs send -p /mnt/mysnap1 /mnt/mysnap2 -f /tmp/send.data

A test case for xfstests follows.

Reported-by: Robert White <rwh...@pobox.com>
Signed-off-by: Filipe David Borba Manana <fdman...@gmail.com>
---
 fs/btrfs/send.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 1a65a40..f51525e 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -1642,7 +1642,8 @@ out:
 static int lookup_dir_item_inode(struct btrfs_root *root,
                                 u64 dir, const char *name, int name_len,
                                 u64 *found_inode,
-                                u8 *found_type)
+                                u8 *found_type,
+                                int *found_is_root)
 {
        int ret = 0;
        struct btrfs_dir_item *di;
@@ -1666,6 +1667,8 @@ static int lookup_dir_item_inode(struct btrfs_root *root,
        btrfs_dir_item_key_to_cpu(path->nodes[0], di, &key);
        *found_inode = key.objectid;
        *found_type = btrfs_dir_type(path->nodes[0], di);
+       if (found_is_root)
+               *found_is_root = (key.type == BTRFS_ROOT_ITEM_KEY);
 
 out:
        btrfs_free_path(path);
@@ -1816,7 +1819,7 @@ static int will_overwrite_ref(struct send_ctx *sctx, u64 
dir, u64 dir_gen,
        }
 
        ret = lookup_dir_item_inode(sctx->parent_root, dir, name, name_len,
-                       &other_inode, &other_type);
+                                   &other_inode, &other_type, NULL);
        if (ret < 0 && ret != -ENOENT)
                goto out;
        if (ret) {
@@ -1861,6 +1864,7 @@ static int did_overwrite_ref(struct send_ctx *sctx,
        u64 gen;
        u64 ow_inode;
        u8 other_type;
+       int other_is_root = 0;
 
        if (!sctx->parent_root)
                goto out;
@@ -1871,10 +1875,10 @@ static int did_overwrite_ref(struct send_ctx *sctx,
 
        /* check if the ref was overwritten by another ref */
        ret = lookup_dir_item_inode(sctx->send_root, dir, name, name_len,
-                       &ow_inode, &other_type);
+                                   &ow_inode, &other_type, &other_is_root);
        if (ret < 0 && ret != -ENOENT)
                goto out;
-       if (ret) {
+       if (ret || other_is_root) {
                /* was never and will never be overwritten */
                ret = 0;
                goto out;
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Reply via email to