ext4: fix extent tree corruption caused by hole punch

commit c36575e663e302dbaa4d16b9c72d2c9a913a9aef upstream.

When depth of extent tree is greater than 1, logical start value of
interior node is not correctly updated in ext4_ext_rm_idx.

Signed-off-by: Forrest Liu <forrestl@synology.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Ashish Sangwan <ashishsangwan2@gmail.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 191580a..fbb92e6 100644 (file)
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2093,13 +2093,14 @@ ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block,
  * removes index from the index block.
  */
 static int ext4_ext_rm_idx(handle_t *handle, struct inode *inode,
-                       struct ext4_ext_path *path)
+                       struct ext4_ext_path *path, int depth)
 {
        int err;
        ext4_fsblk_t leaf;
 
        /* free index block */
-       path--;
+       depth--;
+       path = path + depth;
        leaf = ext4_idx_pblock(path->p_idx);
        if (unlikely(path->p_hdr->eh_entries == 0)) {
                EXT4_ERROR_INODE(inode, "path->p_hdr->eh_entries == 0");
@@ -2124,6 +2125,19 @@ static int ext4_ext_rm_idx(handle_t *handle, struct inode *inode,
 
        ext4_free_blocks(handle, inode, NULL, leaf, 1,
                         EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
+
+       while (--depth >= 0) {
+               if (path->p_idx != EXT_FIRST_INDEX(path->p_hdr))
+                       break;
+               path--;
+               err = ext4_ext_get_access(handle, inode, path);
+               if (err)
+                       break;
+               path->p_idx->ei_block = (path+1)->p_idx->ei_block;
+               err = ext4_ext_dirty(handle, inode, path);
+               if (err)
+                       break;
+       }
        return err;
 }
 
@@ -2454,7 +2468,7 @@ ext4_ext_rm_leaf(handle_t *handle, struct inode *inode,
        /* if this leaf is free, then we should
         * remove it from index block above */
        if (err == 0 && eh->eh_entries == 0 && path[depth].p_bh != NULL)
-               err = ext4_ext_rm_idx(handle, inode, path + depth);
+               err = ext4_ext_rm_idx(handle, inode, path, depth);
 
 out:
        return err;
@@ -2587,7 +2601,7 @@ again:
                                /* index is empty, remove it;
                                 * handle must be already prepared by the
                                 * truncatei_leaf() */
-                               err = ext4_ext_rm_idx(handle, inode, path + i);
+                               err = ext4_ext_rm_idx(handle, inode, path, i);
                        }
                        /* root level has p_bh == NULL, brelse() eats this */
                        brelse(path[i].p_bh);