ext4: fix extent tree corruption caused by hole punch

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>
Cc: stable@vger.kernel.org

1 files changed, 18 insertions, 4 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 26af22832a84..5ae1674ec12f 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2226,13 +2226,14 @@ errout:
  * 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");
@@ -2257,6 +2258,19 @@ 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;
 }
 
@@ -2599,7 +2613,7 @@ 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;
@@ -2802,7 +2816,7 @@ 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);