ext4: ignore last group w/o enough space when resizing instead of BUG'ing

If the last group does not have enough space for group tables, ignore
it instead of calling BUG_ON().

Reported-by: Daniel Drake <dsd@laptop.org>
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org

1 files changed, 9 insertions, 3 deletions

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 41f6ef68e2e1..28031c4e15e9 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -200,8 +200,11 @@ static void free_flex_gd(struct ext4_new_flex_group_data *flex_gd)
  * be a partial of a flex group.
  *
  * @sb: super block of fs to which the groups belongs
+ *
+ * Returns 0 on a successful allocation of the metadata blocks in the
+ * block group.
  */
-static void ext4_alloc_group_tables(struct super_block *sb,
+static int ext4_alloc_group_tables(struct super_block *sb,
                                 struct ext4_new_flex_group_data *flex_gd,
                                 int flexbg_size)
 {
@@ -226,6 +229,8 @@ static void ext4_alloc_group_tables(struct super_block *sb,
                (last_group & ~(flexbg_size - 1))));
 next_group:
         group = group_data[0].group;
+        if (src_group >= group_data[0].group + flex_gd->count)
+                return -ENOSPC;
         start_blk = ext4_group_first_block_no(sb, src_group);
         last_blk = start_blk + group_data[src_group - group].blocks_count;
 
@@ -235,7 +240,6 @@ next_group:
 
         start_blk += overhead;
 
-        BUG_ON(src_group >= group_data[0].group + flex_gd->count);
         /* We collect contiguous blocks as much as possible. */
         src_group++;
         for (; src_group <= last_group; src_group++)
@@ -300,6 +304,7 @@ next_group:
                                group_data[i].free_blocks_count);
                 }
         }
+        return 0;
 }
 
 static struct buffer_head *bclean(handle_t *handle, struct super_block *sb,
@@ -1729,7 +1734,8 @@ int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
          */
         while (ext4_setup_next_flex_gd(sb, flex_gd, n_blocks_count,
                                               flexbg_size)) {
-                ext4_alloc_group_tables(sb, flex_gd, flexbg_size);
+                if (ext4_alloc_group_tables(sb, flex_gd, flexbg_size) != 0)
+                        break;
                 err = ext4_flex_group_add(sb, resize_inode, flex_gd);
                 if (unlikely(err))
                         break;