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

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 41f6ef68e2e1e8c7fedfb5f5faaf575d6df3bb81..28031c4e15e9c1653c91d1a9816bd8ecbe009ae2 100644 (file)
--- 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;