ocfs2: do not set fs read-only if rec[0] is empty while committing truncate

While appending an extent to a file, it will call these functions:
ocfs2_insert_extent

  -> call ocfs2_grow_tree() if there's no free rec
     -> ocfs2_add_branch add a new branch to extent tree,
        now rec[0] in the leaf of rightmost path is empty
  -> ocfs2_do_insert_extent
     -> ocfs2_rotate_tree_right
       -> ocfs2_extend_rotate_transaction
          -> jbd2_journal_restart if jbd2_journal_extend fail
     -> ocfs2_insert_path
        -> ocfs2_extend_trans
          -> jbd2_journal_restart if jbd2_journal_extend fail
        -> ocfs2_insert_at_leaf
     -> ocfs2_et_update_clusters
Function jbd2_journal_restart() may be called and it may happened that
buffers dirtied in ocfs2_add_branch() are committed
while buffers dirtied in ocfs2_insert_at_leaf() and
ocfs2_et_update_clusters() are not.
So an empty rec[0] is left in rightmost path which will cause
read-only filesystem when call ocfs2_commit_truncate()
with the error message: "Inode %lu has an empty extent record".

This is not a serious problem, so remove the rightmost path when call
ocfs2_commit_truncate().

Signed-off-by: joyce.xue <xuejiufei@huawei.com>
Reviewed-by: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
index 9a0fd49..77cbd1e 100644 (file)
--- a/fs/ocfs2/alloc.c
+++ b/fs/ocfs2/alloc.c
@@ -3131,6 +3131,30 @@ out:
        return ret;
 }
 
+static int ocfs2_remove_rightmost_empty_extent(struct ocfs2_super *osb,
+                               struct ocfs2_extent_tree *et,
+                               struct ocfs2_path *path,
+                               struct ocfs2_cached_dealloc_ctxt *dealloc)
+{
+       handle_t *handle;
+       int ret;
+       int credits = path->p_tree_depth * 2 + 1;
+
+       handle = ocfs2_start_trans(osb, credits);
+       if (IS_ERR(handle)) {
+               ret = PTR_ERR(handle);
+               mlog_errno(ret);
+               return ret;
+       }
+
+       ret = ocfs2_remove_rightmost_path(handle, et, path, dealloc);
+       if (ret)
+               mlog_errno(ret);
+
+       ocfs2_commit_trans(osb, handle);
+       return ret;
+}
+
 /*
  * Left rotation of btree records.
  *
@@ -7108,15 +7132,23 @@ start:
                 * to check it up here before changing the tree.
                */
                if (root_el->l_tree_depth && rec->e_int_clusters == 0) {
-                       ocfs2_error(inode->i_sb, "Inode %lu has an empty "
+                       mlog(ML_ERROR, "Inode %lu has an empty "
                                    "extent record, depth %u\n", inode->i_ino,
                                    le16_to_cpu(root_el->l_tree_depth));
-                       status = -EROFS;
-                       goto bail;
+                       status = ocfs2_remove_rightmost_empty_extent(osb,
+                                       &et, path, &dealloc);
+                       if (status) {
+                               mlog_errno(status);
+                               goto bail;
+                       }
+
+                       ocfs2_reinit_path(path, 1);
+                       goto start;
+               } else {
+                       trunc_cpos = le32_to_cpu(rec->e_cpos);
+                       trunc_len = 0;
+                       blkno = 0;
                }
-               trunc_cpos = le32_to_cpu(rec->e_cpos);
-               trunc_len = 0;
-               blkno = 0;
        } else if (le32_to_cpu(rec->e_cpos) >= new_highest_cpos) {
                /*
                 * Truncate entire record.