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>

1 files changed, 38 insertions, 6 deletions

diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
index 9a0fd494fe74..77cbd1e3c950 100644
--- 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.