ocfs2: Access the xattr bucket only before modifying it.

In ocfs2_xattr_value_truncate, we may call b-tree codes which will
extend the journal transaction. It has a potential problem that it
may let the already-accessed-but-not-dirtied buffers gone. So we'd
better access the bucket after we call ocfs2_xattr_value_truncate.
And as for the root buffer for the xattr value, b-tree code will
acess and dirty it, so we don't need to worry about it.

Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

1 files changed, 8 insertions, 9 deletions

diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c
index e1d638af6ac3..915039fffe6e 100644
--- a/fs/ocfs2/xattr.c
+++ b/fs/ocfs2/xattr.c
@@ -4729,13 +4729,6 @@ static int ocfs2_xattr_bucket_value_truncate(struct inode *inode,
         vb.vb_xv = (struct ocfs2_xattr_value_root *)
                 (vb.vb_bh->b_data + offset % blocksize);
 
-        ret = ocfs2_xattr_bucket_journal_access(ctxt->handle, bucket,
-                                                OCFS2_JOURNAL_ACCESS_WRITE);
-        if (ret) {
-                mlog_errno(ret);
-                goto out;
-        }
-
         /*
          * From here on out we have to dirty the bucket.  The generic
          * value calls only modify one of the bucket's bhs, but we need
@@ -4748,12 +4741,18 @@ static int ocfs2_xattr_bucket_value_truncate(struct inode *inode,
         ret = ocfs2_xattr_value_truncate(inode, &vb, len, ctxt);
         if (ret) {
                 mlog_errno(ret);
-                goto out_dirty;
+                goto out;
+        }
+
+        ret = ocfs2_xattr_bucket_journal_access(ctxt->handle, bucket,
+                                                OCFS2_JOURNAL_ACCESS_WRITE);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
         }
 
         xe->xe_value_size = cpu_to_le64(len);
 
-out_dirty:
         ocfs2_xattr_bucket_journal_dirty(ctxt->handle, bucket);
 
 out: