ocfs2: skip existing hole when removing the last extent_rec in punching-hole codes.

Tristan Ye · jlbec · commit 9a790ba1ec02 · 2011-05-13T11:26:20.000-07:00
In the case of removing a partial extent record which covers a hole, current
punching-hole logic will try to remove more than the length of whole extent
record, which leads to the failure of following assert(fs/ocfs2/alloc.c):

5507         BUG_ON(cpos &lt; le32_to_cpu(rec-&gt;e_cpos) || trunc_range &gt; rec_range);

This patch tries to skip existing hole at the last attempt of removing a partial
extent record, what's more, it also adds some necessary comments for better
understanding of punching-hole codes.

Signed-off-by: Tristan Ye &lt;tristan.ye@oracle.com&gt;
Signed-off-by: Joel Becker &lt;jlbec@evilplan.org&gt;
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
@@ -1607,6 +1607,9 @@ static void ocfs2_calc_trunc_pos(struct inode *inode,
 	range = le32_to_cpu(rec->e_cpos) + ocfs2_rec_clusters(el, rec);
 
 	if (le32_to_cpu(rec->e_cpos) >= trunc_start) {
+		/*
+		 * remove an entire extent record.
+		 */
 		*trunc_cpos = le32_to_cpu(rec->e_cpos);
 		/*
 		 * Skip holes if any.
@@ -1617,7 +1620,16 @@ static void ocfs2_calc_trunc_pos(struct inode *inode,
 		*blkno = le64_to_cpu(rec->e_blkno);
 		*trunc_end = le32_to_cpu(rec->e_cpos);
 	} else if (range > trunc_start) {
+		/*
+		 * remove a partial extent record, which means we're
+		 * removing the last extent record.
+		 */
 		*trunc_cpos = trunc_start;
+		/*
+		 * skip hole if any.
+		 */
+		if (range < *trunc_end)
+			*trunc_end = range;
 		*trunc_len = *trunc_end - trunc_start;
 		coff = trunc_start - le32_to_cpu(rec->e_cpos);
 		*blkno = le64_to_cpu(rec->e_blkno) +
