ext4: BUG_ON fix: check if page has buffers before calling page_buffers()
We need to make check if a page does not have buffes by checking
page_has_buffers(page) before calling page_buffers(page) in
ext4_writepage(). Otherwise page_buffers() could throw a BUG_ON.
Thanks also to Markus Trippelsdorf and Avinash Kurup who also reported
the problem.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reported-by: Sedat Dilek <sedat.dilek@googlemail.com>
Tested-by: Sedat Dilek <sedat.dilek@googlemail.com>
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 2d6c6c8..1916164 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2718,7 +2718,7 @@
* try to create them using __block_write_begin. If this
* fails, redirty the page and move on.
*/
- if (!page_buffers(page)) {
+ if (!page_has_buffers(page)) {
if (__block_write_begin(page, 0, len,
noalloc_get_block_write)) {
redirty_page:
@@ -2732,12 +2732,10 @@
if (walk_page_buffers(NULL, page_bufs, 0, len, NULL,
ext4_bh_delay_or_unwritten)) {
/*
- * We don't want to do block allocation So redirty the
- * page and return We may reach here when we do a
- * journal commit via
- * journal_submit_inode_data_buffers. If we don't
- * have mapping block we just ignore them. We can also
- * reach here via shrink_page_list
+ * We don't want to do block allocation, so redirty
+ * the page and return. We may reach here when we do
+ * a journal commit via journal_submit_inode_data_buffers.
+ * We can also reach here via shrink_page_list
*/
goto redirty_page;
}