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>
This commit is contained in:
Theodore Ts'o 2010-10-28 17:33:57 -04:00
parent 81280572ca
commit b1142e8fec
1 changed files with 5 additions and 7 deletions

View File

@ -2718,7 +2718,7 @@ static int ext4_writepage(struct page *page,
* 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 @@ static int ext4_writepage(struct page *page,
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;
}