Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 1f94533d authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: fix a BUG_ON crash by checking that page has buffers attached to it 



In ext4_num_dirty_pages() we were calling page_buffers() before
checking to see if the page actually had pages attached to it; this
would cause a BUG check crash in the inline function page_buffers().

Thanks to Markus Trippelsdorf for reporting this bug.

Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent c1fccc06

fs/ext4/inode.c

+11 −11
Original line number Diff line number Diff line
@@ -1146,8 +1146,8 @@ static int check_block_validity(struct inode *inode, const char *msg, 
}



/*

 * Return the number of dirty pages in the given inode starting at

 * page frame idx.

 * Return the number of contiguous dirty pages in a given inode

 * starting at page frame idx.

 */

static pgoff_t ext4_num_dirty_pages(struct inode *inode, pgoff_t idx,

				    unsigned int max_pages)
@@ -1181,15 +1181,15 @@ static pgoff_t ext4_num_dirty_pages(struct inode *inode, pgoff_t idx, 
				unlock_page(page);

				break;

			}

			head = page_buffers(page);

			bh = head;

			if (page_has_buffers(page)) {

				bh = head = page_buffers(page);

				do {

					if (!buffer_delay(bh) &&

				    !buffer_unwritten(bh)) {

					    !buffer_unwritten(bh))

						done = 1;

					break;

					bh = bh->b_this_page;

				} while (!done && (bh != head));

			}

			} while ((bh = bh->b_this_page) != head);

			unlock_page(page);

			if (done)

				break;