Messages in this thread Patch in this message | | | Date | Thu, 10 Dec 2009 20:25:28 -0800 | From | Greg KH <> | Subject | [50/90] ext4: fix a BUG_ON crash by checking that page has buffers attached to it |
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2.6.31-stable review patch. If anyone has any objections, please let us know.
------------------ (cherry picked from commit 1f94533d9cd75f6d2826018d54a971b9cc085992)
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: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> --- fs/ext4/inode.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-)
--- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1147,8 +1147,8 @@ static int check_block_validity(struct i } /* - * 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) @@ -1182,15 +1182,15 @@ static pgoff_t ext4_num_dirty_pages(stru unlock_page(page); break; } - head = page_buffers(page); - bh = head; - do { - if (!buffer_delay(bh) && - !buffer_unwritten(bh)) { - done = 1; - break; - } - } while ((bh = bh->b_this_page) != head); + if (page_has_buffers(page)) { + bh = head = page_buffers(page); + do { + if (!buffer_delay(bh) && + !buffer_unwritten(bh)) + done = 1; + bh = bh->b_this_page; + } while (!done && (bh != head)); + } unlock_page(page); if (done) break;
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