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| author | Theodore Ts'o <tytso@mit.edu> | 2009-09-30 22:57:41 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2009-09-30 22:57:41 -0400 |
| commit | 1f94533d9cd75f6d2826018d54a971b9cc085992 (patch) | |
| tree | 16c85061eabfcdece2487909bc08c45d2c01d84f /fs | |
| parent | c1fccc0696bcaff6008c11865091f5ec4b0937ab (diff) | |
| download | lwn-1f94533d9cd75f6d2826018d54a971b9cc085992.tar.gz lwn-1f94533d9cd75f6d2826018d54a971b9cc085992.zip | |
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: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/ext4/inode.c | 22 |
1 files changed, 11 insertions, 11 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index ec367bce7215..6e65d0e25ed3 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -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; - 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; |