From: Dave Chinner <[email protected]> Upstream commit: 6ffc4db5de61d36e969a26bc94509c59246c81f8
xfs_is_delayed_page() checks to see if a page has buffers matching the given IO type passed in. It does so by walking the buffer heads on the page and checking if the state flags match the IO type. However, the "acceptable" variable that is calculated is overwritten every time a new buffer is checked. Hence if the first buffer on the page is of the right type, this state is lost if the second buffer is not of the correct type. This means that xfs_aops_discard_page() may not discard delalloc regions when it is supposed to, and xfs_convert_page() may not cluster IO as efficiently as possible. This problem only occurs on filesystems with a block size smaller than page size. Also, rename xfs_is_delayed_page() to xfs_check_page_type() to better describe what it is doing - it is not delalloc specific anymore. The problem was first noticed by Peter Watkins. Signed-off-by: Dave Chinner <[email protected]> Reviewed-by: Christoph Hellwig <[email protected]> Reviewed-by: Mark Tinguely <[email protected]> Signed-off-by: Ben Myers <[email protected]> --- fs/xfs/linux-2.6/xfs_aops.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) Index: b/fs/xfs/linux-2.6/xfs_aops.c =================================================================== --- a/fs/xfs/linux-2.6/xfs_aops.c +++ b/fs/xfs/linux-2.6/xfs_aops.c @@ -636,7 +636,7 @@ xfs_map_at_offset( * or delayed allocate extent. */ STATIC int -xfs_is_delayed_page( +xfs_check_page_type( struct page *page, unsigned int type) { @@ -650,11 +650,11 @@ xfs_is_delayed_page( bh = head = page_buffers(page); do { if (buffer_unwritten(bh)) - acceptable = (type == IO_UNWRITTEN); + acceptable += (type == IO_UNWRITTEN); else if (buffer_delay(bh)) - acceptable = (type == IO_DELALLOC); + acceptable += (type == IO_DELALLOC); else if (buffer_dirty(bh) && buffer_mapped(bh)) - acceptable = (type == IO_OVERWRITE); + acceptable += (type == IO_OVERWRITE); else break; } while ((bh = bh->b_this_page) != head); @@ -697,7 +697,7 @@ xfs_convert_page( goto fail_unlock_page; if (page->mapping != inode->i_mapping) goto fail_unlock_page; - if (!xfs_is_delayed_page(page, (*ioendp)->io_type)) + if (!xfs_check_page_type(page, (*ioendp)->io_type)) goto fail_unlock_page; /* @@ -847,7 +847,7 @@ xfs_aops_discard_page( struct buffer_head *bh, *head; loff_t offset = page_offset(page); - if (!xfs_is_delayed_page(page, IO_DELALLOC)) + if (!xfs_check_page_type(page, IO_DELALLOC)) goto out_invalidate; if (XFS_FORCED_SHUTDOWN(ip->i_mount)) -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
