From 7a801ac6f5067539ceb5fad0fe90ec49fc156e47 Mon Sep 17 00:00:00 2001 From: Jeff Moyer Date: Thu, 9 Sep 2010 16:37:33 -0700 Subject: [PATCH] O_DIRECT: fix the splitting up of contiguous I/O commit c2c6ca4 (direct-io: do not merge logically non-contiguous requests) introduced a bug whereby all O_DIRECT I/Os were submitted a page at a time to the block layer. The problem is that the code expected dio->block_in_file to correspond to the current page in the dio. In fact, it corresponds to the previous page submitted via submit_page_section. This was purely an oversight, as the dio->cur_page_fs_offset field was introduced for just this purpose. This patch simply uses the correct variable when calculating whether there is a mismatch between contiguous logical blocks and contiguous physical blocks (as described in the comments). I also switched the if conditional following this check to an else if, to ensure that we never call dio_bio_submit twice for the same dio (in theory, this should not happen, anyway). I've tested this by running blktrace and verifying that a 64KB I/O was submitted as a single I/O. I also ran the patched kernel through xfstests' aio tests using xfs, ext4 (with 1k and 4k block sizes) and btrfs and verified that there were no regressions as compared to an unpatched kernel. Signed-off-by: Jeff Moyer Acked-by: Josef Bacik Cc: Christoph Hellwig Cc: Chris Mason Cc: [2.6.35.x] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/direct-io.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/direct-io.c b/fs/direct-io.c index 51f270b479b..48d74c7391d 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -634,7 +634,7 @@ static int dio_send_cur_page(struct dio *dio) int ret = 0; if (dio->bio) { - loff_t cur_offset = dio->block_in_file << dio->blkbits; + loff_t cur_offset = dio->cur_page_fs_offset; loff_t bio_next_offset = dio->logical_offset_in_bio + dio->bio->bi_size; @@ -659,7 +659,7 @@ static int dio_send_cur_page(struct dio *dio) * Submit now if the underlying fs is about to perform a * metadata read */ - if (dio->boundary) + else if (dio->boundary) dio_bio_submit(dio); } -- 2.34.1