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authorJeff Moyer <jmoyer@redhat.com>2010-09-09 16:37:33 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-09-09 18:57:22 -0700
commit7a801ac6f5067539ceb5fad0fe90ec49fc156e47 (patch)
tree6c2219eccccb3e71f8930993b7460290e787cd12
parent4e70598c3b56e6fec551454c495d4d4025834749 (diff)
downloadlinux-7a801ac6f5067539ceb5fad0fe90ec49fc156e47.tar.bz2
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 <jmoyer@redhat.com> Acked-by: Josef Bacik <jbacik@redhat.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Chris Mason <chris.mason@oracle.com> Cc: <stable@kernel.org> [2.6.35.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/direct-io.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 51f270b479b6..48d74c7391d1 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);
}