The patch titled
Direct I/O bio size regression fix
has been added to the -mm tree. Its filename is
direct-i-o-bio-size-regression-fix.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
From: David Chinner <dgc@xxxxxxx>
The change introduced here in 2.6.15:
http://kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=defd94b75409b983f94548ea2f52ff5787ddb848
sets the request queue max_sector size unconditionally to 1024 sectors in
blk_queue_max_sectors() even if the underlying hardware can support a
larger number of sectors.
Hence when building direct I/O bios, we have the situation where:
- dio_new_bio() limits bio vector size artifically to
1024 sectors / page size because bio_get_nr_vecs()
is used q->max_sectors to size the new bio; and
- dio_bio_add_page() limits the total bio size to 1024
sectors because bio_add_page() now uses q->max_sectors
to limit the size of the bio.
Therefore, we can't build direct I/Os larger than 1024 sectors even
if the hardware supports large I/Os. This is a regression as before
this mod we were able to issue direct I/Os limited by either the
maximum number of vectors in an bio or the hardware limits.
The patch allows direct I/O to build bios as large as the underlying
hardware will allow.
Signed-off-by: Dave Chinner <dgc@xxxxxxx>
Cc: <stable@xxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
fs/bio.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff -puN fs/bio.c~direct-i-o-bio-size-regression-fix fs/bio.c
--- 25/fs/bio.c~direct-i-o-bio-size-regression-fix Mon Apr 24 15:56:45 2006
+++ 25-akpm/fs/bio.c Mon Apr 24 15:56:45 2006
@@ -305,7 +305,7 @@ int bio_get_nr_vecs(struct block_device
request_queue_t *q = bdev_get_queue(bdev);
int nr_pages;
- nr_pages = ((q->max_sectors << 9) + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ nr_pages = ((q->max_hw_sectors << 9) + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (nr_pages > q->max_phys_segments)
nr_pages = q->max_phys_segments;
if (nr_pages > q->max_hw_segments)
@@ -447,7 +447,7 @@ int bio_add_page(struct bio *bio, struct
unsigned int offset)
{
struct request_queue *q = bdev_get_queue(bio->bi_bdev);
- return __bio_add_page(q, bio, page, len, offset, q->max_sectors);
+ return __bio_add_page(q, bio, page, len, offset, q->max_hw_sectors);
}
struct bio_map_data {
_
Patches currently in -mm which might be from dgc@xxxxxxx are
direct-i-o-bio-size-regression-fix.patch
-
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