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[PATCH] dm io: fix bi_max_vecs 

The existing code allocates an extra slot in bi_io_vec[] and uses it to store
the region number.

This patch hides the extra slot from bio_add_page() so the region number can't
get overwritten.

Also remove a hard-coded SECTOR_SHIFT and fix a typo in a comment.

Signed-off-by: Heinz Mauelshagen <hjm@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: Milan Broz <mbroz@redhat.com>
Cc: dm-devel@redhat.com
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Heinz Mauelshagen 2006-12-08 02:41:01 -08:00 committed by Linus Torvalds
parent 5cd307c565
commit f00b16ad66
1 changed files with 9 additions and 6 deletions
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15
drivers/md/dm-io.c
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@ -92,12 +92,12 @@ void dm_io_put(unsigned int num_pages)
*---------------------------------------------------------------*/
static inline void bio_set_region(struct bio *bio, unsigned region)
{
bio->bi_io_vec[bio->bi_max_vecs - 1].bv_len = region;
bio->bi_io_vec[bio->bi_max_vecs].bv_len = region;
}
static inline unsigned bio_get_region(struct bio *bio)
{
return bio->bi_io_vec[bio->bi_max_vecs - 1].bv_len;
return bio->bi_io_vec[bio->bi_max_vecs].bv_len;
}
/*-----------------------------------------------------------------
@ -136,6 +136,7 @@ static int endio(struct bio *bio, unsigned int done, int error)
zero_fill_bio(bio);
dec_count(io, bio_get_region(bio), error);
bio->bi_max_vecs++;
bio_put(bio);
return 0;
@ -250,16 +251,18 @@ static void do_region(int rw, unsigned int region, struct io_region *where,
while (remaining) {
/*
* Allocate a suitably sized bio, we add an extra
* bvec for bio_get/set_region().
* Allocate a suitably sized-bio: we add an extra
* bvec for bio_get/set_region() and decrement bi_max_vecs
* to hide it from bio_add_page().
*/
num_bvecs = (remaining / (PAGE_SIZE >> 9)) + 2;
num_bvecs = (remaining / (PAGE_SIZE >> SECTOR_SHIFT)) + 2;
bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, _bios);
bio->bi_sector = where->sector + (where->count - remaining);
bio->bi_bdev = where->bdev;
bio->bi_end_io = endio;
bio->bi_private = io;
bio->bi_destructor = dm_bio_destructor;
bio->bi_max_vecs--;
bio_set_region(bio, region);
/*
@ -302,7 +305,7 @@ static void dispatch_io(int rw, unsigned int num_regions,
}
/*
* Drop the extra refence that we were holding to avoid
* Drop the extra reference that we were holding to avoid
* the io being completed too early.
*/
dec_count(io, 0, 0);