On 08/31/2016 12:27 AM, Mikulas Patocka wrote: ... > > Drop that "#ifdef CONFIG_BCACHE". Anyone should be allowed to create a big > bio, not just bcache. Yes. Please, do not hide it behind #ifdef. If it is in code, it should be enabled always. There can third party modules or some new code appears and creating strange config dependence only adds more problems later. Milan > > That one test has no performance impact, there is no need to hide it > behind #ifdef. > > Mikulas > >> From: Mikulas Patocka <mpatocka@xxxxxxxxxx> >> Date: Tue, 30 Aug 2016 16:38:42 -0400 >> Subject: [PATCH] dm crypt: fix error with too large bcache bios >> >> When dm-crypt processes writes, it allocates a new bio in >> crypt_alloc_buffer(). The bio is allocated from a bio set and it can >> have at most BIO_MAX_PAGES vector entries, however the incoming bio can be >> larger if it was allocated by bcache. If the incoming bio is larger, >> bio_alloc_bioset() fails and an error is returned. >> >> To avoid the error, we test for a too large bio in the function >> crypt_map() and use dm_accept_partial_bio() to split the bio. >> dm_accept_partial_bio() trims the current bio to the desired size and >> asks DM core to send another bio with the rest of the data. >> >> This fix is wrapped with a check for CONFIG_BCACHE because there >> currently isn't any other code that generates too large bios. So unless >> bcache is configured there is no point wasting time making this check. >> >> Signed-off-by: Mikulas Patocka <mpatocka redhat com> >> Cc: stable@xxxxxxxxxxxxxxx # v3.16+ >> --- >> drivers/md/dm-crypt.c | 6 ++++++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c >> index eedba67..743f548 100644 >> --- a/drivers/md/dm-crypt.c >> +++ b/drivers/md/dm-crypt.c >> @@ -1924,6 +1924,12 @@ static int crypt_map(struct dm_target *ti, struct bio *bio) >> return DM_MAPIO_REMAPPED; >> } >> >> +#ifdef CONFIG_BCACHE >> + if (unlikely(bio->bi_iter.bi_size > (BIO_MAX_PAGES << PAGE_SHIFT)) && >> + bio_data_dir(bio) == WRITE) >> + dm_accept_partial_bio(bio, ((BIO_MAX_PAGES << PAGE_SHIFT) >> SECTOR_SHIFT)); >> +#endif >> + >> io = dm_per_bio_data(bio, cc->per_bio_data_size); >> crypt_io_init(io, cc, bio, dm_target_offset(ti, bio->bi_iter.bi_sector)); >> io->ctx.req = (struct skcipher_request *)(io + 1); >> -- >> 2.7.4 (Apple Git-66) >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-block" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
