Martin, Thank you for new patch. The function bio_split says "The newly allocated bio will point to @bio's bi_io_vec; it is the caller's responsibility to ensure that @bio is not freed before the split." in its comments. I'm not sure whether some caller uses this limitation or not, so I modifid the raid function. If you want to modify bio_split function, you have to modify the comment also. The patch you shared has no problem, I think. I'll test it and share the result. I used the script from the algolia blog to reproduce the symptoms. They share it on Github. (https://github.com/algolia/trimtester) Thank you. Seunguk Shin -----Original Message----- From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid-owner@xxxxxxxxxxxxxxx] On Behalf Of Martin K. Petersen Sent: Monday, July 20, 2015 9:34 PM To: Seunguk Shin Cc: neilb@xxxxxxx; linux-raid@xxxxxxxxxxxxxxx Subject: Re: [PATCH] raid0: data corruption when using trim >>>>> "Seunguk" == Seunguk Shin <seunguk.shin@xxxxxxxxxxx> writes: Seunguk, Thanks for tracking this down. Instead of explicitly coding around the issue in raid0/raid10/linear I would prefer to fix bio_split(). It seems like a deficiency in the interface that it does not handle this transparently. Do you have a reproducible test case? If so it would be great if you could try the following patch and let us know the results. Thank you! -- Martin K. Petersen Oracle Linux Engineering commit 779e6b55da74108460baa8194d82806c4d7db523 Author: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Date: Mon Jul 20 08:05:30 2015 -0400 block: Do a full clone when splitting discard bios Commit 20d0189b1012 "block: Introduce new bio_split()" permits sharing the bio_vec between the two resulting bios. That's fine for read/write requests where the bio_vec is immutable. For discards, however, we need to be able to attach a payload and update the bio_vec so the page can get mapped to a scatterlist entry. Therefore the bio_vec can not be shared when splitting discards and we must do a full clone. Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Reported-by: Seunguk Shin <seunguk.shin@xxxxxxxxxxx> Cc: Jens Axboe <axboe@xxxxxx> Cc: Kent Overstreet <kent.overstreet@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> # v3.14+ diff --git a/block/bio.c b/block/bio.c index 2a00d349cd68..616b0e6f910a 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1842,7 +1842,15 @@ struct bio *bio_split(struct bio *bio, int sectors, BUG_ON(sectors <= 0); BUG_ON(sectors >= bio_sectors(bio)); - split = bio_clone_fast(bio, gfp, bs); + /* + * Discards need a mutable bio_vec to accommodate the payload + * required by the DSM TRIM and UNMAP commands. + */ + if (bio->bi_rw & REQ_DISCARD) + split = bio_clone_bioset(bio, gfp, bs); + else + split = bio_clone_fast(bio, gfp, bs); + if (!split) return NULL; -- To unsubscribe from this list: send the line "unsubscribe linux-raid" 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-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
