kernel/linux.git/block/blk-map.c, branch v6.1.168

block: fix sanity checks in blk_rq_map_user_bvec

2024-11-08T15:26:45+00:00

[ Upstream commit 2ff949441802a8d076d9013c7761f63e8ae5a9bd ] blk_rq_map_user_bvec contains a check bytes + bv->bv_len > nr_iter which causes unnecessary failures in NVMe passthrough I/O, reproducible as follows: - register a 2 page, page-aligned buffer against a ring - use that buffer to do a 1 page io_uring NVMe passthrough read The second (i = 1) iteration of the loop in blk_rq_map_user_bvec will then have nr_iter == 1 page, bytes == 1 page, bv->bv_len == 1 page, so the check bytes + bv->bv_len > nr_iter will succeed, causing the I/O to fail. This failure is unnecessary, as when the check succeeds, it means we've checked the entire buffer that will be used by the request - i.e. blk_rq_map_user_bvec should complete successfully. Therefore, terminate the loop early and return successfully when the check bytes + bv->bv_len > nr_iter succeeds. While we're at it, also remove the check that all segments in the bvec are single-page. While this seems to be true for all users of the function, it doesn't appear to be required anywhere downstream. CC: stable@vger.kernel.org Signed-off-by: Xinyu Zhang Co-developed-by: Uday Shankar Signed-off-by: Uday Shankar Fixes: 37987547932c ("block: extend functionality to map bvec iterator") Link: https://lore.kernel.org/r/20241023211519.4177873-1-ushankar@purestorage.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

block: Fix WARNING in _copy_from_iter

2024-03-01T12:26:25+00:00

[ Upstream commit 13f3956eb5681a4045a8dfdef48df5dc4d9f58a6 ] Syzkaller reports a warning in _copy_from_iter because an iov_iter is supposedly used in the wrong direction. The reason is that syzcaller managed to generate a request with a transfer direction of SG_DXFER_TO_FROM_DEV. This instructs the kernel to copy user buffers into the kernel, read into the copied buffers and then copy the data back to user space. Thus the iovec is used in both directions. Detect this situation in the block layer and construct a new iterator with the correct direction for the copy-in. Reported-by: syzbot+a532b03fdfee2c137666@syzkaller.appspotmail.com Closes: https://lore.kernel.org/lkml/0000000000009b92c10604d7a5e9@google.com/t/ Reported-by: syzbot+63dec323ac56c28e644f@syzkaller.appspotmail.com Closes: https://lore.kernel.org/lkml/0000000000003faaa105f6e7c658@google.com/T/ Signed-off-by: Christian A. Ehrhardt Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20240121202634.275068-1-lk@c--e.de Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

block: fix bio-cache for passthru IO

2023-06-05T07:26:21+00:00

commit 46930b7cc7727271c9c27aac1fdc97a8645e2d00 upstream. commit <8af870aa5b847> ("block: enable bio caching use for passthru IO") introduced bio-cache for passthru IO. In case when nr_vecs are greater than BIO_INLINE_VECS, bio and bvecs are allocated from mempool (instead of percpu cache) and REQ_ALLOC_CACHE is cleared. This causes the side effect of not freeing bio/bvecs into mempool on completion. This patch lets the passthru IO fallback to allocation using bio_kmalloc when nr_vecs are greater than BIO_INLINE_VECS. The corresponding bio is freed during call to blk_mq_map_bio_put during completion. Cc: stable@vger.kernel.org # 6.1 fixes <8af870aa5b847> ("block: enable bio caching use for passthru IO") Signed-off-by: Anuj Gupta Signed-off-by: Kanchan Joshi Link: https://lore.kernel.org/r/20230523111709.145676-1-anuj20.g@samsung.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

block: extend functionality to map bvec iterator

2022-09-30T13:51:13+00:00

Extend blk_rq_map_user_iov so that it can handle bvec iterator, using the new blk_rq_map_user_bvec function. It maps the pages from bvec iterator into a bio and place the bio into request. This helper will be used by nvme for uring-passthrough path when IO is done using pre-mapped buffers. Signed-off-by: Kanchan Joshi Signed-off-by: Anuj Gupta Suggested-by: Christoph Hellwig Link: https://lore.kernel.org/r/20220930062749.152261-11-anuj20.g@samsung.com Signed-off-by: Jens Axboe

block: factor out blk_rq_map_bio_alloc helper

2022-09-30T13:51:13+00:00

Move bio allocation logic from bio_map_user_iov to a new helper blk_rq_map_bio_alloc. It is named so because functionality is opposite of what is done inside blk_mq_map_bio_put. This is a prep patch. Signed-off-by: Kanchan Joshi Link: https://lore.kernel.org/r/20220930062749.152261-10-anuj20.g@samsung.com Signed-off-by: Jens Axboe

block: rename bio_map_put to blk_mq_map_bio_put

2022-09-30T13:51:13+00:00

This patch renames existing bio_map_put function to blk_mq_map_bio_put. Signed-off-by: Anuj Gupta Suggested-by: Christoph Hellwig Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20220930062749.152261-9-anuj20.g@samsung.com Signed-off-by: Jens Axboe

block: add blk_rq_map_user_io

2022-09-30T13:51:13+00:00

Create a helper blk_rq_map_user_io for mapping of vectored as well as non-vectored requests. This will help in saving dupilcation of code at few places in scsi and nvme. Signed-off-by: Anuj Gupta Suggested-by: Christoph Hellwig Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20220930062749.152261-4-anuj20.g@samsung.com Signed-off-by: Jens Axboe

block/blk-map: Remove set but unused variable 'added'

2022-09-05T17:44:37+00:00

The variable added is not effectively used in the function, so delete it. block/blk-map.c:273:16: warning: variable 'added' set but not used. Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=2049 Reported-by: Abaci Robot Signed-off-by: Jiapeng Chong Link: https://lore.kernel.org/r/20220905063253.120082-1-jiapeng.chong@linux.alibaba.com Signed-off-by: Jens Axboe

block: use on-stack page vec for <= UIO_FASTIOV

2022-08-22T16:07:56+00:00

Avoid a kmalloc+kfree for each page array, if we only have a few pages that are mapped. An alloc+free for each IO is quite expensive, and it's pretty pointless if we're only dealing with 1 or a few vecs. Use UIO_FASTIOV like we do in other spots to set a sane limit for how big of an IO we want to avoid allocations for. Reviewed-by: Chaitanya Kulkarni Signed-off-by: Jens Axboe

block: enable bio caching use for passthru IO

2022-08-22T16:07:56+00:00

bdev based polled O_DIRECT is currently quite a bit faster than passthru on the same device, and one of the reaons is that we're not able to use the bio caching for passthru IO. If REQ_POLLED is set on the request, use the fs bio set for grabbing a bio from the caches, if available. This saves 5-6% of CPU over head for polled passthru IO. Reviewed-by: Chaitanya Kulkarni Signed-off-by: Jens Axboe