| Message ID | 20241028090840.446180-1-hch@lst.de (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] block: fix queue limits checks in blk_rq_map_user_bvec for real | expand |
On 28/10/2024 09:07, Christoph Hellwig wrote: > blk_rq_map_user_bvec currently only has ad-hoc checks for queue limits, > and the last fix to it enabled valid NVMe I/O to pass, but also allowed > invalid one for drivers that set a max_segment_size or seg_boundary > limit. > > Fix it once for all by using the bio_split_rw_at helper from the I/O > path that indicates if and where a bio would be have to be split to > adhere to the queue limits, and it it returns a positive value, turn super nit: check "it it " > that into -EREMOTEIO to retry using the copy path. > > Fixes: 2ff949441802 ("block: fix sanity checks in blk_rq_map_user_bvec") > Signed-off-by: Christoph Hellwig <hch@lst.de> FWIW, Reviewed-by: John Garry <john.g.garry@oracle.com> > --- > > Changes since v1: > - correctly shift the max_hw_sectors value. Tested by actually > checking for max_hw_sectors exceeding I/Os to fail properly > > block/blk-map.c | 56 +++++++++++++++---------------------------------- > 1 file changed, 17 insertions(+), 39 deletions(-) > > diff --git a/block/blk-map.c b/block/blk-map.c > index 6ef2ec1f7d78..b5fd1d857461 100644 > --- a/block/blk-map.c > +++ b/block/blk-map.c > @@ -561,55 +561,33 @@ EXPORT_SYMBOL(blk_rq_append_bio); > /* Prepare bio for passthrough IO given ITER_BVEC iter */ > static int blk_rq_map_user_bvec(struct request *rq, const struct iov_iter *iter) > { > - struct request_queue *q = rq->q; > - size_t nr_iter = iov_iter_count(iter); > - size_t nr_segs = iter->nr_segs; > - struct bio_vec *bvecs, *bvprvp = NULL; > - const struct queue_limits *lim = &q->limits; > - unsigned int nsegs = 0, bytes = 0; > + const struct queue_limits *lim = &rq->q->limits; > + unsigned int max_bytes = lim->max_hw_sectors << SECTOR_SHIFT; > + unsigned int nsegs; > struct bio *bio; > - size_t i; > + int ret; > > - if (!nr_iter || (nr_iter >> SECTOR_SHIFT) > queue_max_hw_sectors(q)) > - return -EINVAL; > - if (nr_segs > queue_max_segments(q)) > + if (!iov_iter_count(iter) || iov_iter_count(iter) > max_bytes) > return -EINVAL; > > - /* no iovecs to alloc, as we already have a BVEC iterator */ > + /* reuse the bvecs from the iterator instead of allocating new ones */ > bio = blk_rq_map_bio_alloc(rq, 0, GFP_KERNEL); > - if (bio == NULL) > + if (!bio) > return -ENOMEM; > - > bio_iov_bvec_set(bio, (struct iov_iter *)iter); totally separate comment to this patch, but I think that bio_iov_bvec_set() could be changed to accept const struct iov_iter * (and so we could drop the casting here) > - blk_rq_bio_prep(rq, bio, nr_segs); > - > - /* loop to perform a bunch of sanity checks */ > - bvecs = (struct bio_vec *)iter->bvec; > - for (i = 0; i < nr_segs; i++) { > - struct bio_vec *bv = &bvecs[i]; > - > - /* > - * If the queue doesn't support SG gaps and adding this > - * offset would create a gap, fallback to copy. > - */ > - if (bvprvp && bvec_gap_to_prev(lim, bvprvp, bv->bv_offset)) { > - blk_mq_map_bio_put(bio); > - return -EREMOTEIO; > - } > - /* check full condition */ > - if (nsegs >= nr_segs || bytes > UINT_MAX - bv->bv_len) > - goto put_bio; > - if (bytes + bv->bv_len > nr_iter) > - break; > > - nsegs++; > - bytes += bv->bv_len; > - bvprvp = bv; > + /* check that the data layout matches the hardware restrictions */ > + ret = bio_split_rw_at(bio, lim, &nsegs, max_bytes); > + if (ret) { > + /* if we would have to split the bio, copy instead */ > + if (ret > 0) > + ret = -EREMOTEIO; > + blk_mq_map_bio_put(bio); > + return ret; > } > + > + blk_rq_bio_prep(rq, bio, nsegs); > return 0; > -put_bio: > - blk_mq_map_bio_put(bio); > - return -EINVAL; > } > > /**
On Mon, 28 Oct 2024 10:07:48 +0100, Christoph Hellwig wrote: > blk_rq_map_user_bvec currently only has ad-hoc checks for queue limits, > and the last fix to it enabled valid NVMe I/O to pass, but also allowed > invalid one for drivers that set a max_segment_size or seg_boundary > limit. > > Fix it once for all by using the bio_split_rw_at helper from the I/O > path that indicates if and where a bio would be have to be split to > adhere to the queue limits, and it it returns a positive value, turn > that into -EREMOTEIO to retry using the copy path. > > [...] Applied, thanks! [1/1] block: fix queue limits checks in blk_rq_map_user_bvec for real commit: be0e822bb3f5259c7f9424ba97e8175211288813 Best regards,
diff --git a/block/blk-map.c b/block/blk-map.c index 6ef2ec1f7d78..b5fd1d857461 100644 --- a/block/blk-map.c +++ b/block/blk-map.c @@ -561,55 +561,33 @@ EXPORT_SYMBOL(blk_rq_append_bio); /* Prepare bio for passthrough IO given ITER_BVEC iter */ static int blk_rq_map_user_bvec(struct request *rq, const struct iov_iter *iter) { - struct request_queue *q = rq->q; - size_t nr_iter = iov_iter_count(iter); - size_t nr_segs = iter->nr_segs; - struct bio_vec *bvecs, *bvprvp = NULL; - const struct queue_limits *lim = &q->limits; - unsigned int nsegs = 0, bytes = 0; + const struct queue_limits *lim = &rq->q->limits; + unsigned int max_bytes = lim->max_hw_sectors << SECTOR_SHIFT; + unsigned int nsegs; struct bio *bio; - size_t i; + int ret; - if (!nr_iter || (nr_iter >> SECTOR_SHIFT) > queue_max_hw_sectors(q)) - return -EINVAL; - if (nr_segs > queue_max_segments(q)) + if (!iov_iter_count(iter) || iov_iter_count(iter) > max_bytes) return -EINVAL; - /* no iovecs to alloc, as we already have a BVEC iterator */ + /* reuse the bvecs from the iterator instead of allocating new ones */ bio = blk_rq_map_bio_alloc(rq, 0, GFP_KERNEL); - if (bio == NULL) + if (!bio) return -ENOMEM; - bio_iov_bvec_set(bio, (struct iov_iter *)iter); - blk_rq_bio_prep(rq, bio, nr_segs); - - /* loop to perform a bunch of sanity checks */ - bvecs = (struct bio_vec *)iter->bvec; - for (i = 0; i < nr_segs; i++) { - struct bio_vec *bv = &bvecs[i]; - - /* - * If the queue doesn't support SG gaps and adding this - * offset would create a gap, fallback to copy. - */ - if (bvprvp && bvec_gap_to_prev(lim, bvprvp, bv->bv_offset)) { - blk_mq_map_bio_put(bio); - return -EREMOTEIO; - } - /* check full condition */ - if (nsegs >= nr_segs || bytes > UINT_MAX - bv->bv_len) - goto put_bio; - if (bytes + bv->bv_len > nr_iter) - break; - nsegs++; - bytes += bv->bv_len; - bvprvp = bv; + /* check that the data layout matches the hardware restrictions */ + ret = bio_split_rw_at(bio, lim, &nsegs, max_bytes); + if (ret) { + /* if we would have to split the bio, copy instead */ + if (ret > 0) + ret = -EREMOTEIO; + blk_mq_map_bio_put(bio); + return ret; } + + blk_rq_bio_prep(rq, bio, nsegs); return 0; -put_bio: - blk_mq_map_bio_put(bio); - return -EINVAL; } /**
blk_rq_map_user_bvec currently only has ad-hoc checks for queue limits, and the last fix to it enabled valid NVMe I/O to pass, but also allowed invalid one for drivers that set a max_segment_size or seg_boundary limit. Fix it once for all by using the bio_split_rw_at helper from the I/O path that indicates if and where a bio would be have to be split to adhere to the queue limits, and it it returns a positive value, turn that into -EREMOTEIO to retry using the copy path. Fixes: 2ff949441802 ("block: fix sanity checks in blk_rq_map_user_bvec") Signed-off-by: Christoph Hellwig <hch@lst.de> --- Changes since v1: - correctly shift the max_hw_sectors value. Tested by actually checking for max_hw_sectors exceeding I/Os to fail properly block/blk-map.c | 56 +++++++++++++++---------------------------------- 1 file changed, 17 insertions(+), 39 deletions(-)