From fbe004c30353f41f3b370cf3b36c4205821fdb61 Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Thu, 23 Apr 2015 22:37:18 -0700 Subject: [PATCH] block: make generic_make_request handle arbitrarily sized bios The way the block layer is currently written, it goes to great lengths to avoid having to split bios; upper layer code (such as bio_add_page()) checks what the underlying device can handle and tries to always create bios that don't need to be split. But this approach becomes unwieldy and eventually breaks down with stacked devices and devices with dynamic limits, and it adds a lot of complexity. If the block layer could split bios as needed, we could eliminate a lot of complexity elsewhere - particularly in stacked drivers. Code that creates bios can then create whatever size bios are convenient, and more importantly stacked drivers don't have to deal with both their own bio size limitations and the limitations of the (potentially multiple) devices underneath them. In the future this will let us delete merge_bvec_fn and a bunch of other code. We do this by adding calls to blk_queue_split() to the various make_request functions that need it - a few can already handle arbitrary size bios. Note that we add the call _after_ any call to blk_queue_bounce(); this means that blk_queue_split() and blk_recalc_rq_segments() don't need to be concerned with bouncing affecting segment merging. Some make_request_fn() callbacks were simple enough to audit and verify they don't need blk_queue_split() calls. The skipped ones are: * nfhd_make_request (arch/m68k/emu/nfblock.c) * axon_ram_make_request (arch/powerpc/sysdev/axonram.c) * simdisk_make_request (arch/xtensa/platforms/iss/simdisk.c) * brd_make_request (ramdisk - drivers/block/brd.c) * mtip_submit_request (drivers/block/mtip32xx/mtip32xx.c) * loop_make_request * null_queue_bio * bcache's make_request fns Some others are almost certainly safe to remove now, but will be left for future patches. Cc: Jens Axboe Cc: Christoph Hellwig Cc: Al Viro Cc: Ming Lei Cc: Neil Brown Cc: Alasdair Kergon Cc: Mike Snitzer Cc: dm-devel@redhat.com Cc: Lars Ellenberg Cc: drbd-user@lists.linbit.com Cc: Jiri Kosina Cc: Geoff Levand Cc: Jim Paris Cc: Philip Kelleher Cc: Minchan Kim Cc: Nitin Gupta Cc: Oleg Drokin Cc: Andreas Dilger Acked-by: NeilBrown (for the 'md/md.c' bits) Acked-by: Mike Snitzer Reviewed-by: Martin K. Petersen Signed-off-by: Kent Overstreet [dpark: skip more mq-based drivers, resolve merge conflicts, etc.] Signed-off-by: Dongsu Park Signed-off-by: Ming Lin Signed-off-by: Jens Axboe --- block/blk-core.c | 19 ++- block/blk-merge.c | 159 ++++++++++++++++++-- block/blk-mq.c | 4 + block/blk-sysfs.c | 3 + drivers/block/drbd/drbd_req.c | 2 + drivers/block/pktcdvd.c | 6 +- drivers/block/ps3vram.c | 2 + drivers/block/rsxx/dev.c | 2 + drivers/block/umem.c | 2 + drivers/block/zram/zram_drv.c | 2 + drivers/md/dm.c | 2 + drivers/md/md.c | 2 + drivers/s390/block/dcssblk.c | 2 + drivers/s390/block/xpram.c | 2 + drivers/staging/lustre/lustre/llite/lloop.c | 2 + include/linux/blkdev.h | 3 + 16 files changed, 192 insertions(+), 22 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index d1796b54e97a6..60912e983f16a 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -643,6 +643,10 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) if (q->id < 0) goto fail_q; + q->bio_split = bioset_create(BIO_POOL_SIZE, 0); + if (!q->bio_split) + goto fail_id; + q->backing_dev_info.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE; q->backing_dev_info.capabilities = BDI_CAP_CGROUP_WRITEBACK; @@ -651,7 +655,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) err = bdi_init(&q->backing_dev_info); if (err) - goto fail_id; + goto fail_split; setup_timer(&q->backing_dev_info.laptop_mode_wb_timer, laptop_mode_timer_fn, (unsigned long) q); @@ -693,6 +697,8 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id) fail_bdi: bdi_destroy(&q->backing_dev_info); +fail_split: + bioset_free(q->bio_split); fail_id: ida_simple_remove(&blk_queue_ida, q->id); fail_q: @@ -1610,6 +1616,8 @@ static void blk_queue_bio(struct request_queue *q, struct bio *bio) struct request *req; unsigned int request_count = 0; + blk_queue_split(q, &bio, q->bio_split); + /* * low level driver can indicate that it wants pages above a * certain limit bounced to low memory (ie for highmem, or even @@ -1832,15 +1840,6 @@ generic_make_request_checks(struct bio *bio) goto end_io; } - if (likely(bio_is_rw(bio) && - nr_sectors > queue_max_hw_sectors(q))) { - printk(KERN_ERR "bio too big device %s (%u > %u)\n", - bdevname(bio->bi_bdev, b), - bio_sectors(bio), - queue_max_hw_sectors(q)); - goto end_io; - } - part = bio->bi_bdev->bd_part; if (should_fail_request(part, bio->bi_iter.bi_size) || should_fail_request(&part_to_disk(part)->part0, diff --git a/block/blk-merge.c b/block/blk-merge.c index a455b9860143c..d9c3a75e4a60a 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -9,12 +9,158 @@ #include "blk.h" +static struct bio *blk_bio_discard_split(struct request_queue *q, + struct bio *bio, + struct bio_set *bs) +{ + unsigned int max_discard_sectors, granularity; + int alignment; + sector_t tmp; + unsigned split_sectors; + + /* Zero-sector (unknown) and one-sector granularities are the same. */ + granularity = max(q->limits.discard_granularity >> 9, 1U); + + max_discard_sectors = min(q->limits.max_discard_sectors, UINT_MAX >> 9); + max_discard_sectors -= max_discard_sectors % granularity; + + if (unlikely(!max_discard_sectors)) { + /* XXX: warn */ + return NULL; + } + + if (bio_sectors(bio) <= max_discard_sectors) + return NULL; + + split_sectors = max_discard_sectors; + + /* + * If the next starting sector would be misaligned, stop the discard at + * the previous aligned sector. + */ + alignment = (q->limits.discard_alignment >> 9) % granularity; + + tmp = bio->bi_iter.bi_sector + split_sectors - alignment; + tmp = sector_div(tmp, granularity); + + if (split_sectors > tmp) + split_sectors -= tmp; + + return bio_split(bio, split_sectors, GFP_NOIO, bs); +} + +static struct bio *blk_bio_write_same_split(struct request_queue *q, + struct bio *bio, + struct bio_set *bs) +{ + if (!q->limits.max_write_same_sectors) + return NULL; + + if (bio_sectors(bio) <= q->limits.max_write_same_sectors) + return NULL; + + return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs); +} + +static struct bio *blk_bio_segment_split(struct request_queue *q, + struct bio *bio, + struct bio_set *bs) +{ + struct bio *split; + struct bio_vec bv, bvprv; + struct bvec_iter iter; + unsigned seg_size = 0, nsegs = 0; + int prev = 0; + + struct bvec_merge_data bvm = { + .bi_bdev = bio->bi_bdev, + .bi_sector = bio->bi_iter.bi_sector, + .bi_size = 0, + .bi_rw = bio->bi_rw, + }; + + bio_for_each_segment(bv, bio, iter) { + if (q->merge_bvec_fn && + q->merge_bvec_fn(q, &bvm, &bv) < (int) bv.bv_len) + goto split; + + bvm.bi_size += bv.bv_len; + + if (bvm.bi_size >> 9 > queue_max_sectors(q)) + goto split; + + /* + * If the queue doesn't support SG gaps and adding this + * offset would create a gap, disallow it. + */ + if (q->queue_flags & (1 << QUEUE_FLAG_SG_GAPS) && + prev && bvec_gap_to_prev(&bvprv, bv.bv_offset)) + goto split; + + if (prev && blk_queue_cluster(q)) { + if (seg_size + bv.bv_len > queue_max_segment_size(q)) + goto new_segment; + if (!BIOVEC_PHYS_MERGEABLE(&bvprv, &bv)) + goto new_segment; + if (!BIOVEC_SEG_BOUNDARY(q, &bvprv, &bv)) + goto new_segment; + + seg_size += bv.bv_len; + bvprv = bv; + prev = 1; + continue; + } +new_segment: + if (nsegs == queue_max_segments(q)) + goto split; + + nsegs++; + bvprv = bv; + prev = 1; + seg_size = bv.bv_len; + } + + return NULL; +split: + split = bio_clone_bioset(bio, GFP_NOIO, bs); + + split->bi_iter.bi_size -= iter.bi_size; + bio->bi_iter = iter; + + if (bio_integrity(bio)) { + bio_integrity_advance(bio, split->bi_iter.bi_size); + bio_integrity_trim(split, 0, bio_sectors(split)); + } + + return split; +} + +void blk_queue_split(struct request_queue *q, struct bio **bio, + struct bio_set *bs) +{ + struct bio *split; + + if ((*bio)->bi_rw & REQ_DISCARD) + split = blk_bio_discard_split(q, *bio, bs); + else if ((*bio)->bi_rw & REQ_WRITE_SAME) + split = blk_bio_write_same_split(q, *bio, bs); + else + split = blk_bio_segment_split(q, *bio, q->bio_split); + + if (split) { + bio_chain(split, *bio); + generic_make_request(*bio); + *bio = split; + } +} +EXPORT_SYMBOL(blk_queue_split); + static unsigned int __blk_recalc_rq_segments(struct request_queue *q, struct bio *bio, bool no_sg_merge) { struct bio_vec bv, bvprv = { NULL }; - int cluster, high, highprv = 1; + int cluster, prev = 0; unsigned int seg_size, nr_phys_segs; struct bio *fbio, *bbio; struct bvec_iter iter; @@ -36,7 +182,6 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, cluster = blk_queue_cluster(q); seg_size = 0; nr_phys_segs = 0; - high = 0; for_each_bio(bio) { bio_for_each_segment(bv, bio, iter) { /* @@ -46,13 +191,7 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, if (no_sg_merge) goto new_segment; - /* - * the trick here is making sure that a high page is - * never considered part of another segment, since - * that might change with the bounce page. - */ - high = page_to_pfn(bv.bv_page) > queue_bounce_pfn(q); - if (!high && !highprv && cluster) { + if (prev && cluster) { if (seg_size + bv.bv_len > queue_max_segment_size(q)) goto new_segment; @@ -72,8 +211,8 @@ new_segment: nr_phys_segs++; bvprv = bv; + prev = 1; seg_size = bv.bv_len; - highprv = high; } bbio = bio; } diff --git a/block/blk-mq.c b/block/blk-mq.c index 94559025c5e65..81edbd95bda87 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1287,6 +1287,8 @@ static void blk_mq_make_request(struct request_queue *q, struct bio *bio) return; } + blk_queue_split(q, &bio, q->bio_split); + if (!is_flush_fua && !blk_queue_nomerges(q) && blk_attempt_plug_merge(q, bio, &request_count, &same_queue_rq)) return; @@ -1372,6 +1374,8 @@ static void blk_sq_make_request(struct request_queue *q, struct bio *bio) return; } + blk_queue_split(q, &bio, q->bio_split); + if (!is_flush_fua && !blk_queue_nomerges(q) && blk_attempt_plug_merge(q, bio, &request_count, NULL)) return; diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index b1f34e463c0f0..3e44a9da2a135 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -561,6 +561,9 @@ static void blk_release_queue(struct kobject *kobj) blk_trace_shutdown(q); + if (q->bio_split) + bioset_free(q->bio_split); + ida_simple_remove(&blk_queue_ida, q->id); call_rcu(&q->rcu_head, blk_free_queue_rcu); } diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c index 9cb41166366ef..923c857b395b3 100644 --- a/drivers/block/drbd/drbd_req.c +++ b/drivers/block/drbd/drbd_req.c @@ -1499,6 +1499,8 @@ void drbd_make_request(struct request_queue *q, struct bio *bio) struct drbd_device *device = (struct drbd_device *) q->queuedata; unsigned long start_jif; + blk_queue_split(q, &bio, q->bio_split); + start_jif = jiffies; /* diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c index a7a259e031da9..ee7ad5e44632e 100644 --- a/drivers/block/pktcdvd.c +++ b/drivers/block/pktcdvd.c @@ -2447,6 +2447,10 @@ static void pkt_make_request(struct request_queue *q, struct bio *bio) char b[BDEVNAME_SIZE]; struct bio *split; + blk_queue_bounce(q, &bio); + + blk_queue_split(q, &bio, q->bio_split); + pd = q->queuedata; if (!pd) { pr_err("%s incorrect request queue\n", @@ -2477,8 +2481,6 @@ static void pkt_make_request(struct request_queue *q, struct bio *bio) goto end_io; } - blk_queue_bounce(q, &bio); - do { sector_t zone = get_zone(bio->bi_iter.bi_sector, pd); sector_t last_zone = get_zone(bio_end_sector(bio) - 1, pd); diff --git a/drivers/block/ps3vram.c b/drivers/block/ps3vram.c index 49b4706b162c8..d89fcac595151 100644 --- a/drivers/block/ps3vram.c +++ b/drivers/block/ps3vram.c @@ -606,6 +606,8 @@ static void ps3vram_make_request(struct request_queue *q, struct bio *bio) dev_dbg(&dev->core, "%s\n", __func__); + blk_queue_split(q, &bio, q->bio_split); + spin_lock_irq(&priv->lock); busy = !bio_list_empty(&priv->list); bio_list_add(&priv->list, bio); diff --git a/drivers/block/rsxx/dev.c b/drivers/block/rsxx/dev.c index 63b9d2ffa8ee4..3163e4cdc2cc5 100644 --- a/drivers/block/rsxx/dev.c +++ b/drivers/block/rsxx/dev.c @@ -151,6 +151,8 @@ static void rsxx_make_request(struct request_queue *q, struct bio *bio) struct rsxx_bio_meta *bio_meta; int st = -EINVAL; + blk_queue_split(q, &bio, q->bio_split); + might_sleep(); if (!card) diff --git a/drivers/block/umem.c b/drivers/block/umem.c index 3b3afd2ec5d62..04d65790a8862 100644 --- a/drivers/block/umem.c +++ b/drivers/block/umem.c @@ -531,6 +531,8 @@ static void mm_make_request(struct request_queue *q, struct bio *bio) (unsigned long long)bio->bi_iter.bi_sector, bio->bi_iter.bi_size); + blk_queue_split(q, &bio, q->bio_split); + spin_lock_irq(&card->lock); *card->biotail = bio; bio->bi_next = NULL; diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 68c3d48004646..aec781acee9d5 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -900,6 +900,8 @@ static void zram_make_request(struct request_queue *queue, struct bio *bio) if (unlikely(!zram_meta_get(zram))) goto error; + blk_queue_split(queue, &bio, queue->bio_split); + if (!valid_io_request(zram, bio->bi_iter.bi_sector, bio->bi_iter.bi_size)) { atomic64_inc(&zram->stats.invalid_io); diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 7f367fcace035..069f8d7e890e6 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1799,6 +1799,8 @@ static void dm_make_request(struct request_queue *q, struct bio *bio) map = dm_get_live_table(md, &srcu_idx); + blk_queue_split(q, &bio, q->bio_split); + generic_start_io_acct(rw, bio_sectors(bio), &dm_disk(md)->part0); /* if we're suspended, we have to queue this io for later */ diff --git a/drivers/md/md.c b/drivers/md/md.c index ac4381a6625ce..e1d8723720ccb 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -257,6 +257,8 @@ static void md_make_request(struct request_queue *q, struct bio *bio) unsigned int sectors; int cpu; + blk_queue_split(q, &bio, q->bio_split); + if (mddev == NULL || mddev->pers == NULL || !mddev->ready) { bio_io_error(bio); diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c index 8bcb822b0bac5..29ea2394c8966 100644 --- a/drivers/s390/block/dcssblk.c +++ b/drivers/s390/block/dcssblk.c @@ -826,6 +826,8 @@ dcssblk_make_request(struct request_queue *q, struct bio *bio) unsigned long source_addr; unsigned long bytes_done; + blk_queue_split(q, &bio, q->bio_split); + bytes_done = 0; dev_info = bio->bi_bdev->bd_disk->private_data; if (dev_info == NULL) diff --git a/drivers/s390/block/xpram.c b/drivers/s390/block/xpram.c index 93856b9b62144..02871f1db562e 100644 --- a/drivers/s390/block/xpram.c +++ b/drivers/s390/block/xpram.c @@ -190,6 +190,8 @@ static void xpram_make_request(struct request_queue *q, struct bio *bio) unsigned long page_addr; unsigned long bytes; + blk_queue_split(q, &bio, q->bio_split); + if ((bio->bi_iter.bi_sector & 7) != 0 || (bio->bi_iter.bi_size & 4095) != 0) /* Request is not page-aligned. */ diff --git a/drivers/staging/lustre/lustre/llite/lloop.c b/drivers/staging/lustre/lustre/llite/lloop.c index cc00fd10fbcf7..1e33d540b2234 100644 --- a/drivers/staging/lustre/lustre/llite/lloop.c +++ b/drivers/staging/lustre/lustre/llite/lloop.c @@ -340,6 +340,8 @@ static void loop_make_request(struct request_queue *q, struct bio *old_bio) int rw = bio_rw(old_bio); int inactive; + blk_queue_split(q, &old_bio, q->bio_split); + if (!lo) goto err; diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 243f29e779ec5..ca778d9c7d812 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -463,6 +463,7 @@ struct request_queue { struct blk_mq_tag_set *tag_set; struct list_head tag_set_list; + struct bio_set *bio_split; }; #define QUEUE_FLAG_QUEUED 1 /* uses generic tag queueing */ @@ -783,6 +784,8 @@ extern void blk_rq_unprep_clone(struct request *rq); extern int blk_insert_cloned_request(struct request_queue *q, struct request *rq); extern void blk_delay_queue(struct request_queue *, unsigned long); +extern void blk_queue_split(struct request_queue *, struct bio **, + struct bio_set *); extern void blk_recount_segments(struct request_queue *, struct bio *); extern int scsi_verify_blk_ioctl(struct block_device *, unsigned int); extern int scsi_cmd_blk_ioctl(struct block_device *, fmode_t, -- 2.39.5