From 868f604b1de2ddbdcf194d7792a0d91d7da719c1 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Wed, 5 Apr 2017 14:05:51 +1000 Subject: [PATCH] md/linear: improve bio splitting. linear_make_request() uses fs_bio_set, which is meant for filesystems to use, and loops, possible allocating from the same bio set multiple times. These behaviors can theoretically cause deadlocks, though as linear requests are hardly ever split, it is unlikely in practice. Change to use mddev->bio_set - otherwise unused for linear, and submit the tail of a split request to generic_make_request() for it to handle. Signed-off-by: NeilBrown Signed-off-by: Shaohua Li --- drivers/md/linear.c | 73 +++++++++++++++++++++++++---------------------------- 1 file changed, 34 insertions(+), 39 deletions(-) diff --git a/drivers/md/linear.c b/drivers/md/linear.c index 3e38e02..f16316f 100644 --- a/drivers/md/linear.c +++ b/drivers/md/linear.c @@ -249,53 +249,48 @@ static void linear_make_request(struct mddev *mddev, struct bio *bio) { char b[BDEVNAME_SIZE]; struct dev_info *tmp_dev; - struct bio *split; sector_t start_sector, end_sector, data_offset; + sector_t bio_sector = bio->bi_iter.bi_sector; if (unlikely(bio->bi_opf & REQ_PREFLUSH)) { md_flush_request(mddev, bio); return; } - do { - sector_t bio_sector = bio->bi_iter.bi_sector; - tmp_dev = which_dev(mddev, bio_sector); - start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors; - end_sector = tmp_dev->end_sector; - data_offset = tmp_dev->rdev->data_offset; - bio->bi_bdev = tmp_dev->rdev->bdev; - - if (unlikely(bio_sector >= end_sector || - bio_sector < start_sector)) - goto out_of_bounds; - - if (unlikely(bio_end_sector(bio) > end_sector)) { - /* This bio crosses a device boundary, so we have to - * split it. - */ - split = bio_split(bio, end_sector - bio_sector, - GFP_NOIO, fs_bio_set); - bio_chain(split, bio); - } else { - split = bio; - } + tmp_dev = which_dev(mddev, bio_sector); + start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors; + end_sector = tmp_dev->end_sector; + data_offset = tmp_dev->rdev->data_offset; + + if (unlikely(bio_sector >= end_sector || + bio_sector < start_sector)) + goto out_of_bounds; + + if (unlikely(bio_end_sector(bio) > end_sector)) { + /* This bio crosses a device boundary, so we have to split it */ + struct bio *split = bio_split(bio, end_sector - bio_sector, + GFP_NOIO, mddev->bio_set); + bio_chain(split, bio); + generic_make_request(bio); + bio = split; + } - split->bi_iter.bi_sector = split->bi_iter.bi_sector - - start_sector + data_offset; - - if (unlikely((bio_op(split) == REQ_OP_DISCARD) && - !blk_queue_discard(bdev_get_queue(split->bi_bdev)))) { - /* Just ignore it */ - bio_endio(split); - } else { - if (mddev->gendisk) - trace_block_bio_remap(bdev_get_queue(split->bi_bdev), - split, disk_devt(mddev->gendisk), - bio_sector); - mddev_check_writesame(mddev, split); - generic_make_request(split); - } - } while (split != bio); + bio->bi_bdev = tmp_dev->rdev->bdev; + bio->bi_iter.bi_sector = bio->bi_iter.bi_sector - + start_sector + data_offset; + + if (unlikely((bio_op(bio) == REQ_OP_DISCARD) && + !blk_queue_discard(bdev_get_queue(bio->bi_bdev)))) { + /* Just ignore it */ + bio_endio(bio); + } else { + if (mddev->gendisk) + trace_block_bio_remap(bdev_get_queue(bio->bi_bdev), + bio, disk_devt(mddev->gendisk), + bio_sector); + mddev_check_writesame(mddev, bio); + generic_make_request(bio); + } return; out_of_bounds: -- 2.7.4