hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I9K0H6
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In __blkdev_issue_discard(), q->limits.discard_granularity is read multi times.
WARN_ON_ONCE(!q->limits.discard_granularity) [1] ... q->limits.discard_granularity >> SECTOR_SHIFT [2] ... bio_aligned_discard_max_sectors [3]
It can be changed to 0 after check [1], such as submitting ioctl 'LOOP_SET_STATUS'. This is undesirable. If 'discard_granularity' is set to 0, BUG_ON might be triggered and the loop of 'while(nr_sects)' will never exit(see fixes commit). Fix it by checking 'req_sects' before submit io, return error code directly if it is 0.
Fixes: b35fd7422c2f ("block: check queue's limits.discard_granularity in __blkdev_issue_discard()") Signed-off-by: Li Nan linan122@huawei.com --- block/blk-lib.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/block/blk-lib.c b/block/blk-lib.c index e59c3069e835..564904eeaed5 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -64,6 +64,14 @@ int __blkdev_issue_discard(struct block_device *bdev, sector_t sector, sector_t req_sects = min(nr_sects, bio_discard_limit(bdev, sector));
+ if (!req_sects) { + if (bio) { + bio_io_error(bio); + bio_put(bio); + } + return -EOPNOTSUPP; + } + bio = blk_next_bio(bio, bdev, 0, REQ_OP_DISCARD, gfp_mask); bio->bi_iter.bi_sector = sector; bio->bi_iter.bi_size = req_sects << 9;