[PATCH v2 1/2] block: fail op_is_write() requests to read-only partitions
From: Ilya Dryomov <idryomov@gmail.com>
Date: 2018-01-10 16:19:08
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
Regular block device writes go through blkdev_write_iter(), which does bdev_read_only(), while zeroout/discard/etc requests are never checked, both userspace- and kernel-triggered. Add a generic catch-all check to generic_make_request_checks() to actually enforce ioctl(BLKROSET) and set_disk_ro(), which is used by quite a few drivers for things like snapshots, read-only backing files/images, etc. Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> --- block/blk-core.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index f843ae4f858d..d132bec4a266 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c@@ -2123,6 +2123,20 @@ static inline int bio_check_eod(struct bio *bio, unsigned int nr_sectors) return 0; } +static inline bool bio_check_ro(struct bio *bio) +{ + struct hd_struct *p; + bool ret = false; + + rcu_read_lock(); + p = __disk_get_part(bio->bi_disk, bio->bi_partno); + if (!p || (p->policy && op_is_write(bio_op(bio)))) + ret = true; + rcu_read_unlock(); + + return ret; +} + static noinline_for_stack bool generic_make_request_checks(struct bio *bio) {
@@ -2145,11 +2159,18 @@ generic_make_request_checks(struct bio *bio) goto end_io; } + if (unlikely(bio_check_ro(bio))) { + printk(KERN_ERR + "generic_make_request: Trying to write " + "to read-only block-device %s (partno %d)\n", + bio_devname(bio, b), bio->bi_partno); + goto end_io; + } + /* * For a REQ_NOWAIT based request, return -EOPNOTSUPP * if queue is not a request based queue. */ - if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_rq_based(q)) goto not_supported;
--
2.4.3