From 3079c22ea815775837a4f389ce2f7e1e7b202e09 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 26 Feb 2018 13:01:38 +0100 Subject: genhd: Rename get_disk() to get_disk_and_module() Rename get_disk() to get_disk_and_module() to make sure what the function does. It's not a great name but at least it is now clear that put_disk() is not it's counterpart. Signed-off-by: Jan Kara Signed-off-by: Jens Axboe --- include/linux/genhd.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 5e3531027b51..8e11b9321e55 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -600,7 +600,7 @@ extern void delete_partition(struct gendisk *, int); extern void printk_all_partitions(void); extern struct gendisk *__alloc_disk_node(int minors, int node_id); -extern struct kobject *get_disk(struct gendisk *disk); +extern struct kobject *get_disk_and_module(struct gendisk *disk); extern void put_disk(struct gendisk *disk); extern void blk_register_region(dev_t devt, unsigned long range, struct module *module, -- cgit v1.2.3 From 9df6c29912315186fef1c79cc15b758ace84175b Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 26 Feb 2018 13:01:39 +0100 Subject: genhd: Add helper put_disk_and_module() Add a proper counterpart to get_disk_and_module() - put_disk_and_module(). Currently it is opencoded in several places. Signed-off-by: Jan Kara Signed-off-by: Jens Axboe --- block/blk-cgroup.c | 11 ++--------- block/genhd.c | 20 ++++++++++++++++---- fs/block_dev.c | 19 +++++-------------- include/linux/genhd.h | 1 + 4 files changed, 24 insertions(+), 27 deletions(-) (limited to 'include') diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 4117524ca45b..c2033a232a44 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -812,7 +812,6 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, struct gendisk *disk; struct request_queue *q; struct blkcg_gq *blkg; - struct module *owner; unsigned int major, minor; int key_len, part, ret; char *body; @@ -904,9 +903,7 @@ fail_unlock: spin_unlock_irq(q->queue_lock); rcu_read_unlock(); fail: - owner = disk->fops->owner; - put_disk(disk); - module_put(owner); + put_disk_and_module(disk); /* * If queue was bypassing, we should retry. Do so after a * short msleep(). It isn't strictly necessary but queue @@ -931,13 +928,9 @@ EXPORT_SYMBOL_GPL(blkg_conf_prep); void blkg_conf_finish(struct blkg_conf_ctx *ctx) __releases(ctx->disk->queue->queue_lock) __releases(rcu) { - struct module *owner; - spin_unlock_irq(ctx->disk->queue->queue_lock); rcu_read_unlock(); - owner = ctx->disk->fops->owner; - put_disk(ctx->disk); - module_put(owner); + put_disk_and_module(ctx->disk); } EXPORT_SYMBOL_GPL(blkg_conf_finish); diff --git a/block/genhd.c b/block/genhd.c index 21b2843b27d0..4c0590434591 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -817,10 +817,7 @@ struct gendisk *get_gendisk(dev_t devt, int *partno) } if (disk && unlikely(disk->flags & GENHD_FL_HIDDEN)) { - struct module *owner = disk->fops->owner; - - put_disk(disk); - module_put(owner); + put_disk_and_module(disk); disk = NULL; } return disk; @@ -1483,6 +1480,21 @@ void put_disk(struct gendisk *disk) } EXPORT_SYMBOL(put_disk); +/* + * This is a counterpart of get_disk_and_module() and thus also of + * get_gendisk(). + */ +void put_disk_and_module(struct gendisk *disk) +{ + if (disk) { + struct module *owner = disk->fops->owner; + + put_disk(disk); + module_put(owner); + } +} +EXPORT_SYMBOL(put_disk_and_module); + static void set_disk_ro_uevent(struct gendisk *gd, int ro) { char event[] = "DISK_RO=1"; diff --git a/fs/block_dev.c b/fs/block_dev.c index 4a181fcb5175..1dbbf847911a 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1111,8 +1111,7 @@ static struct block_device *bd_start_claiming(struct block_device *bdev, else whole = bdgrab(bdev); - module_put(disk->fops->owner); - put_disk(disk); + put_disk_and_module(disk); if (!whole) return ERR_PTR(-ENOMEM); @@ -1407,7 +1406,6 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part); static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) { struct gendisk *disk; - struct module *owner; int ret; int partno; int perm = 0; @@ -1433,7 +1431,6 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) disk = get_gendisk(bdev->bd_dev, &partno); if (!disk) goto out; - owner = disk->fops->owner; disk_block_events(disk); mutex_lock_nested(&bdev->bd_mutex, for_part); @@ -1463,8 +1460,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) bdev->bd_queue = NULL; mutex_unlock(&bdev->bd_mutex); disk_unblock_events(disk); - put_disk(disk); - module_put(owner); + put_disk_and_module(disk); goto restart; } } @@ -1525,8 +1521,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) goto out_unlock_bdev; } /* only one opener holds refs to the module and disk */ - put_disk(disk); - module_put(owner); + put_disk_and_module(disk); } bdev->bd_openers++; if (for_part) @@ -1546,8 +1541,7 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) out_unlock_bdev: mutex_unlock(&bdev->bd_mutex); disk_unblock_events(disk); - put_disk(disk); - module_put(owner); + put_disk_and_module(disk); out: bdput(bdev); @@ -1770,8 +1764,6 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) disk->fops->release(disk, mode); } if (!bdev->bd_openers) { - struct module *owner = disk->fops->owner; - disk_put_part(bdev->bd_part); bdev->bd_part = NULL; bdev->bd_disk = NULL; @@ -1779,8 +1771,7 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) victim = bdev->bd_contains; bdev->bd_contains = NULL; - put_disk(disk); - module_put(owner); + put_disk_and_module(disk); } mutex_unlock(&bdev->bd_mutex); bdput(bdev); diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 8e11b9321e55..7f5906fe1b70 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -602,6 +602,7 @@ extern void printk_all_partitions(void); extern struct gendisk *__alloc_disk_node(int minors, int node_id); extern struct kobject *get_disk_and_module(struct gendisk *disk); extern void put_disk(struct gendisk *disk); +extern void put_disk_and_module(struct gendisk *disk); extern void blk_register_region(dev_t devt, unsigned long range, struct module *module, struct kobject *(*probe)(dev_t, int *, void *), -- cgit v1.2.3 From 56c0908c855afbb2bdda17c15d2879949a091ad3 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 26 Feb 2018 13:01:41 +0100 Subject: genhd: Fix BUG in blkdev_open() When two blkdev_open() calls for a partition race with device removal and recreation, we can hit BUG_ON(!bd_may_claim(bdev, whole, holder)) in blkdev_open(). The race can happen as follows: CPU0 CPU1 CPU2 del_gendisk() bdev_unhash_inode(part1); blkdev_open(part1, O_EXCL) blkdev_open(part1, O_EXCL) bdev = bd_acquire() bdev = bd_acquire() blkdev_get(bdev) bd_start_claiming(bdev) - finds old inode 'whole' bd_prepare_to_claim() -> 0 bdev_unhash_inode(whole); blkdev_get(bdev); bd_start_claiming(bdev) - finds new inode 'whole' bd_prepare_to_claim() - this also succeeds as we have different 'whole' here... - bad things happen now as we have two exclusive openers of the same bdev The problem here is that block device opens can see various intermediate states while gendisk is shutting down and then being recreated. We fix the problem by introducing new lookup_sem in gendisk that synchronizes gendisk deletion with get_gendisk() and furthermore by making sure that get_gendisk() does not return gendisk that is being (or has been) deleted. This makes sure that once we ever manage to look up newly created bdev inode, we are also guaranteed that following get_gendisk() will either return failure (and we fail open) or it returns gendisk for the new device and following bdget_disk() will return new bdev inode (i.e., blkdev_open() follows the path as if it is completely run after new device is created). Reported-and-analyzed-by: Hou Tao Tested-by: Hou Tao Signed-off-by: Jan Kara Signed-off-by: Jens Axboe --- block/genhd.c | 21 ++++++++++++++++++++- include/linux/genhd.h | 1 + 2 files changed, 21 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/block/genhd.c b/block/genhd.c index 4c0590434591..9656f9e9f99e 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -717,6 +717,11 @@ void del_gendisk(struct gendisk *disk) blk_integrity_del(disk); disk_del_events(disk); + /* + * Block lookups of the disk until all bdevs are unhashed and the + * disk is marked as dead (GENHD_FL_UP cleared). + */ + down_write(&disk->lookup_sem); /* invalidate stuff */ disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE); @@ -731,6 +736,7 @@ void del_gendisk(struct gendisk *disk) bdev_unhash_inode(disk_devt(disk)); set_capacity(disk, 0); disk->flags &= ~GENHD_FL_UP; + up_write(&disk->lookup_sem); if (!(disk->flags & GENHD_FL_HIDDEN)) sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi"); @@ -816,9 +822,21 @@ struct gendisk *get_gendisk(dev_t devt, int *partno) spin_unlock_bh(&ext_devt_lock); } - if (disk && unlikely(disk->flags & GENHD_FL_HIDDEN)) { + if (!disk) + return NULL; + + /* + * Synchronize with del_gendisk() to not return disk that is being + * destroyed. + */ + down_read(&disk->lookup_sem); + if (unlikely((disk->flags & GENHD_FL_HIDDEN) || + !(disk->flags & GENHD_FL_UP))) { + up_read(&disk->lookup_sem); put_disk_and_module(disk); disk = NULL; + } else { + up_read(&disk->lookup_sem); } return disk; } @@ -1418,6 +1436,7 @@ struct gendisk *__alloc_disk_node(int minors, int node_id) kfree(disk); return NULL; } + init_rwsem(&disk->lookup_sem); disk->node_id = node_id; if (disk_expand_part_tbl(disk, 0)) { free_part_stats(&disk->part0); diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 7f5906fe1b70..c826b0b5232a 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -198,6 +198,7 @@ struct gendisk { void *private_data; int flags; + struct rw_semaphore lookup_sem; struct kobject *slave_dir; struct timer_rand_state *random; -- cgit v1.2.3 From 9c72258870a95671aa301e21ea6639d1d3ec4111 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Fri, 26 Jan 2018 16:58:06 -0800 Subject: blktrace_api.h: fix comment for struct blk_user_trace_setup 'struct blk_user_trace_setup' is passed to BLKTRACESETUP, not BLKTRACESTART. Signed-off-by: Eric Biggers Signed-off-by: Jens Axboe --- include/uapi/linux/blktrace_api.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') diff --git a/include/uapi/linux/blktrace_api.h b/include/uapi/linux/blktrace_api.h index 20d1490d6377..3c50e07ee833 100644 --- a/include/uapi/linux/blktrace_api.h +++ b/include/uapi/linux/blktrace_api.h @@ -131,7 +131,7 @@ enum { #define BLKTRACE_BDEV_SIZE 32 /* - * User setup structure passed with BLKTRACESTART + * User setup structure passed with BLKTRACESETUP */ struct blk_user_trace_setup { char name[BLKTRACE_BDEV_SIZE]; /* output */ -- cgit v1.2.3 From 9c0fb1e313aaf4e8edec22433c8b22dd308e466c Mon Sep 17 00:00:00 2001 From: Jiufei Xue Date: Tue, 27 Feb 2018 20:10:18 +0800 Subject: block: display the correct diskname for bio bio_devname use __bdevname to display the device name, and can only show the major and minor of the part0, Fix this by using disk_name to display the correct name. Fixes: 74d46992e0d9 ("block: replace bi_bdev with a gendisk pointer and partitions index") Reviewed-by: Omar Sandoval Reviewed-by: Christoph Hellwig Signed-off-by: Jiufei Xue Signed-off-by: Jens Axboe --- block/partition-generic.c | 6 ++++++ include/linux/bio.h | 4 +--- 2 files changed, 7 insertions(+), 3 deletions(-) (limited to 'include') diff --git a/block/partition-generic.c b/block/partition-generic.c index 91622db9aedf..08dabcd8b6ae 100644 --- a/block/partition-generic.c +++ b/block/partition-generic.c @@ -51,6 +51,12 @@ const char *bdevname(struct block_device *bdev, char *buf) EXPORT_SYMBOL(bdevname); +const char *bio_devname(struct bio *bio, char *buf) +{ + return disk_name(bio->bi_disk, bio->bi_partno, buf); +} +EXPORT_SYMBOL(bio_devname); + /* * There's very little reason to use this, you should really * have a struct block_device just about everywhere and use diff --git a/include/linux/bio.h b/include/linux/bio.h index d0eb659fa733..ce547a25e8ae 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -511,6 +511,7 @@ void zero_fill_bio(struct bio *bio); extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *); extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int); extern unsigned int bvec_nr_vecs(unsigned short idx); +extern const char *bio_devname(struct bio *bio, char *buffer); #define bio_set_dev(bio, bdev) \ do { \ @@ -529,9 +530,6 @@ do { \ #define bio_dev(bio) \ disk_devt((bio)->bi_disk) -#define bio_devname(bio, buf) \ - __bdevname(bio_dev(bio), (buf)) - #ifdef CONFIG_BLK_CGROUP int bio_associate_blkcg(struct bio *bio, struct cgroup_subsys_state *blkcg_css); void bio_disassociate_task(struct bio *bio); -- cgit v1.2.3