From dbdc1be32591af023db2812706f01e6cd2f42bfc Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 30 Mar 2022 07:29:06 +0200 Subject: [PATCH] block: add a disk_openers helper Add a helper that returns the openers for a given gendisk to avoid having drivers poke into disk->part0 to get at this information in a somewhat cumbersome way. Signed-off-by: Christoph Hellwig Reviewed-by: Jan Kara Link: https://lore.kernel.org/r/20220330052917.2566582-5-hch@lst.de Signed-off-by: Jens Axboe --- drivers/block/nbd.c | 4 ++-- drivers/block/zram/zram_drv.c | 4 ++-- include/linux/blkdev.h | 15 +++++++++++++++ 3 files changed, 19 insertions(+), 4 deletions(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index dab24c58d5cc2..5263893517844 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1219,7 +1219,7 @@ static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg) static void nbd_bdev_reset(struct nbd_device *nbd) { - if (nbd->disk->part0->bd_openers > 1) + if (disk_openers(nbd->disk) > 1) return; set_capacity(nbd->disk, 0); } @@ -1576,7 +1576,7 @@ static void nbd_release(struct gendisk *disk, fmode_t mode) struct nbd_device *nbd = disk->private_data; if (test_bit(NBD_RT_DISCONNECT_ON_CLOSE, &nbd->config->runtime_flags) && - disk->part0->bd_openers == 0) + disk_openers(disk) == 0) nbd_disconnect_and_put(nbd); nbd_config_put(nbd); diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 70d4bd662ab6a..dc5ac5963377c 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1800,7 +1800,7 @@ static ssize_t reset_store(struct device *dev, mutex_lock(&disk->open_mutex); /* Do not reset an active device or claimed device */ - if (disk->part0->bd_openers || zram->claim) { + if (disk_openers(disk) || zram->claim) { mutex_unlock(&disk->open_mutex); return -EBUSY; } @@ -1989,7 +1989,7 @@ static int zram_remove(struct zram *zram) bool claimed; mutex_lock(&zram->disk->open_mutex); - if (zram->disk->part0->bd_openers) { + if (disk_openers(zram->disk)) { mutex_unlock(&zram->disk->open_mutex); return -EBUSY; } diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index c9b5925af5a3b..436645bde13f0 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -176,6 +176,21 @@ static inline bool disk_live(struct gendisk *disk) return !inode_unhashed(disk->part0->bd_inode); } +/** + * disk_openers - returns how many openers are there for a disk + * @disk: disk to check + * + * This returns the number of openers for a disk. Note that this value is only + * stable if disk->open_mutex is held. + * + * Note: Due to a quirk in the block layer open code, each open partition is + * only counted once even if there are multiple openers. + */ +static inline unsigned int disk_openers(struct gendisk *disk) +{ + return disk->part0->bd_openers; +} + /* * The gendisk is refcounted by the part0 block_device, and the bd_device * therein is also used for device model presentation in sysfs. -- 2.30.2