From e5cfefa97bccf956ea0bb6464c1f6c84fd7a8d9f Mon Sep 17 00:00:00 2001 From: Yu Kuai Date: Fri, 17 Feb 2023 10:22:00 +0800 Subject: [PATCH] block: fix scan partition for exclusively open device again As explained in commit 36369f46e917 ("block: Do not reread partition table on exclusively open device"), reread partition on the device that is exclusively opened by someone else is problematic. This patch will make sure partition scan will only be proceed if current thread open the device exclusively, or the device is not opened exclusively, and in the later case, other scanners and exclusive openers will be blocked temporarily until partition scan is done. Fixes: 10c70d95c0f2 ("block: remove the bd_openers checks in blk_drop_partitions") Cc: Suggested-by: Jan Kara Signed-off-by: Yu Kuai Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/20230217022200.3092987-3-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe --- block/genhd.c | 30 ++++++++++++++++++++++++++---- block/ioctl.c | 2 +- 2 files changed, 27 insertions(+), 5 deletions(-) diff --git a/block/genhd.c b/block/genhd.c index 820e27d88cbf..c0a73cd76bb1 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -359,6 +359,7 @@ EXPORT_SYMBOL_GPL(disk_uevent); int disk_scan_partitions(struct gendisk *disk, fmode_t mode) { struct block_device *bdev; + int ret = 0; if (disk->flags & (GENHD_FL_NO_PART | GENHD_FL_HIDDEN)) return -EINVAL; @@ -368,11 +369,27 @@ int disk_scan_partitions(struct gendisk *disk, fmode_t mode) return -EBUSY; set_bit(GD_NEED_PART_SCAN, &disk->state); - bdev = blkdev_get_by_dev(disk_devt(disk), mode, NULL); + /* + * If the device is opened exclusively by current thread already, it's + * safe to scan partitons, otherwise, use bd_prepare_to_claim() to + * synchronize with other exclusive openers and other partition + * scanners. + */ + if (!(mode & FMODE_EXCL)) { + ret = bd_prepare_to_claim(disk->part0, disk_scan_partitions); + if (ret) + return ret; + } + + bdev = blkdev_get_by_dev(disk_devt(disk), mode & ~FMODE_EXCL, NULL); if (IS_ERR(bdev)) - return PTR_ERR(bdev); - blkdev_put(bdev, mode); - return 0; + ret = PTR_ERR(bdev); + else + blkdev_put(bdev, mode); + + if (!(mode & FMODE_EXCL)) + bd_abort_claiming(disk->part0, disk_scan_partitions); + return ret; } /** @@ -494,6 +511,11 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk, if (ret) goto out_unregister_bdi; + /* Make sure the first partition scan will be proceed */ + if (get_capacity(disk) && !(disk->flags & GENHD_FL_NO_PART) && + !test_bit(GD_SUPPRESS_PART_SCAN, &disk->state)) + set_bit(GD_NEED_PART_SCAN, &disk->state); + bdev_add(disk->part0, ddev->devt); if (get_capacity(disk)) disk_scan_partitions(disk, FMODE_READ); diff --git a/block/ioctl.c b/block/ioctl.c index 6dd49d877584..9c5f637ff153 100644 --- a/block/ioctl.c +++ b/block/ioctl.c @@ -528,7 +528,7 @@ static int blkdev_common_ioctl(struct block_device *bdev, fmode_t mode, return -EACCES; if (bdev_is_partition(bdev)) return -EINVAL; - return disk_scan_partitions(bdev->bd_disk, mode & ~FMODE_EXCL); + return disk_scan_partitions(bdev->bd_disk, mode); case BLKTRACESTART: case BLKTRACESTOP: case BLKTRACETEARDOWN: