From df08c32ce3be5be138c1dbfcba203314a3a7cd6f Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Sun, 31 Jul 2016 11:15:13 -0700 Subject: block: fix bdi vs gendisk lifetime mismatch The name for a bdi of a gendisk is derived from the gendisk's devt. However, since the gendisk is destroyed before the bdi it leaves a window where a new gendisk could dynamically reuse the same devt while a bdi with the same name is still live. Arrange for the bdi to hold a reference against its "owner" disk device while it is registered. Otherwise we can hit sysfs duplicate name collisions like the following: WARNING: CPU: 10 PID: 2078 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x64/0x80 sysfs: cannot create duplicate filename '/devices/virtual/bdi/259:1' Hardware name: HP ProLiant DL580 Gen8, BIOS P79 05/06/2015 0000000000000286 0000000002c04ad5 ffff88006f24f970 ffffffff8134caec ffff88006f24f9c0 0000000000000000 ffff88006f24f9b0 ffffffff8108c351 0000001f0000000c ffff88105d236000 ffff88105d1031e0 ffff8800357427f8 Call Trace: [] dump_stack+0x63/0x87 [] __warn+0xd1/0xf0 [] warn_slowpath_fmt+0x5f/0x80 [] sysfs_warn_dup+0x64/0x80 [] sysfs_create_dir_ns+0x7e/0x90 [] kobject_add_internal+0xaa/0x320 [] ? vsnprintf+0x34e/0x4d0 [] kobject_add+0x75/0xd0 [] ? mutex_lock+0x12/0x2f [] device_add+0x125/0x610 [] device_create_groups_vargs+0xd8/0x100 [] device_create_vargs+0x1c/0x20 [] bdi_register+0x8c/0x180 [] bdi_register_dev+0x27/0x30 [] add_disk+0x175/0x4a0 Cc: Reported-by: Yi Zhang Tested-by: Yi Zhang Signed-off-by: Dan Williams Fixed up missing 0 return in bdi_register_owner(). Signed-off-by: Jens Axboe --- mm/backing-dev.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'mm') diff --git a/mm/backing-dev.c b/mm/backing-dev.c index efe237742074..8fde443f36d7 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -825,6 +825,20 @@ int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev) } EXPORT_SYMBOL(bdi_register_dev); +int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner) +{ + int rc; + + rc = bdi_register(bdi, NULL, "%u:%u", MAJOR(owner->devt), + MINOR(owner->devt)); + if (rc) + return rc; + bdi->owner = owner; + get_device(owner); + return 0; +} +EXPORT_SYMBOL(bdi_register_owner); + /* * Remove bdi from bdi_list, and ensure that it is no longer visible */ @@ -849,6 +863,11 @@ void bdi_unregister(struct backing_dev_info *bdi) device_unregister(bdi->dev); bdi->dev = NULL; } + + if (bdi->owner) { + put_device(bdi->owner); + bdi->owner = NULL; + } } void bdi_exit(struct backing_dev_info *bdi) -- cgit v1.2.3