• Dan Williams's avatar
    block: fix bdi vs gendisk lifetime mismatch · df08c32c
    Dan Williams authored
    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:
      [<ffffffff8134caec>] dump_stack+0x63/0x87
      [<ffffffff8108c351>] __warn+0xd1/0xf0
      [<ffffffff8108c3cf>] warn_slowpath_fmt+0x5f/0x80
      [<ffffffff812a0d34>] sysfs_warn_dup+0x64/0x80
      [<ffffffff812a0e1e>] sysfs_create_dir_ns+0x7e/0x90
      [<ffffffff8134faaa>] kobject_add_internal+0xaa/0x320
      [<ffffffff81358d4e>] ? vsnprintf+0x34e/0x4d0
      [<ffffffff8134ff55>] kobject_add+0x75/0xd0
      [<ffffffff816e66b2>] ? mutex_lock+0x12/0x2f
      [<ffffffff8148b0a5>] device_add+0x125/0x610
      [<ffffffff8148b788>] device_create_groups_vargs+0xd8/0x100
      [<ffffffff8148b7cc>] device_create_vargs+0x1c/0x20
      [<ffffffff811b775c>] bdi_register+0x8c/0x180
      [<ffffffff811b7877>] bdi_register_dev+0x27/0x30
      [<ffffffff813317f5>] add_disk+0x175/0x4a0
    
    Cc: <stable@vger.kernel.org>
    Reported-by: 's avatarYi Zhang <yizhan@redhat.com>
    Tested-by: 's avatarYi Zhang <yizhan@redhat.com>
    Signed-off-by: 's avatarDan Williams <dan.j.williams@intel.com>
    
    Fixed up missing 0 return in bdi_register_owner().
    Signed-off-by: 's avatarJens Axboe <axboe@fb.com>
    df08c32c
backing-dev.h 13.9 KB