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scsi, block: fix duplicate bdi name registration crashes

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Warnings of the following form occur because scsi reuses a devt number
while the block layer still has it referenced as the name of the bdi
[1]:

 WARNING: CPU: 1 PID: 93 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x62/0x80
 sysfs: cannot create duplicate filename '/devices/virtual/bdi/8:192'
 [..]
 Call Trace:
  dump_stack+0x86/0xc3
  __warn+0xcb/0xf0
  warn_slowpath_fmt+0x5f/0x80
  ? kernfs_path_from_node+0x4f/0x60
  sysfs_warn_dup+0x62/0x80
  sysfs_create_dir_ns+0x77/0x90
  kobject_add_internal+0xb2/0x350
  kobject_add+0x75/0xd0
  device_add+0x15a/0x650
  device_create_groups_vargs+0xe0/0xf0
  device_create_vargs+0x1c/0x20
  bdi_register+0x90/0x240
  ? lockdep_init_map+0x57/0x200
  bdi_register_owner+0x36/0x60
  device_add_disk+0x1bb/0x4e0
  ? __pm_runtime_use_autosuspend+0x5c/0x70
  sd_probe_async+0x10d/0x1c0
  async_run_entry_fn+0x39/0x170

This is a brute-force fix to pass the devt release information from
sd_probe() to the locations where we register the bdi,
device_add_disk(), and unregister the bdi, blk_cleanup_queue().

Thanks to Omar for the quick reproducer script [2]. This patch survives
where an unmodified kernel fails in a few seconds.

[1]: https://marc.info/?l=linux-scsi&m=147116857810716&w=4
[2]: http://marc.info/?l=linux-block&m=148554717109098&w=2

Cc: James Bottomley <[email protected]>
Cc: Bart Van Assche <[email protected]>
Cc: "Martin K. Petersen" <[email protected]>
Cc: Jan Kara <[email protected]>
Reported-by: Omar Sandoval <[email protected]>
Tested-by: Omar Sandoval <[email protected]>
Signed-off-by: Dan Williams <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Bart Van Assche <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This commit is contained in:
Dan Williams 2017-02-01 14:05:23 -08:00 • committed by Jens Axboe
commit 0dba1314d4
5 changed files with 64 additions and 8 deletions
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21
block/genhd.c
View file

@ -572,6 +572,20 @@ exit:
disk_part_iter_exit(&piter);
}
void put_disk_devt(struct disk_devt *disk_devt)
{
if (disk_devt && atomic_dec_and_test(&disk_devt->count))
disk_devt->release(disk_devt);
}
EXPORT_SYMBOL(put_disk_devt);
void get_disk_devt(struct disk_devt *disk_devt)
{
if (disk_devt)
atomic_inc(&disk_devt->count);
}
EXPORT_SYMBOL(get_disk_devt);
/**
* device_add_disk - add partitioning information to kernel list
* @parent: parent device for the disk
@ -612,6 +626,13 @@ void device_add_disk(struct device *parent, struct gendisk *disk)
disk_alloc_events(disk);
/*
* Take a reference on the devt and assign it to queue since it
* must not be reallocated while the bdi is registered
*/
disk->queue->disk_devt = disk->disk_devt;
get_disk_devt(disk->disk_devt);
/* Register BDI before referencing it from bdev */
bdi = disk->queue->backing_dev_info;
bdi_register_owner(bdi, disk_to_dev(disk));