| Message ID | 146998891350.29275.1589003488607819550.stgit@dwillia2-desk3.amr.corp.intel.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On 07/31/2016 12:15 PM, Dan Williams wrote: > 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: Yi Zhang <yizhan@redhat.com> > Tested-by: Yi Zhang <yizhan@redhat.com> > Signed-off-by: Dan Williams <dan.j.williams@intel.com> Added for 4.8, thanks Dan.
diff --git a/block/genhd.c b/block/genhd.c index 3c9dede4e04f..f6f7ffcd4eab 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -614,7 +614,7 @@ void device_add_disk(struct device *parent, struct gendisk *disk) /* Register BDI before referencing it from bdev */ bdi = &disk->queue->backing_dev_info; - bdi_register_dev(bdi, disk_devt(disk)); + bdi_register_owner(bdi, disk_to_dev(disk)); blk_register_region(disk_devt(disk), disk->minors, NULL, exact_match, exact_lock, disk); diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h index 3f103076d0bf..c357f27d5483 100644 --- a/include/linux/backing-dev-defs.h +++ b/include/linux/backing-dev-defs.h @@ -163,6 +163,7 @@ struct backing_dev_info { wait_queue_head_t wb_waitq; struct device *dev; + struct device *owner; struct timer_list laptop_mode_wb_timer; diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 491a91717788..43b93a947e61 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -24,6 +24,7 @@ __printf(3, 4) int bdi_register(struct backing_dev_info *bdi, struct device *parent, const char *fmt, ...); int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev); +int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner); void bdi_unregister(struct backing_dev_info *bdi); int __must_check bdi_setup_and_register(struct backing_dev_info *, char *); diff --git a/mm/backing-dev.c b/mm/backing-dev.c index efe237742074..7b51cb7905be 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -825,6 +825,19 @@ 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); +} +EXPORT_SYMBOL(bdi_register_owner); + /* * Remove bdi from bdi_list, and ensure that it is no longer visible */ @@ -849,6 +862,11 @@ 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)