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scsi, block: fix duplicate bdi name registration crashes 

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 <James.Bottomley@hansenpartnership.com>
Cc: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Jan Kara <jack@suse.cz>
Reported-by: Omar Sandoval <osandov@osandov.com>
Tested-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Dan Williams 2017-02-01 14:05:23 -08:00 committed by Jens Axboe
parent efa7c9f97e
commit 0dba1314d4
5 changed files with 64 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
block/blk-core.c
View File

@ -572,6 +572,7 @@ void blk_cleanup_queue(struct request_queue *q)
spin_unlock_irq(lock);
bdi_unregister(q->backing_dev_info);
put_disk_devt(q->disk_devt);
/* @q is and will stay empty, shutdown and put */
blk_put_queue(q);

21
block/genhd.c
View File

@ -572,6 +572,20 @@ static void register_disk(struct device *parent, struct gendisk *disk)
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));

41
drivers/scsi/sd.c
View File

@ -3064,6 +3064,23 @@ static void sd_probe_async(void *data, async_cookie_t cookie)
put_device(&sdkp->dev);
}
struct sd_devt {
int idx;
struct disk_devt disk_devt;
};
void sd_devt_release(struct disk_devt *disk_devt)
{
struct sd_devt *sd_devt = container_of(disk_devt, struct sd_devt,
disk_devt);
spin_lock(&sd_index_lock);
ida_remove(&sd_index_ida, sd_devt->idx);
spin_unlock(&sd_index_lock);
kfree(sd_devt);
}
/**
* sd_probe - called during driver initialization and whenever a
* new scsi device is attached to the system. It is called once
@ -3085,6 +3102,7 @@ static void sd_probe_async(void *data, async_cookie_t cookie)
static int sd_probe(struct device *dev)
{
struct scsi_device *sdp = to_scsi_device(dev);
struct sd_devt *sd_devt;
struct scsi_disk *sdkp;
struct gendisk *gd;
int index;
@ -3110,9 +3128,13 @@ static int sd_probe(struct device *dev)
if (!sdkp)
goto out;
sd_devt = kzalloc(sizeof(*sd_devt), GFP_KERNEL);
if (!sd_devt)
goto out_free;
gd = alloc_disk(SD_MINORS);
if (!gd)
goto out_free;
goto out_free_devt;
do {
if (!ida_pre_get(&sd_index_ida, GFP_KERNEL))
@ -3128,6 +3150,11 @@ static int sd_probe(struct device *dev)
goto out_put;
}
atomic_set(&sd_devt->disk_devt.count, 1);
sd_devt->disk_devt.release = sd_devt_release;
sd_devt->idx = index;
gd->disk_devt = &sd_devt->disk_devt;
error = sd_format_disk_name("sd", index, gd->disk_name, DISK_NAME_LEN);
if (error) {
sdev_printk(KERN_WARNING, sdp, "SCSI disk (sd) name length exceeded.\n");
@ -3167,13 +3194,14 @@ static int sd_probe(struct device *dev)
return 0;
out_free_index:
spin_lock(&sd_index_lock);
ida_remove(&sd_index_ida, index);
spin_unlock(&sd_index_lock);
put_disk_devt(&sd_devt->disk_devt);
sd_devt = NULL;
out_put:
put_disk(gd);
out_free:
kfree(sdkp);
out_free_devt:
kfree(sd_devt);
out:
scsi_autopm_put_device(sdp);
return error;
@ -3232,10 +3260,7 @@ static void scsi_disk_release(struct device *dev)
struct scsi_disk *sdkp = to_scsi_disk(dev);
struct gendisk *disk = sdkp->disk;
spin_lock(&sd_index_lock);
ida_remove(&sd_index_ida, sdkp->index);
spin_unlock(&sd_index_lock);
put_disk_devt(disk->disk_devt);
disk->private_data = NULL;
put_disk(disk);
put_device(&sdkp->device->sdev_gendev);

1
include/linux/blkdev.h
View File

@ -433,6 +433,7 @@ struct request_queue {
struct delayed_work delay_work;
struct backing_dev_info *backing_dev_info;
struct disk_devt *disk_devt;
/*
* The queue owner gets to use this for whatever they like.

8
include/linux/genhd.h
View File

@ -167,6 +167,13 @@ struct blk_integrity {
};
#endif /* CONFIG_BLK_DEV_INTEGRITY */
struct disk_devt {
atomic_t count;
void (*release)(struct disk_devt *disk_devt);
};
void put_disk_devt(struct disk_devt *disk_devt);
void get_disk_devt(struct disk_devt *disk_devt);
struct gendisk {
/* major, first_minor and minors are input parameters only,
@ -176,6 +183,7 @@ struct gendisk {
int first_minor;
int minors; /* maximum number of minors, =1 for
* disks that can't be partitioned. */
struct disk_devt *disk_devt;
char disk_name[DISK_NAME_LEN]; /* name of major driver */
char *(*devnode)(struct gendisk *gd, umode_t *mode);