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@xxxxxxxxxxxxxxxxxxxxx> Cc: Bart Van Assche <bart.vanassche@xxxxxxxxxxx> Cc: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx> Cc: Christoph Hellwig <hch@xxxxxx> Cc: Jens Axboe <axboe@xxxxxxxxx> Cc: Jan Kara <jack@xxxxxxx> Reported-by: Omar Sandoval <osandov@xxxxxxxxxxx> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> --- Changes in v2: * rebased on top of Jan's bdi lifetime series * replace kref_{get,put}() with atomic_{inc,dec_and_test} (Christoph) block/blk-core.c | 1 + block/genhd.c | 7 +++++++ drivers/scsi/sd.c | 41 +++++++++++++++++++++++++++++++++-------- include/linux/blkdev.h | 1 + include/linux/genhd.h | 17 +++++++++++++++++ 5 files changed, 59 insertions(+), 8 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 84fabb51714a..0cd6b3c4b41c 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -595,6 +595,7 @@ 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); diff --git a/block/genhd.c b/block/genhd.c index d9ccd42f3675..124499db04d6 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -612,6 +612,13 @@ 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)); diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index 0b09638fa39b..102111e730ce 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -3067,6 +3067,23 @@ 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 @@ -3088,6 +3105,7 @@ 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; @@ -3113,9 +3131,13 @@ 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)) @@ -3131,6 +3153,11 @@ 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"); @@ -3170,13 +3197,14 @@ 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; @@ -3235,10 +3263,7 @@ 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); diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 3c0ff78b1219..53195a4d597a 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -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. diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 76f39754e7b0..27e7e12c0c2d 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -167,6 +167,22 @@ struct blk_integrity { }; #endif /* CONFIG_BLK_DEV_INTEGRITY */ +struct disk_devt { + atomic_t count; + void (*release)(struct disk_devt *disk_devt); +}; + +static inline void put_disk_devt(struct disk_devt *disk_devt) +{ + if (disk_devt && atomic_dec_and_test(&disk_devt->count)) + disk_devt->release(disk_devt); +} + +static inline void get_disk_devt(struct disk_devt *disk_devt) +{ + if (disk_devt) + atomic_inc(&disk_devt->count); +} struct gendisk { /* major, first_minor and minors are input parameters only, @@ -176,6 +192,7 @@ 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);
