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bdi: add a ->dev_name field to struct backing_dev_info 

Cache a copy of the name for the life time of the backing_dev_info
structure so that we can reference it even after unregistering.

Fixes: 68f23b8906 ("memcg: fix a crash in wb_workfn when a device disappears")
Reported-by: Yufen Yu <yuyufen@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2020-05-04 14:47:56 +02:00 committed by Jens Axboe
parent d51cfc53ad
commit 6bd87eec23
2 changed files with 4 additions and 2 deletions
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1
include/linux/backing-dev-defs.h
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@ -219,6 +219,7 @@ struct backing_dev_info {
wait_queue_head_t wb_waitq;
struct device *dev;
char dev_name[64];
struct device *owner;
struct timer_list laptop_mode_wb_timer;

5
mm/backing-dev.c
View File

@ -938,7 +938,8 @@ int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args)
if (bdi->dev) /* The driver needs to use separate queues per device */
return 0;
dev = device_create_vargs(bdi_class, NULL, MKDEV(0, 0), bdi, fmt, args);
vsnprintf(bdi->dev_name, sizeof(bdi->dev_name), fmt, args);
dev = device_create(bdi_class, NULL, MKDEV(0, 0), bdi, bdi->dev_name);
if (IS_ERR(dev))
return PTR_ERR(dev);
@ -1047,7 +1048,7 @@ const char *bdi_dev_name(struct backing_dev_info *bdi)
{
if (!bdi || !bdi->dev)
return bdi_unknown_name;
return dev_name(bdi->dev);
return bdi->dev_name;
}
EXPORT_SYMBOL_GPL(bdi_dev_name);