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FAILED: patch "[PATCH] bdi: add a ->dev_name field to struct backing_dev_info" failed to apply to 5.4-stable tree

PATCH [email protected] 1 participant 1 message May 12, 2020

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The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6bd87eec23cbc9ed222bed0f5b5b02bf300e9a8d Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <[email protected]>
Date: Mon, 4 May 2020 14:47:56 +0200
Subject: [PATCH] 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 68f23b89067f ("memcg: fix a crash in wb_workfn when a device disappears")
Reported-by Yufen Yu <[email protected]>
Signed-off-by Christoph Hellwig <[email protected]>
Reviewed-by Jan Kara <[email protected]>
Reviewed-by Bart Van Assche <[email protected]>
Signed-off-by Jens Axboe <[email protected]>
include/linux/backing-dev-defs.h +1 -0
index ee577a83cfe6..7367150f962a 100644
@@ -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;
mm/backing-dev.c +3 -2
index c2c44c89ee5d..efc5b83acd2d 100644
@@ -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);