linux-kernel - [PATCH] zram: Allow backing device to be assigned after init

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Message-Id: <20211001181627.394921-1-bgeffon@google.com>
Date:   Fri,  1 Oct 2021 11:16:27 -0700
From:   Brian Geffon <bgeffon@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Minchan Kim <minchan@...nel.org>, Nitin Gupta <ngupta@...are.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Jonathan Corbet <corbet@....net>, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-block@...r.kernel.org,
        Suleiman Souhlal <suleiman@...gle.com>,
        Jesse Barnes <jsbarnes@...gle.com>,
        Brian Geffon <bgeffon@...gle.com>
Subject: [PATCH] zram: Allow backing device to be assigned after init

There does not appear to be a technical reason to not
allow the zram backing device to be assigned after the
zram device is initialized.

This change will allow for the backing device to be assigned
as long as no backing device is already assigned. In that
event backing_dev would return -EEXIST.

Signed-off-by: Brian Geffon <bgeffon@...gle.com>
---
 drivers/block/zram/zram_drv.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index fcaf2750f68f..12b4555ee079 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -462,9 +462,9 @@ static ssize_t backing_dev_store(struct device *dev,
 		return -ENOMEM;
 
 	down_write(&zram->init_lock);
-	if (init_done(zram)) {
-		pr_info("Can't setup backing device for initialized device\n");
-		err = -EBUSY;
+	if (zram->backing_dev) {
+		pr_info("Backing device is already assigned\n");
+		err = -EEXIST;
 		goto out;
 	}
 
-- 
2.33.0.800.g4c38ced690-goog