linux-kernel - [PATCH 5.4 003/151] nbd: dont update block size after device is started

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Message-Id: <20201117122121.556211131@linuxfoundation.org>
Date:   Tue, 17 Nov 2020 14:03:53 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, lining <lining2020x@....com>,
        Ming Lei <ming.lei@...hat.com>,
        Josef Bacik <josef@...icpanda.com>, Jan Kara <jack@...e.cz>,
        Jens Axboe <axboe@...nel.dk>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 003/151] nbd: dont update block size after device is started

From: Ming Lei <ming.lei@...hat.com>

[ Upstream commit b40813ddcd6bf9f01d020804e4cb8febc480b9e4 ]

Mounted NBD device can be resized, one use case is rbd-nbd.

Fix the issue by setting up default block size, then not touch it
in nbd_size_update() any more. This kind of usage is aligned with loop
which has same use case too.

Cc: stable@...r.kernel.org
Fixes: c8a83a6b54d0 ("nbd: Use set_blocksize() to set device blocksize")
Reported-by: lining <lining2020x@....com>
Signed-off-by: Ming Lei <ming.lei@...hat.com>
Cc: Josef Bacik <josef@...icpanda.com>
Cc: Jan Kara <jack@...e.cz>
Tested-by: lining <lining2020x@....com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/block/nbd.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 742f8160b6e28..62a873718b5bb 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -296,7 +296,7 @@ static void nbd_size_clear(struct nbd_device *nbd)
 	}
 }
 
-static void nbd_size_update(struct nbd_device *nbd)
+static void nbd_size_update(struct nbd_device *nbd, bool start)
 {
 	struct nbd_config *config = nbd->config;
 	struct block_device *bdev = bdget_disk(nbd->disk, 0);
@@ -312,7 +312,8 @@ static void nbd_size_update(struct nbd_device *nbd)
 	if (bdev) {
 		if (bdev->bd_disk) {
 			bd_set_size(bdev, config->bytesize);
-			set_blocksize(bdev, config->blksize);
+			if (start)
+				set_blocksize(bdev, config->blksize);
 		} else
 			bdev->bd_invalidated = 1;
 		bdput(bdev);
@@ -327,7 +328,7 @@ static void nbd_size_set(struct nbd_device *nbd, loff_t blocksize,
 	config->blksize = blocksize;
 	config->bytesize = blocksize * nr_blocks;
 	if (nbd->task_recv != NULL)
-		nbd_size_update(nbd);
+		nbd_size_update(nbd, false);
 }
 
 static void nbd_complete_rq(struct request *req)
@@ -1293,7 +1294,7 @@ static int nbd_start_device(struct nbd_device *nbd)
 		args->index = i;
 		queue_work(nbd->recv_workq, &args->work);
 	}
-	nbd_size_update(nbd);
+	nbd_size_update(nbd, true);
 	return error;
 }
 
-- 
2.27.0