nbd: don't update block size after device is started

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@vger.kernel.org
Fixes: c8a83a6b54d0 ("nbd: Use set_blocksize() to set device blocksize")
Reported-by: lining <lining2020x@163.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Jan Kara <jack@suse.cz>
Tested-by: lining <lining2020x@163.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 0bed21c..c4f9ccf 100644 (file)
--- 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);
@@ -313,7 +313,8 @@ static void nbd_size_update(struct nbd_device *nbd)
        if (bdev) {
                if (bdev->bd_disk) {
                        bd_set_nr_sectors(bdev, nr_sectors);
-                       set_blocksize(bdev, config->blksize);
+                       if (start)
+                               set_blocksize(bdev, config->blksize);
                } else
                        set_bit(GD_NEED_PART_SCAN, &nbd->disk->state);
                bdput(bdev);
@@ -328,7 +329,7 @@ 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)
@@ -1308,7 +1309,7 @@ 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;
 }