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nbd: Create size change events for userspace

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The userspace needs to know when nbd devices are ready for use.
Currently no events are created for the userspace which doesn't work for
systemd.

See the discussion here: https://github.com/systemd/systemd/pull/358

This patch uses a central point to setup the nbd-internal sizes. A ioctl
to set a size does not lead to a visible size change. The size of the
block device will be kept at 0 until nbd is connected. As soon as it
connects, the size will be changed to the real value and a uevent is
created. When disconnecting, the blockdevice is set to 0 size and
another uevent is generated.

Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
This commit is contained in:
Markus Pargmann 2015-07-27 07:36:49 +02:00
parent da6ccaaa79
commit 37091fdd83
1 changed files with 58 additions and 21 deletions
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79
drivers/block/nbd.c
View file

@ -100,6 +100,11 @@ static inline struct device *nbd_to_dev(struct nbd_device *nbd)
return disk_to_dev(nbd->disk);
}
static bool nbd_is_connected(struct nbd_device *nbd)
{
return !!nbd->task_recv;
}
static const char *nbdcmd_to_ascii(int cmd)
{
switch (cmd) {
@ -112,6 +117,42 @@ static const char *nbdcmd_to_ascii(int cmd)
return "invalid";
}
static int nbd_size_clear(struct nbd_device *nbd, struct block_device *bdev)
{
bdev->bd_inode->i_size = 0;
set_capacity(nbd->disk, 0);
kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
return 0;
}
static void nbd_size_update(struct nbd_device *nbd, struct block_device *bdev)
{
if (!nbd_is_connected(nbd))
return;
bdev->bd_inode->i_size = nbd->bytesize;
set_capacity(nbd->disk, nbd->bytesize >> 9);
kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
}
static int nbd_size_set(struct nbd_device *nbd, struct block_device *bdev,
int blocksize, int nr_blocks)
{
int ret;
ret = set_blocksize(bdev, blocksize);
if (ret)
return ret;
nbd->blksize = blocksize;
nbd->bytesize = (loff_t)blocksize * (loff_t)nr_blocks;
nbd_size_update(nbd, bdev);
return 0;
}
static void nbd_end_request(struct nbd_device *nbd, struct request *req)
{
int error = req->errors ? -EIO : 0;
@ -401,7 +442,7 @@ static struct device_attribute pid_attr = {
.show = pid_show,
};
static int nbd_thread_recv(struct nbd_device *nbd)
static int nbd_thread_recv(struct nbd_device *nbd, struct block_device *bdev)
{
struct request *req;
int ret;
@ -421,6 +462,8 @@ static int nbd_thread_recv(struct nbd_device *nbd)
return ret;
}
nbd_size_update(nbd, bdev);
while (1) {
req = nbd_read_stat(nbd);
if (IS_ERR(req)) {
@ -431,6 +474,8 @@ static int nbd_thread_recv(struct nbd_device *nbd)
nbd_end_request(nbd, req);
}
nbd_size_clear(nbd, bdev);
device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
nbd->task_recv = NULL;
@ -707,20 +752,19 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
return err;
}
case NBD_SET_BLKSIZE:
nbd->blksize = arg;
nbd->bytesize &= ~(nbd->blksize-1);
bdev->bd_inode->i_size = nbd->bytesize;
set_blocksize(bdev, nbd->blksize);
set_capacity(nbd->disk, nbd->bytesize >> 9);
return 0;
case NBD_SET_BLKSIZE: {
loff_t bsize = nbd->bytesize;
do_div(bsize, arg);
return nbd_size_set(nbd, bdev, arg, bsize);
}
case NBD_SET_SIZE:
nbd->bytesize = arg & ~(nbd->blksize-1);
bdev->bd_inode->i_size = nbd->bytesize;
set_blocksize(bdev, nbd->blksize);
set_capacity(nbd->disk, nbd->bytesize >> 9);
return 0;
return nbd_size_set(nbd, bdev, nbd->blksize,
arg / nbd->blksize);
case NBD_SET_SIZE_BLOCKS:
return nbd_size_set(nbd, bdev, nbd->blksize, arg);
case NBD_SET_TIMEOUT:
nbd->xmit_timeout = arg * HZ;
@ -736,13 +780,6 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
nbd->flags = arg;
return 0;
case NBD_SET_SIZE_BLOCKS:
nbd->bytesize = ((u64) arg) * nbd->blksize;
bdev->bd_inode->i_size = nbd->bytesize;
set_blocksize(bdev, nbd->blksize);
set_capacity(nbd->disk, nbd->bytesize >> 9);
return 0;
case NBD_DO_IT: {
struct task_struct *thread;
int error;
@ -764,7 +801,7 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
}
nbd_dev_dbg_init(nbd);
error = nbd_thread_recv(nbd);
error = nbd_thread_recv(nbd, bdev);
nbd_dev_dbg_close(nbd);
kthread_stop(thread);