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rbd: fix and simplify rbd_ioctl_set_ro()

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->open_count/-EBUSY check is bogus and wrong: when an open device is
set read-only, blkdev_write_iter() refuses further writes with -EPERM.
This is standard behaviour and all other block devices allow this.

set_disk_ro() call is also problematic: we affect the entire device
when called on a single partition.

All rbd_ioctl_set_ro() needs to do is refuse ro -> rw transition for
mapped snapshots.  Everything else can be handled by generic code.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
Ilya Dryomov 2017-10-12 12:35:19 +02:00
parent bb0581f01c
commit 1de797bb24
1 changed files with 6 additions and 28 deletions
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34
drivers/block/rbd.c
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@ -640,46 +640,24 @@ static void rbd_release(struct gendisk *disk, fmode_t mode)
static int rbd_ioctl_set_ro(struct rbd_device *rbd_dev, unsigned long arg)
{
int ret = 0;
int val;
bool ro;
bool ro_changed = false;
int ro;
/* get_user() may sleep, so call it before taking rbd_dev->lock */
if (get_user(val, (int __user *)(arg)))
if (get_user(ro, (int __user *)arg))
return -EFAULT;
ro = val ? true : false;
/* Snapshot doesn't allow to write*/
/* Snapshots can't be marked read-write */
if (rbd_dev->spec->snap_id != CEPH_NOSNAP && !ro)
return -EROFS;
spin_lock_irq(&rbd_dev->lock);
/* prevent others open this device */
if (rbd_dev->open_count > 1) {
ret = -EBUSY;
goto out;
}
if (rbd_dev->mapping.read_only != ro) {
rbd_dev->mapping.read_only = ro;
ro_changed = true;
}
out:
spin_unlock_irq(&rbd_dev->lock);
/* set_disk_ro() may sleep, so call it after releasing rbd_dev->lock */
if (ret == 0 && ro_changed)
set_disk_ro(rbd_dev->disk, ro ? 1 : 0);
return ret;
/* Let blkdev_roset() handle it */
return -ENOTTY;
}
static int rbd_ioctl(struct block_device *bdev, fmode_t mode,
unsigned int cmd, unsigned long arg)
{
struct rbd_device *rbd_dev = bdev->bd_disk->private_data;
int ret = 0;
int ret;
switch (cmd) {
case BLKROSET: