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| author | Pavel Machek <pavel@suse.cz> | 2009-01-15 13:51:03 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-02-12 09:50:38 -0800 |
| commit | e117993af63778e46f68ea7477ff502e90d1c552 (patch) | |
| tree | dd47e3adbb66f390fdacf305c4ab3ddfcef1f269 | |
| parent | f5d7b376ef4ef7acde7049d2c0f6222ccfcd964c (diff) | |
| download | lwn-e117993af63778e46f68ea7477ff502e90d1c552.tar.gz lwn-e117993af63778e46f68ea7477ff502e90d1c552.zip | |
nbd: do not allow two clients at the same time
commit c91192d66d6cea7878b8542c9d9f1873971aba92 upstream.
Two nbd-clients at same time are bad idea, and cause WARN_ON from nbd in
2.6.28-rc7 from sysfs_add_one. This simply prevents that from happening.
To reproduce:
cat /dev/zero | head -c 10000000 > /tmp/delme.fstest.fs
nbd-server 9100 -l /anyone.can.connect > /tmp/delme.fstest.fs &
sleep 1
nbd-client localhost 9100 /dev/nd0 &
nbd-client localhost 9100 /dev/nd0 &
Signed-off-by: Pavel Machek <pavel@suse.cz>
Acked-by: Paul Clements <paul.clements@steeleye.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | drivers/block/nbd.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index d3a91cacee8c..8dcba06d9f8a 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -406,6 +406,7 @@ static int nbd_do_it(struct nbd_device *lo) ret = sysfs_create_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr); if (ret) { printk(KERN_ERR "nbd: sysfs_create_file failed!"); + lo->pid = 0; return ret; } @@ -413,6 +414,7 @@ static int nbd_do_it(struct nbd_device *lo) nbd_end_request(req); sysfs_remove_file(&disk_to_dev(lo->disk)->kobj, &pid_attr.attr); + lo->pid = 0; return 0; } @@ -648,6 +650,8 @@ static int nbd_ioctl(struct block_device *bdev, fmode_t mode, set_capacity(lo->disk, lo->bytesize >> 9); return 0; case NBD_DO_IT: + if (lo->pid) + return -EBUSY; if (!lo->file) return -EINVAL; thread = kthread_create(nbd_thread, lo, lo->disk->disk_name); |