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authorPavel Machek <pavel@suse.cz>2009-01-15 13:51:03 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-01-15 16:39:38 -0800
commitc91192d66d6cea7878b8542c9d9f1873971aba92 (patch)
tree954adf09a2d6f4028aa8c3a842aa07235e3d4be5
parent1bcbf31337391a2f54ef6c1e8871c2de5944a7dc (diff)
nbd: do not allow two clients at the same time
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>
-rw-r--r--drivers/block/nbd.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 7bcc1d8bc96..34f80fa6fed 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);