Messages in this thread Patch in this message | | | Date | Tue, 10 Feb 2009 11:01:39 -0800 | From | Greg KH <> | Subject | [patch 52/53] nbd: do not allow two clients at the same time |
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2.6.28-stable review patch. If anyone has any objections, please let us know. ------------------
From: Pavel Machek <pavel@suse.cz>
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>
--- drivers/block/nbd.c | 4 ++++ 1 file changed, 4 insertions(+)
--- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -406,6 +406,7 @@ static int nbd_do_it(struct nbd_device * 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 * 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 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);
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