From: Milan Broz <mbroz@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: block device read-only handling regression in 2.6.38-rc4 (bisected)
Date: Sun, 13 Feb 2011 03:02:35 +0100 [thread overview]
Message-ID: <4D573BBB.6090200@redhat.com> (raw)
Hi Tejun,
Seems this commit cause regressions:
commit 75f1dc0d076d1c1168f2115f1941ea627d38bd5a
Author: Tejun Heo <tj@kernel.org>
Date: Sat Nov 13 11:55:17 2010 +0100
block: check bdev_read_only() from blkdev_get()
bdev read-only status can be queried using bdev_read_only() and may
change while the device is being opened. Enforce it by checking it
from blkdev_get() after open succeeds.
1) loop device once set read-only is not able to be used read-write afterward
touch /x1.img
losetup -r /dev/loop0 /x1.img
losetup -d /dev/loop0
losetup /dev/loop0 /x1.img
/dev/loop0: Permission denied
2) it breaks read-only dm-snapshots
(Fedora LiveCD operations is broken by this as well.)
(x.img is backing device, xs.img is prepared COW, you can simply run it
once in read-write to create dm-snap header and then re-run this commands)
losetup -r /dev/loop0 /x.img
losetup -r /dev/loop1 /xs.img
dmsetup create x --readonly --table '0 131072 snapshot /dev/loop0 /dev/loop1 p 8'
device-mapper: reload ioctl failed: Permission denied
Milan
next reply other threads:[~2011-02-13 2:02 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-13 2:02 Milan Broz [this message]
2011-02-13 10:58 ` [PATCH] loop: clear read-only flag in loop_clr_fd Tao Ma
2011-02-13 14:11 ` Milan Broz
2011-02-13 15:05 ` Tao Ma
2011-02-13 16:44 ` Milan Broz
2011-02-14 10:30 ` Tejun Heo
2011-02-14 11:47 ` Milan Broz
2011-02-14 13:14 ` [PATCH][RFC] dm: Do not open log and cow device read-write for read-only mappings Milan Broz
2011-02-14 14:09 ` Tejun Heo
2011-02-14 14:23 ` Milan Broz
2011-02-14 15:44 ` Tejun Heo
2011-02-14 23:15 ` NeilBrown
2011-02-15 2:03 ` [dm-devel] " Alasdair G Kergon
2011-02-15 12:17 ` Milan Broz
2011-02-15 12:46 ` Alasdair G Kergon
2011-02-15 15:20 ` Tejun Heo
2011-02-15 15:46 ` Alasdair G Kergon
2011-02-15 15:50 ` Tejun Heo
2011-02-15 16:05 ` Milan Broz
2011-02-15 16:12 ` Tejun Heo
2011-02-15 16:36 ` Milan Broz
2011-02-15 16:41 ` Tejun Heo
2011-02-15 16:56 ` Alasdair G Kergon
2011-02-16 8:46 ` Tejun Heo
2011-02-16 8:46 ` Tejun Heo
2011-02-15 16:58 ` Milan Broz
2011-02-16 8:39 ` Tejun Heo
2011-02-15 15:16 ` [PATCH] Return EROFS if read-only detected on block device Milan Broz
2011-02-14 14:39 ` [dm-devel] [PATCH][RFC] dm: Do not open log and cow device read-write for read-only mappings Alasdair G Kergon
2011-02-14 14:07 ` [PATCH] loop: clear read-only flag in loop_clr_fd Tejun Heo
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