On Fri, Apr 30, 2021 at 09:32:48AM -0400, Brian Foster wrote: > On Thu, Apr 29, 2021 at 05:40:12PM -0700, Darrick J. Wong wrote: > > From: Darrick J. Wong <djwong@xxxxxxxxxx> > > > > While running generic/050 with an external log, I observed this warning > > in dmesg: > > > > Trying to write to read-only block-device sda4 (partno 4) > > WARNING: CPU: 2 PID: 215677 at block/blk-core.c:704 submit_bio_checks+0x256/0x510 > > Call Trace: > > submit_bio_noacct+0x2c/0x430 > > _xfs_buf_ioapply+0x283/0x3c0 [xfs] > > __xfs_buf_submit+0x6a/0x210 [xfs] > > xfs_buf_delwri_submit_buffers+0xf8/0x270 [xfs] > > xfsaild+0x2db/0xc50 [xfs] > > kthread+0x14b/0x170 > > > > I think this happened because we tried to cover the log after a readonly > > mount, and the AIL tried to write the primary superblock to the data > > device. The test marks the data device readonly, but it doesn't do the > > same to the external log device. Therefore, XFS thinks that the log is > > writable, even though AIL writes whine to dmesg because the data device > > is read only. > > > > Fix this by amending xfs_log_writable to prevent writes when the AIL > > can't possible write anything into the filesystem. > > > > Note: As for the external log or the rt devices being readonly-- > > xfs_blkdev_get will complain about that if we aren't doing a norecovery > > mount. > > > > Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx> > > --- > > fs/xfs/xfs_log.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c > > index 06041834daa3..e4839f22ec07 100644 > > --- a/fs/xfs/xfs_log.c > > +++ b/fs/xfs/xfs_log.c > > @@ -358,12 +358,14 @@ xfs_log_writable( > > * Never write to the log on norecovery mounts, if the block device is > > * read-only, or if the filesystem is shutdown. Read-only mounts still > > * allow internal writes for log recovery and unmount purposes, so don't > > - * restrict that case here. > > + * restrict that case here unless the data device is also readonly. > > */ > > The comment update is a little confusing because that second sentence > explicitly refers to the read-only mount case (i.e., why we don't check > XFS_MOUNT_RDONLY here), and that logic/reasoning remains independent of > this change. Perhaps instead change the first part to something like > "... if the data or log device is read-only, ..." ? Will do. Thanks for the review! --D > With that fixed up: > > Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx> > > > if (mp->m_flags & XFS_MOUNT_NORECOVERY) > > return false; > > if (xfs_readonly_buftarg(mp->m_log->l_targ)) > > return false; > > + if (xfs_readonly_buftarg(mp->m_ddev_targp)) > > + return false; > > if (XFS_FORCED_SHUTDOWN(mp)) > > return false; > > return true; > > >
