Date:   Mon, 1 Aug 2022 22:46:20 +0800
From:   Zorro Lang <zlang@...hat.com>
To:     "Darrick J. Wong" <djwong@...nel.org>
Cc:     linux-xfs@...r.kernel.org, fstests@...r.kernel.org, tytso@....edu,
        leah.rumancik@...il.com, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 2/2] dmerror: support external log and realtime devices

On Mon, Aug 01, 2022 at 02:10:12AM +0800, Zorro Lang wrote:
> On Sun, Jul 31, 2022 at 09:48:19AM -0700, Darrick J. Wong wrote:
> > On Sat, Jul 30, 2022 at 06:18:34PM +0800, Zorro Lang wrote:
> > > On Tue, Jul 26, 2022 at 12:48:42PM -0700, Darrick J. Wong wrote:
> > > > From: Darrick J. Wong <djwong@...nel.org>
> > > > 
> > > > Upgrade the dmerror code to coordinate making external scratch log and
> > > > scratch realtime devices error out along with the scratch device.  Note
> > > > that unlike SCRATCH_DEV, we save the old rt/log devices in a separate
> > > > variable and overwrite SCRATCH_{RT,LOG}DEV so that all the helper
> > > > functions continue to work properly.
> > > > 
> > > > This is very similar to what we did for dm-flakey a while back.
> > > > 
> > > > Signed-off-by: Darrick J. Wong <djwong@...nel.org>
> > > > ---
> > > 
> > > Hi Darrick,
> > > 
> > > I'll merge the patch 1/2 this week, but this 2/2 looks like bring in new
> > > failures on ext4 with local.config as [0], for example[1], which is passed[2]
> > > without this patch. It's fine on Btrfs and xfs for me.
> > > 
> > > Thanks,
> > > Zorro
> > > 
> > > [0]
> > > export TEST_DEV=/dev/sda5
> > > export TEST_DIR=/mnt/test
> > > export SCRATCH_DEV=/dev/sda3
> > > export SCRATCH_MNT=/mnt/scratch
> > > export USE_EXTERNAL=yes
> > > export SCRATCH_LOGDEV=/dev/loop0
> > > 
> > > [1]
> > > generic/338 4s ... - output mismatch (see /root/git/xfstests/results//logdev/generic/338.out.bad)
> > >     --- tests/generic/338.out   2022-04-29 23:07:23.330499055 +0800
> > >     +++ /root/git/xfstests/results//logdev/generic/338.out.bad  2022-07-30 18:01:41.900765965 +0800
> > >     @@ -1,2 +1,4 @@
> > >      QA output created by 338   
> > >      Silence is golden
> > >     +mount: /mnt/scratch: wrong fs type, bad option, bad superblock on /dev/mapper/error-test, missing codepage or helper program, or other error.
> > >     +       dmesg(1) may have more information after failed mount system call.
> > 
> > Hmm, any chance you could post the dmesg that goes with this?
> 
> Sure, [1] is the dmesg with this patch. [2] is the dmesg without this patch.

Hi Darrick,

I think I know why it fails, but I don't know how to deal with it offically :)
So cc linux-ext4@ list.

By testing, it fails after /dev/mapper/error-logtest be created. If we keep
SCRATCH_LOGDEV no change, everything is fine for ext4. Or you need to use
"-o journal_path=..." or "-o journal_dev=..." to specify the new journal device
path. Or you have to re-make ext4 with "-J device=/dev/mapper/error-logtest".

See below example:

1) ext4 extranal log device works:
# mke2fs -O journal_dev /dev/loop0
# mkfs.ext4 -F /dev/sda3 -J device=/dev/loop0
# mount /dev/sda3 /mnt/scratch/
# umount /mnt/scratch

2) Still works if only create error-test, don't touch LOGDEV:
# dmsetup create error-test --table "0 104849408 linear /dev/sda3 0"
# mount /dev/mapper/error-test /mnt/scratch/
# umount /mnt/scratch

3) Fails if you create error-logtest ...:
# dmsetup create error-logtest --table "0 2097152 linear /dev/loop0 0"
# mount /dev/mapper/error-test /mnt/scratch/
mount: /mnt/scratch: wrong fs type, bad option, bad superblock on /dev/mapper/error-test, missing codepage or helper program, or other error.
       dmesg(1) may have more information after failed mount system call.

4) ... Except you specify the new logdev path by mount option:
# ls /dev/mapper/error-logtest  -l
lrwxrwxrwx. 1 root root 7 Aug  1 22:28 /dev/mapper/error-logtest -> ../dm-7
# mount /dev/mapper/error-test /mnt/scratch/ -o journal_path=/dev/dm-7
# umount /mnt/scratch

5) And after step 4, I can mount /dev/mapper/error-test again ...
# mount /dev/mapper/error-test /mnt/scratch
# umount /mnt/scratch

I'm not an expert of ext4, that's only my test result, hope to get a clear
explanation for that :)

Thanks,
Zorro

> 
> Thanks,
> Zorro
> 
> [1]
> # ./check -s logdev generic/338
> SECTION       -- logdev
> FSTYP         -- ext4
> PLATFORM      -- Linux/x86_64 hp-dl380pg8-01 5.19.0-0.rc2.21.fc37.x86_64+debug #1 SMP PREEMPT_DYNAMIC Mon Jun 13 14:55:18 UTC 2022
> MKFS_OPTIONS  -- /dev/sda3
> MOUNT_OPTIONS -- -o acl,user_xattr -o context=system_u:object_r:root_t:s0 /dev/sda3 /mnt/scratch
> 
> generic/338 5s ... - output mismatch (see /root/git/xfstests/results//logdev/generic/338.out.bad)
>     --- tests/generic/338.out   2022-04-29 23:07:23.330499055 +0800
>     +++ /root/git/xfstests/results//logdev/generic/338.out.bad  2022-08-01 02:00:17.284965956 +0800
>     @@ -1,2 +1,4 @@
>      QA output created by 338
>      Silence is golden
>     +mount: /mnt/scratch: wrong fs type, bad option, bad superblock on /dev/mapper/error-test, missing codepage or helper program, or other error.
>     +       dmesg(1) may have more information after failed mount system call.
>     ...
>     (Run 'diff -u /root/git/xfstests/tests/generic/338.out /root/git/xfstests/results//logdev/generic/338.out.bad'  to see the entire diff)
> Ran: generic/338
> Failures: generic/338
> Failed 1 of 1 tests
> 
> # dmesg
> [1382503.819432] run fstests generic/338 at 2022-08-01 02:00:13
> [1382504.957989] EXT4-fs (dm-6): failed to open journal device unknown-block(7,0) -16
> [1382504.987712] Buffer I/O error on dev dm-7, logical block 262128, async page read
> [1382505.009371] Buffer I/O error on dev dm-6, logical block 13106160, async page read
> [1382506.576023] 338 (277855): drop_caches: 3
> [1382507.440513] EXT4-fs (sda5): unmounting filesystem.
> 
> [2]
> # ./check -s logdev generic/338
> SECTION       -- logdev
> FSTYP         -- ext4
> PLATFORM      -- Linux/x86_64 hp-dl380pg8-01 5.19.0-0.rc2.21.fc37.x86_64+debug #1 SMP PREEMPT_DYNAMIC Mon Jun 13 14:55:18 UTC 2022
> MKFS_OPTIONS  -- /dev/sda3
> MOUNT_OPTIONS -- -o acl,user_xattr -o context=system_u:object_r:root_t:s0 /dev/sda3 /mnt/scratch
> 
> generic/338 5s ...  3s
> Ran: generic/338
> Passed all 1 tests
> 
> # dmesg
> [1382877.411459] run fstests generic/338 at 2022-08-01 02:06:27
> [1382878.778539] EXT4-fs (dm-6): mounted filesystem with ordered data mode. Quota mode: none.
> [1382878.803639] Buffer I/O error on dev dm-6, logical block 13106160, async page read
> [1382878.951444] 338 (279660): drop_caches: 3
> [1382879.421933] EXT4-fs warning (device dm-6): htree_dirblock_to_tree:1044: inode #2: lblock 0: comm ls: error -5 reading directory block
> [1382879.422007] EXT4-fs error (device dm-6): ext4_get_inode_loc:4587: inode #2: block 1064: comm ls: unable to read itable block
> [1382879.422026] EXT4-fs error (device dm-6) in ext4_reserve_inode_write:5756: IO failure
> [1382879.422031] EXT4-fs error (device dm-6): ext4_dirty_inode:5952: inode #2: comm ls: mark_inode_dirty error
> [1382879.750038] EXT4-fs error (device dm-6): __ext4_find_entry:1635: inode #2: comm xfs_io: reading directory lblock 0
> [1382880.180381] Buffer I/O error on dev dm-6, logical block 0, lost async page write
> [1382880.180961] EXT4-fs (dm-6): unmounting filesystem.
> [1382880.181541] Aborting journal on device loop0.
> [1382880.182777] EXT4-fs error (device dm-6): ext4_put_super:1229: comm umount: Couldn't clean up the journal
> [1382880.182798] EXT4-fs (dm-6): previous I/O error to superblock detected
> [1382880.182817] Buffer I/O error on dev dm-6, logical block 0, lost sync page write
> [1382880.182860] EXT4-fs (dm-6): I/O error while writing superblock
> [1382880.182867] EXT4-fs (dm-6): Remounting filesystem read-only
> [1382880.742572] EXT4-fs (sda5): unmounting filesystem.
> 
> > 
> > --D
> > 
> > >     ...
> > >     (Run 'diff -u /root/git/xfstests/tests/generic/338.out /root/git/xfstests/results//logdev/generic/338.out.bad'  to see the entire diff)
> > > generic/441 5s ... - output mismatch (see /root/git/xfstests/results//logdev/generic/441.out.bad)
> > >     --- tests/generic/441.out   2022-04-29 23:07:23.406499916 +0800
> > >     +++ /root/git/xfstests/results//logdev/generic/441.out.bad  2022-07-30 18:01:46.829822438 +0800
> > >     @@ -1,3 +1,6 @@
> > >      QA output created by 441   
> > >      Format and mount
> > >     -Test passed!
> > >     +mount: /mnt/scratch: wrong fs type, bad option, bad superblock on /dev/mapper/error-test, missing codepage or helper program, or other error.
> > >     +       dmesg(1) may have more information after failed mount system call.
> > >     +Success on second fsync on fd[0]!
> > >     +umount: /mnt/scratch: not mounted.
> > >     ...
> > >     (Run 'diff -u /root/git/xfstests/tests/generic/441.out /root/git/xfstests/results//logdev/generic/441.out.bad'  to see the entire diff)
> > > 
> > > [2]
> > > generic/338 4s ...  5s
> > > generic/441 5s ...  5s
> > > generic/442 3s ...  3s
> > > 
> > > 
> > > >  common/dmerror    |  159 +++++++++++++++++++++++++++++++++++++++++++++++++++--
> > > >  tests/generic/441 |    2 -
> > > >  tests/generic/487 |    2 -
> > > >  3 files changed, 156 insertions(+), 7 deletions(-)
> > > > 
> > > > 
> > > > diff --git a/common/dmerror b/common/dmerror
> > > > index 01a4c8b5..85ef9a16 100644
> > > > --- a/common/dmerror
> > > > +++ b/common/dmerror
> > > > @@ -4,25 +4,88 @@
> > > >  #
> > > >  # common functions for setting up and tearing down a dmerror device
> > > >  
> > > > +_dmerror_setup_vars()
> > > > +{
> > > > +	local backing_dev="$1"
> > > > +	local tag="$2"
> > > > +	local target="$3"
> > > > +
> > > > +	test -z "$target" && target=error
> > > > +	local blk_dev_size=$(blockdev --getsz "$backing_dev")
> > > > +
> > > > +	eval export "DMLINEAR_${tag}TABLE=\"0 $blk_dev_size linear $backing_dev 0\""
> > > > +	eval export "DMERROR_${tag}TABLE=\"0 $blk_dev_size $target $backing_dev 0\""
> > > > +}
> > > > +
> > > >  _dmerror_setup()
> > > >  {
> > > > -	local dm_backing_dev=$SCRATCH_DEV
> > > > +	local rt_target=
> > > > +	local linear_target=
> > > >  
> > > > -	local blk_dev_size=`blockdev --getsz $dm_backing_dev`
> > > > +	for arg in "$@"; do
> > > > +		case "${arg}" in
> > > > +		no_rt)		rt_target=linear;;
> > > > +		no_log)		log_target=linear;;
> > > > +		*)		echo "${arg}: Unknown _dmerror_setup arg.";;
> > > > +		esac
> > > > +	done
> > > >  
> > > > +	# Scratch device
> > > >  	export DMERROR_DEV='/dev/mapper/error-test'
> > > > +	_dmerror_setup_vars $SCRATCH_DEV
> > > >  
> > > > -	export DMLINEAR_TABLE="0 $blk_dev_size linear $dm_backing_dev 0"
> > > > +	# Realtime device.  We reassign SCRATCH_RTDEV so that all the scratch
> > > > +	# helpers continue to work unmodified.
> > > > +	if [ -n "$SCRATCH_RTDEV" ]; then
> > > > +		if [ -z "$NON_ERROR_RTDEV" ]; then
> > > > +			# Set up the device switch
> > > > +			local dm_backing_dev=$SCRATCH_RTDEV
> > > > +			export NON_ERROR_RTDEV="$SCRATCH_RTDEV"
> > > > +			SCRATCH_RTDEV='/dev/mapper/error-rttest'
> > > > +		else
> > > > +			# Already set up; recreate tables
> > > > +			local dm_backing_dev="$NON_ERROR_RTDEV"
> > > > +		fi
> > > >  
> > > > -	export DMERROR_TABLE="0 $blk_dev_size error $dm_backing_dev 0"
> > > > +		_dmerror_setup_vars $dm_backing_dev RT $rt_target
> > > > +	fi
> > > > +
> > > > +	# External log device.  We reassign SCRATCH_LOGDEV so that all the
> > > > +	# scratch helpers continue to work unmodified.
> > > > +	if [ -n "$SCRATCH_LOGDEV" ]; then
> > > > +		if [ -z "$NON_ERROR_LOGDEV" ]; then
> > > > +			# Set up the device switch
> > > > +			local dm_backing_dev=$SCRATCH_LOGDEV
> > > > +			export NON_ERROR_LOGDEV="$SCRATCH_LOGDEV"
> > > > +			SCRATCH_LOGDEV='/dev/mapper/error-logtest'
> > > > +		else
> > > > +			# Already set up; recreate tables
> > > > +			local dm_backing_dev="$NON_ERROR_LOGDEV"
> > > > +		fi
> > > > +
> > > > +		_dmerror_setup_vars $dm_backing_dev LOG $log_target
> > > > +	fi
> > > >  }
> > > >  
> > > >  _dmerror_init()
> > > >  {
> > > > -	_dmerror_setup
> > > > +	_dmerror_setup "$@"
> > > > +
> > > >  	_dmsetup_remove error-test
> > > >  	_dmsetup_create error-test --table "$DMLINEAR_TABLE" || \
> > > >  		_fatal "failed to create dm linear device"
> > > > +
> > > > +	if [ -n "$NON_ERROR_RTDEV" ]; then
> > > > +		_dmsetup_remove error-rttest
> > > > +		_dmsetup_create error-rttest --table "$DMLINEAR_RTTABLE" || \
> > > > +			_fatal "failed to create dm linear rt device"
> > > > +	fi
> > > > +
> > > > +	if [ -n "$NON_ERROR_LOGDEV" ]; then
> > > > +		_dmsetup_remove error-logtest
> > > > +		_dmsetup_create error-logtest --table "$DMLINEAR_LOGTABLE" || \
> > > > +			_fatal "failed to create dm linear log device"
> > > > +	fi
> > > >  }
> > > >  
> > > >  _dmerror_mount()
> > > > @@ -39,11 +102,27 @@ _dmerror_unmount()
> > > >  
> > > >  _dmerror_cleanup()
> > > >  {
> > > > +	test -n "$NON_ERROR_LOGDEV" && $DMSETUP_PROG resume error-logtest &>/dev/null
> > > > +	test -n "$NON_ERROR_RTDEV" && $DMSETUP_PROG resume error-rttest &>/dev/null
> > > >  	$DMSETUP_PROG resume error-test > /dev/null 2>&1
> > > > +
> > > >  	$UMOUNT_PROG $SCRATCH_MNT > /dev/null 2>&1
> > > > +
> > > > +	test -n "$NON_ERROR_LOGDEV" && _dmsetup_remove error-logtest
> > > > +	test -n "$NON_ERROR_RTDEV" && _dmsetup_remove error-rttest
> > > >  	_dmsetup_remove error-test
> > > >  
> > > >  	unset DMERROR_DEV DMLINEAR_TABLE DMERROR_TABLE
> > > > +
> > > > +	if [ -n "$NON_ERROR_LOGDEV" ]; then
> > > > +		SCRATCH_LOGDEV="$NON_ERROR_LOGDEV"
> > > > +		unset NON_ERROR_LOGDEV DMLINEAR_LOGTABLE DMERROR_LOGTABLE
> > > > +	fi
> > > > +
> > > > +	if [ -n "$NON_ERROR_RTDEV" ]; then
> > > > +		SCRATCH_RTDEV="$NON_ERROR_RTDEV"
> > > > +		unset NON_ERROR_RTDEV DMLINEAR_RTTABLE DMERROR_RTTABLE
> > > > +	fi
> > > >  }
> > > >  
> > > >  _dmerror_load_error_table()
> > > > @@ -59,12 +138,47 @@ _dmerror_load_error_table()
> > > >  		suspend_opt="$*"
> > > >  	fi
> > > >  
> > > > +	# Suspend the scratch device before the log and realtime devices so
> > > > +	# that the kernel can freeze and flush the filesystem if the caller
> > > > +	# wanted a freeze.
> > > >  	$DMSETUP_PROG suspend $suspend_opt error-test
> > > >  	[ $? -ne 0 ] && _fail  "dmsetup suspend failed"
> > > >  
> > > > +	if [ -n "$NON_ERROR_RTDEV" ]; then
> > > > +		$DMSETUP_PROG suspend $suspend_opt error-rttest
> > > > +		[ $? -ne 0 ] && _fail "failed to suspend error-rttest"
> > > > +	fi
> > > > +
> > > > +	if [ -n "$NON_ERROR_LOGDEV" ]; then
> > > > +		$DMSETUP_PROG suspend $suspend_opt error-logtest
> > > > +		[ $? -ne 0 ] && _fail "failed to suspend error-logtest"
> > > > +	fi
> > > > +
> > > > +	# Load new table
> > > >  	$DMSETUP_PROG load error-test --table "$DMERROR_TABLE"
> > > >  	load_res=$?
> > > >  
> > > > +	if [ -n "$NON_ERROR_RTDEV" ]; then
> > > > +		$DMSETUP_PROG load error-rttest --table "$DMERROR_RTTABLE"
> > > > +		[ $? -ne 0 ] && _fail "failed to load error table into error-rttest"
> > > > +	fi
> > > > +
> > > > +	if [ -n "$NON_ERROR_LOGDEV" ]; then
> > > > +		$DMSETUP_PROG load error-logtest --table "$DMERROR_LOGTABLE"
> > > > +		[ $? -ne 0 ] && _fail "failed to load error table into error-logtest"
> > > > +	fi
> > > > +
> > > > +	# Resume devices in the opposite order that we suspended them.
> > > > +	if [ -n "$NON_ERROR_LOGDEV" ]; then
> > > > +		$DMSETUP_PROG resume error-logtest
> > > > +		[ $? -ne 0 ] && _fail  "failed to resume error-logtest"
> > > > +	fi
> > > > +
> > > > +	if [ -n "$NON_ERROR_RTDEV" ]; then
> > > > +		$DMSETUP_PROG resume error-rttest
> > > > +		[ $? -ne 0 ] && _fail  "failed to resume error-rttest"
> > > > +	fi
> > > > +
> > > >  	$DMSETUP_PROG resume error-test
> > > >  	resume_res=$?
> > > >  
> > > > @@ -85,12 +199,47 @@ _dmerror_load_working_table()
> > > >  		suspend_opt="$*"
> > > >  	fi
> > > >  
> > > > +	# Suspend the scratch device before the log and realtime devices so
> > > > +	# that the kernel can freeze and flush the filesystem if the caller
> > > > +	# wanted a freeze.
> > > >  	$DMSETUP_PROG suspend $suspend_opt error-test
> > > >  	[ $? -ne 0 ] && _fail  "dmsetup suspend failed"
> > > >  
> > > > +	if [ -n "$NON_ERROR_RTDEV" ]; then
> > > > +		$DMSETUP_PROG suspend $suspend_opt error-rttest
> > > > +		[ $? -ne 0 ] && _fail "failed to suspend error-rttest"
> > > > +	fi
> > > > +
> > > > +	if [ -n "$NON_ERROR_LOGDEV" ]; then
> > > > +		$DMSETUP_PROG suspend $suspend_opt error-logtest
> > > > +		[ $? -ne 0 ] && _fail "failed to suspend error-logtest"
> > > > +	fi
> > > > +
> > > > +	# Load new table
> > > >  	$DMSETUP_PROG load error-test --table "$DMLINEAR_TABLE"
> > > >  	load_res=$?
> > > >  
> > > > +	if [ -n "$NON_ERROR_RTDEV" ]; then
> > > > +		$DMSETUP_PROG load error-rttest --table "$DMLINEAR_RTTABLE"
> > > > +		[ $? -ne 0 ] && _fail "failed to load working table into error-rttest"
> > > > +	fi
> > > > +
> > > > +	if [ -n "$NON_ERROR_LOGDEV" ]; then
> > > > +		$DMSETUP_PROG load error-logtest --table "$DMLINEAR_LOGTABLE"
> > > > +		[ $? -ne 0 ] && _fail "failed to load working table into error-logtest"
> > > > +	fi
> > > > +
> > > > +	# Resume devices in the opposite order that we suspended them.
> > > > +	if [ -n "$NON_ERROR_LOGDEV" ]; then
> > > > +		$DMSETUP_PROG resume error-logtest
> > > > +		[ $? -ne 0 ] && _fail  "failed to resume error-logtest"
> > > > +	fi
> > > > +
> > > > +	if [ -n "$NON_ERROR_RTDEV" ]; then
> > > > +		$DMSETUP_PROG resume error-rttest
> > > > +		[ $? -ne 0 ] && _fail  "failed to resume error-rttest"
> > > > +	fi
> > > > +
> > > >  	$DMSETUP_PROG resume error-test
> > > >  	resume_res=$?
> > > >  
> > > > diff --git a/tests/generic/441 b/tests/generic/441
> > > > index 0ec751da..85f29a3a 100755
> > > > --- a/tests/generic/441
> > > > +++ b/tests/generic/441
> > > > @@ -52,7 +52,7 @@ unset SCRATCH_RTDEV
> > > >  
> > > >  echo "Format and mount"
> > > >  _scratch_mkfs > $seqres.full 2>&1
> > > > -_dmerror_init
> > > > +_dmerror_init no_log
> > > >  _dmerror_mount
> > > >  
> > > >  _require_fs_space $SCRATCH_MNT 65536
> > > > diff --git a/tests/generic/487 b/tests/generic/487
> > > > index fda8828d..3c9b2233 100755
> > > > --- a/tests/generic/487
> > > > +++ b/tests/generic/487
> > > > @@ -45,7 +45,7 @@ unset SCRATCH_RTDEV
> > > >  
> > > >  echo "Format and mount"
> > > >  _scratch_mkfs > $seqres.full 2>&1
> > > > -_dmerror_init
> > > > +_dmerror_init no_log
> > > >  _dmerror_mount
> > > >  
> > > >  datalen=65536
> > > > 
> > > 
> > 

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