Re: [PATCH 4/3] xfs_db: support the needsrepair feature flag in the version command

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Fri, Dec 04, 2020 at 02:32:32PM -0600, Eric Sandeen wrote:
> On 12/3/20 7:13 PM, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > Teach the xfs_db version command about the 'needsrepair' flag, which can
> > be used to force the system administrator to repair the filesystem with
> > xfs_repair.
> 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> >  db/check.c           |    5 ++
> >  db/sb.c              |  159 ++++++++++++++++++++++++++++++++++++++++++++++++--
> >  db/xfs_admin.sh      |    6 ++
> >  man/man8/xfs_admin.8 |   15 +++++
> >  man/man8/xfs_db.8    |    5 ++
> >  5 files changed, 182 insertions(+), 8 deletions(-)
> > 
> > diff --git a/db/check.c b/db/check.c
> > index 33736e33e833..485e855e8b78 100644
> > --- a/db/check.c
> > +++ b/db/check.c
> > @@ -3970,6 +3970,11 @@ scan_ag(
> >  			dbprintf(_("mkfs not completed successfully\n"));
> >  		error++;
> >  	}
> > +	if (xfs_sb_version_needsrepair(sb)) {
> > +		if (!sflag)
> > +			dbprintf(_("filesystem needs xfs_repair\n"));
> > +		error++;
> > +	}
> 
> ok this just marks it as an encountered error... *shrug* seems fine
> 
> >  	set_dbmap(agno, XFS_SB_BLOCK(mp), 1, DBM_SB, agno, XFS_SB_BLOCK(mp));
> >  	if (sb->sb_logstart && XFS_FSB_TO_AGNO(mp, sb->sb_logstart) == agno)
> >  		set_dbmap(agno, XFS_FSB_TO_AGBNO(mp, sb->sb_logstart),
> > diff --git a/db/sb.c b/db/sb.c
> > index d09f653dcedf..2c13d44d9954 100644
> > --- a/db/sb.c
> > +++ b/db/sb.c
> > @@ -379,6 +379,11 @@ uuid_f(
> >  				progname);
> >  			return 0;
> >  		}
> > +		if (xfs_sb_version_needsrepair(&mp->m_sb)) {
> > +			dbprintf(_("%s: filesystem needs xfs_repair\n"),
> > +				progname);
> > +			return 0;
> > +		}
> >  
> >  		if (!strcasecmp(argv[1], "generate")) {
> >  			platform_uuid_generate(&uu);
> > @@ -501,6 +506,7 @@ do_label(xfs_agnumber_t agno, char *label)
> >  		memcpy(&lbl[0], &tsb.sb_fname, sizeof(tsb.sb_fname));
> >  		return &lbl[0];
> >  	}
> > +
> >  	/* set label */
> >  	if ((len = strlen(label)) > sizeof(tsb.sb_fname)) {
> >  		if (agno == 0)
> > @@ -543,6 +549,12 @@ label_f(
> >  			return 0;
> >  		}
> >  
> > +		if (xfs_sb_version_needsrepair(&mp->m_sb)) {
> > +			dbprintf(_("%s: filesystem needs xfs_repair\n"),
> > +				progname);
> > +			return 0;
> > +		}
> > +
> 
> why are uuid_f and label_f uniquely disallowed from operating on a needsrepair
> filesystem?  (is it because they are unique in that they rewrite all superblocks?)

Because ... the fs needs repair, so the admin should repair the fs
before they try to modify the fs.  We don't allow mounting, so we
shouldn't allow label/uuid changes.

> How will we know when newly written routines should also exclude
> these filesystems?  Should this just be caught earlier and refuse to operate
> at all, maybe unless "-x" is specified?
> 
> Or if it's the "they write all supers" that's the problem, should we factor that
> out into a helper that does the needsrepair check and bails if set?
> 
> >  		dbprintf(_("writing all SBs\n"));
> >  		for (ag = 0; ag < mp->m_sb.sb_agcount; ag++)
> >  			if ((p = do_label(ag, argv[1])) == NULL) {
> > @@ -584,6 +596,7 @@ version_help(void)
> >  " 'version attr1'    - enable v1 inline extended attributes\n"
> >  " 'version attr2'    - enable v2 inline extended attributes\n"
> >  " 'version log2'     - enable v2 log format\n"
> > +" 'version needsrepair' - flag filesystem as requiring repair\n"
> >  "\n"
> >  "The version function prints currently enabled features for a filesystem\n"
> >  "according to the version field of its primary superblock.\n"
> > @@ -620,6 +633,118 @@ do_version(xfs_agnumber_t agno, uint16_t version, uint32_t features)
> >  	return 1;
> >  }
> >  
> > +struct v5feat {
> > +	uint32_t		compat;
> > +	uint32_t		ro_compat;
> > +	uint32_t		incompat;
> > +	uint32_t		log_incompat;
> > +};
> > +
> > +static void
> > +get_v5_features(
> > +	struct xfs_mount	*mp,
> > +	struct v5feat		*feat)
> > +{
> > +	feat->compat = mp->m_sb.sb_features_compat;
> > +	feat->ro_compat = mp->m_sb.sb_features_ro_compat;
> > +	feat->incompat = mp->m_sb.sb_features_incompat;
> > +	feat->log_incompat = mp->m_sb.sb_features_log_incompat;
> > +}
> > +
> > +static bool
> > +set_v5_features(
> > +	struct xfs_mount	*mp,
> > +	const struct v5feat	*upgrade)
> > +{
> > +	struct xfs_sb		tsb;
> > +	struct v5feat		old;
> > +	xfs_agnumber_t		agno = 0;
> > +	xfs_agnumber_t		revert_agno = 0;
> > +
> > +	if (upgrade->compat == mp->m_sb.sb_features_compat &&
> > +	    upgrade->ro_compat == mp->m_sb.sb_features_ro_compat &&
> > +	    upgrade->incompat == mp->m_sb.sb_features_incompat &&
> > +	    upgrade->log_incompat == mp->m_sb.sb_features_log_incompat)
> > +		return true;
> > +
> > +	/* Upgrade primary superblock. */
> > +	if (!get_sb(agno, &tsb))
> > +		goto fail;
> > +
> > +	dbprintf(_("Upgrading V5 filesystem\n"));
> > +
> > +	/* Save old values */
> > +	old.compat = tsb.sb_features_compat;
> > +	old.ro_compat = tsb.sb_features_ro_compat;
> > +	old.incompat = tsb.sb_features_incompat;
> > +	old.log_incompat = tsb.sb_features_log_incompat;
> > +
> > +	/* Update feature flags and force user to run repair before mounting. */
> > +	tsb.sb_features_compat |= upgrade->compat;
> > +	tsb.sb_features_ro_compat |= upgrade->ro_compat;
> > +	tsb.sb_features_incompat |= upgrade->incompat;
> > +	tsb.sb_features_log_incompat |= upgrade->log_incompat;
> > +	tsb.sb_features_incompat |= XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR;
> 
> Should this be optional?
> 
> I guess if we ever have a V5 feature upgrade that does not need repair, we can
> make it optional at that point.  the feture you have added, needsrepair, does in
> fact need repair.  :)

The bigtime upgrade doesn't require a repair, but it seemed like a good
idea to make the admin run repair to ensure customer satisfaction. ;)

> > +	libxfs_sb_to_disk(iocur_top->data, &tsb);
> > +
> > +	/* Write new primary superblock */
> > +	write_cur();
> > +	if (!iocur_top->bp || iocur_top->bp->b_error)
> > +		goto fail;
> > +
> > +	/* Update the secondary superblocks, or revert. */
> > +	for (agno = 1; agno < mp->m_sb.sb_agcount; agno++) {
> > +		if (!get_sb(agno, &tsb)) {
> > +			agno--;
> > +			goto revert;
> > +		}
> > +
> > +		/* Set features on secondary suepr. */
> > +		tsb.sb_features_compat |= upgrade->compat;
> > +		tsb.sb_features_ro_compat |= upgrade->ro_compat;
> > +		tsb.sb_features_incompat |= upgrade->incompat;
> > +		tsb.sb_features_log_incompat |= upgrade->log_incompat;
> > +		libxfs_sb_to_disk(iocur_top->data, &tsb);
> > +		write_cur();
> > +
> > +		/* Write or abort. */
> > +		if (!iocur_top->bp || iocur_top->bp->b_error)
> > +			goto revert;
> > +	}
> > +
> > +	/* All superblocks updated, update the incore values. */
> > +	mp->m_sb.sb_features_compat |= upgrade->compat;
> > +	mp->m_sb.sb_features_ro_compat |= upgrade->ro_compat;
> > +	mp->m_sb.sb_features_incompat |= upgrade->incompat;
> > +	mp->m_sb.sb_features_log_incompat |= upgrade->log_incompat;
> > +	mp->m_sb.sb_features_incompat |= XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR;
> > +
> > +	dbprintf(_("Upgraded V5 filesystem.  Please run xfs_repair.\n"));
> > +	return true;
> > +
> > +revert:
> > +	/*
> > +	 * Try to revert feature flag changes, and don't worry if we fail.
> > +	 * We're probably in a mess anyhow, and the admin will have to run
> > +	 * repair anyways.
> > +	 */
> > +	for (revert_agno = 0; revert_agno <= agno; revert_agno++) {
> > +		if (!get_sb(revert_agno, &tsb))
> > +			continue;
> > +
> > +		tsb.sb_features_compat = old.compat;
> > +		tsb.sb_features_ro_compat = old.ro_compat;
> > +		tsb.sb_features_incompat = old.incompat;
> > +		tsb.sb_features_log_incompat = old.log_incompat;
> > +		libxfs_sb_to_disk(iocur_top->data, &tsb);
> > +		write_cur();
> > +	}
> > +fail:
> > +	dbprintf(
> > +_("Failed to upgrade V5 filesystem at AG %d, please run xfs_repair.\n"), agno);
> > +	return false;
> > +}
> > +
> >  static char *
> >  version_string(
> >  	xfs_sb_t	*sbp)
> > @@ -691,15 +816,12 @@ version_string(
> >  		strcat(s, ",INOBTCNT");
> >  	if (xfs_sb_version_hasbigtime(sbp))
> >  		strcat(s, ",BIGTIME");
> > +	if (xfs_sb_version_needsrepair(sbp))
> > +		strcat(s, ",NEEDSREPAIR");
> >  	return s;
> >  }
> >  
> > -/*
> > - * XXX: this only supports reading and writing to version 4 superblock fields.
> > - * V5 superblocks always define certain V4 feature bits - they are blocked from
> > - * being changed if a V5 sb is detected, but otherwise v5 superblock features
> > - * are not handled here.
> > - */
> > +/* Upgrade a superblock to support a feature. */
> >  static int
> >  version_f(
> >  	int		argc,
> > @@ -710,6 +832,9 @@ version_f(
> >  	xfs_agnumber_t	ag;
> >  
> >  	if (argc == 2) {	/* WRITE VERSION */
> > +		struct v5feat	v5features;
> > +
> > +		get_v5_features(mp, &v5features);
> >  
> >  		if ((x.isreadonly & LIBXFS_ISREADONLY) || !expert_mode) {
> >  			dbprintf(_("%s: not in expert mode, writing disabled\n"),
> > @@ -717,8 +842,23 @@ version_f(
> >  			return 0;
> >  		}
> >  
> > +		if (xfs_sb_version_needsrepair(&mp->m_sb)) {
> > +			dbprintf(_("%s: filesystem needs xfs_repair\n"),
> > +				progname);
> > +			return 0;
> > +		}
> 
> I guess this enforces a repair after each version change, which makes sense.
> 
> > +
> >  		/* Logic here derived from the IRIX xfs_chver(1M) script. */
> > -		if (!strcasecmp(argv[1], "extflg")) {
> > +		if (!strcasecmp(argv[1], "needsrepair")) {
> > +			if (!xfs_sb_version_hascrc(&mp->m_sb)) {
> > +				dbprintf(
> > +		_("needsrepair flag cannot be enabled on pre-V5 filesystems\n"));
> > +				exitcode = 1;
> > +				return 1;
> > +			}
> > +
> > +			v5features.incompat |= XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR;
> > +		} else if (!strcasecmp(argv[1], "extflg")) {
> >  			switch (XFS_SB_VERSION_NUM(&mp->m_sb)) {
> >  			case XFS_SB_VERSION_1:
> >  				version = 0x0004 | XFS_SB_VERSION_EXTFLGBIT;
> > @@ -809,6 +949,11 @@ version_f(
> >  			mp->m_sb.sb_versionnum = version;
> >  			mp->m_sb.sb_features2 = features;
> >  		}
> > +
> > +		if (!set_v5_features(mp, &v5features)) {
> > +			exitcode = 1;
> > +			return 1;
> > +		}
> >  	}
> >  
> >  	if (argc == 3) {	/* VERSIONNUM + FEATURES2 */
> > diff --git a/db/xfs_admin.sh b/db/xfs_admin.sh
> > index bd325da2f776..41a14d4521ba 100755
> > --- a/db/xfs_admin.sh
> > +++ b/db/xfs_admin.sh
> > @@ -9,7 +9,7 @@ DB_OPTS=""
> >  REPAIR_OPTS=""
> >  USAGE="Usage: xfs_admin [-efjlpuV] [-c 0|1] [-L label] [-U uuid] device [logdev]"
> >  
> > -while getopts "efjlpuc:L:U:V" c
> > +while getopts "efjlpuc:L:O:U:V" c
> >  do
> >  	case $c in
> >  	c)	REPAIR_OPTS=$REPAIR_OPTS" -c lazycount="$OPTARG;;
> > @@ -19,6 +19,9 @@ do
> >  	l)	DB_OPTS=$DB_OPTS" -r -c label";;
> >  	L)	DB_OPTS=$DB_OPTS" -c 'label "$OPTARG"'";;
> >  	p)	DB_OPTS=$DB_OPTS" -c 'version projid32bit'";;
> > +	O)	DB_OPTS=$DB_OPTS" -c 'version "$OPTARG"'";
> > +		# Force repair to run by adding a single space to REPAIR_OPTS
> > +		REPAIR_OPTS="$REPAIR_OPTS ";;
> >  	u)	DB_OPTS=$DB_OPTS" -r -c uuid";;
> >  	U)	DB_OPTS=$DB_OPTS" -c 'uuid "$OPTARG"'";;
> >  	V)	xfs_db -p xfs_admin -V
> > @@ -48,6 +51,7 @@ case $# in
> >  		fi
> >  		if [ -n "$REPAIR_OPTS" ]
> >  		then
> > +			echo "Running xfs_repair to ensure filesystem consistency."
> >  			# Hide normal repair output which is sent to stderr
> >  			# assuming the filesystem is fine when a user is
> >  			# running xfs_admin.
> > diff --git a/man/man8/xfs_admin.8 b/man/man8/xfs_admin.8
> > index 8afc873fb50a..b423981d8049 100644
> > --- a/man/man8/xfs_admin.8
> > +++ b/man/man8/xfs_admin.8
> > @@ -6,6 +6,8 @@ xfs_admin \- change parameters of an XFS filesystem
> >  [
> >  .B \-eflpu
> >  ] [
> > +.BI \-O " feature"
> > +] [
> >  .BR "\-c 0" | 1
> >  ] [
> >  .B \-L
> > @@ -103,6 +105,19 @@ The filesystem label can be cleared using the special "\c
> >  " value for
> >  .IR label .
> >  .TP
> > +.BI \-O " feature"
> > +Add a new feature to the filesystem.
> > +Only one feature can be specified at a time.
> > +Features are as follows:
> > +.RS 0.7i
> > +.TP
> > +.B needsrepair
> > +If this is a V5 filesystem, flag the filesystem as needing repairs.
> > +Until
> > +.BR xfs_repair (8)
> > +is run, the filesystem will not be mountable.
> > +.RE
> > +.TP
> 
> At some point I would like to add "projid32bit" and "extflg" and "log2" etc
> to the "-O" documentation, and maybe deprecate the old feature-specific
> options, since "-O projid32bit" et al come for free now.

<Nod>

--D

> >  .BI \-U " uuid"
> >  Set the UUID of the filesystem to
> >  .IR uuid .
> > diff --git a/man/man8/xfs_db.8 b/man/man8/xfs_db.8
> > index 587274957de3..7331cf196bb0 100644
> > --- a/man/man8/xfs_db.8
> > +++ b/man/man8/xfs_db.8
> > @@ -971,6 +971,11 @@ may toggle between
> >  and
> >  .B attr2
> >  at will (older kernels may not support the newer version).
> > +The filesystem can be flagged as requiring a run through
> > +.BR xfs_repair (8)
> > +if the
> > +.B needsrepair
> > +option is specified and the filesystem is formatted with the V5 format.
> >  .IP
> >  If no argument is given, the current version and feature bits are printed.
> >  With one argument, this command will write the updated version number
> >