[PATCH 1/2] mkfs: discard only after all validations

[PATCH 1/2] mkfs: discard only after all validations

[Jan Tulak]

Discard should happen only when everything has been validated, just
before we start writing to the device. If it happens earlier, it is
possible that mkfs will abort, but managed to already wipe data. This
patch moves the discard to the latest possible moment.

Signed-off-by: Jan Tulak <jtulak@redhat.com>
---
 mkfs/xfs_mkfs.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
index 2e53c1e8..81d9859a 100644
--- a/mkfs/xfs_mkfs.c
+++ b/mkfs/xfs_mkfs.c
@@ -2389,8 +2389,7 @@ _("log stripe unit (%d bytes) is too large (maximum is 256KiB)\n"
 static void
 open_devices(
 	struct mkfs_params	*cfg,
-	struct libxfs_xinit	*xi,
-	bool			discard)
+	struct libxfs_xinit	*xi)
 {
 	uint64_t		sector_mask;
 
@@ -2419,8 +2418,16 @@ open_devices(
 	xi->dsize &= sector_mask;
 	xi->rtsize &= sector_mask;
 	xi->logBBsize &= (uint64_t)-1 << (max(cfg->lsectorlog, 10) - BBSHIFT);
+}
 
-
+static void
+discard_data(
+	struct libxfs_xinit	*xi,
+	bool			discard)
+{
+	/*
+	 * This function has to be called after libxfs has been initialized.
+	 */
 	if (!discard)
 		return;
 
@@ -3901,7 +3908,7 @@ main(
 	/*
 	 * Open and validate the device configurations
 	 */
-	open_devices(&cfg, &xi, (discard && !dry_run));
+	open_devices(&cfg, &xi);
 	validate_datadev(&cfg, &cli);
 	validate_logdev(&cfg, &cli, &logfile);
 	validate_rtdev(&cfg, &cli, &rtfile);
@@ -3952,6 +3959,11 @@ main(
 			exit(0);
 	}
 
+	/*
+	 * All values have been validated, discard the old device layout.
+	 */
+	discard_data(&xi, (discard && !dry_run));
+
 	/*
 	 * we need the libxfs buffer cache from here on in.
 	 */
-- 
2.18.0

[PATCH 2/2] mkfs: move 'mounted' check before 'existing fs' check

[Jan Tulak]

Check if a device is mounted (and issue an error about that) before
asking for -f flag.

Example of the old behaviour I'm changing:
$ mkfs.xfs /dev/sda1
mkfs.xfs: /dev/sda1 appears to contain an existing filesystem (xfs).
mkfs.xfs: Use the -f option to force overwrite.

$ mkfs.xfs -f /dev/sda1
mkfs.xfs: /dev/sda1 contains a mounted filesystem

Signed-off-by: Jan Tulak <jtulak@redhat.com>
---
 mkfs/xfs_mkfs.c | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
index 81d9859a..97e78647 100644
--- a/mkfs/xfs_mkfs.c
+++ b/mkfs/xfs_mkfs.c
@@ -1012,7 +1012,6 @@ check_device_type(
 	bool		no_size,
 	bool		no_name,
 	int		*create,
-	bool		force_overwrite,
 	const char	*optname)
 {
 	struct stat statbuf;
@@ -1043,13 +1042,6 @@ check_device_type(
 		return;
 	}

-	if (!force_overwrite && check_overwrite(name)) {
-		fprintf(stderr,
-	_("%s: Use the -f option to force overwrite.\n"),
-			progname);
-		exit(1);
-	}
-
 	/*
 	 * We only want to completely truncate and recreate an existing file if
 	 * we were specifically told it was a file. Set the create flag only in
@@ -1079,6 +1071,20 @@ check_device_type(
 	usage();
 }

+static void
+validate_overwrite(
+	const char	*name,
+	bool		force_overwrite)
+{
+	if (!force_overwrite && check_overwrite(name)) {
+		fprintf(stderr,
+	_("%s: Use the -f option to force overwrite.\n"),
+			progname);
+		exit(1);
+	}
+
+}
+
 static void
 validate_ag_geometry(
 	int		blocklog,
@@ -1731,18 +1737,15 @@ validate_sectorsize(
 	 * files or block devices and set the control parameters correctly.
 	 */
 	check_device_type(dfile, &cli->xi->disfile, !cli->dsize, !dfile,
-			  dry_run ? NULL : &cli->xi->dcreat,
-			  force_overwrite, "d");
+			  dry_run ? NULL : &cli->xi->dcreat, "d");
 	if (!cli->loginternal)
 		check_device_type(cli->xi->logname, &cli->xi->lisfile,
 				  !cli->logsize, !cli->xi->logname,
-				  dry_run ? NULL : &cli->xi->lcreat,
-				  force_overwrite, "l");
+				  dry_run ? NULL : &cli->xi->lcreat, "l");
 	if (cli->xi->rtname)
 		check_device_type(cli->xi->rtname, &cli->xi->risfile,
 				  !cli->rtsize, !cli->xi->rtname,
-				  dry_run ? NULL : &cli->xi->rcreat,
-				  force_overwrite, "r");
+				  dry_run ? NULL : &cli->xi->rcreat, "r");

 	/*
 	 * Explicitly disable direct IO for image files so we don't error out on
@@ -3909,6 +3912,7 @@ main(
 	 * Open and validate the device configurations
 	 */
 	open_devices(&cfg, &xi);
+	validate_overwrite(dfile, force_overwrite);
 	validate_datadev(&cfg, &cli);
 	validate_logdev(&cfg, &cli, &logfile);
 	validate_rtdev(&cfg, &cli, &rtfile);
--
2.18.0

Re: [PATCH 1/2] mkfs: discard only after all validations

[Darrick J. Wong]

On Wed, Sep 19, 2018 at 02:56:16PM +0200, Jan Tulak wrote:
> Discard should happen only when everything has been validated, just
> before we start writing to the device. If it happens earlier, it is
> possible that mkfs will abort, but managed to already wipe data. This
> patch moves the discard to the latest possible moment.
> 
> Signed-off-by: Jan Tulak <jtulak@redhat.com>
> ---
>  mkfs/xfs_mkfs.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
> index 2e53c1e8..81d9859a 100644
> --- a/mkfs/xfs_mkfs.c
> +++ b/mkfs/xfs_mkfs.c
> @@ -2389,8 +2389,7 @@ _("log stripe unit (%d bytes) is too large (maximum is 256KiB)\n"
>  static void
>  open_devices(
>  	struct mkfs_params	*cfg,
> -	struct libxfs_xinit	*xi,
> -	bool			discard)
> +	struct libxfs_xinit	*xi)
>  {
>  	uint64_t		sector_mask;
>  
> @@ -2419,8 +2418,16 @@ open_devices(
>  	xi->dsize &= sector_mask;
>  	xi->rtsize &= sector_mask;
>  	xi->logBBsize &= (uint64_t)-1 << (max(cfg->lsectorlog, 10) - BBSHIFT);
> +}
>  
> -
> +static void
> +discard_data(

Perhaps discard_devices(), since this function can DISCARD more than
just the data device.

> +	struct libxfs_xinit	*xi,
> +	bool			discard)
> +{
> +	/*
> +	 * This function has to be called after libxfs has been initialized.
> +	 */
>  	if (!discard)
>  		return;
>  

While we're on the topic, I notice that we skip discard for any device
that's actually a file.  Seeing as fallocate(PUNCH_HOLE) works on files
(and block devices), is there a reason why we avoid punching out fs
image files?

> @@ -3901,7 +3908,7 @@ main(
>  	/*
>  	 * Open and validate the device configurations
>  	 */
> -	open_devices(&cfg, &xi, (discard && !dry_run));
> +	open_devices(&cfg, &xi);
>  	validate_datadev(&cfg, &cli);
>  	validate_logdev(&cfg, &cli, &logfile);
>  	validate_rtdev(&cfg, &cli, &rtfile);
> @@ -3952,6 +3959,11 @@ main(
>  			exit(0);
>  	}
>  
> +	/*
> +	 * All values have been validated, discard the old device layout.
> +	 */
> +	discard_data(&xi, (discard && !dry_run));

if (discard && !dry_run)
	discard_devices(&xi);

?

--D

> +
>  	/*
>  	 * we need the libxfs buffer cache from here on in.
>  	 */
> -- 
> 2.18.0
> 

Re: [PATCH 2/2] mkfs: move 'mounted' check before 'existing fs' check

[Darrick J. Wong]

On Wed, Sep 19, 2018 at 02:56:17PM +0200, Jan Tulak wrote:
> Check if a device is mounted (and issue an error about that) before
> asking for -f flag.
> 
> Example of the old behaviour I'm changing:
> $ mkfs.xfs /dev/sda1
> mkfs.xfs: /dev/sda1 appears to contain an existing filesystem (xfs).
> mkfs.xfs: Use the -f option to force overwrite.
> 
> $ mkfs.xfs -f /dev/sda1
> mkfs.xfs: /dev/sda1 contains a mounted filesystem

I'm confused by the commit message -- what is the new behavior?

Is it this?

$ mkfs.xfs /dev/sda1
mkfs.xfs: /dev/sda1 contains a mounted filesystem

$ mkfs.xfs -f /dev/sda1
mkfs.xfs: /dev/sda1 contains a mounted filesystem

--D

> Signed-off-by: Jan Tulak <jtulak@redhat.com>
> ---
>  mkfs/xfs_mkfs.c | 32 ++++++++++++++++++--------------
>  1 file changed, 18 insertions(+), 14 deletions(-)
> 
> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
> index 81d9859a..97e78647 100644
> --- a/mkfs/xfs_mkfs.c
> +++ b/mkfs/xfs_mkfs.c
> @@ -1012,7 +1012,6 @@ check_device_type(
>  	bool		no_size,
>  	bool		no_name,
>  	int		*create,
> -	bool		force_overwrite,
>  	const char	*optname)
>  {
>  	struct stat statbuf;
> @@ -1043,13 +1042,6 @@ check_device_type(
>  		return;
>  	}
> 
> -	if (!force_overwrite && check_overwrite(name)) {
> -		fprintf(stderr,
> -	_("%s: Use the -f option to force overwrite.\n"),
> -			progname);
> -		exit(1);
> -	}
> -
>  	/*
>  	 * We only want to completely truncate and recreate an existing file if
>  	 * we were specifically told it was a file. Set the create flag only in
> @@ -1079,6 +1071,20 @@ check_device_type(
>  	usage();
>  }
> 
> +static void
> +validate_overwrite(
> +	const char	*name,
> +	bool		force_overwrite)
> +{
> +	if (!force_overwrite && check_overwrite(name)) {
> +		fprintf(stderr,
> +	_("%s: Use the -f option to force overwrite.\n"),
> +			progname);
> +		exit(1);
> +	}
> +
> +}
> +
>  static void
>  validate_ag_geometry(
>  	int		blocklog,
> @@ -1731,18 +1737,15 @@ validate_sectorsize(
>  	 * files or block devices and set the control parameters correctly.
>  	 */
>  	check_device_type(dfile, &cli->xi->disfile, !cli->dsize, !dfile,
> -			  dry_run ? NULL : &cli->xi->dcreat,
> -			  force_overwrite, "d");
> +			  dry_run ? NULL : &cli->xi->dcreat, "d");
>  	if (!cli->loginternal)
>  		check_device_type(cli->xi->logname, &cli->xi->lisfile,
>  				  !cli->logsize, !cli->xi->logname,
> -				  dry_run ? NULL : &cli->xi->lcreat,
> -				  force_overwrite, "l");
> +				  dry_run ? NULL : &cli->xi->lcreat, "l");
>  	if (cli->xi->rtname)
>  		check_device_type(cli->xi->rtname, &cli->xi->risfile,
>  				  !cli->rtsize, !cli->xi->rtname,
> -				  dry_run ? NULL : &cli->xi->rcreat,
> -				  force_overwrite, "r");
> +				  dry_run ? NULL : &cli->xi->rcreat, "r");
> 
>  	/*
>  	 * Explicitly disable direct IO for image files so we don't error out on
> @@ -3909,6 +3912,7 @@ main(
>  	 * Open and validate the device configurations
>  	 */
>  	open_devices(&cfg, &xi);
> +	validate_overwrite(dfile, force_overwrite);
>  	validate_datadev(&cfg, &cli);
>  	validate_logdev(&cfg, &cli, &logfile);
>  	validate_rtdev(&cfg, &cli, &rtfile);
> --
> 2.18.0

Re: [PATCH 2/2] mkfs: move 'mounted' check before 'existing fs' check

[Jan Tulak]

On Wed, Sep 19, 2018 at 4:49 PM Darrick J. Wong <darrick.wong@oracle.com> wrote:
>
> On Wed, Sep 19, 2018 at 02:56:17PM +0200, Jan Tulak wrote:
> > Check if a device is mounted (and issue an error about that) before
> > asking for -f flag.
> >
> > Example of the old behaviour I'm changing:
> > $ mkfs.xfs /dev/sda1
> > mkfs.xfs: /dev/sda1 appears to contain an existing filesystem (xfs).
> > mkfs.xfs: Use the -f option to force overwrite.
> >
> > $ mkfs.xfs -f /dev/sda1
> > mkfs.xfs: /dev/sda1 contains a mounted filesystem
>
> I'm confused by the commit message -- what is the new behavior?
>
> Is it this?
>
> $ mkfs.xfs /dev/sda1
> mkfs.xfs: /dev/sda1 contains a mounted filesystem
>
> $ mkfs.xfs -f /dev/sda1
> mkfs.xfs: /dev/sda1 contains a mounted filesystem

Yes. I should put it right into the commit message.

Jan

-- 
Jan Tulak
jtulak@redhat.com / jan@tulak.me

Re: [PATCH 1/2] mkfs: discard only after all validations

[Jan Tulak]

On Wed, Sep 19, 2018 at 4:44 PM Darrick J. Wong <darrick.wong@oracle.com> wrote:

snip

> > @@ -2419,8 +2418,16 @@ open_devices(
> >       xi->dsize &= sector_mask;
> >       xi->rtsize &= sector_mask;
> >       xi->logBBsize &= (uint64_t)-1 << (max(cfg->lsectorlog, 10) - BBSHIFT);
> > +}
> >
> > -
> > +static void
> > +discard_data(
>
> Perhaps discard_devices(), since this function can DISCARD more than
> just the data device.

Agreed.


>
> > +     struct libxfs_xinit     *xi,
> > +     bool                    discard)
> > +{
> > +     /*
> > +      * This function has to be called after libxfs has been initialized.
> > +      */
> >       if (!discard)
> >               return;
> >
>
> While we're on the topic, I notice that we skip discard for any device
> that's actually a file.  Seeing as fallocate(PUNCH_HOLE) works on files
> (and block devices), is there a reason why we avoid punching out fs
> image files?
>

>From what I remember, it went along this: If the user is trying to
mkfs an existing file, we don't want to destroy anything they did with
the file before (sparse file, allocations...).

> > @@ -3901,7 +3908,7 @@ main(
> >       /*
> >        * Open and validate the device configurations
> >        */
> > -     open_devices(&cfg, &xi, (discard && !dry_run));
> > +     open_devices(&cfg, &xi);
> >       validate_datadev(&cfg, &cli);
> >       validate_logdev(&cfg, &cli, &logfile);
> >       validate_rtdev(&cfg, &cli, &rtfile);
> > @@ -3952,6 +3959,11 @@ main(
> >                       exit(0);
> >       }
> >
> > +     /*
> > +      * All values have been validated, discard the old device layout.
> > +      */
> > +     discard_data(&xi, (discard && !dry_run));
>
> if (discard && !dry_run)
>         discard_devices(&xi);
>
> ?

Yes, this makes more sense.

Jan

--
Jan Tulak
jtulak@redhat.com / jan@tulak.me

Re: [PATCH 1/2] mkfs: discard only after all validations

[Dave Chinner]

On Wed, Sep 19, 2018 at 07:44:05AM -0700, Darrick J. Wong wrote:
> On Wed, Sep 19, 2018 at 02:56:16PM +0200, Jan Tulak wrote:
> > Discard should happen only when everything has been validated, just
> > before we start writing to the device. If it happens earlier, it is
> > possible that mkfs will abort, but managed to already wipe data. This
> > patch moves the discard to the latest possible moment.
> > 
> > Signed-off-by: Jan Tulak <jtulak@redhat.com>
> > ---
> >  mkfs/xfs_mkfs.c | 20 ++++++++++++++++----
> >  1 file changed, 16 insertions(+), 4 deletions(-)
> > 
> > diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
> > index 2e53c1e8..81d9859a 100644
> > --- a/mkfs/xfs_mkfs.c
> > +++ b/mkfs/xfs_mkfs.c
> > @@ -2389,8 +2389,7 @@ _("log stripe unit (%d bytes) is too large (maximum is 256KiB)\n"
> >  static void
> >  open_devices(
> >  	struct mkfs_params	*cfg,
> > -	struct libxfs_xinit	*xi,
> > -	bool			discard)
> > +	struct libxfs_xinit	*xi)
> >  {
> >  	uint64_t		sector_mask;
> >  
> > @@ -2419,8 +2418,16 @@ open_devices(
> >  	xi->dsize &= sector_mask;
> >  	xi->rtsize &= sector_mask;
> >  	xi->logBBsize &= (uint64_t)-1 << (max(cfg->lsectorlog, 10) - BBSHIFT);
> > +}
> >  
> > -
> > +static void
> > +discard_data(
> 
> Perhaps discard_devices(), since this function can DISCARD more than
> just the data device.
> 
> > +	struct libxfs_xinit	*xi,
> > +	bool			discard)
> > +{
> > +	/*
> > +	 * This function has to be called after libxfs has been initialized.
> > +	 */
> >  	if (!discard)
> >  		return;
> >  
> 
> While we're on the topic, I notice that we skip discard for any device
> that's actually a file.  Seeing as fallocate(PUNCH_HOLE) works on files
> (and block devices), is there a reason why we avoid punching out fs
> image files?

Yeah - preallocated image files shouldn't be punched, because it
defeats the whole purpose of setting up preallocated image files.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

[PATCH 1/2 v2] mkfs: discard only after all validations

[Jan Tulak]

Discard should happen only when everything has been validated, just
before we start writing to the device. If it happens earlier, it is
possible that mkfs will abort, but managed to already wipe data. This
patch moves the discard to the latest possible moment.

Signed-off-by: Jan Tulak <jtulak@redhat.com>
---
CHANGES:
v2
* discard_data -> discard_devices
* move the discard condition outside of the function

---
 mkfs/xfs_mkfs.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
index 2e53c1e8..c97c69e8 100644
--- a/mkfs/xfs_mkfs.c
+++ b/mkfs/xfs_mkfs.c
@@ -2389,8 +2389,7 @@ _("log stripe unit (%d bytes) is too large (maximum is 256KiB)\n"
 static void
 open_devices(
 	struct mkfs_params	*cfg,
-	struct libxfs_xinit	*xi,
-	bool			discard)
+	struct libxfs_xinit	*xi)
 {
 	uint64_t		sector_mask;
 
@@ -2419,10 +2418,15 @@ open_devices(
 	xi->dsize &= sector_mask;
 	xi->rtsize &= sector_mask;
 	xi->logBBsize &= (uint64_t)-1 << (max(cfg->lsectorlog, 10) - BBSHIFT);
+}
 
-
-	if (!discard)
-		return;
+static void
+discard_devices(
+	struct libxfs_xinit	*xi)
+{
+	/*
+	 * This function has to be called after libxfs has been initialized.
+	 */
 
 	if (!xi->disfile)
 		discard_blocks(xi->ddev, xi->dsize);
@@ -3901,7 +3905,7 @@ main(
 	/*
 	 * Open and validate the device configurations
 	 */
-	open_devices(&cfg, &xi, (discard && !dry_run));
+	open_devices(&cfg, &xi);
 	validate_datadev(&cfg, &cli);
 	validate_logdev(&cfg, &cli, &logfile);
 	validate_rtdev(&cfg, &cli, &rtfile);
@@ -3952,6 +3956,12 @@ main(
 			exit(0);
 	}
 
+	/*
+	 * All values have been validated, discard the old device layout.
+	 */
+	if (discard && !dry_run)
+		discard_devices(&xi);
+
 	/*
 	 * we need the libxfs buffer cache from here on in.
 	 */
-- 
2.18.0

Re: [PATCH 2/2] mkfs: move 'mounted' check before 'existing fs' check

[Darrick J. Wong]

On Wed, Sep 19, 2018 at 05:05:38PM +0200, Jan Tulak wrote:
> On Wed, Sep 19, 2018 at 4:49 PM Darrick J. Wong <darrick.wong@oracle.com> wrote:
> >
> > On Wed, Sep 19, 2018 at 02:56:17PM +0200, Jan Tulak wrote:
> > > Check if a device is mounted (and issue an error about that) before
> > > asking for -f flag.
> > >
> > > Example of the old behaviour I'm changing:
> > > $ mkfs.xfs /dev/sda1
> > > mkfs.xfs: /dev/sda1 appears to contain an existing filesystem (xfs).
> > > mkfs.xfs: Use the -f option to force overwrite.
> > >
> > > $ mkfs.xfs -f /dev/sda1
> > > mkfs.xfs: /dev/sda1 contains a mounted filesystem
> >
> > I'm confused by the commit message -- what is the new behavior?
> >
> > Is it this?
> >
> > $ mkfs.xfs /dev/sda1
> > mkfs.xfs: /dev/sda1 contains a mounted filesystem
> >
> > $ mkfs.xfs -f /dev/sda1
> > mkfs.xfs: /dev/sda1 contains a mounted filesystem
> 
> Yes. I should put it right into the commit message.

With that added,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> 
> Jan
> 
> -- 
> Jan Tulak
> jtulak@redhat.com / jan@tulak.me

Re: [PATCH 1/2 v2] mkfs: discard only after all validations

[Darrick J. Wong]

On Thu, Sep 20, 2018 at 11:20:06AM +0200, Jan Tulak wrote:
> Discard should happen only when everything has been validated, just
> before we start writing to the device. If it happens earlier, it is
> possible that mkfs will abort, but managed to already wipe data. This
> patch moves the discard to the latest possible moment.
> 
> Signed-off-by: Jan Tulak <jtulak@redhat.com>

Looks ok to me,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
> CHANGES:
> v2
> * discard_data -> discard_devices
> * move the discard condition outside of the function
> 
> ---
>  mkfs/xfs_mkfs.c | 22 ++++++++++++++++------
>  1 file changed, 16 insertions(+), 6 deletions(-)
> 
> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
> index 2e53c1e8..c97c69e8 100644
> --- a/mkfs/xfs_mkfs.c
> +++ b/mkfs/xfs_mkfs.c
> @@ -2389,8 +2389,7 @@ _("log stripe unit (%d bytes) is too large (maximum is 256KiB)\n"
>  static void
>  open_devices(
>  	struct mkfs_params	*cfg,
> -	struct libxfs_xinit	*xi,
> -	bool			discard)
> +	struct libxfs_xinit	*xi)
>  {
>  	uint64_t		sector_mask;
>  
> @@ -2419,10 +2418,15 @@ open_devices(
>  	xi->dsize &= sector_mask;
>  	xi->rtsize &= sector_mask;
>  	xi->logBBsize &= (uint64_t)-1 << (max(cfg->lsectorlog, 10) - BBSHIFT);
> +}
>  
> -
> -	if (!discard)
> -		return;
> +static void
> +discard_devices(
> +	struct libxfs_xinit	*xi)
> +{
> +	/*
> +	 * This function has to be called after libxfs has been initialized.
> +	 */
>  
>  	if (!xi->disfile)
>  		discard_blocks(xi->ddev, xi->dsize);
> @@ -3901,7 +3905,7 @@ main(
>  	/*
>  	 * Open and validate the device configurations
>  	 */
> -	open_devices(&cfg, &xi, (discard && !dry_run));
> +	open_devices(&cfg, &xi);
>  	validate_datadev(&cfg, &cli);
>  	validate_logdev(&cfg, &cli, &logfile);
>  	validate_rtdev(&cfg, &cli, &rtfile);
> @@ -3952,6 +3956,12 @@ main(
>  			exit(0);
>  	}
>  
> +	/*
> +	 * All values have been validated, discard the old device layout.
> +	 */
> +	if (discard && !dry_run)
> +		discard_devices(&xi);
> +
>  	/*
>  	 * we need the libxfs buffer cache from here on in.
>  	 */
> -- 
> 2.18.0
>