diff mbox series

libxfs: disallow filesystems with reverse mapping and reflink and realtime

Message ID 20200930145840.GL49547@magnolia
State Superseded
Headers show
Series libxfs: disallow filesystems with reverse mapping and reflink and realtime | expand

Commit Message

Darrick J. Wong Sept. 30, 2020, 2:58 p.m. UTC
From: Darrick J. Wong <darrick.wong@oracle.com>

Neither the kernel nor the code in xfsprogs support filesystems that
have (either reverse mapping btrees or reflink) enabled and a realtime
volume configured.  The kernel rejects such combinations and mkfs
refuses to format such a config, but xfsprogs doesn't check and can do
Bad Things, so port those checks before someone shreds their filesystem.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 libxfs/init.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

Comments

Eric Sandeen Sept. 30, 2020, 3:31 p.m. UTC | #1
On 9/30/20 9:58 AM, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> Neither the kernel nor the code in xfsprogs support filesystems that
> have (either reverse mapping btrees or reflink) enabled and a realtime
> volume configured.  The kernel rejects such combinations and mkfs
> refuses to format such a config, but xfsprogs doesn't check and can do
> Bad Things, so port those checks before someone shreds their filesystem.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

seems fine in general but a couple thoughts...

> ---
>  libxfs/init.c |   14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/libxfs/init.c b/libxfs/init.c
> index cb8967bc77d4..1a966084ffea 100644
> --- a/libxfs/init.c
> +++ b/libxfs/init.c
> @@ -724,6 +724,20 @@ libxfs_mount(
>  		exit(1);
>  	}
>  
> +	if (xfs_sb_version_hasreflink(sbp) && sbp->sb_rblocks) {

Hm, we really don't use xfs_sb_version_hasrealtime() very consistently, but it might
be worth doing here?

I wish we had a feature flag to cross-ref against, a corruption in sb_rblocks will lead
to an untouchable filesystem, but I guess there's nothing we can do about that.

Actually, would it help to cross-check against the rtdev arg as well?  Should we do anything
different if the user actually specified a realtime device on the commandline?

I mean, I suppose 

> +		fprintf(stderr,
> +	_("%s: Reflink not compatible with realtime device. Please try a newer xfsprogs.\n"),

I like this optimism.  ;)


> +				progname);
> +		exit(1);
> +	}
> +
> +	if (xfs_sb_version_hasrmapbt(sbp) && sbp->sb_rblocks) {
> +		fprintf(stderr,
> +	_("%s: Reverse mapping btree not compatible with realtime device. Please try a newer xfsprogs.\n"),
> +				progname);
> +		exit(1);
> +	}
> +
>  	xfs_da_mount(mp);
>  
>  	if (xfs_sb_version_hasattr2(&mp->m_sb))
>
Darrick J. Wong Sept. 30, 2020, 3:52 p.m. UTC | #2
On Wed, Sep 30, 2020 at 10:31:21AM -0500, Eric Sandeen wrote:
> On 9/30/20 9:58 AM, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > Neither the kernel nor the code in xfsprogs support filesystems that
> > have (either reverse mapping btrees or reflink) enabled and a realtime
> > volume configured.  The kernel rejects such combinations and mkfs
> > refuses to format such a config, but xfsprogs doesn't check and can do
> > Bad Things, so port those checks before someone shreds their filesystem.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> 
> seems fine in general but a couple thoughts...
> 
> > ---
> >  libxfs/init.c |   14 ++++++++++++++
> >  1 file changed, 14 insertions(+)
> > 
> > diff --git a/libxfs/init.c b/libxfs/init.c
> > index cb8967bc77d4..1a966084ffea 100644
> > --- a/libxfs/init.c
> > +++ b/libxfs/init.c
> > @@ -724,6 +724,20 @@ libxfs_mount(
> >  		exit(1);
> >  	}
> >  
> > +	if (xfs_sb_version_hasreflink(sbp) && sbp->sb_rblocks) {
> 
> Hm, we really don't use xfs_sb_version_hasrealtime() very
> consistently, but it might be worth doing here?

Nah, I'll move it to rtmount_init.

> I wish we had a feature flag to cross-ref against, a corruption in
> sb_rblocks will lead to an untouchable filesystem, but I guess there's
> nothing we can do about that.

I guess xfs_repair could add a -E killrt=1 flag that would read the sb,
zero out sb_rblocks, and pass that to libxfs_mount.

> Actually, would it help to cross-check against the rtdev arg as well?
> Should we do anything different if the user actually specified a
> realtime device on the commandline?

I doubt it?  I mean, the fs allege it has an rt volume and some
unsupported feature; it doesn't matter if the user did or didn't pass an
rtdev.

> I mean, I suppose 

you suppose...?

> 
> > +		fprintf(stderr,
> > +	_("%s: Reflink not compatible with realtime device. Please try a newer xfsprogs.\n"),
> 
> I like this optimism.  ;)

Optimism?

/me now has an xfsprogs that /does/ support rt rmap and reflink, though
at current patch review rates it won't hit the list until 2024, and
that's assuming I can keep ahead of all the bitrot in rtrmap...

--D

> 
> 
> > +				progname);
> > +		exit(1);
> > +	}
> > +
> > +	if (xfs_sb_version_hasrmapbt(sbp) && sbp->sb_rblocks) {
> > +		fprintf(stderr,
> > +	_("%s: Reverse mapping btree not compatible with realtime device. Please try a newer xfsprogs.\n"),
> > +				progname);
> > +		exit(1);
> > +	}
> > +
> >  	xfs_da_mount(mp);
> >  
> >  	if (xfs_sb_version_hasattr2(&mp->m_sb))
> >
diff mbox series

Patch

diff --git a/libxfs/init.c b/libxfs/init.c
index cb8967bc77d4..1a966084ffea 100644
--- a/libxfs/init.c
+++ b/libxfs/init.c
@@ -724,6 +724,20 @@  libxfs_mount(
 		exit(1);
 	}
 
+	if (xfs_sb_version_hasreflink(sbp) && sbp->sb_rblocks) {
+		fprintf(stderr,
+	_("%s: Reflink not compatible with realtime device. Please try a newer xfsprogs.\n"),
+				progname);
+		exit(1);
+	}
+
+	if (xfs_sb_version_hasrmapbt(sbp) && sbp->sb_rblocks) {
+		fprintf(stderr,
+	_("%s: Reverse mapping btree not compatible with realtime device. Please try a newer xfsprogs.\n"),
+				progname);
+		exit(1);
+	}
+
 	xfs_da_mount(mp);
 
 	if (xfs_sb_version_hasattr2(&mp->m_sb))