Re: [PATCH] mkfs: fix symlink target if_bytes computation for protofile

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

On Tue, Dec 11, 2018 at 02:42:32PM -0800, Darrick J. Wong wrote:
> On Tue, Dec 11, 2018 at 02:36:32PM -0600, Eric Sandeen wrote:
> > On 12/11/18 1:02 PM, Darrick J. Wong wrote:
> > > From: Darrick J. Wong <darrick.wong@oracle.com>
> > > 
> > > When creating a local format symlink, we expect the target buffer in the
> > > data fork to have enough space to contain the null, but we also expect
> > > if_bytes to reflect the length of the target /not/ including the null.
> > > If we don't adjust if_bytes down by one byte, we can run off into
> > > uninitialized memory.  Fix this, which should clean up the spurious
> > > xfs/019 failures for good.
> > > 
> > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > Ugh.  Why do we even have protofiles?  I have never seen these in use
> > in real life.  Can we just deprecate this half-baked crap?  :/
> > 
> > You suggested on IRC that we just use xfs_init_local fork; I had looked
> > at that when I did the first patch and for some reason didn't use it,
> 
> Admittedly I wondered if we can leak memory that way, but AFAICT a new
> inode shouldn't really have if_bytes > 0, right?
> 
> > but looking again it seems ... ok.  I hate how all of this stuff is
> > re-implemented in the protofile crap code and it seems like we can't
> > re-use too many of the libxfs functions directly but may as well use
> > this if we can, right?
> 
> Funny you mention it, but I've been quietly refactoring the xfs_inode.c
> code into libxfs as part of preparing for the metadata directory
> feature, which has enabled me to cut a considerable amount of opencoded
> crap out of mkfs and repair.  Granted, I still have to make sure it all
> /works/, but ... yes this all should be using libxfs functions. :)
> 
> Uh, I'll give this patch a spin and see what happens.

Seems fine to me, so...
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> 
> --D
> 
> > =========
> > 
> > mkfs: don't open code local fork setup in protofile code
> > 
> > Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> > ---
> > 
> > diff --git a/libxfs/libxfs_api_defs.h b/libxfs/libxfs_api_defs.h
> > index ad5d65de..c3792e12 100644
> > --- a/libxfs/libxfs_api_defs.h
> > +++ b/libxfs/libxfs_api_defs.h
> > @@ -149,5 +149,6 @@
> >  #define xfs_dir_get_ops			libxfs_dir_get_ops
> >  #define xfs_default_ifork_ops		libxfs_default_ifork_ops
> >  #define xfs_fs_geometry			libxfs_fs_geometry
> > +#define xfs_init_local_fork		libxfs_init_local_fork
> >  
> >  #endif /* __LIBXFS_API_DEFS_H__ */
> > diff --git a/mkfs/proto.c b/mkfs/proto.c
> > index 103795f1..3bba4917 100644
> > --- a/mkfs/proto.c
> > +++ b/mkfs/proto.c
> > @@ -237,13 +237,7 @@ newfile(
> >  	flags = 0;
> >  	mp = ip->i_mount;
> >  	if (symlink && len <= XFS_IFORK_DSIZE(ip)) {
> > -		/* Copy the name's trailing NULL as well */
> > -		libxfs_idata_realloc(ip, len + 1, XFS_DATA_FORK);
> > -		if (buf)
> > -			memmove(ip->i_df.if_u1.if_data, buf, len + 1);
> > -		ip->i_d.di_size = len;
> > -		ip->i_df.if_flags &= ~XFS_IFEXTENTS;
> > -		ip->i_df.if_flags |= XFS_IFINLINE;
> > +		libxfs_init_local_fork(ip, XFS_DATA_FORK, buf, len);
> >  		ip->i_d.di_format = XFS_DINODE_FMT_LOCAL;
> >  		flags = XFS_ILOG_DDATA;
> >  	} else if (len > 0) {
> >