Re: [PATCH 04/35] whiteout/NFSD: Don't return information about whiteouts to userspace

[Jan Blunck <jblunck@suse.de>]

On Fri, Apr 16, J. Bruce Fields wrote:

> Seems OK.  (Though is there any way we could avoid having to add the
> check to every filldir callback?  Isn't the default going to be
> disinterest in whiteouts?  How are we avoiding all the same checks in
> the case of lookup?)
> 

Bruce,

the alternative would be to include the check in the fs readdir()
implementation, and therefore prevent the call of the filler. I think this
patch would be even bigger.

Jan

> --b.
> 
> On Thu, Apr 15, 2010 at 04:04:11PM -0700, Valerie Aurora wrote:
> > From: Jan Blunck <jblunck@suse.de>
> > 
> > Userspace isn't ready for handling another file type, so silently drop
> > whiteout directory entries before they leave the kernel.
> > 
> > Signed-off-by: Jan Blunck <jblunck@suse.de>
> > Signed-off-by: David Woodhouse <dwmw2@infradead.org>
> > Signed-off-by: Valerie Aurora <vaurora@redhat.com>
> > Cc: linux-nfs@vger.kernel.org
> > Cc: "J. Bruce Fields" <bfields@fieldses.org>
> > Cc: Neil Brown <neilb@suse.de>
> > ---
> >  fs/compat.c       |    9 +++++++++
> >  fs/nfsd/nfs3xdr.c |    5 +++++
> >  fs/nfsd/nfs4xdr.c |    5 +++++
> >  fs/nfsd/nfsxdr.c  |    4 ++++
> >  fs/readdir.c      |    9 +++++++++
> >  5 files changed, 32 insertions(+), 0 deletions(-)
> > 
> > diff --git a/fs/compat.c b/fs/compat.c
> > index 00d90c2..624e1a5 100644
> > --- a/fs/compat.c
> > +++ b/fs/compat.c
> > @@ -838,6 +838,9 @@ static int compat_fillonedir(void *__buf, const char *name, int namlen,
> >  	struct compat_old_linux_dirent __user *dirent;
> >  	compat_ulong_t d_ino;
> >  
> > +	if (d_type == DT_WHT)
> > +		return 0;
> > +
> >  	if (buf->result)
> >  		return -EINVAL;
> >  	d_ino = ino;
> > @@ -909,6 +912,9 @@ static int compat_filldir(void *__buf, const char *name, int namlen,
> >  	compat_ulong_t d_ino;
> >  	int reclen = ALIGN(NAME_OFFSET(dirent) + namlen + 2, sizeof(compat_long_t));
> >  
> > +	if (d_type == DT_WHT)
> > +		return 0;
> > +
> >  	buf->error = -EINVAL;	/* only used if we fail.. */
> >  	if (reclen > buf->count)
> >  		return -EINVAL;
> > @@ -998,6 +1004,9 @@ static int compat_filldir64(void * __buf, const char * name, int namlen, loff_t
> >  	int reclen = ALIGN(jj + namlen + 1, sizeof(u64));
> >  	u64 off;
> >  
> > +	if (d_type == DT_WHT)
> > +		return 0;
> > +
> >  	buf->error = -EINVAL;	/* only used if we fail.. */
> >  	if (reclen > buf->count)
> >  		return -EINVAL;
> > diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
> > index 2a533a0..9b96f5a 100644
> > --- a/fs/nfsd/nfs3xdr.c
> > +++ b/fs/nfsd/nfs3xdr.c
> > @@ -885,6 +885,11 @@ encode_entry(struct readdir_cd *ccd, const char *name, int namlen,
> >  	int		elen;		/* estimated entry length in words */
> >  	int		num_entry_words = 0;	/* actual number of words */
> >  
> > +	if (d_type == DT_WHT) {
> > +		cd->common.err = nfs_ok;
> > +		return 0;
> > +	}
> > +
> >  	if (cd->offset) {
> >  		u64 offset64 = offset;
> >  
> > diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> > index 78c7e24..8839ba8 100644
> > --- a/fs/nfsd/nfs4xdr.c
> > +++ b/fs/nfsd/nfs4xdr.c
> > @@ -2268,6 +2268,11 @@ nfsd4_encode_dirent(void *ccdv, const char *name, int namlen,
> >  		return 0;
> >  	}
> >  
> > +	if (d_type == DT_WHT) {
> > +		cd->common.err = nfs_ok;
> > +		return 0;
> > +	}
> > +
> >  	if (cd->offset)
> >  		xdr_encode_hyper(cd->offset, (u64) offset);
> >  
> > diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
> > index 4ce005d..0e57d4b 100644
> > --- a/fs/nfsd/nfsxdr.c
> > +++ b/fs/nfsd/nfsxdr.c
> > @@ -503,6 +503,10 @@ nfssvc_encode_entry(void *ccdv, const char *name,
> >  			namlen, name, offset, ino);
> >  	 */
> >  
> > +	if (d_type == DT_WHT) {
> > +		cd->common.err = nfs_ok;
> > +		return 0;
> > +	}
> >  	if (offset > ~((u32) 0)) {
> >  		cd->common.err = nfserr_fbig;
> >  		return -EINVAL;
> > diff --git a/fs/readdir.c b/fs/readdir.c
> > index 7723401..3a48491 100644
> > --- a/fs/readdir.c
> > +++ b/fs/readdir.c
> > @@ -77,6 +77,9 @@ static int fillonedir(void * __buf, const char * name, int namlen, loff_t offset
> >  	struct old_linux_dirent __user * dirent;
> >  	unsigned long d_ino;
> >  
> > +	if (d_type == DT_WHT)
> > +		return 0;
> > +
> >  	if (buf->result)
> >  		return -EINVAL;
> >  	d_ino = ino;
> > @@ -154,6 +157,9 @@ static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
> >  	unsigned long d_ino;
> >  	int reclen = ALIGN(NAME_OFFSET(dirent) + namlen + 2, sizeof(long));
> >  
> > +	if (d_type == DT_WHT)
> > +		return 0;
> > +
> >  	buf->error = -EINVAL;	/* only used if we fail.. */
> >  	if (reclen > buf->count)
> >  		return -EINVAL;
> > @@ -239,6 +245,9 @@ static int filldir64(void * __buf, const char * name, int namlen, loff_t offset,
> >  	struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;
> >  	int reclen = ALIGN(NAME_OFFSET(dirent) + namlen + 1, sizeof(u64));
> >  
> > +	if (d_type == DT_WHT)
> > +		return 0;
> > +
> >  	buf->error = -EINVAL;	/* only used if we fail.. */
> >  	if (reclen > buf->count)
> >  		return -EINVAL;
> > -- 
> > 1.6.3.3
> >