On Wed, 2025-05-07 at 10:45 -0400, cel@kernel.org wrote:
From: Chuck Lever chuck.lever@oracle.com
RFC 7862 states that if an NFS server implements a CLONE operation, it MUST also implement FATTR4_CLONE_BLKSIZE. NFSD implements CLONE, but does not implement FATTR4_CLONE_BLKSIZE.
Note that in Section 12.2, RFC 7862 claims that FATTR4_CLONE_BLKSIZE is RECOMMENDED, not REQUIRED. Likely this is because a minor version is not permitted to add a REQUIRED attribute. Confusing.
Isn't CLONE itself an optional operation? It wouldn't make sense to REQUIRE this attribute on servers that don't support CLONE, so I think it makes sense that it should be optional. Anyway, I'm just being pedantic.
We assume this attribute reports a block size as a count of bytes, as RFC 7862 does not specify a unit.
Reported-by: Roland Mainz roland.mainz@nrubsig.org Suggested-by: Christoph Hellwig hch@infradead.org Reviewed-by: Roland Mainz roland.mainz@nrubsig.org Cc: stable@vger.kernel.org # v6.7+ Signed-off-by: Chuck Lever chuck.lever@oracle.com
fs/nfsd/nfs4xdr.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index e67420729ecd..9eb8e5704622 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -3391,6 +3391,23 @@ static __be32 nfsd4_encode_fattr4_suppattr_exclcreat(struct xdr_stream *xdr, return nfsd4_encode_bitmap4(xdr, supp[0], supp[1], supp[2]); } +/*
- Copied from generic_remap_checks/generic_remap_file_range_prep.
- These generic functions use the file system's s_blocksize, but
- individual file systems aren't required to use
- generic_remap_file_range_prep. Until there is a mechanism for
- determining a particular file system's (or file's) clone block
- size, this is the best NFSD can do.
- */
+static __be32 nfsd4_encode_fattr4_clone_blksize(struct xdr_stream *xdr,
const struct nfsd4_fattr_args *args)+{
- struct inode *inode = d_inode(args->dentry);
- return nfsd4_encode_uint32_t(xdr, inode->i_sb->s_blocksize);
+}
#ifdef CONFIG_NFSD_V4_SECURITY_LABEL static __be32 nfsd4_encode_fattr4_sec_label(struct xdr_stream *xdr, const struct nfsd4_fattr_args *args) @@ -3545,7 +3562,7 @@ static const nfsd4_enc_attr nfsd4_enc_fattr4_encode_ops[] = { [FATTR4_MODE_SET_MASKED] = nfsd4_encode_fattr4__noop, [FATTR4_SUPPATTR_EXCLCREAT] = nfsd4_encode_fattr4_suppattr_exclcreat, [FATTR4_FS_CHARSET_CAP] = nfsd4_encode_fattr4__noop,
- [FATTR4_CLONE_BLKSIZE] = nfsd4_encode_fattr4__noop,
- [FATTR4_CLONE_BLKSIZE] = nfsd4_encode_fattr4_clone_blksize, [FATTR4_SPACE_FREED] = nfsd4_encode_fattr4__noop, [FATTR4_CHANGE_ATTR_TYPE] = nfsd4_encode_fattr4__noop,
Reviewed-by: Jeff Layton jlayton@kernel.org