NFSD: Implement SEEK

This patch adds server support for the NFS v4.2 operation SEEK, which
returns the position of the next hole or data segment in a file.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 49 insertions, 0 deletions

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 5e0dc528a0e8..cdeb3cfd6f32 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1013,6 +1013,49 @@ nfsd4_write(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
 	return status;
 }
 
+static __be32
+nfsd4_seek(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
+		struct nfsd4_seek *seek)
+{
+	int whence;
+	__be32 status;
+	struct file *file;
+
+	status = nfs4_preprocess_stateid_op(SVC_NET(rqstp), cstate,
+					    &seek->seek_stateid,
+					    RD_STATE, &file);
+	if (status) {
+		dprintk("NFSD: nfsd4_seek: couldn't process stateid!\n");
+		return status;
+	}
+
+	switch (seek->seek_whence) {
+	case NFS4_CONTENT_DATA:
+		whence = SEEK_DATA;
+		break;
+	case NFS4_CONTENT_HOLE:
+		whence = SEEK_HOLE;
+		break;
+	default:
+		status = nfserr_union_notsupp;
+		goto out;
+	}
+
+	/*
+	 * Note:  This call does change file->f_pos, but nothing in NFSD
+	 *        should ever file->f_pos.
+	 */
+	seek->seek_pos = vfs_llseek(file, seek->seek_offset, whence);
+	if (seek->seek_pos < 0)
+		status = nfserrno(seek->seek_pos);
+	else if (seek->seek_pos >= i_size_read(file_inode(file)))
+		seek->seek_eof = true;
+
+out:
+	fput(file);
+	return status;
+}
+
 /* This routine never returns NFS_OK!  If there are no other errors, it
  * will return NFSERR_SAME or NFSERR_NOT_SAME depending on whether the
  * attributes matched.  VERIFY is implemented by mapping NFSERR_SAME
@@ -1881,6 +1924,12 @@ static struct nfsd4_operation nfsd4_ops[] = {
 		.op_get_currentstateid = (stateid_getter)nfsd4_get_freestateid,
 		.op_rsize_bop = (nfsd4op_rsize)nfsd4_only_status_rsize,
 	},
+
+	/* NFSv4.2 operations */
+	[OP_SEEK] = {
+		.op_func = (nfsd4op_func)nfsd4_seek,
+		.op_name = "OP_SEEK",
+	},
 };
 
 int nfsd4_max_reply(struct svc_rqst *rqstp, struct nfsd4_op *op)