NFSD: Simplify READ_PLUS

Chuck had suggested reverting READ_PLUS so it returns a single DATA
segment covering the requested read range. This prepares the server for
a future "sparse read" function so support can easily be added without
needing to rip out the old READ_PLUS code at the same time.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index bcfeb1a922c0d334989ac2cf312d1567ad73adc7..1e4990fb1692248bd8420e54a65216986113d533 100644 (file)
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -4767,79 +4767,37 @@ nfsd4_encode_offload_status(struct nfsd4_compoundres *resp, __be32 nfserr,
 
 static __be32
 nfsd4_encode_read_plus_data(struct nfsd4_compoundres *resp,
-                           struct nfsd4_read *read,
-                           unsigned long *maxcount, u32 *eof,
-                           loff_t *pos)
+                           struct nfsd4_read *read)
 {
-       struct xdr_stream *xdr = resp->xdr;
+       bool splice_ok = test_bit(RQ_SPLICE_OK, &resp->rqstp->rq_flags);
        struct file *file = read->rd_nf->nf_file;
-       int starting_len = xdr->buf->len;
-       loff_t hole_pos;
-       __be32 nfserr;
-       __be32 *p, tmp;
-       __be64 tmp64;
-
-       hole_pos = pos ? *pos : vfs_llseek(file, read->rd_offset, SEEK_HOLE);
-       if (hole_pos > read->rd_offset)
-               *maxcount = min_t(unsigned long, *maxcount, hole_pos - read->rd_offset);
-       *maxcount = min_t(unsigned long, *maxcount, (xdr->buf->buflen - xdr->buf->len));
+       struct xdr_stream *xdr = resp->xdr;
+       unsigned long maxcount;
+       __be32 nfserr, *p;
 
        /* Content type, offset, byte count */
        p = xdr_reserve_space(xdr, 4 + 8 + 4);
        if (!p)
-               return nfserr_resource;
+               return nfserr_io;
+       if (resp->xdr->buf->page_len && splice_ok) {
+               WARN_ON_ONCE(splice_ok);
+               return nfserr_serverfault;
+       }
 
-       read->rd_vlen = xdr_reserve_space_vec(xdr, resp->rqstp->rq_vec, *maxcount);
-       if (read->rd_vlen < 0)
-               return nfserr_resource;
+       maxcount = min_t(unsigned long, read->rd_length,
+                        (xdr->buf->buflen - xdr->buf->len));
 
-       nfserr = nfsd_readv(resp->rqstp, read->rd_fhp, file, read->rd_offset,
-                           resp->rqstp->rq_vec, read->rd_vlen, maxcount, eof);
+       if (file->f_op->splice_read && splice_ok)
+               nfserr = nfsd4_encode_splice_read(resp, read, file, maxcount);
+       else
+               nfserr = nfsd4_encode_readv(resp, read, file, maxcount);
        if (nfserr)
                return nfserr;
-       xdr_truncate_encode(xdr, starting_len + 16 + xdr_align_size(*maxcount));
-
-       tmp = htonl(NFS4_CONTENT_DATA);
-       write_bytes_to_xdr_buf(xdr->buf, starting_len,      &tmp,   4);
-       tmp64 = cpu_to_be64(read->rd_offset);
-       write_bytes_to_xdr_buf(xdr->buf, starting_len + 4,  &tmp64, 8);
-       tmp = htonl(*maxcount);
-       write_bytes_to_xdr_buf(xdr->buf, starting_len + 12, &tmp,   4);
-
-       tmp = xdr_zero;
-       write_bytes_to_xdr_buf(xdr->buf, starting_len + 16 + *maxcount, &tmp,
-                              xdr_pad_size(*maxcount));
-       return nfs_ok;
-}
-
-static __be32
-nfsd4_encode_read_plus_hole(struct nfsd4_compoundres *resp,
-                           struct nfsd4_read *read,
-                           unsigned long *maxcount, u32 *eof)
-{
-       struct file *file = read->rd_nf->nf_file;
-       loff_t data_pos = vfs_llseek(file, read->rd_offset, SEEK_DATA);
-       loff_t f_size = i_size_read(file_inode(file));
-       unsigned long count;
-       __be32 *p;
-
-       if (data_pos == -ENXIO)
-               data_pos = f_size;
-       else if (data_pos <= read->rd_offset || (data_pos < f_size && data_pos % PAGE_SIZE))
-               return nfsd4_encode_read_plus_data(resp, read, maxcount, eof, &f_size);
-       count = data_pos - read->rd_offset;
 
-       /* Content type, offset, byte count */
-       p = xdr_reserve_space(resp->xdr, 4 + 8 + 8);
-       if (!p)
-               return nfserr_resource;
-
-       *p++ = htonl(NFS4_CONTENT_HOLE);
+       *p++ = cpu_to_be32(NFS4_CONTENT_DATA);
        p = xdr_encode_hyper(p, read->rd_offset);
-       p = xdr_encode_hyper(p, count);
+       *p = cpu_to_be32(read->rd_length);
 
-       *eof = (read->rd_offset + count) >= f_size;
-       *maxcount = min_t(unsigned long, count, *maxcount);
        return nfs_ok;
 }
 
@@ -4847,69 +4805,36 @@ static __be32
 nfsd4_encode_read_plus(struct nfsd4_compoundres *resp, __be32 nfserr,
                       struct nfsd4_read *read)
 {
-       unsigned long maxcount, count;
+       struct file *file = read->rd_nf->nf_file;
        struct xdr_stream *xdr = resp->xdr;
-       struct file *file;
        int starting_len = xdr->buf->len;
-       int last_segment = xdr->buf->len;
-       int segments = 0;
-       __be32 *p, tmp;
-       bool is_data;
-       loff_t pos;
-       u32 eof;
+       u32 segments = 0;
+       __be32 *p;
 
        if (nfserr)
                return nfserr;
-       file = read->rd_nf->nf_file;
 
        /* eof flag, segment count */
        p = xdr_reserve_space(xdr, 4 + 4);
        if (!p)
-               return nfserr_resource;
+               return nfserr_io;
        xdr_commit_encode(xdr);
 
-       maxcount = min_t(unsigned long, read->rd_length,
-                        (xdr->buf->buflen - xdr->buf->len));
-       count    = maxcount;
-
-       eof = read->rd_offset >= i_size_read(file_inode(file));
-       if (eof)
+       read->rd_eof = read->rd_offset >= i_size_read(file_inode(file));
+       if (read->rd_eof)
                goto out;
 
-       pos = vfs_llseek(file, read->rd_offset, SEEK_HOLE);
-       is_data = pos > read->rd_offset;
-
-       while (count > 0 && !eof) {
-               maxcount = count;
-               if (is_data)
-                       nfserr = nfsd4_encode_read_plus_data(resp, read, &maxcount, &eof,
-                                               segments == 0 ? &pos : NULL);
-               else
-                       nfserr = nfsd4_encode_read_plus_hole(resp, read, &maxcount, &eof);
-               if (nfserr)
-                       goto out;
-               count -= maxcount;
-               read->rd_offset += maxcount;
-               is_data = !is_data;
-               last_segment = xdr->buf->len;
-               segments++;
-       }
-
-out:
-       if (nfserr && segments == 0)
+       nfserr = nfsd4_encode_read_plus_data(resp, read);
+       if (nfserr) {
                xdr_truncate_encode(xdr, starting_len);
-       else {
-               if (nfserr) {
-                       xdr_truncate_encode(xdr, last_segment);
-                       nfserr = nfs_ok;
-                       eof = 0;
-               }
-               tmp = htonl(eof);
-               write_bytes_to_xdr_buf(xdr->buf, starting_len,     &tmp, 4);
-               tmp = htonl(segments);
-               write_bytes_to_xdr_buf(xdr->buf, starting_len + 4, &tmp, 4);
+               return nfserr;
        }
 
+       segments++;
+
+out:
+       p = xdr_encode_bool(p, read->rd_eof);
+       *p = cpu_to_be32(segments);
        return nfserr;
 }