NFSD: Add READ_PLUS hole segment encoding

However, we still only reply to the READ_PLUS call with a single segment
at this time.

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

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 206670a2029005a8ced07984a4eee7fcd89f7197..74645c5c44bd94042079034aaa9fbc1ee5bb6e8a 100644 (file)
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -4608,10 +4608,13 @@ nfsd4_encode_read_plus_data(struct nfsd4_compoundres *resp,
        struct xdr_stream *xdr = &resp->xdr;
        struct file *file = read->rd_nf->nf_file;
        int starting_len = xdr->buf->len;
+       loff_t hole_pos = vfs_llseek(file, read->rd_offset, SEEK_HOLE);
        __be32 nfserr;
        __be32 *p, tmp;
        __be64 tmp64;
 
+       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));
 
        /* Content type, offset, byte count */
@@ -4637,6 +4640,27 @@ nfsd4_encode_read_plus_data(struct nfsd4_compoundres *resp,
        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;
+       __be32 *p;
+
+       /* 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   = xdr_encode_hyper(p, read->rd_offset);
+        p   = xdr_encode_hyper(p, maxcount);
+
+       *eof = (read->rd_offset + maxcount) >= i_size_read(file_inode(file));
+       return nfs_ok;
+}
+
 static __be32
 nfsd4_encode_read_plus(struct nfsd4_compoundres *resp, __be32 nfserr,
                       struct nfsd4_read *read)
@@ -4647,6 +4671,7 @@ nfsd4_encode_read_plus(struct nfsd4_compoundres *resp, __be32 nfserr,
        int starting_len = xdr->buf->len;
        int segments = 0;
        __be32 *p, tmp;
+       loff_t pos;
        u32 eof;
 
        if (nfserr)
@@ -4665,11 +4690,23 @@ nfsd4_encode_read_plus(struct nfsd4_compoundres *resp, __be32 nfserr,
        maxcount = min_t(unsigned long, maxcount, read->rd_length);
 
        eof = read->rd_offset >= i_size_read(file_inode(file));
-       if (!eof) {
+       if (eof)
+               goto out;
+
+       pos = vfs_llseek(file, read->rd_offset, SEEK_DATA);
+       if (pos == -ENXIO)
+               pos = i_size_read(file_inode(file));
+
+       if (pos > read->rd_offset) {
+               maxcount = pos - read->rd_offset;
+               nfserr = nfsd4_encode_read_plus_hole(resp, read, maxcount, &eof);
+               segments++;
+       } else {
                nfserr = nfsd4_encode_read_plus_data(resp, read, maxcount, &eof);
                segments++;
        }
 
+out:
        if (nfserr)
                xdr_truncate_encode(xdr, starting_len);
        else {