NFS: support large reads and writes on the wire

 Most NFS server implementations allow up to 64KB reads and writes on the
 wire.  The Solaris NFS server allows up to a megabyte, for instance.

 Now the Linux NFS client supports transfer sizes up to 1MB, too.  This will
 help reduce protocol and context switch overhead on read/write intensive NFS
 workloads, and support larger atomic read and write operations on servers
 that support them.

 Test-plan:
 Connectathon and iozone on mount point with wsize=rsize>32768 over TCP.
 Tests with NFS over UDP to verify the maximum RPC payload size cap.

 Signed-off-by: Chuck Lever <cel@netapp.com>
 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 10 insertions, 15 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 4e6558df54b8..acde2c5725bf 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -221,10 +221,10 @@ nfs_calc_block_size(u64 tsize)
 static inline unsigned long
 nfs_block_size(unsigned long bsize, unsigned char *nrbitsp)
 {
-        if (bsize < 1024)
-                bsize = NFS_DEF_FILE_IO_BUFFER_SIZE;
-        else if (bsize >= NFS_MAX_FILE_IO_BUFFER_SIZE)
-                bsize = NFS_MAX_FILE_IO_BUFFER_SIZE;
+        if (bsize < NFS_MIN_FILE_IO_SIZE)
+                bsize = NFS_DEF_FILE_IO_SIZE;
+        else if (bsize >= NFS_MAX_FILE_IO_SIZE)
+                bsize = NFS_MAX_FILE_IO_SIZE;
 
         return nfs_block_bits(bsize, nrbitsp);
 }
@@ -307,20 +307,15 @@ nfs_sb_init(struct super_block *sb, rpc_authflavor_t authflavor)
         max_rpc_payload = nfs_block_size(rpc_max_payload(server->client), NULL);
         if (server->rsize > max_rpc_payload)
                 server->rsize = max_rpc_payload;
-        if (server->wsize > max_rpc_payload)
-                server->wsize = max_rpc_payload;
-
+        if (server->rsize > NFS_MAX_FILE_IO_SIZE)
+                server->rsize = NFS_MAX_FILE_IO_SIZE;
         server->rpages = (server->rsize + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
-        if (server->rpages > NFS_READ_MAXIOV) {
-                server->rpages = NFS_READ_MAXIOV;
-                server->rsize = server->rpages << PAGE_CACHE_SHIFT;
-        }
 
+        if (server->wsize > max_rpc_payload)
+                server->wsize = max_rpc_payload;
+        if (server->wsize > NFS_MAX_FILE_IO_SIZE)
+                server->wsize = NFS_MAX_FILE_IO_SIZE;
         server->wpages = (server->wsize + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
-        if (server->wpages > NFS_WRITE_MAXIOV) {
-                server->wpages = NFS_WRITE_MAXIOV;
-                server->wsize = server->wpages << PAGE_CACHE_SHIFT;
-        }
 
         if (sb->s_blocksize == 0)
                 sb->s_blocksize = nfs_block_bits(server->wsize,