[PATCH] kNFSd: Convert nfsd to use a list of pages instead of one big buffer

This means:
  1/ We don't need an order-4 allocation for each nfsd that starts
  2/ We don't need an order-4 allocation in skb_linearize when
     we receive a 32K write request
  3/ It will be easier to incorporate the zero-copy read changes

The pages are handed around using an xdr_buf (instead of svc_buf)
much like the NFS client so future crypto code can use the same
data structure for both client and server.

The code assumes that most requests and replies fit in a single page.
The exceptions are assumed to have some largish 'data' bit, and the
rest must fit in a single page.
The 'data' bits are file data, readdir data, and symlinks.
There must be only one 'data' bit per request.
This is all fine for nfs/nlm.

This isn't complete:
  1/ NFSv4 hasn't been converted yet (it won't compile)
  2/ NFSv3 allows symlinks upto 4096, but the code will only support
     upto about 3800 at the moment
  3/ readdir responses are limited to about 3800.

but I thought that patch was big enough, and the rest can come
later.


This patch introduces vfs_readv and vfs_writev as parallels to
vfs_read and vfs_write.  This means there is a fair bit of
duplication in read_write.c that should probably be tidied up...

1 files changed, 2 insertions, 0 deletions

diff --git a/kernel/ksyms.c b/kernel/ksyms.c
index 7ecffcd552d1..6628b24ba827 100644
--- a/kernel/ksyms.c
+++ b/kernel/ksyms.c
@@ -253,7 +253,9 @@ EXPORT_SYMBOL(find_inode_number);
 EXPORT_SYMBOL(is_subdir);
 EXPORT_SYMBOL(get_unused_fd);
 EXPORT_SYMBOL(vfs_read);
+EXPORT_SYMBOL(vfs_readv);
 EXPORT_SYMBOL(vfs_write);
+EXPORT_SYMBOL(vfs_writev);
 EXPORT_SYMBOL(vfs_create);
 EXPORT_SYMBOL(vfs_mkdir);
 EXPORT_SYMBOL(vfs_mknod);