[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/include/linux/fs.h b/include/linux/fs.h
index 0adb782c7ac7..9a3e78ba7592 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -795,6 +795,8 @@ struct seq_file;
 
 extern ssize_t vfs_read(struct file *, char *, size_t, loff_t *);
 extern ssize_t vfs_write(struct file *, const char *, size_t, loff_t *);
+extern ssize_t vfs_readv(struct file *, struct iovec *, int, size_t, loff_t *);
+extern ssize_t vfs_writev(struct file *, const struct iovec *, int, size_t, loff_t *);
 
 /*
  * NOTE: write_inode, delete_inode, clear_inode, put_inode can be called