nfs: add mirroring support to pgio layer

This patch adds mirrored write support to the pgio layer. The default
is to use one mirror, but pgio callers may define callbacks to change
this to any value up to the (arbitrarily selected) limit of 16.

The basic idea is to break out members of nfs_pageio_descriptor that cannot
be shared between mirrored DSes and put them in a new structure.

Signed-off-by: Weston Andros Adamson <dros@primarydata.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 05f9a87cdab4..ef1c703e487b 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -469,6 +469,7 @@ void nfs_init_cinfo(struct nfs_commit_info *cinfo,
                     struct nfs_direct_req *dreq);
 int nfs_key_timeout_notify(struct file *filp, struct inode *inode);
 bool nfs_ctx_key_to_expire(struct nfs_open_context *ctx);
+void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio);
 
 #ifdef CONFIG_MIGRATION
 extern int nfs_migrate_page(struct address_space *,