NFSv4.1: add generic layer hooks for pnfs COMMIT

We create three major hooks for the pnfs code.

pnfs_mark_request_commit() is called during writeback_done from
nfs_mark_request_commit, which gives the driver an opportunity to
claim it wants control over commiting a particular req.

pnfs_choose_commit_list() is called from nfs_scan_list
to choose which list a given req should be added to, based on
where we intend to send it for COMMIT.  It is up to the driver
to have preallocated list headers for each destination it may need.

pnfs_commit_list() is how the driver actually takes control, it is
used instead of nfs_commit_list().

In order to pass information between the above functions, we create
a union in nfs_page to hold a lseg (which is possible because the req is
not on any list while in transition), and add some flags to indicate
if we need to use the pnfs code.

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

2 files changed, 6 insertions, 1 deletions

diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 4179c368844b..eddda6ce7c42 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -226,6 +226,7 @@ struct nfs_inode {
 #define NFS_INO_FSCACHE         (5)             /* inode can be cached by FS-Cache */
 #define NFS_INO_FSCACHE_LOCK    (6)             /* FS-Cache cookie management lock */
 #define NFS_INO_COMMIT          (7)             /* inode is committing unstable writes */
+#define NFS_INO_PNFS_COMMIT     (8)             /* use pnfs code for commit */
 
 static inline struct nfs_inode *NFS_I(const struct inode *inode)
 {
diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
index 92d54c81f51e..8023e4e25133 100644
--- a/include/linux/nfs_page.h
+++ b/include/linux/nfs_page.h
@@ -33,11 +33,15 @@ enum {
         PG_CLEAN,
         PG_NEED_COMMIT,
         PG_NEED_RESCHED,
+        PG_PNFS_COMMIT,
 };
 
 struct nfs_inode;
 struct nfs_page {
-        struct list_head        wb_list;        /* Defines state of page: */
+        union {
+                struct list_head        wb_list;        /* Defines state of page: */
+                struct pnfs_layout_segment *wb_commit_lseg; /* Used when PG_PNFS_COMMIT set */
+        };
         struct page             *wb_page;       /* page to read in/write out */
         struct nfs_open_context *wb_context;    /* File state context info */
         struct nfs_lock_context *wb_lock_context;       /* lock context info */