NFSv2/v3/v4: Prepare the nfs_page struct to allow for short reads.

fs/nfs/pagelist.c

@@ -88,6 +88,7 @@ nfs_create_request(struct file *file, struct inode *inode,
 	 * long write-back delay. This will be adjusted in
 	 * update_nfs_request below if the region is not locked. */
 	req->wb_page    = page;
+	atomic_set(&req->wb_complete, 0);
 	req->wb_index	= page->index;
 	page_cache_get(page);
 	req->wb_offset  = offset;

include/linux/nfs_page.h

@@ -17,10 +17,14 @@
 #include <linux/sunrpc/auth.h>
 #include <linux/nfs_xdr.h>
 
+#include <asm/atomic.h>
+
 /*
  * Valid flags for a dirty buffer
  */
 #define PG_BUSY			0
+#define PG_NEED_COMMIT		1
+#define PG_NEED_RESCHED		2
 
 struct nfs_page {
 	struct list_head	wb_list,	/* Defines state of page: */
@@ -31,6 +35,7 @@ struct nfs_page {
 	struct rpc_cred		*wb_cred;
 	struct nfs4_state	*wb_state;
 	struct page		*wb_page;	/* page to read in/write out */
+	atomic_t		wb_complete;	/* i/os we're waiting for */
 	wait_queue_head_t	wb_wait;	/* wait queue */
 	unsigned long		wb_index;	/* Offset >> PAGE_CACHE_SHIFT */
 	unsigned int		wb_offset,	/* Offset & ~PAGE_CACHE_MASK */
@@ -42,6 +47,8 @@ struct nfs_page {
 };
 
 #define NFS_WBACK_BUSY(req)	(test_bit(PG_BUSY,&(req)->wb_flags))
+#define NFS_NEED_COMMIT(req)	(test_bit(PG_NEED_COMMIT,&(req)->wb_flags))
+#define NFS_NEED_RESCHED(req)	(test_bit(PG_NEED_RESCHED,&(req)->wb_flags))
 
 extern	struct nfs_page *nfs_create_request(struct file *, struct inode *,
 					    struct page *,
@@ -115,6 +122,38 @@ nfs_list_remove_request(struct nfs_page *req)
 	req->wb_list_head = NULL;
 }
 
+static inline int
+nfs_defer_commit(struct nfs_page *req)
+{
+	if (test_and_set_bit(PG_NEED_COMMIT, &req->wb_flags))
+		return 0;
+	return 1;
+}
+
+static inline void
+nfs_clear_commit(struct nfs_page *req)
+{
+	smp_mb__before_clear_bit();
+	clear_bit(PG_NEED_COMMIT, &req->wb_flags);
+	smp_mb__after_clear_bit();
+}
+
+static inline int
+nfs_defer_reschedule(struct nfs_page *req)
+{
+	if (test_and_set_bit(PG_NEED_RESCHED, &req->wb_flags))
+		return 0;
+	return 1;
+}
+
+static inline void
+nfs_clear_reschedule(struct nfs_page *req)
+{
+	smp_mb__before_clear_bit();
+	clear_bit(PG_NEED_RESCHED, &req->wb_flags);
+	smp_mb__after_clear_bit();
+}
+
 static inline struct nfs_page *
 nfs_list_entry(struct list_head *head)
 {

include/linux/nfs_xdr.h

@@ -656,6 +656,8 @@ struct nfs4_compound {
 
 #endif /* CONFIG_NFS_V4 */
 
+struct nfs_page;
+
 struct nfs_read_data {
 	int			flags;
 	struct rpc_task		task;
@@ -664,12 +666,14 @@ struct nfs_read_data {
 	fl_owner_t		lockowner;
 	struct nfs_fattr	fattr;	/* fattr storage */
 	struct list_head	pages;	/* Coalesced read requests */
+	struct nfs_page		*req;	/* multi ops per nfs_page */
 	struct page		*pagevec[NFS_READ_MAXIOV];
 	struct nfs_readargs args;
 	struct nfs_readres  res;
 #ifdef CONFIG_NFS_V4
 	unsigned long		timestamp;	/* For lease renewal */
 #endif
+	void (*complete) (struct nfs_read_data *, int);
 };
 
 struct nfs_write_data {
@@ -681,16 +685,16 @@ struct nfs_write_data {
 	struct nfs_fattr	fattr;
 	struct nfs_writeverf	verf;
 	struct list_head	pages;		/* Coalesced requests we wish to flush */
+	struct nfs_page		*req;		/* multi ops per nfs_page */
 	struct page		*pagevec[NFS_WRITE_MAXIOV];
 	struct nfs_writeargs	args;		/* argument struct */
 	struct nfs_writeres	res;		/* result struct */
 #ifdef CONFIG_NFS_V4
 	unsigned long		timestamp;	/* For lease renewal */
 #endif
+	void (*complete) (struct nfs_write_data *, int);
 };
 
-struct nfs_page;
-
 /*
  * RPC procedure vector for NFSv2/NFSv3 demuxing
  */