FS: Use stable writes when not doing a bulk flush

Trond Myklebust · Trond Myklebust · commit b31268ac793f · 2011-03-21T21:08:17.000-04:00
If we're only doing a single write, and there are no other unstable
writes being queued up, we might want to just flip to using a stable
write RPC call.

Reviewed-by: NeilBrown &lt;neilb@suse.de&gt;
Signed-off-by: Trond Myklebust &lt;Trond.Myklebust@netapp.com&gt;
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
@@ -223,6 +223,7 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
 	desc->pg_count = 0;
 	desc->pg_bsize = bsize;
 	desc->pg_base = 0;
+	desc->pg_moreio = 0;
 	desc->pg_inode = inode;
 	desc->pg_doio = doio;
 	desc->pg_ioflags = io_flags;
@@ -335,9 +336,11 @@ int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
 			   struct nfs_page *req)
 {
 	while (!nfs_pageio_do_add_request(desc, req)) {
+		desc->pg_moreio = 1;
 		nfs_pageio_doio(desc);
 		if (desc->pg_error < 0)
 			return 0;
+		desc->pg_moreio = 0;
 	}
 	return 1;
 }
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
@@ -179,8 +179,8 @@ static int wb_priority(struct writeback_control *wbc)
 	if (wbc->for_reclaim)
 		return FLUSH_HIGHPRI | FLUSH_STABLE;
 	if (wbc->for_kupdate || wbc->for_background)
-		return FLUSH_LOWPRI;
-	return 0;
+		return FLUSH_LOWPRI | FLUSH_COND_STABLE;
+	return FLUSH_COND_STABLE;
 }
 
 /*
@@ -863,7 +863,7 @@ static int nfs_write_rpcsetup(struct nfs_page *req,
 	data->args.context = get_nfs_open_context(req->wb_context);
 	data->args.lock_context = req->wb_lock_context;
 	data->args.stable  = NFS_UNSTABLE;
-	if (how & FLUSH_STABLE) {
+	if (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
 		data->args.stable = NFS_DATA_SYNC;
 		if (!nfs_need_commit(NFS_I(inode)))
 			data->args.stable = NFS_FILE_SYNC;
@@ -912,6 +912,12 @@ static int nfs_flush_multi(struct nfs_pageio_descriptor *desc)
 
 	nfs_list_remove_request(req);
 
+	if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
+	    (desc->pg_moreio || NFS_I(desc->pg_inode)->ncommit ||
+	     desc->pg_count > wsize))
+		desc->pg_ioflags &= ~FLUSH_COND_STABLE;
+
+
 	nbytes = desc->pg_count;
 	do {
 		size_t len = min(nbytes, wsize);
@@ -1002,6 +1008,10 @@ static int nfs_flush_one(struct nfs_pageio_descriptor *desc)
 	if ((!lseg) && list_is_singular(&data->pages))
 		lseg = pnfs_update_layout(desc->pg_inode, req->wb_context, IOMODE_RW);
 
+	if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
+	    (desc->pg_moreio || NFS_I(desc->pg_inode)->ncommit))
+		desc->pg_ioflags &= ~FLUSH_COND_STABLE;
+
 	/* Set up the argument struct */
 	ret = nfs_write_rpcsetup(req, data, &nfs_write_full_ops, desc->pg_count, 0, lseg, desc->pg_ioflags);
 out:
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
@@ -33,6 +33,8 @@
 #define FLUSH_STABLE		4	/* commit to stable storage */
 #define FLUSH_LOWPRI		8	/* low priority background flush */
 #define FLUSH_HIGHPRI		16	/* high priority memory reclaim flush */
+#define FLUSH_COND_STABLE	32	/* conditional stable write - only stable
+					 * if everything fits in one RPC */
 
 #ifdef __KERNEL__
 
diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
@@ -57,6 +57,7 @@ struct nfs_pageio_descriptor {
 	size_t			pg_count;
 	size_t			pg_bsize;
 	unsigned int		pg_base;
+	char			pg_moreio;
 
 	struct inode		*pg_inode;
 	int			(*pg_doio)(struct nfs_pageio_descriptor *);

Original file line number	Diff line number	Diff line change
`@@ -223,6 +223,7 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,`
`223`	`223`	`desc->pg_count = 0;`
`224`	`224`	`desc->pg_bsize = bsize;`
`225`	`225`	`desc->pg_base = 0;`
	`226`	`+ desc->pg_moreio = 0;`
`226`	`227`	`desc->pg_inode = inode;`
`227`	`228`	`desc->pg_doio = doio;`
`228`	`229`	`desc->pg_ioflags = io_flags;`
`@@ -335,9 +336,11 @@ int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,`
`335`	`336`	`struct nfs_page *req)`
`336`	`337`	`{`
`337`	`338`	`while (!nfs_pageio_do_add_request(desc, req)) {`
	`339`	`+ desc->pg_moreio = 1;`
`338`	`340`	`nfs_pageio_doio(desc);`
`339`	`341`	`if (desc->pg_error < 0)`
`340`	`342`	`return 0;`
	`343`	`+ desc->pg_moreio = 0;`
`341`	`344`	`}`
`342`	`345`	`return 1;`
`343`	`346`	`}`