[PATCH 17/17] orangefs: implement writepages

[Martin Brandenburg]

Go through pages and look for a consecutive writable region.  After
finding 128 consecutive writable pages or when finding a non-consecutive
region, do the write.

Signed-off-by: Martin Brandenburg <martin@xxxxxxxxxxxx>
---
 fs/orangefs/inode.c           | 135 +++++++++++++++++++++++++++++++++-
 fs/orangefs/orangefs-kernel.h |   1 +
 fs/orangefs/super.c           |   1 +
 3 files changed, 135 insertions(+), 2 deletions(-)

diff --git a/fs/orangefs/inode.c b/fs/orangefs/inode.c
index 178734920e45..34b98d2ed377 100644
--- a/fs/orangefs/inode.c
+++ b/fs/orangefs/inode.c
@@ -15,6 +15,8 @@
 #include "orangefs-kernel.h"
 #include "orangefs-bufmap.h"
 
+#define ORANGEFS_WRITEPAGES_COUNT 128
+
 static int orangefs_writepage_locked(struct page *page,
     struct writeback_control *wbc)
 {
@@ -44,10 +46,10 @@ static int orangefs_writepage_locked(struct page *page,
 			len = i_size_read(inode);
 		}
 	} else {
-/*		BUG();*/
+		end_page_writeback(page);
 		/* It's not private so there's nothing to write, right? */
 		printk("writepage not private!\n");
-		end_page_writeback(page);
+		BUG();
 		return 0;
 
 	}
@@ -230,6 +232,134 @@ static int orangefs_readpage(struct file *file, struct page *page)
 	return ret;
 }
 
+struct orangefs_writepages {
+	loff_t off;
+	size_t len;
+	struct page *pages[ORANGEFS_WRITEPAGES_COUNT];
+	int npages;
+};
+
+static int orangefs_writepages_work(struct orangefs_writepages *ow,
+    struct writeback_control *wbc)
+{
+	struct inode *inode = ow->pages[0]->mapping->host;
+	struct orangefs_write_request *wr;
+	struct iov_iter iter;
+	struct bio_vec *bv;
+	ssize_t ret;
+	loff_t off;
+	int i;
+
+	bv = kcalloc(ORANGEFS_WRITEPAGES_COUNT, sizeof(struct bio_vec),
+	    GFP_KERNEL);
+	if (!bv)
+		return -ENOMEM;
+
+	for (i = 0; i < ow->npages; i++) {
+		set_page_writeback(ow->pages[i]);
+		bv[i].bv_page = ow->pages[i];
+		/* uh except the last one maybe... */
+		if (i == ow->npages - 1 && ow->len % PAGE_SIZE)
+			bv[i].bv_len = ow->len % PAGE_SIZE;
+		else
+			bv[i].bv_len = PAGE_SIZE;
+		bv[i].bv_offset = 0;
+	}
+	iov_iter_bvec(&iter, ITER_BVEC | WRITE, bv, ow->npages, ow->len);
+
+	off = ow->off;
+	ret = wait_for_direct_io(ORANGEFS_IO_WRITE, inode, &off, &iter, ow->len,
+	    0, NULL);
+	if (ret < 0) {
+		for (i = 0; i < ow->npages; i++) {
+			SetPageError(ow->pages[i]);
+			mapping_set_error(ow->pages[i]->mapping, ret);
+			end_page_writeback(ow->pages[i]);
+			unlock_page(ow->pages[i]);
+		}
+	} else {
+		for (i = 0; i < ow->npages; i++) {
+			if (PagePrivate(ow->pages[i])) {
+				wr = (struct orangefs_write_request *)
+				    page_private(ow->pages[i]);
+				ClearPagePrivate(ow->pages[i]);
+				wr_release(wr);
+			}
+			end_page_writeback(ow->pages[i]);
+			unlock_page(ow->pages[i]);
+		}
+	}
+	kfree(bv);
+	return ret;
+}
+
+static int orangefs_writepages_callback(struct page *page,
+    struct writeback_control *wbc, void *data)
+{
+	struct orangefs_writepages *ow = data;
+	struct orangefs_write_request *wr;
+	int ret;
+
+	if (!PagePrivate(page)) {
+		unlock_page(page);
+		/* It's not private so there's nothing to write, right? */
+		printk("writepages_callback not private!\n");
+		BUG();
+		return 0;
+	}
+	wr = (struct orangefs_write_request *)page_private(page);
+
+	if (wr->len != PAGE_SIZE) {
+		ret = orangefs_writepage_locked(page, wbc);
+		mapping_set_error(page->mapping, ret);
+		unlock_page(page);
+	} else {
+		ret = -1;
+		if (ow->npages == 0) {
+			ow->off = wr->pos;
+			ow->len = wr->len;
+			ow->pages[ow->npages++] = page;
+			ret = 0;
+		}
+		if (ow->off + ow->len == wr->pos) {
+			ow->len += wr->len;
+			ow->pages[ow->npages++] = page;
+			ret = 0;
+		}
+		if (ret == -1) {
+			ret = orangefs_writepage_locked(page, wbc);
+			mapping_set_error(page->mapping, ret);
+			unlock_page(page);
+		} else {
+			if (ow->npages == ORANGEFS_WRITEPAGES_COUNT) {
+				orangefs_writepages_work(ow, wbc);
+				memset(ow, 0, sizeof *ow);
+			}
+		}
+	}
+	return ret;
+}
+
+static int orangefs_writepages(struct address_space *mapping,
+    struct writeback_control *wbc)
+{
+	struct orangefs_writepages *ow;
+	struct blk_plug plug;
+	int ret;
+	ow = kzalloc(sizeof(struct orangefs_writepages), GFP_KERNEL);
+	if (!ow)
+		return -ENOMEM;
+	mutex_lock(&ORANGEFS_SB(mapping->host->i_sb)->writepages_mutex);
+	blk_start_plug(&plug);
+	ret = write_cache_pages(mapping, wbc, orangefs_writepages_callback, ow);
+	if (ow->npages)
+		ret = orangefs_writepages_work(ow, wbc);
+	blk_finish_plug(&plug);
+	mutex_unlock(&ORANGEFS_SB(mapping->host->i_sb)->writepages_mutex);
+	kfree(ow);
+	return ret;
+}
+
 static int orangefs_write_begin(struct file *file,
     struct address_space *mapping, loff_t pos, unsigned len, unsigned flags,
     struct page **pagep, void **fsdata)
@@ -325,6 +455,7 @@ static ssize_t orangefs_direct_IO(struct kiocb *iocb,
 static const struct address_space_operations orangefs_address_operations = {
 	.writepage = orangefs_writepage,
 	.readpage = orangefs_readpage,
+	.writepages = orangefs_writepages,
 	.set_page_dirty = __set_page_dirty_nobuffers,
 	.write_begin = orangefs_write_begin,
 	.write_end = orangefs_write_end,
diff --git a/fs/orangefs/orangefs-kernel.h b/fs/orangefs/orangefs-kernel.h
index 256851bab7a5..9e23f97fb5cc 100644
--- a/fs/orangefs/orangefs-kernel.h
+++ b/fs/orangefs/orangefs-kernel.h
@@ -220,6 +220,7 @@ struct orangefs_sb_info_s {
 	int mount_pending;
 	int no_list;
 	struct list_head list;
+	struct mutex writepages_mutex;
 };
 
 struct orangefs_stats {
diff --git a/fs/orangefs/super.c b/fs/orangefs/super.c
index 83abe5ec2d11..204e1ac7f228 100644
--- a/fs/orangefs/super.c
+++ b/fs/orangefs/super.c
@@ -467,6 +467,7 @@ static int orangefs_fill_sb(struct super_block *sb,
 
 	sb->s_export_op = &orangefs_export_ops;
 	sb->s_root = root_dentry;
+	mutex_init(&ORANGEFS_SB(sb)->writepages_mutex);
 	return 0;
 }
 
-- 
2.19.0