[PATCH 3/3] i/o accounting and control

[Andrea Righi <righi.andrea@gmail.com>]

Apply the io-throttle controller to the opportune kernel functions. Both
accounting and throttling functionalities are performed by
cgroup_io_throttle().

Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
---
 block/blk-core.c    |    2 ++
 fs/buffer.c         |   10 ++++++++++
 fs/direct-io.c      |    3 +++
 mm/page-writeback.c |   20 ++++++++++++++++++++
 mm/readahead.c      |    5 +++++
 5 files changed, 40 insertions(+), 0 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 1905aab..2ac5463 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -26,6 +26,7 @@
 #include <linux/swap.h>
 #include <linux/writeback.h>
 #include <linux/task_io_accounting_ops.h>
+#include <linux/blk-io-throttle.h>
 #include <linux/interrupt.h>
 #include <linux/cpu.h>
 #include <linux/blktrace_api.h>
@@ -1482,6 +1483,7 @@ void submit_bio(int rw, struct bio *bio)
 			count_vm_events(PGPGOUT, count);
 		} else {
 			task_io_account_read(bio->bi_size);
+			cgroup_io_throttle(bio->bi_bdev, bio->bi_size, 1);
 			count_vm_events(PGPGIN, count);
 		}
 
diff --git a/fs/buffer.c b/fs/buffer.c
index 0f51c0f..6f41c3a 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -35,6 +35,7 @@
 #include <linux/suspend.h>
 #include <linux/buffer_head.h>
 #include <linux/task_io_accounting_ops.h>
+#include <linux/blk-io-throttle.h>
 #include <linux/bio.h>
 #include <linux/notifier.h>
 #include <linux/cpu.h>
@@ -700,6 +701,9 @@ EXPORT_SYMBOL(mark_buffer_dirty_inode);
 static int __set_page_dirty(struct page *page,
 		struct address_space *mapping, int warn)
 {
+	struct block_device *bdev = NULL;
+	size_t cgroup_io_acct = 0;
+
 	if (unlikely(!mapping))
 		return !TestSetPageDirty(page);
 
@@ -711,16 +715,22 @@ static int __set_page_dirty(struct page *page,
 		WARN_ON_ONCE(warn && !PageUptodate(page));
 
 		if (mapping_cap_account_dirty(mapping)) {
+			bdev = (mapping->host &&
+				mapping->host->i_sb->s_bdev) ?
+				mapping->host->i_sb->s_bdev : NULL;
+
 			__inc_zone_page_state(page, NR_FILE_DIRTY);
 			__inc_bdi_stat(mapping->backing_dev_info,
 					BDI_RECLAIMABLE);
 			task_io_account_write(PAGE_CACHE_SIZE);
+			cgroup_io_acct = PAGE_CACHE_SIZE;
 		}
 		radix_tree_tag_set(&mapping->page_tree,
 				page_index(page), PAGECACHE_TAG_DIRTY);
 	}
 	write_unlock_irq(&mapping->tree_lock);
 	__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
+	cgroup_io_throttle(bdev, cgroup_io_acct, 0);
 
 	return 1;
 }
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 9e81add..42c8e54 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -35,6 +35,7 @@
 #include <linux/buffer_head.h>
 #include <linux/rwsem.h>
 #include <linux/uio.h>
+#include <linux/blk-io-throttle.h>
 #include <asm/atomic.h>
 
 /*
@@ -666,6 +667,8 @@ submit_page_section(struct dio *dio, struct page *page,
 		/*
 		 * Read accounting is performed in submit_bio()
 		 */
+		struct block_device *bdev = dio->bio ? dio->bio->bi_bdev : NULL;
+		cgroup_io_throttle(bdev, len, 1);
 		task_io_account_write(len);
 	}
 
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 789b6ad..8e5e99d 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -23,6 +23,7 @@
 #include <linux/init.h>
 #include <linux/backing-dev.h>
 #include <linux/task_io_accounting_ops.h>
+#include <linux/blk-io-throttle.h>
 #include <linux/blkdev.h>
 #include <linux/mpage.h>
 #include <linux/rmap.h>
@@ -430,6 +431,9 @@ static void balance_dirty_pages(struct address_space *mapping)
 	unsigned long write_chunk = sync_writeback_pages();
 
 	struct backing_dev_info *bdi = mapping->backing_dev_info;
+	struct block_device *bdev = (mapping->host &&
+					mapping->host->i_sb->s_bdev) ?
+					mapping->host->i_sb->s_bdev : NULL;
 
 	for (;;) {
 		struct writeback_control wbc = {
@@ -512,6 +516,14 @@ static void balance_dirty_pages(struct address_space *mapping)
 		return;		/* pdflush is already working this queue */
 
 	/*
+	 * Apply the cgroup i/o throttling limitations. The accounting of write
+	 * activity in page cache is performed in __set_page_dirty(), but since
+	 * we cannot sleep there, 0 bytes are accounted here and the function
+	 * is invoked only for throttling purpose.
+	 */
+	cgroup_io_throttle(bdev, 0, 1);
+
+	/*
 	 * In laptop mode, we wait until hitting the higher threshold before
 	 * starting background writeout, and then write out all the way down
 	 * to the lower threshold.  So slow writers cause minimal disk activity.
@@ -1077,6 +1089,8 @@ int __set_page_dirty_nobuffers(struct page *page)
 	if (!TestSetPageDirty(page)) {
 		struct address_space *mapping = page_mapping(page);
 		struct address_space *mapping2;
+		struct block_device *bdev = NULL;
+		size_t cgroup_io_acct = 0;
 
 		if (!mapping)
 			return 1;
@@ -1087,10 +1101,15 @@ int __set_page_dirty_nobuffers(struct page *page)
 			BUG_ON(mapping2 != mapping);
 			WARN_ON_ONCE(!PagePrivate(page) && !PageUptodate(page));
 			if (mapping_cap_account_dirty(mapping)) {
+				bdev = (mapping->host &&
+					mapping->host->i_sb->s_bdev) ?
+					mapping->host->i_sb->s_bdev : NULL;
+
 				__inc_zone_page_state(page, NR_FILE_DIRTY);
 				__inc_bdi_stat(mapping->backing_dev_info,
 						BDI_RECLAIMABLE);
 				task_io_account_write(PAGE_CACHE_SIZE);
+				cgroup_io_acct = PAGE_CACHE_SIZE;
 			}
 			radix_tree_tag_set(&mapping->page_tree,
 				page_index(page), PAGECACHE_TAG_DIRTY);
@@ -1100,6 +1119,7 @@ int __set_page_dirty_nobuffers(struct page *page)
 			/* !PageAnon && !swapper_space */
 			__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
 		}
+		cgroup_io_throttle(bdev, cgroup_io_acct, 1);
 		return 1;
 	}
 	return 0;
diff --git a/mm/readahead.c b/mm/readahead.c
index d8723a5..ec83e63 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -14,6 +14,7 @@
 #include <linux/blkdev.h>
 #include <linux/backing-dev.h>
 #include <linux/task_io_accounting_ops.h>
+#include <linux/blk-io-throttle.h>
 #include <linux/pagevec.h>
 #include <linux/pagemap.h>
 
@@ -58,6 +59,9 @@ int read_cache_pages(struct address_space *mapping, struct list_head *pages,
 			int (*filler)(void *, struct page *), void *data)
 {
 	struct page *page;
+	struct block_device *bdev =
+		(mapping->host && mapping->host->i_sb->s_bdev) ?
+		mapping->host->i_sb->s_bdev : NULL;
 	int ret = 0;
 
 	while (!list_empty(pages)) {
@@ -76,6 +80,7 @@ int read_cache_pages(struct address_space *mapping, struct list_head *pages,
 			break;
 		}
 		task_io_account_read(PAGE_CACHE_SIZE);
+		cgroup_io_throttle(bdev, PAGE_CACHE_SIZE, 1);
 	}
 	return ret;
 }
-- 
1.5.4.3