[PATCH] f2fs: limit # of inmemory pages

[Jaegeuk Kim <jaegeuk@kernel.org>]

If some abnormal users try lots of atomic write operations, f2fs is able to
produce pinned pages in the main memory which affects system performance.
This patch limits that as 20% over total memory size, and if f2fs reaches
to the limit, it will drop all the inmemory pages.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
 fs/f2fs/data.c    |  8 ++++++++
 fs/f2fs/f2fs.h    |  3 +++
 fs/f2fs/node.c    |  4 ++++
 fs/f2fs/node.h    |  1 +
 fs/f2fs/segment.c | 38 ++++++++++++++++++++++++++++++++++++++
 fs/f2fs/super.c   |  1 +
 6 files changed, 55 insertions(+)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 95fdbe3e6cca..7fd09837820a 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1944,6 +1944,12 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
 
 	trace_f2fs_write_begin(inode, pos, len, flags);
 
+	if (f2fs_is_atomic_file(inode) &&
+			!available_free_memory(sbi, INMEM_PAGES)) {
+		err = -ENOMEM;
+		goto fail;
+	}
+
 	/*
 	 * We should check this at this moment to avoid deadlock on inode page
 	 * and #0 page. The locking rule for inline_data conversion should be:
@@ -2021,6 +2027,8 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
 fail:
 	f2fs_put_page(page, 1);
 	f2fs_write_failed(mapping, pos + len);
+	if (f2fs_is_atomic_file(inode))
+		drop_inmem_pages_all(sbi);
 	return err;
 }
 
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index a53fa3dbccf8..e0ef31cb2cc6 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -606,6 +606,7 @@ struct f2fs_inode_info {
 #endif
 	struct list_head dirty_list;	/* dirty list for dirs and files */
 	struct list_head gdirty_list;	/* linked in global dirty list */
+	struct list_head inmem_ilist;	/* list for inmem inodes */
 	struct list_head inmem_pages;	/* inmemory pages managed by f2fs */
 	struct task_struct *inmem_task;	/* store inmemory task */
 	struct mutex inmem_lock;	/* lock for inmemory pages */
@@ -971,6 +972,7 @@ enum inode_type {
 	DIR_INODE,			/* for dirty dir inode */
 	FILE_INODE,			/* for dirty regular/symlink inode */
 	DIRTY_META,			/* for all dirtied inode metadata */
+	ATOMIC_FILE,			/* for all atomic files */
 	NR_INODE_TYPE,
 };
 
@@ -2556,6 +2558,7 @@ void destroy_node_manager_caches(void);
  */
 bool need_SSR(struct f2fs_sb_info *sbi);
 void register_inmem_page(struct inode *inode, struct page *page);
+void drop_inmem_pages_all(struct f2fs_sb_info *sbi);
 void drop_inmem_pages(struct inode *inode);
 void drop_inmem_page(struct inode *inode, struct page *page);
 int commit_inmem_pages(struct inode *inode);
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index b95b2784e7d8..ac629d6258ca 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -74,6 +74,10 @@ bool available_free_memory(struct f2fs_sb_info *sbi, int type)
 				atomic_read(&sbi->total_ext_node) *
 				sizeof(struct extent_node)) >> PAGE_SHIFT;
 		res = mem_size < ((avail_ram * nm_i->ram_thresh / 100) >> 1);
+	} else if (type == INMEM_PAGES) {
+		/* it allows 20% / total_ram for inmemory pages */
+		mem_size = get_pages(sbi, F2FS_INMEM_PAGES);
+		res = mem_size < (val.totalram / 5);
 	} else {
 		if (!sbi->sb->s_bdi->wb.dirty_exceeded)
 			return true;
diff --git a/fs/f2fs/node.h b/fs/f2fs/node.h
index e91b08b4a51a..0ee3e5ff49a3 100644
--- a/fs/f2fs/node.h
+++ b/fs/f2fs/node.h
@@ -140,6 +140,7 @@ enum mem_type {
 	DIRTY_DENTS,	/* indicates dirty dentry pages */
 	INO_ENTRIES,	/* indicates inode entries */
 	EXTENT_CACHE,	/* indicates extent cache */
+	INMEM_PAGES,	/* indicates inmemory pages */
 	BASE_CHECK,	/* check kernel status */
 };
 
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index bfbcff8339c5..049bbeb8ebff 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -186,6 +186,7 @@ bool need_SSR(struct f2fs_sb_info *sbi)
 
 void register_inmem_page(struct inode *inode, struct page *page)
 {
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
 	struct f2fs_inode_info *fi = F2FS_I(inode);
 	struct inmem_pages *new;
 
@@ -204,6 +205,10 @@ void register_inmem_page(struct inode *inode, struct page *page)
 	mutex_lock(&fi->inmem_lock);
 	get_page(page);
 	list_add_tail(&new->list, &fi->inmem_pages);
+	spin_lock(&sbi->inode_lock[ATOMIC_FILE]);
+	if (list_empty(&fi->inmem_ilist))
+		list_add_tail(&fi->inmem_ilist, &sbi->inode_list[ATOMIC_FILE]);
+	spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
 	inc_page_count(F2FS_I_SB(inode), F2FS_INMEM_PAGES);
 	mutex_unlock(&fi->inmem_lock);
 
@@ -262,12 +267,41 @@ static int __revoke_inmem_pages(struct inode *inode,
 	return err;
 }
 
+void drop_inmem_pages_all(struct f2fs_sb_info *sbi)
+{
+	struct list_head *head = &sbi->inode_list[ATOMIC_FILE];
+	struct inode *inode;
+	struct f2fs_inode_info *fi;
+next:
+	spin_lock(&sbi->inode_lock[ATOMIC_FILE]);
+	if (list_empty(head)) {
+		spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
+		return;
+	}
+	fi = list_first_entry(head, struct f2fs_inode_info, inmem_ilist);
+	inode = igrab(&fi->vfs_inode);
+	spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
+
+	if (inode) {
+		drop_inmem_pages(inode);
+		iput(inode);
+	}
+	congestion_wait(BLK_RW_ASYNC, HZ/50);
+	cond_resched();
+	goto next;
+}
+
 void drop_inmem_pages(struct inode *inode)
 {
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
 	struct f2fs_inode_info *fi = F2FS_I(inode);
 
 	mutex_lock(&fi->inmem_lock);
 	__revoke_inmem_pages(inode, &fi->inmem_pages, true, false);
+	spin_lock(&sbi->inode_lock[ATOMIC_FILE]);
+	if (!list_empty(&fi->inmem_ilist))
+		list_del_init(&fi->inmem_ilist);
+	spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
 	mutex_unlock(&fi->inmem_lock);
 
 	clear_inode_flag(inode, FI_ATOMIC_FILE);
@@ -399,6 +433,10 @@ int commit_inmem_pages(struct inode *inode)
 		/* drop all uncommitted pages */
 		__revoke_inmem_pages(inode, &fi->inmem_pages, true, false);
 	}
+	spin_lock(&sbi->inode_lock[ATOMIC_FILE]);
+	if (!list_empty(&fi->inmem_ilist))
+		list_del_init(&fi->inmem_ilist);
+	spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
 	mutex_unlock(&fi->inmem_lock);
 
 	clear_inode_flag(inode, FI_ATOMIC_COMMIT);
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 840a0876005b..fc3b74e53670 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -651,6 +651,7 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb)
 	init_rwsem(&fi->i_sem);
 	INIT_LIST_HEAD(&fi->dirty_list);
 	INIT_LIST_HEAD(&fi->gdirty_list);
+	INIT_LIST_HEAD(&fi->inmem_ilist);
 	INIT_LIST_HEAD(&fi->inmem_pages);
 	mutex_init(&fi->inmem_lock);
 	init_rwsem(&fi->dio_rwsem[READ]);
-- 
2.14.0.rc1.383.gd1ce394fe2-goog