f2fs: Update to proper 3.4 support

http://git.kernel.org/cgit/linux/kernel/git/jaegeuk/f2fs.git/log/?h=linux-3.4

Conflicts:
	fs/f2fs/f2fs.h

Change-Id: Ica17871e847d4807c7ef24ea77dd4bff5451f5c7

16 files changed, 785 insertions, 265 deletions

diff --git a/fs/f2fs/acl.c b/fs/f2fs/acl.c
index 9c71fc55..2385ef8b 100644
--- a/fs/f2fs/acl.c
+++ b/fs/f2fs/acl.c
@@ -17,9 +17,6 @@
 #include "xattr.h"
 #include "acl.h"
 
-#define get_inode_mode(i)	((is_inode_flag_set(F2FS_I(i), FI_ACL_MODE)) ? \
-					(F2FS_I(i)->i_acl_mode) : ((i)->i_mode))
-
 static inline size_t f2fs_acl_size(int count)
 {
 	if (count <= 4) {
@@ -82,7 +79,6 @@ static struct posix_acl *f2fs_acl_from_disk(const char *value, size_t size)
 		case ACL_GROUP_OBJ:
 		case ACL_MASK:
 		case ACL_OTHER:
-			acl->a_entries[i].e_id = ACL_UNDEFINED_ID;
 			entry = (struct f2fs_acl_entry *)((char *)entry +
 					sizeof(struct f2fs_acl_entry_short));
 			break;
@@ -285,7 +281,7 @@ int f2fs_acl_chmod(struct inode *inode)
 	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
 	struct posix_acl *acl;
 	int error;
-	mode_t mode = get_inode_mode(inode);
+	umode_t mode = get_inode_mode(inode);
 
 	if (!test_opt(sbi, POSIX_ACL))
 		return 0;
diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index ecba8da3..0b4710c1 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -69,7 +69,6 @@ repeat:
 		goto repeat;
 	}
 out:
-	mark_page_accessed(page);
 	return page;
 }
 
@@ -137,13 +136,11 @@ int ra_meta_pages(struct f2fs_sb_info *sbi, int start, int nrpages, int type)
 		if (!page)
 			continue;
 		if (PageUptodate(page)) {
-			mark_page_accessed(page);
 			f2fs_put_page(page, 1);
 			continue;
 		}
 
 		f2fs_submit_page_mbio(sbi, page, blk_addr, &fio);
-		mark_page_accessed(page);
 		f2fs_put_page(page, 0);
 	}
 out:
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 3358ae12..feb6ca23 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -12,6 +12,7 @@
 #include <linux/f2fs_fs.h>
 #include <linux/buffer_head.h>
 #include <linux/mpage.h>
+#include <linux/aio.h>
 #include <linux/writeback.h>
 #include <linux/backing-dev.h>
 #include <linux/blkdev.h>
@@ -25,40 +26,33 @@
 
 static void f2fs_read_end_io(struct bio *bio, int err)
 {
-	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
-	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
+	struct bio_vec *bvec;
+	int i;
 
-	do {
+	__bio_for_each_segment(bvec, bio, i, 0) {
 		struct page *page = bvec->bv_page;
 
-		if (--bvec >= bio->bi_io_vec)
-			prefetchw(&bvec->bv_page->flags);
-
-		if (unlikely(!uptodate)) {
+		if (!err) {
+			SetPageUptodate(page);
+		} else {
 			ClearPageUptodate(page);
 			SetPageError(page);
-		} else {
-			SetPageUptodate(page);
 		}
 		unlock_page(page);
-	} while (bvec >= bio->bi_io_vec);
-
+	}
 	bio_put(bio);
 }
 
 static void f2fs_write_end_io(struct bio *bio, int err)
 {
-	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
-	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
 	struct f2fs_sb_info *sbi = bio->bi_private;
+	struct bio_vec *bvec;
+	int i;
 
-	do {
+	__bio_for_each_segment(bvec, bio, i, 0) {
 		struct page *page = bvec->bv_page;
 
-		if (--bvec >= bio->bi_io_vec)
-			prefetchw(&bvec->bv_page->flags);
-
-		if (unlikely(!uptodate)) {
+		if (unlikely(err)) {
 			SetPageError(page);
 			set_bit(AS_EIO, &page->mapping->flags);
 			set_ckpt_flags(sbi->ckpt, CP_ERROR_FLAG);
@@ -66,7 +60,7 @@ static void f2fs_write_end_io(struct bio *bio, int err)
 		}
 		end_page_writeback(page);
 		dec_page_count(sbi, F2FS_WRITEBACK);
-	} while (bvec >= bio->bi_io_vec);
+	}
 
 	if (sbi->wait_io) {
 		complete(sbi->wait_io);
@@ -141,7 +135,7 @@ void f2fs_submit_merged_bio(struct f2fs_sb_info *sbi,
 
 	io = is_read_io(rw) ? &sbi->read_io : &sbi->write_io[btype];
 
-	mutex_lock(&io->io_mutex);
+	down_write(&io->io_rwsem);
 
 	/* change META to META_FLUSH in the checkpoint procedure */
 	if (type >= META_FLUSH) {
@@ -149,7 +143,7 @@ void f2fs_submit_merged_bio(struct f2fs_sb_info *sbi,
 		io->fio.rw = WRITE_FLUSH_FUA | REQ_META | REQ_PRIO;
 	}
 	__submit_merged_bio(io);
-	mutex_unlock(&io->io_mutex);
+	up_write(&io->io_rwsem);
 }
 
 /*
@@ -187,7 +181,7 @@ void f2fs_submit_page_mbio(struct f2fs_sb_info *sbi, struct page *page,
 
 	verify_block_addr(sbi, blk_addr);
 
-	mutex_lock(&io->io_mutex);
+	down_write(&io->io_rwsem);
 
 	if (!is_read)
 		inc_page_count(sbi, F2FS_WRITEBACK);
@@ -211,7 +205,7 @@ alloc_new:
 
 	io->last_block_in_bio = blk_addr;
 
-	mutex_unlock(&io->io_mutex);
+	up_write(&io->io_rwsem);
 	trace_f2fs_submit_page_mbio(page, fio->rw, fio->type, blk_addr);
 }
 
@@ -921,6 +915,16 @@ skip_write:
 	return 0;
 }
 
+static void f2fs_write_failed(struct address_space *mapping, loff_t to)
+{
+	struct inode *inode = mapping->host;
+
+	if (to > inode->i_size) {
+		truncate_pagecache(inode, 0, inode->i_size);
+		truncate_blocks(inode, inode->i_size);
+	}
+}
+
 static int f2fs_write_begin(struct file *file, struct address_space *mapping,
 		loff_t pos, unsigned len, unsigned flags,
 		struct page **pagep, void **fsdata)
@@ -938,11 +942,13 @@ static int f2fs_write_begin(struct file *file, struct address_space *mapping,
 repeat:
 	err = f2fs_convert_inline_data(inode, pos + len);
 	if (err)
-		return err;
+		goto fail;
 
 	page = grab_cache_page_write_begin(mapping, index, flags);
-	if (!page)
-		return -ENOMEM;
+	if (!page) {
+		err = -ENOMEM;
+		goto fail;
+	}
 
 	/* to avoid latency during memory pressure */
 	unlock_page(page);
@@ -956,10 +962,9 @@ repeat:
 	set_new_dnode(&dn, inode, NULL, NULL, 0);
 	err = f2fs_reserve_block(&dn, index);
 	f2fs_unlock_op(sbi);
-
 	if (err) {
 		f2fs_put_page(page, 0);
-		return err;
+		goto fail;
 	}
 inline_data:
 	lock_page(page);
@@ -989,19 +994,20 @@ inline_data:
 			err = f2fs_read_inline_data(inode, page);
 			if (err) {
 				page_cache_release(page);
-				return err;
+				goto fail;
 			}
 		} else {
 			err = f2fs_submit_page_bio(sbi, page, dn.data_blkaddr,
 							READ_SYNC);
 			if (err)
-				return err;
+				goto fail;
 		}
 
 		lock_page(page);
 		if (unlikely(!PageUptodate(page))) {
 			f2fs_put_page(page, 1);
-			return -EIO;
+			err = -EIO;
+			goto fail;
 		}
 		if (unlikely(page->mapping != mapping)) {
 			f2fs_put_page(page, 1);
@@ -1012,6 +1018,9 @@ out:
 	SetPageUptodate(page);
 	clear_cold_data(page);
 	return 0;
+fail:
+	f2fs_write_failed(mapping, pos + len);
+	return err;
 }
 
 static int f2fs_write_end(struct file *file,
@@ -1023,7 +1032,6 @@ static int f2fs_write_end(struct file *file,
 
 	trace_f2fs_write_end(inode, pos, len, copied);
 
-	SetPageUptodate(page);
 	set_page_dirty(page);
 
 	if (pos + copied > i_size_read(inode)) {
@@ -1048,17 +1056,22 @@ static int check_direct_IO(struct inode *inode, int rw,
 	if (offset & blocksize_mask)
 		return -EINVAL;
 
-	for (i = 0; i < nr_segs; i++)
-		if (iov[i].iov_len & blocksize_mask)
-			return -EINVAL;
+       for (i = 0; i < nr_segs; i++)
+               if (iov[i].iov_len & blocksize_mask)
+                       return -EINVAL;
+
 	return 0;
 }
 
 static ssize_t f2fs_direct_IO(int rw, struct kiocb *iocb,
-		const struct iovec *iov, loff_t offset, unsigned long nr_segs)
+				const struct iovec *iov, loff_t offset,
+				unsigned long nr_segs)
 {
 	struct file *file = iocb->ki_filp;
-	struct inode *inode = file->f_mapping->host;
+	struct address_space *mapping = file->f_mapping;
+	struct inode *inode = mapping->host;
+	size_t count = iov_length(iov, nr_segs);
+	int err;
 
 	/* Let buffer I/O handle the inline data case. */
 	if (f2fs_has_inline_data(inode))
@@ -1070,8 +1083,11 @@ static ssize_t f2fs_direct_IO(int rw, struct kiocb *iocb,
 	/* clear fsync mark to recover these blocks */
 	fsync_mark_clear(F2FS_SB(inode->i_sb), inode->i_ino);
 
-	return blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
+	err = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
 							get_data_block);
+	if (err < 0 && (rw & WRITE))
+		f2fs_write_failed(mapping, offset + count);
+	return err;
 }
 
 static void f2fs_invalidate_data_page(struct page *page, unsigned long offset)
diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
index b52c12cf..3f99266c 100644
--- a/fs/f2fs/debug.c
+++ b/fs/f2fs/debug.c
@@ -345,21 +345,14 @@ void __init f2fs_create_root_stats(void)
 
 	f2fs_debugfs_root = debugfs_create_dir("f2fs", NULL);
 	if (!f2fs_debugfs_root)
-		goto bail;
+		return;
 
 	file = debugfs_create_file("status", S_IRUGO, f2fs_debugfs_root,
 			NULL, &stat_fops);
-	if (!file)
-		goto free_debugfs_dir;
-
-	return;
-
-free_debugfs_dir:
-	debugfs_remove(f2fs_debugfs_root);
-
-bail:
-	f2fs_debugfs_root = NULL;
-	return;
+	if (!file) {
+		debugfs_remove(f2fs_debugfs_root);
+		f2fs_debugfs_root = NULL;
+	}
 }
 
 void f2fs_destroy_root_stats(void)
diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index b84d3812..f74cb987 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -61,7 +61,7 @@ static unsigned char f2fs_type_by_mode[S_IFMT >> S_SHIFT] = {
 
 static void set_de_type(struct f2fs_dir_entry *de, struct inode *inode)
 {
-	mode_t mode = inode->i_mode;
+	umode_t mode = inode->i_mode;
 	de->file_type = f2fs_type_by_mode[(mode & S_IFMT) >> S_SHIFT];
 }
 
@@ -77,8 +77,8 @@ static unsigned long dir_block_index(unsigned int level,
 	return bidx;
 }
 
-static bool early_match_name(const char *name, size_t namelen,
-			f2fs_hash_t namehash, struct f2fs_dir_entry *de)
+static bool early_match_name(size_t namelen, f2fs_hash_t namehash,
+				struct f2fs_dir_entry *de)
 {
 	if (le16_to_cpu(de->name_len) != namelen)
 		return false;
@@ -90,7 +90,7 @@ static bool early_match_name(const char *name, size_t namelen,
 }
 
 static struct f2fs_dir_entry *find_in_block(struct page *dentry_page,
-			const char *name, size_t namelen, int *max_slots,
+			struct qstr *name, int *max_slots,
 			f2fs_hash_t namehash, struct page **res_page)
 {
 	struct f2fs_dir_entry *de;
@@ -109,9 +109,10 @@ static struct f2fs_dir_entry *find_in_block(struct page *dentry_page,
 			continue;
 		}
 		de = &dentry_blk->dentry[bit_pos];
-		if (early_match_name(name, namelen, namehash, de)) {
+		if (early_match_name(name->len, namehash, de)) {
 			if (!memcmp(dentry_blk->filename[bit_pos],
-							name, namelen)) {
+							name->name,
+							name->len)) {
 				*res_page = dentry_page;
 				goto found;
 			}
@@ -120,6 +121,13 @@ static struct f2fs_dir_entry *find_in_block(struct page *dentry_page,
 			*max_slots = max_len;
 			max_len = 0;
 		}
+
+		/*
+		 * For the most part, it should be a bug when name_len is zero.
+		 * We stop here for figuring out where the bugs are occurred.
+		 */
+		f2fs_bug_on(!de->name_len);
+
 		bit_pos += GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
 	}
 
@@ -132,10 +140,10 @@ found:
 }
 
 static struct f2fs_dir_entry *find_in_level(struct inode *dir,
-		unsigned int level, const char *name, size_t namelen,
+			unsigned int level, struct qstr *name,
 			f2fs_hash_t namehash, struct page **res_page)
 {
-	int s = GET_DENTRY_SLOTS(namelen);
+	int s = GET_DENTRY_SLOTS(name->len);
 	unsigned int nbucket, nblock;
 	unsigned int bidx, end_block;
 	struct page *dentry_page;
@@ -160,8 +168,8 @@ static struct f2fs_dir_entry *find_in_level(struct inode *dir,
 			continue;
 		}
 
-		de = find_in_block(dentry_page, name, namelen,
-					&max_slots, namehash, res_page);
+		de = find_in_block(dentry_page, name, &max_slots,
+					namehash, res_page);
 		if (de)
 			break;
 
@@ -187,8 +195,6 @@ static struct f2fs_dir_entry *find_in_level(struct inode *dir,
 struct f2fs_dir_entry *f2fs_find_entry(struct inode *dir,
 			struct qstr *child, struct page **res_page)
 {
-	const char *name = child->name;
-	size_t namelen = child->len;
 	unsigned long npages = dir_blocks(dir);
 	struct f2fs_dir_entry *de = NULL;
 	f2fs_hash_t name_hash;
@@ -200,12 +206,11 @@ struct f2fs_dir_entry *f2fs_find_entry(struct inode *dir,
 
 	*res_page = NULL;
 
-	name_hash = f2fs_dentry_hash(name, namelen);
+	name_hash = f2fs_dentry_hash(child);
 	max_depth = F2FS_I(dir)->i_current_depth;
 
 	for (level = 0; level < max_depth; level++) {
-		de = find_in_level(dir, level, name,
-				namelen, name_hash, res_page);
+		de = find_in_level(dir, level, child, name_hash, res_page);
 		if (de)
 			break;
 	}
@@ -298,14 +303,13 @@ static int make_empty_dir(struct inode *inode,
 	struct page *dentry_page;
 	struct f2fs_dentry_block *dentry_blk;
 	struct f2fs_dir_entry *de;
-	void *kaddr;
 
 	dentry_page = get_new_data_page(inode, page, 0, true);
 	if (IS_ERR(dentry_page))
 		return PTR_ERR(dentry_page);
 
-	kaddr = kmap_atomic(dentry_page);
-	dentry_blk = (struct f2fs_dentry_block *)kaddr;
+
+	dentry_blk = kmap_atomic(dentry_page);
 
 	de = &dentry_blk->dentry[0];
 	de->name_len = cpu_to_le16(1);
@@ -323,7 +327,7 @@ static int make_empty_dir(struct inode *inode,
 
 	test_and_set_bit_le(0, &dentry_blk->dentry_bitmap);
 	test_and_set_bit_le(1, &dentry_blk->dentry_bitmap);
-	kunmap_atomic(kaddr);
+	kunmap_atomic(dentry_blk);
 
 	set_page_dirty(dentry_page);
 	f2fs_put_page(dentry_page, 1);
@@ -333,11 +337,12 @@ static int make_empty_dir(struct inode *inode,
 static struct page *init_inode_metadata(struct inode *inode,
 		struct inode *dir, const struct qstr *name)
 {
+	struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
 	struct page *page;
 	int err;
 
 	if (is_inode_flag_set(F2FS_I(inode), FI_NEW_INODE)) {
-		page = new_inode_page(inode, name);
+		page = new_inode_page(inode);
 		if (IS_ERR(page))
 			return page;
 
@@ -362,7 +367,8 @@ static struct page *init_inode_metadata(struct inode *inode,
 		set_cold_node(inode, page);
 	}
 
-	init_dent_inode(name, page);
+	if (name)
+		init_dent_inode(name, page);
 
 	/*
 	 * This file should be checkpointed during fsync.
@@ -370,6 +376,12 @@ static struct page *init_inode_metadata(struct inode *inode,
 	 */
 	if (is_inode_flag_set(F2FS_I(inode), FI_INC_LINK)) {
 		file_lost_pino(inode);
+		/*
+		 * If link the tmpfile to alias through linkat path,
+		 * we should remove this inode from orphan list.
+		 */
+		if (inode->i_nlink == 0)
+			remove_orphan_inode(sbi, inode->i_ino);
 		inc_nlink(inode);
 	}
 	return page;
@@ -453,7 +465,7 @@ int __f2fs_add_link(struct inode *dir, const struct qstr *name,
 	int err = 0;
 	int i;
 
-	dentry_hash = f2fs_dentry_hash(name->name, name->len);
+	dentry_hash = f2fs_dentry_hash(name);
 	level = 0;
 	current_depth = F2FS_I(dir)->i_current_depth;
 	if (F2FS_I(dir)->chash == dentry_hash) {
@@ -529,6 +541,27 @@ fail:
 	return err;
 }
 
+int f2fs_do_tmpfile(struct inode *inode, struct inode *dir)
+{
+	struct page *page;
+	int err = 0;
+
+	down_write(&F2FS_I(inode)->i_sem);
+	page = init_inode_metadata(inode, dir, NULL);
+	if (IS_ERR(page)) {
+		err = PTR_ERR(page);
+		goto fail;
+	}
+	/* we don't need to mark_inode_dirty now */
+	update_inode(inode, page);
+	f2fs_put_page(page, 1);
+
+	clear_inode_flag(F2FS_I(inode), FI_NEW_INODE);
+fail:
+	up_write(&F2FS_I(inode)->i_sem);
+	return err;
+}
+
 /*
  * It only removes the dentry from the dentry page,corresponding name
  * entry in name page does not need to be touched during deletion.
@@ -541,14 +574,13 @@ void f2fs_delete_entry(struct f2fs_dir_entry *dentry, struct page *page,
 	struct address_space *mapping = page->mapping;
 	struct inode *dir = mapping->host;
 	int slots = GET_DENTRY_SLOTS(le16_to_cpu(dentry->name_len));
-	void *kaddr = page_address(page);
 	int i;
 
 	lock_page(page);
 	f2fs_wait_on_page_writeback(page, DATA);
 
-	dentry_blk = (struct f2fs_dentry_block *)kaddr;
-	bit_pos = dentry - (struct f2fs_dir_entry *)dentry_blk->dentry;
+	dentry_blk = page_address(page);
+	bit_pos = dentry - dentry_blk->dentry;
 	for (i = 0; i < slots; i++)
 		test_and_clear_bit_le(bit_pos + i, &dentry_blk->dentry_bitmap);
 
@@ -603,7 +635,6 @@ bool f2fs_empty_dir(struct inode *dir)
 	unsigned long nblock = dir_blocks(dir);
 
 	for (bidx = 0; bidx < nblock; bidx++) {
-		void *kaddr;
 		dentry_page = get_lock_data_page(dir, bidx);
 		if (IS_ERR(dentry_page)) {
 			if (PTR_ERR(dentry_page) == -ENOENT)
@@ -612,8 +643,8 @@ bool f2fs_empty_dir(struct inode *dir)
 				return false;
 		}
 
-		kaddr = kmap_atomic(dentry_page);
-		dentry_blk = (struct f2fs_dentry_block *)kaddr;
+
+		dentry_blk = kmap_atomic(dentry_page);
 		if (bidx == 0)
 			bit_pos = 2;
 		else
@@ -621,7 +652,7 @@ bool f2fs_empty_dir(struct inode *dir)
 		bit_pos = find_next_bit_le(&dentry_blk->dentry_bitmap,
 						NR_DENTRY_IN_BLOCK,
 						bit_pos);
-		kunmap_atomic(kaddr);
+		kunmap_atomic(dentry_blk);
 
 		f2fs_put_page(dentry_page, 1);
 
@@ -634,11 +665,11 @@ bool f2fs_empty_dir(struct inode *dir)
 static int f2fs_readdir(struct file *file, void *dirent, filldir_t filldir)
 {
 	unsigned long pos = file->f_pos;
-	struct inode *inode = file->f_dentry->d_inode;
-	unsigned long npages = dir_blocks(inode);
 	unsigned char *types = NULL;
 	unsigned int bit_pos = 0, start_bit_pos = 0;
 	int over = 0;
+	struct inode *inode = file_inode(file);
+	unsigned long npages = dir_blocks(inode);
 	struct f2fs_dentry_block *dentry_blk = NULL;
 	struct f2fs_dir_entry *de = NULL;
 	struct page *dentry_page = NULL;
@@ -682,7 +713,7 @@ static int f2fs_readdir(struct file *file, void *dirent, filldir_t filldir)
 					le32_to_cpu(de->ino), d_type);
 			if (over) {
 				file->f_pos += bit_pos - start_bit_pos;
-				goto success;
+				goto stop;
 			}
 			slots = GET_DENTRY_SLOTS(le16_to_cpu(de->name_len));
 			bit_pos += slots;
@@ -693,7 +724,7 @@ static int f2fs_readdir(struct file *file, void *dirent, filldir_t filldir)
 		f2fs_put_page(dentry_page, 1);
 		dentry_page = NULL;
 	}
-success:
+stop:
 	if (dentry_page && !IS_ERR(dentry_page)) {
 		kunmap(dentry_page);
 		f2fs_put_page(dentry_page, 1);
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 14afbe76..c7911438 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -22,7 +22,7 @@
 
 #ifdef CONFIG_F2FS_CHECK_FS
 #define f2fs_bug_on(condition)	BUG_ON(condition)
-#define f2fs_down_write(x, y)	down_write_nest_lock(x, y)
+#define f2fs_down_write(x, y)	down_write(x)
 #else
 #define f2fs_bug_on(condition)
 #define f2fs_down_write(x, y)	down_write(x)
@@ -31,6 +31,7 @@
 /*
  * For mount options
  */
+#define F2FS_SUPER_MAGIC	0xF2F52010	/* F2FS Magic Number */
 #define F2FS_MOUNT_BG_GC		0x00000001
 #define F2FS_MOUNT_DISABLE_ROLL_FORWARD	0x00000002
 #define F2FS_MOUNT_DISCARD		0x00000004
@@ -40,6 +41,7 @@
 #define F2FS_MOUNT_DISABLE_EXT_IDENTIFY	0x00000040
 #define F2FS_MOUNT_INLINE_XATTR		0x00000080
 #define F2FS_MOUNT_INLINE_DATA		0x00000100
+#define F2FS_MOUNT_FLUSH_MERGE		0x00000200
 
 #define clear_opt(sbi, option)	(sbi->mount_opt.opt &= ~F2FS_MOUNT_##option)
 #define set_opt(sbi, option)	(sbi->mount_opt.opt |= F2FS_MOUNT_##option)
@@ -190,7 +192,7 @@ struct extent_info {
 	rwlock_t ext_lock;	/* rwlock for consistency */
 	unsigned int fofs;	/* start offset in a file */
 	u32 blk_addr;		/* start block address of the extent */
-	unsigned int len;	/* lenth of the extent */
+	unsigned int len;	/* length of the extent */
 };
 
 /*
@@ -255,6 +257,8 @@ struct f2fs_nm_info {
 	unsigned int nat_cnt;		/* the # of cached nat entries */
 	struct list_head nat_entries;	/* cached nat entry list (clean) */
 	struct list_head dirty_nat_entries; /* cached nat entry list (dirty) */
+	struct list_head nat_entry_set;	/* nat entry set list */
+	unsigned int dirty_nat_cnt;	/* total num of nat entries in set */
 
 	/* free node ids management */
 	struct radix_tree_root free_nid_root;/* root of the free_nid cache */
@@ -320,6 +324,21 @@ enum {
 	NO_CHECK_TYPE
 };
 
+struct flush_cmd {
+	struct flush_cmd *next;
+	struct completion wait;
+	int ret;
+};
+
+struct flush_cmd_control {
+	struct task_struct *f2fs_issue_flush;	/* flush thread */
+	wait_queue_head_t flush_wait_queue;	/* waiting queue for wake-up */
+	struct flush_cmd *issue_list;		/* list for command issue */
+	struct flush_cmd *dispatch_list;	/* list for command dispatch */
+	spinlock_t issue_lock;			/* for issue list lock */
+	struct flush_cmd *issue_tail;		/* list tail of issue list */
+};
+
 struct f2fs_sm_info {
 	struct sit_info *sit_info;		/* whole segment information */
 	struct free_segmap_info *free_info;	/* free segment information */
@@ -345,6 +364,10 @@ struct f2fs_sm_info {
 
 	unsigned int ipu_policy;	/* in-place-update policy */
 	unsigned int min_ipu_util;	/* in-place-update threshold */
+
+	/* for flush command control */
+	struct flush_cmd_control *cmd_control_info;
+
 };
 
 /*
@@ -395,7 +418,7 @@ struct f2fs_bio_info {
 	struct bio *bio;		/* bios to merge */
 	sector_t last_block_in_bio;	/* last block number */
 	struct f2fs_io_info fio;	/* store buffered io info. */
-	struct mutex io_mutex;		/* mutex for bio */
+	struct rw_semaphore io_rwsem;	/* blocking op for bio */
 };
 
 struct f2fs_sb_info {
@@ -1058,6 +1081,27 @@ static inline int f2fs_readonly(struct super_block *sb)
 	return sb->s_flags & MS_RDONLY;
 }
 
+static inline void f2fs_stop_checkpoint(struct f2fs_sb_info *sbi)
+{
+	set_ckpt_flags(sbi->ckpt, CP_ERROR_FLAG);
+	sbi->sb->s_flags |= MS_RDONLY;
+}
+
+static inline struct inode *file_inode(struct file *f)
+{
+	return f->f_path.dentry->d_inode;
+}
+
+#define get_inode_mode(i) \
+	((is_inode_flag_set(F2FS_I(i), FI_ACL_MODE)) ? \
+	 (F2FS_I(i)->i_acl_mode) : ((i)->i_mode))
+
+/* get offset of first page in next direct node */
+#define PGOFS_OF_NEXT_DNODE(pgofs, fi)				\
+	((pgofs < ADDRS_PER_INODE(fi)) ? ADDRS_PER_INODE(fi) :	\
+	(pgofs - ADDRS_PER_INODE(fi) + ADDRS_PER_BLOCK) /	\
+	ADDRS_PER_BLOCK * ADDRS_PER_BLOCK + ADDRS_PER_INODE(fi))
+
 /*
  * file.c
  */
@@ -1100,6 +1144,7 @@ void f2fs_set_link(struct inode *, struct f2fs_dir_entry *,
 int update_dent_inode(struct inode *, const struct qstr *);
 int __f2fs_add_link(struct inode *, const struct qstr *, struct inode *);
 void f2fs_delete_entry(struct f2fs_dir_entry *, struct page *, struct inode *);
+int f2fs_do_tmpfile(struct inode *, struct inode *);
 int f2fs_make_empty(struct inode *, struct inode *);
 bool f2fs_empty_dir(struct inode *);
 
@@ -1119,7 +1164,7 @@ void f2fs_msg(struct super_block *, const char *, const char *, ...);
 /*
  * hash.c
  */
-f2fs_hash_t f2fs_dentry_hash(const char *, size_t);
+f2fs_hash_t f2fs_dentry_hash(const struct qstr *);
 
 /*
  * node.c
@@ -1137,7 +1182,7 @@ int truncate_inode_blocks(struct inode *, pgoff_t);
 int truncate_xattr_node(struct inode *, struct page *);
 int wait_on_node_pages_writeback(struct f2fs_sb_info *, nid_t);
 void remove_inode_page(struct inode *);
-struct page *new_inode_page(struct inode *, const struct qstr *);
+struct page *new_inode_page(struct inode *);
 struct page *new_node_page(struct dnode_of_data *, unsigned int, struct page *);
 void ra_node_page(struct f2fs_sb_info *, nid_t);
 struct page *get_node_page(struct f2fs_sb_info *, pgoff_t);
@@ -1164,6 +1209,9 @@ void destroy_node_manager_caches(void);
  */
 void f2fs_balance_fs(struct f2fs_sb_info *);
 void f2fs_balance_fs_bg(struct f2fs_sb_info *);
+int f2fs_issue_flush(struct f2fs_sb_info *);
+int create_flush_cmd_control(struct f2fs_sb_info *);
+void destroy_flush_cmd_control(struct f2fs_sb_info *);
 void invalidate_blocks(struct f2fs_sb_info *, block_t);
 void refresh_sit_entry(struct f2fs_sb_info *, block_t, block_t);
 void clear_prefree_segments(struct f2fs_sb_info *);
@@ -1256,7 +1304,6 @@ bool space_for_roll_forward(struct f2fs_sb_info *);
 struct f2fs_stat_info {
 	struct list_head stat_list;
 	struct f2fs_sb_info *sbi;
-	struct mutex stat_lock;
 	int all_area_segs, sit_area_segs, nat_area_segs, ssa_area_segs;
 	int main_area_segs, main_area_sections, main_area_zones;
 	int hit_ext, total_ext;
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 0e147b6c..0e88a75c 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -19,6 +19,7 @@
 #include <linux/compat.h>
 #include <linux/uaccess.h>
 #include <linux/mount.h>
+#include <linux/pagevec.h>
 
 #include "f2fs.h"
 #include "node.h"
@@ -31,22 +32,13 @@ static int f2fs_vm_page_mkwrite(struct vm_area_struct *vma,
 						struct vm_fault *vmf)
 {
 	struct page *page = vmf->page;
-	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
+	struct inode *inode = file_inode(vma->vm_file);
 	struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
 	struct dnode_of_data dn;
 	int err;
 
 	f2fs_balance_fs(sbi);
 
-	/* F2FS backport: We replace in old kernels sb_start_pagefault(inode->i_sb) with vfs_check_frozen()
-	 * and remove the original sb_end_pagefault(inode->i_sb) after the out label
-	 *
-	 * The introduction of sb_{start,end}_pagefault() was made post-3.2 kernels by Jan Kara
-	 * and merged in commit a0e881b7c189fa2bd76c024dbff91e79511c971d.
-	 * Discussed at https://lkml.org/lkml/2012/3/5/278
-	 *
-	 * - Alex
-	 */
 	vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
 
 	/* block allocation */
@@ -91,8 +83,8 @@ out:
 }
 
 static const struct vm_operations_struct f2fs_file_vm_ops = {
-	.fault        = filemap_fault,
-	.page_mkwrite = f2fs_vm_page_mkwrite,
+	.fault		= filemap_fault,
+	.page_mkwrite	= f2fs_vm_page_mkwrite,
 };
 
 static int get_parent_ino(struct inode *inode, nid_t *pino)
@@ -193,18 +185,161 @@ int f2fs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 		ret = wait_on_node_pages_writeback(sbi, inode->i_ino);
 		if (ret)
 			goto out;
-		ret = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
+		ret = f2fs_issue_flush(F2FS_SB(inode->i_sb));
 	}
 out:
 	trace_f2fs_sync_file_exit(inode, need_cp, datasync, ret);
 	return ret;
 }
 
+static pgoff_t __get_first_dirty_index(struct address_space *mapping,
+						pgoff_t pgofs, int whence)
+{
+	struct pagevec pvec;
+	int nr_pages;
+
+	if (whence != SEEK_DATA)
+		return 0;
+
+	/* find first dirty page index */
+	pagevec_init(&pvec, 0);
+	nr_pages = pagevec_lookup_tag(&pvec, mapping, &pgofs, PAGECACHE_TAG_DIRTY, 1);
+	pgofs = nr_pages ? pvec.pages[0]->index: LONG_MAX;
+	pagevec_release(&pvec);
+	return pgofs;
+}
+
+static bool __found_offset(block_t blkaddr, pgoff_t dirty, pgoff_t pgofs,
+							int whence)
+{
+	switch (whence) {
+	case SEEK_DATA:
+		if ((blkaddr == NEW_ADDR && dirty == pgofs) ||
+			(blkaddr != NEW_ADDR && blkaddr != NULL_ADDR))
+			return true;
+		break;
+	case SEEK_HOLE:
+		if (blkaddr == NULL_ADDR)
+			return true;
+		break;
+	}
+	return false;
+}
+
+static inline int unsigned_offsets(struct file *file)
+{
+	return file->f_mode & FMODE_UNSIGNED_OFFSET;
+}
+
+static loff_t vfs_setpos(struct file *file, loff_t offset, loff_t maxsize)
+{
+	if (offset < 0 && !unsigned_offsets(file))
+		return -EINVAL;
+	if (offset > maxsize)
+		return -EINVAL;
+
+	if (offset != file->f_pos) {
+		file->f_pos = offset;
+		file->f_version = 0;
+	}
+	return offset;
+}
+
+static loff_t f2fs_seek_block(struct file *file, loff_t offset, int whence)
+{
+	struct inode *inode = file->f_mapping->host;
+	loff_t maxbytes = inode->i_sb->s_maxbytes;
+	struct dnode_of_data dn;
+	pgoff_t pgofs, end_offset, dirty;
+	loff_t data_ofs = offset;
+	loff_t isize;
+	int err = 0;
+
+	mutex_lock(&inode->i_mutex);
+
+	isize = i_size_read(inode);
+	if (offset >= isize)
+		goto fail;
+
+	/* handle inline data case */
+	if (f2fs_has_inline_data(inode)) {
+		if (whence == SEEK_HOLE)
+			data_ofs = isize;
+		goto found;
+	}
+
+	pgofs = (pgoff_t)(offset >> PAGE_CACHE_SHIFT);
+
+	dirty = __get_first_dirty_index(inode->i_mapping, pgofs, whence);
+
+	for (; data_ofs < isize; data_ofs = pgofs << PAGE_CACHE_SHIFT) {
+		set_new_dnode(&dn, inode, NULL, NULL, 0);
+		err = get_dnode_of_data(&dn, pgofs, LOOKUP_NODE_RA);
+		if (err && err != -ENOENT) {
+			goto fail;
+		} else if (err == -ENOENT) {
+			/* direct node is not exist */
+			if (whence == SEEK_DATA) {
+				pgofs = PGOFS_OF_NEXT_DNODE(pgofs,
+							F2FS_I(inode));
+				continue;
+			} else {
+				goto found;
+			}
+		}
+
+		end_offset = ADDRS_PER_PAGE(dn.node_page, F2FS_I(inode));
+
+		/* find data/hole in dnode block */
+		for (; dn.ofs_in_node < end_offset;
+				dn.ofs_in_node++, pgofs++,
+				data_ofs = pgofs << PAGE_CACHE_SHIFT) {
+			block_t blkaddr;
+			blkaddr = datablock_addr(dn.node_page, dn.ofs_in_node);
+
+			if (__found_offset(blkaddr, dirty, pgofs, whence)) {
+				f2fs_put_dnode(&dn);
+				goto found;
+			}
+		}
+		f2fs_put_dnode(&dn);
+	}
+
+	if (whence == SEEK_DATA)
+		goto fail;
+found:
+	if (whence == SEEK_HOLE && data_ofs > isize)
+		data_ofs = isize;
+	mutex_unlock(&inode->i_mutex);
+	return vfs_setpos(file, data_ofs, maxbytes);
+fail:
+	mutex_unlock(&inode->i_mutex);
+	return -ENXIO;
+}
+
+static loff_t f2fs_llseek(struct file *file, loff_t offset, int whence)
+{
+	struct inode *inode = file->f_mapping->host;
+	loff_t maxbytes = inode->i_sb->s_maxbytes;
+
+	switch (whence) {
+	case SEEK_SET:
+	case SEEK_CUR:
+	case SEEK_END:
+		return generic_file_llseek_size(file, offset, whence,
+						maxbytes);
+	case SEEK_DATA:
+	case SEEK_HOLE:
+		return f2fs_seek_block(file, offset, whence);
+	}
+
+	return -EINVAL;
+}
+
 static int f2fs_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	file_accessed(file);
 	vma->vm_ops = &f2fs_file_vm_ops;
-	vma->vm_flags |= VM_CAN_NONLINEAR;
 	return 0;
 }
 
@@ -260,13 +395,15 @@ static void truncate_partial_data_page(struct inode *inode, u64 from)
 		return;
 
 	lock_page(page);
-	if (unlikely(page->mapping != inode->i_mapping)) {
-		f2fs_put_page(page, 1);
-		return;
-	}
+	if (unlikely(!PageUptodate(page) ||
+			page->mapping != inode->i_mapping))
+		goto out;
+
 	f2fs_wait_on_page_writeback(page, DATA);
 	zero_user(page, offset, PAGE_CACHE_SIZE - offset);
 	set_page_dirty(page);
+
+out:
 	f2fs_put_page(page, 1);
 }
 
@@ -575,7 +712,7 @@ noalloc:
 static long f2fs_fallocate(struct file *file, int mode,
 				loff_t offset, loff_t len)
 {
-	struct inode *inode = file->f_path.dentry->d_inode;
+	struct inode *inode = file_inode(file);
 	long ret;
 
 	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
@@ -614,7 +751,7 @@ static inline __u32 f2fs_mask_flags(umode_t mode, __u32 flags)
 
 long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
-	struct inode *inode = filp->f_dentry->d_inode;
+	struct inode *inode = file_inode(filp);
 	struct f2fs_inode_info *fi = F2FS_I(inode);
 	unsigned int flags;
 	int ret;
@@ -627,7 +764,7 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	{
 		unsigned int oldflags;
 
-		ret = mnt_want_write(filp->f_path.mnt);
+		ret = mnt_want_write_file(filp);
 		if (ret)
 			return ret;
 
@@ -664,7 +801,7 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		inode->i_ctime = CURRENT_TIME;
 		mark_inode_dirty(inode);
 out:
-		mnt_drop_write(filp->f_path.mnt);
+		mnt_drop_write_file(filp);
 		return ret;
 	}
 	default:
@@ -690,7 +827,7 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 #endif
 
 const struct file_operations f2fs_file_operations = {
-	.llseek		= generic_file_llseek,
+	.llseek		= f2fs_llseek,
 	.read		= do_sync_read,
 	.write		= do_sync_write,
 	.aio_read	= generic_file_aio_read,
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 115de744..47c51eda 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -45,6 +45,11 @@ static int gc_thread_func(void *data)
 		if (kthread_should_stop())
 			break;
 
+		if (sbi->sb->s_frozen >= SB_FREEZE_WRITE) {
+			wait_ms = increase_sleep_time(gc_th, wait_ms);
+			continue;
+		}
+
 		/*
 		 * [GC triggering condition]
 		 * 0. GC is not conducted currently.
@@ -246,7 +251,7 @@ static inline unsigned int get_gc_cost(struct f2fs_sb_info *sbi,
 }
 
 /*
- * This function is called from two pathes.
+ * This function is called from two paths.
  * One is garbage collection and the other is SSR segment selection.
  * When it is called during GC, it just gets a victim segment
  * and it does not remove it from dirty seglist.
diff --git a/fs/f2fs/hash.c b/fs/f2fs/hash.c
index 6eb8d269..948d17bf 100644
--- a/fs/f2fs/hash.c
+++ b/fs/f2fs/hash.c
@@ -69,12 +69,14 @@ static void str2hashbuf(const char *msg, size_t len, unsigned int *buf, int num)
 		*buf++ = pad;
 }
 
-f2fs_hash_t f2fs_dentry_hash(const char *name, size_t len)
+f2fs_hash_t f2fs_dentry_hash(const struct qstr *name_info)
 {
 	__u32 hash;
 	f2fs_hash_t f2fs_hash;
 	const char *p;
 	__u32 in[8], buf[4];
+	const char *name = name_info->name;
+	size_t len = name_info->len;
 
 	if ((len <= 2) && (name[0] == '.') &&
 		(name[1] == '.' || name[1] == '\0'))
diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index eb481282..679ee78f 100644
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -12,7 +12,6 @@
 #include <linux/f2fs_fs.h>
 #include <linux/buffer_head.h>
 #include <linux/writeback.h>
-#include <linux/bitops.h>
 
 #include "f2fs.h"
 #include "node.h"
@@ -22,20 +21,20 @@
 void f2fs_set_inode_flags(struct inode *inode)
 {
 	unsigned int flags = F2FS_I(inode)->i_flags;
-	unsigned int new_fl = 0;
+
+	inode->i_flags &= ~(S_SYNC | S_APPEND | S_IMMUTABLE |
+			S_NOATIME | S_DIRSYNC);
 
 	if (flags & FS_SYNC_FL)
-		new_fl |= S_SYNC;
+		inode->i_flags |= S_SYNC;
 	if (flags & FS_APPEND_FL)
-		new_fl |= S_APPEND;
+		inode->i_flags |= S_APPEND;
 	if (flags & FS_IMMUTABLE_FL)
-		new_fl |= S_IMMUTABLE;
+		inode->i_flags |= S_IMMUTABLE;
 	if (flags & FS_NOATIME_FL)
-		new_fl |= S_NOATIME;
+		inode->i_flags |= S_NOATIME;
 	if (flags & FS_DIRSYNC_FL)
-		new_fl |= S_DIRSYNC;
-	set_mask_bits(&inode->i_flags,
-			S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC, new_fl);
+		inode->i_flags |= S_DIRSYNC;
 }
 
 static void __get_inode_rdev(struct inode *inode, struct f2fs_inode *ri)
@@ -289,4 +288,5 @@ void f2fs_evict_inode(struct inode *inode)
 
 no_delete:
 	end_writeback(inode);
+	invalidate_mapping_pages(NODE_MAPPING(sbi), inode->i_ino, inode->i_ino);
 }
diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index ea38fc58..cb9abf94 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -13,6 +13,7 @@
 #include <linux/pagemap.h>
 #include <linux/sched.h>
 #include <linux/ctype.h>
+#include <linux/dcache.h>
 
 #include "f2fs.h"
 #include "node.h"
@@ -22,14 +23,13 @@
 
 static struct inode *f2fs_new_inode(struct inode *dir, umode_t mode)
 {
-	struct super_block *sb = dir->i_sb;
-	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
 	nid_t ino;
 	struct inode *inode;
 	bool nid_free = false;
 	int err;
 
-	inode = new_inode(sb);
+	inode = new_inode(dir->i_sb);
 	if (!inode)
 		return ERR_PTR(-ENOMEM);
 
@@ -41,18 +41,9 @@ static struct inode *f2fs_new_inode(struct inode *dir, umode_t mode)
 	}
 	f2fs_unlock_op(sbi);
 
-	inode->i_uid = current_fsuid();
-
-	if (dir->i_mode & S_ISGID) {
-		inode->i_gid = dir->i_gid;
-		if (S_ISDIR(mode))
-			mode |= S_ISGID;
-	} else {
-		inode->i_gid = current_fsgid();
-	}
+	inode_init_owner(inode, dir, mode);
 
 	inode->i_ino = ino;
-	inode->i_mode = mode;
 	inode->i_blocks = 0;
 	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 	inode->i_generation = sbi->s_next_generation++;
@@ -109,10 +100,9 @@ static inline void set_cold_files(struct f2fs_sb_info *sbi, struct inode *inode,
 }
 
 static int f2fs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
-						struct nameidata *nd)
+		       struct nameidata *nd)
 {
-	struct super_block *sb = dir->i_sb;
-	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
 	struct inode *inode;
 	nid_t ino = 0;
 	int err;
@@ -155,8 +145,7 @@ static int f2fs_link(struct dentry *old_dentry, struct inode *dir,
 		struct dentry *dentry)
 {
 	struct inode *inode = old_dentry->d_inode;
-	struct super_block *sb = dir->i_sb;
-	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
 	int err;
 
 	f2fs_balance_fs(sbi);
@@ -181,7 +170,7 @@ out:
 
 struct dentry *f2fs_get_parent(struct dentry *child)
 {
-	struct qstr dotdot = { .name = "..", .len = 2 };
+	struct qstr dotdot = {.len = 2, .name = ".."};
 	unsigned long ino = f2fs_inode_by_name(child->d_inode, &dotdot);
 	if (!ino)
 		return ERR_PTR(-ENOENT);
@@ -189,7 +178,7 @@ struct dentry *f2fs_get_parent(struct dentry *child)
 }
 
 static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
-		struct nameidata *nd)
+					struct nameidata *nd)
 {
 	struct inode *inode = NULL;
 	struct f2fs_dir_entry *de;
@@ -216,8 +205,7 @@ static struct dentry *f2fs_lookup(struct inode *dir, struct dentry *dentry,
 
 static int f2fs_unlink(struct inode *dir, struct dentry *dentry)
 {
-	struct super_block *sb = dir->i_sb;
-	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
 	struct inode *inode = dentry->d_inode;
 	struct f2fs_dir_entry *de;
 	struct page *page;
@@ -251,8 +239,7 @@ fail:
 static int f2fs_symlink(struct inode *dir, struct dentry *dentry,
 					const char *symname)
 {
-	struct super_block *sb = dir->i_sb;
-	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
 	struct inode *inode;
 	size_t symlen = strlen(symname) + 1;
 	int err;
@@ -339,8 +326,7 @@ static int f2fs_rmdir(struct inode *dir, struct dentry *dentry)
 static int f2fs_mknod(struct inode *dir, struct dentry *dentry,
 				umode_t mode, dev_t rdev)
 {
-	struct super_block *sb = dir->i_sb;
-	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	struct f2fs_sb_info *sbi = F2FS_SB(dir->i_sb);
 	struct inode *inode;
 	int err = 0;
 
@@ -378,8 +364,7 @@ out:
 static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
 			struct inode *new_dir, struct dentry *new_dentry)
 {
-	struct super_block *sb = old_dir->i_sb;
-	struct f2fs_sb_info *sbi = F2FS_SB(sb);
+	struct f2fs_sb_info *sbi = F2FS_SB(old_dir->i_sb);
 	struct inode *old_inode = old_dentry->d_inode;
 	struct inode *new_inode = new_dentry->d_inode;
 	struct page *old_dir_page;
@@ -402,8 +387,6 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
 			goto out_old;
 	}
 
-	f2fs_lock_op(sbi);
-
 	if (new_inode) {
 
 		err = -ENOTEMPTY;
@@ -416,6 +399,8 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
 		if (!new_entry)
 			goto out_dir;
 
+		f2fs_lock_op(sbi);
+
 		err = acquire_orphan_inode(sbi);
 		if (err)
 			goto put_out_dir;
@@ -444,9 +429,13 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
 		update_inode_page(old_inode);
 		update_inode_page(new_inode);
 	} else {
+		f2fs_lock_op(sbi);
+
 		err = f2fs_add_link(new_dentry, old_inode);
-		if (err)
+		if (err) {
+			f2fs_unlock_op(sbi);
 			goto out_dir;
+		}
 
 		if (old_dir_entry) {
 			inc_nlink(new_dir);
@@ -481,6 +470,7 @@ static int f2fs_rename(struct inode *old_dir, struct dentry *old_dentry,
 	return 0;
 
 put_out_dir:
+	f2fs_unlock_op(sbi);
 	kunmap(new_page);
 	f2fs_put_page(new_page, 0);
 out_dir:
@@ -488,7 +478,6 @@ out_dir:
 		kunmap(old_dir_page);
 		f2fs_put_page(old_dir_page, 0);
 	}
-	f2fs_unlock_op(sbi);
 out_old:
 	kunmap(old_page);
 	f2fs_put_page(old_page, 0);
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index a494e721..fa1e0c98 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -25,6 +25,7 @@
 
 static struct kmem_cache *nat_entry_slab;
 static struct kmem_cache *free_nid_slab;
+static struct kmem_cache *nat_entry_set_slab;
 
 bool available_free_memory(struct f2fs_sb_info *sbi, int type)
 {
@@ -90,12 +91,8 @@ static struct page *get_next_nat_page(struct f2fs_sb_info *sbi, nid_t nid)
 
 	/* get current nat block page with lock */
 	src_page = get_meta_page(sbi, src_off);
-
-	/* Dirty src_page means that it is already the new target NAT page. */
-	if (PageDirty(src_page))
-		return src_page;
-
 	dst_page = grab_meta_page(sbi, dst_off);
+	f2fs_bug_on(PageDirty(src_page));
 
 	src_addr = page_address(src_page);
 	dst_addr = page_address(dst_page);
@@ -845,7 +842,7 @@ void remove_inode_page(struct inode *inode)
 	truncate_node(&dn);
 }
 
-struct page *new_inode_page(struct inode *inode, const struct qstr *name)
+struct page *new_inode_page(struct inode *inode)
 {
 	struct dnode_of_data dn;
 
@@ -984,7 +981,6 @@ repeat:
 		goto repeat;
 	}
 got_it:
-	mark_page_accessed(page);
 	return page;
 }
 
@@ -1039,7 +1035,6 @@ page_hit:
 		f2fs_put_page(page, 1);
 		return ERR_PTR(-EIO);
 	}
-	mark_page_accessed(page);
 	return page;
 }
 
@@ -1745,7 +1740,90 @@ skip:
 	return err;
 }
 
-static bool flush_nats_in_journal(struct f2fs_sb_info *sbi)
+static struct nat_entry_set *grab_nat_entry_set(void)
+{
+	struct nat_entry_set *nes =
+			f2fs_kmem_cache_alloc(nat_entry_set_slab, GFP_ATOMIC);
+
+	nes->entry_cnt = 0;
+	INIT_LIST_HEAD(&nes->set_list);
+	INIT_LIST_HEAD(&nes->entry_list);
+	return nes;
+}
+
+static void release_nat_entry_set(struct nat_entry_set *nes,
+						struct f2fs_nm_info *nm_i)
+{
+	f2fs_bug_on(!list_empty(&nes->entry_list));
+
+	nm_i->dirty_nat_cnt -= nes->entry_cnt;
+	list_del(&nes->set_list);
+	kmem_cache_free(nat_entry_set_slab, nes);
+}
+
+static void adjust_nat_entry_set(struct nat_entry_set *nes,
+						struct list_head *head)
+{
+	struct nat_entry_set *next = nes;
+
+	if (list_is_last(&nes->set_list, head))
+		return;
+
+	list_for_each_entry_continue(next, head, set_list)
+		if (nes->entry_cnt <= next->entry_cnt)
+			break;
+
+	list_move_tail(&nes->set_list, &next->set_list);
+}
+
+static void add_nat_entry(struct nat_entry *ne, struct list_head *head)
+{
+	struct nat_entry_set *nes;
+	nid_t start_nid = START_NID(ne->ni.nid);
+
+	list_for_each_entry(nes, head, set_list) {
+		if (nes->start_nid == start_nid) {
+			list_move_tail(&ne->list, &nes->entry_list);
+			nes->entry_cnt++;
+			adjust_nat_entry_set(nes, head);
+			return;
+		}
+	}
+
+	nes = grab_nat_entry_set();
+
+	nes->start_nid = start_nid;
+	list_move_tail(&ne->list, &nes->entry_list);
+	nes->entry_cnt++;
+	list_add(&nes->set_list, head);
+}
+
+static void merge_nats_in_set(struct f2fs_sb_info *sbi)
+{
+	struct f2fs_nm_info *nm_i = NM_I(sbi);
+	struct list_head *dirty_list = &nm_i->dirty_nat_entries;
+	struct list_head *set_list = &nm_i->nat_entry_set;
+	struct nat_entry *ne, *tmp;
+
+	write_lock(&nm_i->nat_tree_lock);
+	list_for_each_entry_safe(ne, tmp, dirty_list, list) {
+		if (nat_get_blkaddr(ne) == NEW_ADDR)
+			continue;
+		add_nat_entry(ne, set_list);
+		nm_i->dirty_nat_cnt++;
+	}
+	write_unlock(&nm_i->nat_tree_lock);
+}
+
+static bool __has_cursum_space(struct f2fs_summary_block *sum, int size)
+{
+	if (nats_in_cursum(sum) + size <= NAT_JOURNAL_ENTRIES)
+		return true;
+	else
+		return false;
+}
+
+static void remove_nats_in_journal(struct f2fs_sb_info *sbi)
 {
 	struct f2fs_nm_info *nm_i = NM_I(sbi);
 	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
@@ -1753,12 +1831,6 @@ static bool flush_nats_in_journal(struct f2fs_sb_info *sbi)
 	int i;
 
 	mutex_lock(&curseg->curseg_mutex);
-
-	if (nats_in_cursum(sum) < NAT_JOURNAL_ENTRIES) {
-		mutex_unlock(&curseg->curseg_mutex);
-		return false;
-	}
-
 	for (i = 0; i < nats_in_cursum(sum); i++) {
 		struct nat_entry *ne;
 		struct f2fs_nat_entry raw_ne;
@@ -1768,23 +1840,21 @@ static bool flush_nats_in_journal(struct f2fs_sb_info *sbi)
 retry:
 		write_lock(&nm_i->nat_tree_lock);
 		ne = __lookup_nat_cache(nm_i, nid);
-		if (ne) {
-			__set_nat_cache_dirty(nm_i, ne);
-			write_unlock(&nm_i->nat_tree_lock);
-			continue;
-		}
+		if (ne)
+			goto found;
+
 		ne = grab_nat_entry(nm_i, nid);
 		if (!ne) {
 			write_unlock(&nm_i->nat_tree_lock);
 			goto retry;
 		}
 		node_info_from_raw_nat(&ne->ni, &raw_ne);
+found:
 		__set_nat_cache_dirty(nm_i, ne);
 		write_unlock(&nm_i->nat_tree_lock);
 	}
 	update_nats_in_cursum(sum, -i);
 	mutex_unlock(&curseg->curseg_mutex);
-	return true;
 }
 
 /*
@@ -1795,80 +1865,91 @@ void flush_nat_entries(struct f2fs_sb_info *sbi)
 	struct f2fs_nm_info *nm_i = NM_I(sbi);
 	struct curseg_info *curseg = CURSEG_I(sbi, CURSEG_HOT_DATA);
 	struct f2fs_summary_block *sum = curseg->sum_blk;
-	struct nat_entry *ne, *cur;
-	struct page *page = NULL;
-	struct f2fs_nat_block *nat_blk = NULL;
-	nid_t start_nid = 0, end_nid = 0;
-	bool flushed;
-
-	flushed = flush_nats_in_journal(sbi);
+	struct nat_entry_set *nes, *tmp;
+	struct list_head *head = &nm_i->nat_entry_set;
+	bool to_journal = true;
 
-	if (!flushed)
-		mutex_lock(&curseg->curseg_mutex);
+	/* merge nat entries of dirty list to nat entry set temporarily */
+	merge_nats_in_set(sbi);
 
-	/* 1) flush dirty nat caches */
-	list_for_each_entry_safe(ne, cur, &nm_i->dirty_nat_entries, list) {
-		nid_t nid;
-		struct f2fs_nat_entry raw_ne;
-		int offset = -1;
-
-		if (nat_get_blkaddr(ne) == NEW_ADDR)
-			continue;
-
-		nid = nat_get_nid(ne);
+	/*
+	 * if there are no enough space in journal to store dirty nat
+	 * entries, remove all entries from journal and merge them
+	 * into nat entry set.
+	 */
+	if (!__has_cursum_space(sum, nm_i->dirty_nat_cnt)) {
+		remove_nats_in_journal(sbi);
 
-		if (flushed)
-			goto to_nat_page;
+		/*
+		 * merge nat entries of dirty list to nat entry set temporarily
+		 */
+		merge_nats_in_set(sbi);
+	}
 
-		/* if there is room for nat enries in curseg->sumpage */
-		offset = lookup_journal_in_cursum(sum, NAT_JOURNAL, nid, 1);
-		if (offset >= 0) {
-			raw_ne = nat_in_journal(sum, offset);
-			goto flush_now;
-		}
-to_nat_page:
-		if (!page || (start_nid > nid || nid > end_nid)) {
-			if (page) {
-				f2fs_put_page(page, 1);
-				page = NULL;
-			}
-			start_nid = START_NID(nid);
-			end_nid = start_nid + NAT_ENTRY_PER_BLOCK - 1;
+	if (!nm_i->dirty_nat_cnt)
+		return;
 
-			/*
-			 * get nat block with dirty flag, increased reference
-			 * count, mapped and lock
-			 */
+	/*
+	 * there are two steps to flush nat entries:
+	 * #1, flush nat entries to journal in current hot data summary block.
+	 * #2, flush nat entries to nat page.
+	 */
+	list_for_each_entry_safe(nes, tmp, head, set_list) {
+		struct f2fs_nat_block *nat_blk;
+		struct nat_entry *ne, *cur;
+		struct page *page;
+		nid_t start_nid = nes->start_nid;
+
+		if (to_journal && !__has_cursum_space(sum, nes->entry_cnt))
+			to_journal = false;
+
+		if (to_journal) {
+			mutex_lock(&curseg->curseg_mutex);
+		} else {
 			page = get_next_nat_page(sbi, start_nid);
 			nat_blk = page_address(page);
+			f2fs_bug_on(!nat_blk);
 		}
 
-		f2fs_bug_on(!nat_blk);
-		raw_ne = nat_blk->entries[nid - start_nid];
-flush_now:
-		raw_nat_from_node_info(&raw_ne, &ne->ni);
-
-		if (offset < 0) {
-			nat_blk->entries[nid - start_nid] = raw_ne;
-		} else {
-			nat_in_journal(sum, offset) = raw_ne;
-			nid_in_journal(sum, offset) = cpu_to_le32(nid);
-		}
+		/* flush dirty nats in nat entry set */
+		list_for_each_entry_safe(ne, cur, &nes->entry_list, list) {
+			struct f2fs_nat_entry *raw_ne;
+			nid_t nid = nat_get_nid(ne);
+			int offset;
+
+			if (to_journal) {
+				offset = lookup_journal_in_cursum(sum,
+							NAT_JOURNAL, nid, 1);
+				f2fs_bug_on(offset < 0);
+				raw_ne = &nat_in_journal(sum, offset);
+				nid_in_journal(sum, offset) = cpu_to_le32(nid);
+			} else {
+				raw_ne = &nat_blk->entries[nid - start_nid];
+			}
+			raw_nat_from_node_info(raw_ne, &ne->ni);
 
-		if (nat_get_blkaddr(ne) == NULL_ADDR &&
+			if (nat_get_blkaddr(ne) == NULL_ADDR &&
 				add_free_nid(sbi, nid, false) <= 0) {
-			write_lock(&nm_i->nat_tree_lock);
-			__del_from_nat_cache(nm_i, ne);
-			write_unlock(&nm_i->nat_tree_lock);
-		} else {
-			write_lock(&nm_i->nat_tree_lock);
-			__clear_nat_cache_dirty(nm_i, ne);
-			write_unlock(&nm_i->nat_tree_lock);
+				write_lock(&nm_i->nat_tree_lock);
+				__del_from_nat_cache(nm_i, ne);
+				write_unlock(&nm_i->nat_tree_lock);
+			} else {
+				write_lock(&nm_i->nat_tree_lock);
+				__clear_nat_cache_dirty(nm_i, ne);
+				write_unlock(&nm_i->nat_tree_lock);
+			}
 		}
+
+		if (to_journal)
+			mutex_unlock(&curseg->curseg_mutex);
+		else
+			f2fs_put_page(page, 1);
+
+		release_nat_entry_set(nes, nm_i);
 	}
-	if (!flushed)
-		mutex_unlock(&curseg->curseg_mutex);
-	f2fs_put_page(page, 1);
+
+	f2fs_bug_on(!list_empty(head));
+	f2fs_bug_on(nm_i->dirty_nat_cnt);
 }
 
 static int init_node_manager(struct f2fs_sb_info *sbi)
@@ -1897,6 +1978,7 @@ static int init_node_manager(struct f2fs_sb_info *sbi)
 	INIT_RADIX_TREE(&nm_i->nat_root, GFP_ATOMIC);
 	INIT_LIST_HEAD(&nm_i->nat_entries);
 	INIT_LIST_HEAD(&nm_i->dirty_nat_entries);
+	INIT_LIST_HEAD(&nm_i->nat_entry_set);
 
 	mutex_init(&nm_i->build_lock);
 	spin_lock_init(&nm_i->free_nid_list_lock);
@@ -1977,19 +2059,30 @@ int __init create_node_manager_caches(void)
 	nat_entry_slab = f2fs_kmem_cache_create("nat_entry",
 			sizeof(struct nat_entry));
 	if (!nat_entry_slab)
-		return -ENOMEM;
+		goto fail;
 
 	free_nid_slab = f2fs_kmem_cache_create("free_nid",
 			sizeof(struct free_nid));
-	if (!free_nid_slab) {
-		kmem_cache_destroy(nat_entry_slab);
-		return -ENOMEM;
-	}
+	if (!free_nid_slab)
+		goto destory_nat_entry;
+
+	nat_entry_set_slab = f2fs_kmem_cache_create("nat_entry_set",
+			sizeof(struct nat_entry_set));
+	if (!nat_entry_set_slab)
+		goto destory_free_nid;
 	return 0;
+
+destory_free_nid:
+	kmem_cache_destroy(free_nid_slab);
+destory_nat_entry:
+	kmem_cache_destroy(nat_entry_slab);
+fail:
+	return -ENOMEM;
 }
 
 void destroy_node_manager_caches(void)
 {
+	kmem_cache_destroy(nat_entry_set_slab);
 	kmem_cache_destroy(free_nid_slab);
 	kmem_cache_destroy(nat_entry_slab);
 }
diff --git a/fs/f2fs/node.h b/fs/f2fs/node.h
index 7281112c..8a116a40 100644
--- a/fs/f2fs/node.h
+++ b/fs/f2fs/node.h
@@ -89,6 +89,13 @@ enum mem_type {
 	DIRTY_DENTS	/* indicates dirty dentry pages */
 };
 
+struct nat_entry_set {
+	struct list_head set_list;	/* link with all nat sets */
+	struct list_head entry_list;	/* link with dirty nat entries */
+	nid_t start_nid;		/* start nid of nats in set */
+	unsigned int entry_cnt;		/* the # of nat entries in set */
+};
+
 /*
  * For free nid mangement
  */
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 3110c295..3461bc10 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -13,6 +13,7 @@
 #include <linux/bio.h>
 #include <linux/blkdev.h>
 #include <linux/prefetch.h>
+#include <linux/kthread.h>
 #include <linux/vmalloc.h>
 #include <linux/swap.h>
 
@@ -195,6 +196,132 @@ void f2fs_balance_fs_bg(struct f2fs_sb_info *sbi)
 		f2fs_sync_fs(sbi->sb, true);
 }
 
+struct __submit_bio_ret {
+	struct completion event;
+	int error;
+};
+
+static void __submit_bio_wait_endio(struct bio *bio, int error)
+{
+	struct __submit_bio_ret *ret = bio->bi_private;
+
+	ret->error = error;
+	complete(&ret->event);
+}
+
+static int __submit_bio_wait(int rw, struct bio *bio)
+{
+	struct __submit_bio_ret ret;
+
+	rw |= REQ_SYNC;
+	init_completion(&ret.event);
+	bio->bi_private = &ret;
+	bio->bi_end_io = __submit_bio_wait_endio;
+	submit_bio(rw, bio);
+	wait_for_completion(&ret.event);
+
+	return ret.error;
+}
+
+static int issue_flush_thread(void *data)
+{
+	struct f2fs_sb_info *sbi = data;
+	struct flush_cmd_control *fcc = SM_I(sbi)->cmd_control_info;
+	wait_queue_head_t *q = &fcc->flush_wait_queue;
+repeat:
+	if (kthread_should_stop())
+		return 0;
+
+	spin_lock(&fcc->issue_lock);
+	if (fcc->issue_list) {
+		fcc->dispatch_list = fcc->issue_list;
+		fcc->issue_list = fcc->issue_tail = NULL;
+	}
+	spin_unlock(&fcc->issue_lock);
+
+	if (fcc->dispatch_list) {
+		struct bio *bio = bio_alloc(GFP_NOIO, 0);
+		struct flush_cmd *cmd, *next;
+		int ret;
+
+		bio->bi_bdev = sbi->sb->s_bdev;
+		ret = __submit_bio_wait(WRITE_FLUSH, bio);
+
+		for (cmd = fcc->dispatch_list; cmd; cmd = next) {
+			cmd->ret = ret;
+			next = cmd->next;
+			complete(&cmd->wait);
+		}
+		bio_put(bio);
+		fcc->dispatch_list = NULL;
+	}
+
+	wait_event_interruptible(*q,
+			kthread_should_stop() || fcc->issue_list);
+	goto repeat;
+}
+
+int f2fs_issue_flush(struct f2fs_sb_info *sbi)
+{
+	struct flush_cmd_control *fcc = SM_I(sbi)->cmd_control_info;
+	struct flush_cmd cmd;
+
+	if (!test_opt(sbi, FLUSH_MERGE))
+		return blkdev_issue_flush(sbi->sb->s_bdev, GFP_KERNEL, NULL);
+
+	init_completion(&cmd.wait);
+	cmd.next = NULL;
+
+	spin_lock(&fcc->issue_lock);
+	if (fcc->issue_list)
+		fcc->issue_tail->next = &cmd;
+	else
+		fcc->issue_list = &cmd;
+	fcc->issue_tail = &cmd;
+	spin_unlock(&fcc->issue_lock);
+
+	if (!fcc->dispatch_list)
+		wake_up(&fcc->flush_wait_queue);
+
+	wait_for_completion(&cmd.wait);
+
+	return cmd.ret;
+}
+
+int create_flush_cmd_control(struct f2fs_sb_info *sbi)
+{
+	dev_t dev = sbi->sb->s_bdev->bd_dev;
+	struct flush_cmd_control *fcc;
+	int err = 0;
+
+	fcc = kzalloc(sizeof(struct flush_cmd_control), GFP_KERNEL);
+	if (!fcc)
+		return -ENOMEM;
+	spin_lock_init(&fcc->issue_lock);
+	init_waitqueue_head(&fcc->flush_wait_queue);
+	SM_I(sbi)->cmd_control_info = fcc;
+	fcc->f2fs_issue_flush = kthread_run(issue_flush_thread, sbi,
+				"f2fs_flush-%u:%u", MAJOR(dev), MINOR(dev));
+	if (IS_ERR(fcc->f2fs_issue_flush)) {
+		err = PTR_ERR(fcc->f2fs_issue_flush);
+		kfree(fcc);
+		SM_I(sbi)->cmd_control_info = NULL;
+		return err;
+	}
+
+	return err;
+}
+
+void destroy_flush_cmd_control(struct f2fs_sb_info *sbi)
+{
+	struct flush_cmd_control *fcc = SM_I(sbi)->cmd_control_info;
+
+	if (fcc && fcc->f2fs_issue_flush)
+		kthread_stop(fcc->f2fs_issue_flush);
+	kfree(fcc);
+	SM_I(sbi)->cmd_control_info = NULL;
+}
+
 static void __locate_dirty_segment(struct f2fs_sb_info *sbi, unsigned int segno,
 		enum dirty_type dirty_type)
 {
@@ -1057,12 +1184,37 @@ void rewrite_node_page(struct f2fs_sb_info *sbi,
 	mutex_unlock(&curseg->curseg_mutex);
 }
 
+static inline bool is_merged_page(struct f2fs_sb_info *sbi,
+					struct page *page, enum page_type type)
+{
+	enum page_type btype = PAGE_TYPE_OF_BIO(type);
+	struct f2fs_bio_info *io = &sbi->write_io[btype];
+	struct bio_vec *bvec;
+	int i;
+
+	down_read(&io->io_rwsem);
+	if (!io->bio)
+		goto out;
+
+	__bio_for_each_segment(bvec, io->bio, i, 0) {
+		if (page == bvec->bv_page) {
+			up_read(&io->io_rwsem);
+			return true;
+		}
+	}
+
+out:
+	up_read(&io->io_rwsem);
+	return false;
+}
+
 void f2fs_wait_on_page_writeback(struct page *page,
 				enum page_type type)
 {
 	struct f2fs_sb_info *sbi = F2FS_SB(page->mapping->host->i_sb);
 	if (PageWriteback(page)) {
-		f2fs_submit_merged_bio(sbi, type, WRITE);
+		if (is_merged_page(sbi, page, type))
+			f2fs_submit_merged_bio(sbi, type, WRITE);
 		wait_on_page_writeback(page);
 	}
 }
@@ -1577,7 +1729,7 @@ static int build_curseg(struct f2fs_sb_info *sbi)
 	struct curseg_info *array;
 	int i;
 
-	array = kzalloc(sizeof(*array) * NR_CURSEG_TYPE, GFP_KERNEL);
+	array = kcalloc(NR_CURSEG_TYPE, sizeof(*array), GFP_KERNEL);
 	if (!array)
 		return -ENOMEM;
 
@@ -1776,6 +1928,12 @@ int build_segment_manager(struct f2fs_sb_info *sbi)
 	sm_info->nr_discards = 0;
 	sm_info->max_discards = 0;
 
+	if (test_opt(sbi, FLUSH_MERGE) && !f2fs_readonly(sbi->sb)) {
+		err = create_flush_cmd_control(sbi);
+		if (err)
+			return err;
+	}
+
 	err = build_sit_info(sbi);
 	if (err)
 		return err;
@@ -1882,8 +2040,10 @@ static void destroy_sit_info(struct f2fs_sb_info *sbi)
 void destroy_segment_manager(struct f2fs_sb_info *sbi)
 {
 	struct f2fs_sm_info *sm_info = SM_I(sbi);
+
 	if (!sm_info)
 		return;
+	destroy_flush_cmd_control(sbi);
 	destroy_dirty_segmap(sbi);
 	destroy_curseg(sbi);
 	destroy_free_segmap(sbi);
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index ada9e025..96c1af26 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -51,6 +51,7 @@ enum {
 	Opt_disable_ext_identify,
 	Opt_inline_xattr,
 	Opt_inline_data,
+	Opt_flush_merge,
 	Opt_err,
 };
 
@@ -67,6 +68,7 @@ static match_table_t f2fs_tokens = {
 	{Opt_disable_ext_identify, "disable_ext_identify"},
 	{Opt_inline_xattr, "inline_xattr"},
 	{Opt_inline_data, "inline_data"},
+	{Opt_flush_merge, "flush_merge"},
 	{Opt_err, NULL},
 };
 
@@ -334,6 +336,9 @@ static int parse_options(struct super_block *sb, char *options)
 		case Opt_inline_data:
 			set_opt(sbi, INLINE_DATA);
 			break;
+		case Opt_flush_merge:
+			set_opt(sbi, FLUSH_MERGE);
+			break;
 		default:
 			f2fs_msg(sb, KERN_ERR,
 				"Unrecognized mount option \"%s\" or missing value",
@@ -354,7 +359,7 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb)
 
 	init_once((void *) fi);
 
-	/* Initilize f2fs-specific inode info */
+	/* Initialize f2fs-specific inode info */
 	fi->vfs_inode.i_version = 1;
 	atomic_set(&fi->dirty_dents, 0);
 	fi->i_current_depth = 1;
@@ -461,6 +466,22 @@ int f2fs_sync_fs(struct super_block *sb, int sync)
 	return 0;
 }
 
+static int f2fs_freeze(struct super_block *sb)
+{
+	int err;
+
+	if (f2fs_readonly(sb))
+		return 0;
+
+	err = f2fs_sync_fs(sb, 1);
+	return err;
+}
+
+static int f2fs_unfreeze(struct super_block *sb)
+{
+	return 0;
+}
+
 static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	struct super_block *sb = dentry->d_sb;
@@ -493,7 +514,7 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
 {
 	struct f2fs_sb_info *sbi = F2FS_SB(root->d_sb);
 
-	if (!(root->d_sb->s_flags & MS_RDONLY) && test_opt(sbi, BG_GC))
+	if (!f2fs_readonly(sbi->sb) && test_opt(sbi, BG_GC))
 		seq_printf(seq, ",background_gc=%s", "on");
 	else
 		seq_printf(seq, ",background_gc=%s", "off");
@@ -521,6 +542,8 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
 		seq_puts(seq, ",disable_ext_identify");
 	if (test_opt(sbi, INLINE_DATA))
 		seq_puts(seq, ",inline_data");
+	if (!f2fs_readonly(sbi->sb) && test_opt(sbi, FLUSH_MERGE))
+		seq_puts(seq, ",flush_merge");
 	seq_printf(seq, ",active_logs=%u", sbi->active_logs);
 
 	return 0;
@@ -571,6 +594,10 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
 	struct f2fs_sb_info *sbi = F2FS_SB(sb);
 	struct f2fs_mount_info org_mount_opt;
 	int err, active_logs;
+	bool need_restart_gc = false;
+	bool need_stop_gc = false;
+
+	sync_filesystem(sb);
 
 	/*
 	 * Save the old mount options in case we
@@ -586,9 +613,9 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
 
 	/*
 	 * Previous and new state of filesystem is RO,
-	 * so no point in checking GC conditions.
+	 * so skip checking GC and FLUSH_MERGE conditions.
 	 */
-	if ((sb->s_flags & MS_RDONLY) && (*flags & MS_RDONLY))
+	if (f2fs_readonly(sb) && (*flags & MS_RDONLY))
 		goto skip;
 
 	/*
@@ -600,18 +627,39 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
 		if (sbi->gc_thread) {
 			stop_gc_thread(sbi);
 			f2fs_sync_fs(sb, 1);
+			need_restart_gc = true;
 		}
 	} else if (test_opt(sbi, BG_GC) && !sbi->gc_thread) {
 		err = start_gc_thread(sbi);
 		if (err)
 			goto restore_opts;
+		need_stop_gc = true;
+	}
+
+	/*
+	 * We stop issue flush thread if FS is mounted as RO
+	 * or if flush_merge is not passed in mount option.
+	 */
+	if ((*flags & MS_RDONLY) || !test_opt(sbi, FLUSH_MERGE)) {
+		destroy_flush_cmd_control(sbi);
+	} else if (test_opt(sbi, FLUSH_MERGE) && !SM_I(sbi)->cmd_control_info) {
+		err = create_flush_cmd_control(sbi);
+		if (err)
+			goto restore_gc;
 	}
 skip:
 	/* Update the POSIXACL Flag */
 	 sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
 		(test_opt(sbi, POSIX_ACL) ? MS_POSIXACL : 0);
 	return 0;
-
+restore_gc:
+	if (need_restart_gc) {
+		if (start_gc_thread(sbi))
+			f2fs_msg(sbi->sb, KERN_WARNING,
+				"background gc thread is stop");
+	} else if (need_stop_gc) {
+		stop_gc_thread(sbi);
+	}
 restore_opts:
 	sbi->mount_opt = org_mount_opt;
 	sbi->active_logs = active_logs;
@@ -628,6 +676,8 @@ static struct super_operations f2fs_sops = {
 	.evict_inode	= f2fs_evict_inode,
 	.put_super	= f2fs_put_super,
 	.sync_fs	= f2fs_sync_fs,
+	.freeze_fs	= f2fs_freeze,
+	.unfreeze_fs	= f2fs_unfreeze,
 	.statfs		= f2fs_statfs,
 	.remount_fs	= f2fs_remount,
 };
@@ -900,11 +950,11 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 	sbi->por_doing = false;
 	spin_lock_init(&sbi->stat_lock);
 
-	mutex_init(&sbi->read_io.io_mutex);
+	init_rwsem(&sbi->read_io.io_rwsem);
 	sbi->read_io.sbi = sbi;
 	sbi->read_io.bio = NULL;
 	for (i = 0; i < NR_PAGE_TYPE; i++) {
-		mutex_init(&sbi->write_io[i].io_mutex);
+		init_rwsem(&sbi->write_io[i].io_rwsem);
 		sbi->write_io[i].sbi = sbi;
 		sbi->write_io[i].bio = NULL;
 	}
@@ -1031,7 +1081,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 	 * If filesystem is not mounted as read-only then
 	 * do start the gc_thread.
 	 */
-	if (!(sb->s_flags & MS_RDONLY)) {
+	if (!f2fs_readonly(sb)) {
 		/* After POR, we can run background GC thread.*/
 		err = start_gc_thread(sbi);
 		if (err)
diff --git a/include/trace/events/f2fs.h b/include/trace/events/f2fs.h
index 81e131ed..a08c68d1 100644
--- a/include/trace/events/f2fs.h
+++ b/include/trace/events/f2fs.h
@@ -805,7 +805,6 @@ TRACE_EVENT(f2fs_writepages,
 		__field(char,	tagged_writepages)
 		__field(char,	for_reclaim)
 		__field(char,	range_cyclic)
-		__field(char,	for_sync)
 	),
 
 	TP_fast_assign(
@@ -824,12 +823,11 @@ TRACE_EVENT(f2fs_writepages,
 		__entry->tagged_writepages	= wbc->tagged_writepages;
 		__entry->for_reclaim	= wbc->for_reclaim;
 		__entry->range_cyclic	= wbc->range_cyclic;
-		__entry->for_sync	= wbc->for_sync;
 	),
 
 	TP_printk("dev = (%d,%d), ino = %lu, %s, %s, nr_to_write %ld, "
 		"skipped %ld, start %lld, end %lld, wb_idx %lu, sync_mode %d, "
-		"kupdate %u background %u tagged %u reclaim %u cyclic %u sync %u",
+		"kupdate %u background %u tagged %u reclaim %u cyclic %u",
 		show_dev_ino(__entry),
 		show_block_type(__entry->type),
 		show_file_type(__entry->dir),
@@ -843,8 +841,7 @@ TRACE_EVENT(f2fs_writepages,
 		__entry->for_background,
 		__entry->tagged_writepages,
 		__entry->for_reclaim,
-		__entry->range_cyclic,
-		__entry->for_sync)
+		__entry->range_cyclic)
 );
 
 TRACE_EVENT(f2fs_submit_page_mbio,