Merge tag 'for-f2fs-4.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs

Pull f2fs fixes from Jaegeuk Kim:
 "Fix a performance regression and a bug"

* tag 'for-f2fs-4.1-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs:
  f2fs: fix wrong error hanlder in f2fs_follow_link
  Revert "f2fs: enhance multi-threads performance"

fs/f2fs/data.c

@@ -1513,6 +1513,7 @@ static int f2fs_write_data_pages(struct address_space *mapping,
 {
 	struct inode *inode = mapping->host;
 	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	bool locked = false;
 	int ret;
 	long diff;
 
@@ -1533,7 +1534,13 @@ static int f2fs_write_data_pages(struct address_space *mapping,
 
 	diff = nr_pages_to_write(sbi, DATA, wbc);
 
+	if (!S_ISDIR(inode->i_mode)) {
+		mutex_lock(&sbi->writepages);
+		locked = true;
+	}
 	ret = write_cache_pages(mapping, wbc, __f2fs_writepage, mapping);
+	if (locked)
+		mutex_unlock(&sbi->writepages);
 
 	f2fs_submit_merged_bio(sbi, DATA, WRITE);
 

fs/f2fs/f2fs.h

@@ -625,6 +625,7 @@ struct f2fs_sb_info {
 	struct mutex cp_mutex;			/* checkpoint procedure lock */
 	struct rw_semaphore cp_rwsem;		/* blocking FS operations */
 	struct rw_semaphore node_write;		/* locking node writes */
+	struct mutex writepages;		/* mutex for writepages() */
 	wait_queue_head_t cp_wait;
 
 	struct inode_management im[MAX_INO_ENTRY];      /* manage inode cache */

fs/f2fs/namei.c

@@ -298,16 +298,14 @@ fail:
 
 static void *f2fs_follow_link(struct dentry *dentry, struct nameidata *nd)
 {
-	struct page *page;
+	struct page *page = page_follow_link_light(dentry, nd);
 
-	page = page_follow_link_light(dentry, nd);
-	if (IS_ERR(page))
+	if (IS_ERR_OR_NULL(page))
 		return page;
 
 	/* this is broken symlink case */
 	if (*nd_get_link(nd) == 0) {
-		kunmap(page);
-		page_cache_release(page);
+		page_put_link(dentry, nd, page);
 		return ERR_PTR(-ENOENT);
 	}
 	return page;

fs/f2fs/super.c

@@ -1035,6 +1035,7 @@ try_onemore:
 	sbi->raw_super = raw_super;
 	sbi->raw_super_buf = raw_super_buf;
 	mutex_init(&sbi->gc_mutex);
+	mutex_init(&sbi->writepages);
 	mutex_init(&sbi->cp_mutex);
 	init_rwsem(&sbi->node_write);
 	clear_sbi_flag(sbi, SBI_POR_DOING);