f2fs: add an sysfs entry to control the directory level

This patch adds an sysfs entry to control dir_level used by the large directory.

The description of this entry is:

 dir_level                    This parameter controls the directory level to
			      support large directory. If a directory has a
			      number of files, it can reduce the file lookup
			      latency by increasing this dir_level value.
			      Otherwise, it needs to decrease this value to
			      reduce the space overhead. The default value is 0.

Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 475560e5ee7..1bd91536215 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -184,6 +184,7 @@ F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, max_small_discards, max_discards);
 F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, ipu_policy, ipu_policy);
 F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, min_ipu_util, min_ipu_util);
 F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, max_victim_search, max_victim_search);
+F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, dir_level, dir_level);
 
 #define ATTR_LIST(name) (&f2fs_attr_##name.attr)
 static struct attribute *f2fs_attrs[] = {
@@ -196,6 +197,7 @@ static struct attribute *f2fs_attrs[] = {
 	ATTR_LIST(ipu_policy),
 	ATTR_LIST(min_ipu_util),
 	ATTR_LIST(max_victim_search),
+	ATTR_LIST(dir_level),
 	NULL,
 };
 
@@ -359,6 +361,9 @@ static struct inode *f2fs_alloc_inode(struct super_block *sb)
 	if (test_opt(F2FS_SB(sb), INLINE_XATTR))
 		set_inode_flag(fi, FI_INLINE_XATTR);
 
+	/* Will be used by directory only */
+	fi->i_dir_level = F2FS_SB(sb)->dir_level;
+
 	return &fi->vfs_inode;
 }
 
@@ -785,6 +790,8 @@ static void init_sb_info(struct f2fs_sb_info *sbi)
 
 	for (i = 0; i < NR_COUNT_TYPE; i++)
 		atomic_set(&sbi->nr_pages[i], 0);
+
+	sbi->dir_level = DEF_DIR_LEVEL;
 }
 
 /*