f2fs: add auto tuning for small devices

If f2fs is running on top of very small devices, it's worth to avoid abusing
free LBAs. In order to achieve that, this patch introduces some parameter
tuning.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index f11c4bc..dbb774a 100644 (file)
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -596,6 +596,8 @@ static inline int utilization(struct f2fs_sb_info *sbi)
 #define DEF_MIN_FSYNC_BLOCKS   8
 #define DEF_MIN_HOT_BLOCKS     16
 
+#define SMALL_VOLUME_SEGMENTS  (16 * 512)      /* 16GB */
+
 enum {
        F2FS_IPU_FORCE,
        F2FS_IPU_SSR,

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 16d157e..9b6c53b 100644 (file)
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -2515,6 +2515,18 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
        return 0;
 }
 
+static void f2fs_tuning_parameters(struct f2fs_sb_info *sbi)
+{
+       struct f2fs_sm_info *sm_i = SM_I(sbi);
+
+       /* adjust parameters according to the volume size */
+       if (sm_i->main_segments <= SMALL_VOLUME_SEGMENTS) {
+               sbi->alloc_mode = ALLOC_MODE_REUSE;
+               sm_i->dcc_info->discard_granularity = 1;
+               sm_i->ipu_policy = 1 << F2FS_IPU_FORCE;
+       }
+}
+
 static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 {
        struct f2fs_sb_info *sbi;
@@ -2867,6 +2879,8 @@ skip_recovery:
 
        f2fs_join_shrinker(sbi);
 
+       f2fs_tuning_parameters(sbi);
+
        f2fs_msg(sbi->sb, KERN_NOTICE, "Mounted with checkpoint version = %llx",
                                cur_cp_version(F2FS_CKPT(sbi)));
        f2fs_update_time(sbi, CP_TIME);