f2fs: throttle the memory footprint with a sysfs entry

This patch introduces ram_thresh, a sysfs entry, which controls the memory
footprint used by the free nid list and the nat cache.

Previously, the free nid list was controlled by MAX_FREE_NIDS, while the nat
cache was managed by NM_WOUT_THRESHOLD.
However, this approach cannot be applied dynamically according to the system.

So, this patch adds ram_thresh that users can specify the threshold, which is
in order of 1 / 1024.
For example, if the total ram size is 4GB and the value is set to 10 by default,
f2fs tries to control the number of free nids and nat caches not to consume over
10 * (4GB / 1024) = 10MB.

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

1 files changed, 5 insertions, 0 deletions

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index dbe402b1a4b7..34c47b2010bc 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -74,6 +74,7 @@ static match_table_t f2fs_tokens = {
 enum {
         GC_THREAD,      /* struct f2fs_gc_thread */
         SM_INFO,        /* struct f2fs_sm_info */
+        NM_INFO,        /* struct f2fs_nm_info */
         F2FS_SBI,       /* struct f2fs_sb_info */
 };
 
@@ -92,6 +93,8 @@ static unsigned char *__struct_ptr(struct f2fs_sb_info *sbi, int struct_type)
                 return (unsigned char *)sbi->gc_thread;
         else if (struct_type == SM_INFO)
                 return (unsigned char *)SM_I(sbi);
+        else if (struct_type == NM_INFO)
+                return (unsigned char *)NM_I(sbi);
         else if (struct_type == F2FS_SBI)
                 return (unsigned char *)sbi;
         return NULL;
@@ -183,6 +186,7 @@ F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, reclaim_segments, rec_prefree_segments);
 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(NM_INFO, f2fs_nm_info, ram_thresh, ram_thresh);
 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);
 
@@ -198,6 +202,7 @@ static struct attribute *f2fs_attrs[] = {
         ATTR_LIST(min_ipu_util),
         ATTR_LIST(max_victim_search),
         ATTR_LIST(dir_level),
+        ATTR_LIST(ram_thresh),
         NULL,
 };