f2fs: wake up discard_thread iff there is a candidate

This patch fixes to avoid needless wake ups.

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

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 8306bea..8375257 100644 (file)
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -1494,8 +1494,7 @@ skip:
                kmem_cache_free(discard_entry_slab, entry);
        }
 
-       dcc->discard_wake = 1;
-       wake_up_interruptible_all(&dcc->discard_wait_queue);
+       wake_up_discard_thread(sbi, false);
 }
 
 static int create_discard_cmd_control(struct f2fs_sb_info *sbi)

diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index b9b4f85..613b2fa 100644 (file)
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -798,3 +798,28 @@ static inline long nr_pages_to_write(struct f2fs_sb_info *sbi, int type,
        wbc->nr_to_write = desired;
        return desired - nr_to_write;
 }
+
+static inline void wake_up_discard_thread(struct f2fs_sb_info *sbi, bool force)
+{
+       struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
+       bool wakeup = false;
+       int i;
+
+       if (force)
+               goto wake_up;
+
+       mutex_lock(&dcc->cmd_lock);
+       for (i = MAX_PLIST_NUM - 1;
+                       i >= 0 && plist_issue(dcc->pend_list_tag[i]); i--) {
+               if (!list_empty(&dcc->pend_list[i])) {
+                       wakeup = true;
+                       break;
+               }
+       }
+       mutex_unlock(&dcc->cmd_lock);
+       if (!wakeup)
+               return;
+wake_up:
+       dcc->discard_wake = 1;
+       wake_up_interruptible_all(&dcc->discard_wait_queue);
+}

diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index b9ad904..962735d 100644 (file)
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -178,13 +178,9 @@ static ssize_t f2fs_sbi_store(struct f2fs_attr *a,
        if (!strcmp(a->attr.name, "iostat_enable") && *ui == 0)
                f2fs_reset_iostat(sbi);
        if (!strcmp(a->attr.name, "gc_urgent") && t == 1 && sbi->gc_thread) {
-               struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
-
                sbi->gc_thread->gc_wake = 1;
                wake_up_interruptible_all(&sbi->gc_thread->gc_wait_queue_head);
-
-               dcc->discard_wake = 1;
-               wake_up_interruptible_all(&dcc->discard_wait_queue);
+               wake_up_discard_thread(sbi, true);
        }
 
        return count;