f2fs: fix the starvation problem on cp_rwsem

This patch removes the logic previously introduced to address the starvation
on cp_rwsem.

One potential there-in bug is that we should cover the wait.list with spin_lock,
but the previous code broke this rule.

And, actually current rwsem handles this starvation issue reasonably, so that we
didn't need to do this before neither.

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

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index a955a59dfdbe390bbbf2109a6e9a1ec072006a49..308967b7167414caa46b29a108c9d0f65061e19a 100644 (file)
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -18,8 +18,6 @@
 #include <linux/crc32.h>
 #include <linux/magic.h>
 #include <linux/kobject.h>
-#include <linux/wait.h>
-#include <linux/sched.h>
 
 /*
  * For mount options
@@ -360,7 +358,6 @@ struct f2fs_sb_info {
        struct inode *meta_inode;               /* cache meta blocks */
        struct mutex cp_mutex;                  /* checkpoint procedure lock */
        struct rw_semaphore cp_rwsem;           /* blocking FS operations */
-       wait_queue_head_t cp_wait;              /* checkpoint wait queue */
        struct mutex node_write;                /* locking node writes */
        struct mutex writepages;                /* mutex for writepages() */
        int por_doing;                          /* recovery is doing or not */
@@ -516,13 +513,6 @@ static inline void clear_ckpt_flags(struct f2fs_checkpoint *cp, unsigned int f)
 
 static inline void f2fs_lock_op(struct f2fs_sb_info *sbi)
 {
-       /*
-        * If the checkpoint thread is waiting for cp_rwsem, add cuurent task
-        * into wait list to avoid the checkpoint thread starvation
-        */
-       while (!list_empty(&sbi->cp_rwsem.wait_list))
-               wait_event_interruptible(sbi->cp_wait,
-                               list_empty(&sbi->cp_rwsem.wait_list));
        down_read(&sbi->cp_rwsem);
 }
 
@@ -539,9 +529,6 @@ static inline void f2fs_lock_all(struct f2fs_sb_info *sbi)
 static inline void f2fs_unlock_all(struct f2fs_sb_info *sbi)
 {
        up_write(&sbi->cp_rwsem);
-
-       /* wake up all tasks blocked by checkpoint */
-       wake_up_all(&sbi->cp_wait);
 }
 
 /*

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 539c009d4138cdff7953ba56c8342cc9b8fc7c1a..3b786c85b5cd45ce60464c99aea8fb69533fe63f 100644 (file)
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -841,7 +841,6 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
        spin_lock_init(&sbi->stat_lock);
        init_rwsem(&sbi->bio_sem);
        init_rwsem(&sbi->cp_rwsem);
-       init_waitqueue_head(&sbi->cp_wait);
        init_sb_info(sbi);
 
        /* get an inode for meta space */