Commit b1838f89 authored by Jaegeuk Kim's avatar Jaegeuk Kim
Browse files

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: default avatarJaegeuk Kim <jaegeuk.kim@samsung.com>
parent 3d1e3807

fs/f2fs/f2fs.h

+0 −13
Original line number Diff line number Diff line
@@ -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);

}



/*

fs/f2fs/super.c

+0 −1
Original line number Diff line number Diff line
@@ -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 */

CRA Git | Maintained and supported by SUSTech CRA and CCSE