From 721bd4d5c3f957f98157b6dcac9c4a4dd828e3ff Mon Sep 17 00:00:00 2001 From: Gu Zheng Date: Fri, 5 Sep 2014 18:31:00 +0800 Subject: [PATCH] f2fs: use lock-less list(llist) to simplify the flush cmd management We use flush cmd control to collect many flush cmds, and flush them together. In this case, we use two list to manage the flush cmds (collect and dispatch), and one spin lock is used to protect this. In fact, the lock-less list(llist) is very suitable to this case, and we use simplify this routine. - v2: -use llist_for_each_entry_safe to fix possible use-after-free issue. -remove the unused field from struct flush_cmd. Thanks for Yu's suggestion. - Signed-off-by: Gu Zheng Signed-off-by: Jaegeuk Kim --- fs/f2fs/f2fs.h | 8 +++----- fs/f2fs/segment.c | 29 +++++++++-------------------- 2 files changed, 12 insertions(+), 25 deletions(-) diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index dd7b171a1b16..1def9eeedbf1 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -347,18 +347,16 @@ enum { }; struct flush_cmd { - struct flush_cmd *next; struct completion wait; + struct llist_node llnode; int ret; }; struct flush_cmd_control { struct task_struct *f2fs_issue_flush; /* flush thread */ wait_queue_head_t flush_wait_queue; /* waiting queue for wake-up */ - struct flush_cmd *issue_list; /* list for command issue */ - struct flush_cmd *dispatch_list; /* list for command dispatch */ - spinlock_t issue_lock; /* for issue list lock */ - struct flush_cmd *issue_tail; /* list tail of issue list */ + struct llist_head issue_list; /* list for command issue */ + struct llist_node *dispatch_list; /* list for command dispatch */ }; struct f2fs_sm_info { diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index d1ff2250cc35..e158d6358474 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -206,24 +206,20 @@ repeat: if (kthread_should_stop()) return 0; - spin_lock(&fcc->issue_lock); - if (fcc->issue_list) { - fcc->dispatch_list = fcc->issue_list; - fcc->issue_list = fcc->issue_tail = NULL; - } - spin_unlock(&fcc->issue_lock); - - if (fcc->dispatch_list) { + if (!llist_empty(&fcc->issue_list)) { struct bio *bio = bio_alloc(GFP_NOIO, 0); struct flush_cmd *cmd, *next; int ret; + fcc->dispatch_list = llist_del_all(&fcc->issue_list); + fcc->dispatch_list = llist_reverse_order(fcc->dispatch_list); + bio->bi_bdev = sbi->sb->s_bdev; ret = submit_bio_wait(WRITE_FLUSH, bio); - for (cmd = fcc->dispatch_list; cmd; cmd = next) { + llist_for_each_entry_safe(cmd, next, + fcc->dispatch_list, llnode) { cmd->ret = ret; - next = cmd->next; complete(&cmd->wait); } bio_put(bio); @@ -231,7 +227,7 @@ repeat: } wait_event_interruptible(*q, - kthread_should_stop() || fcc->issue_list); + kthread_should_stop() || !llist_empty(&fcc->issue_list)); goto repeat; } @@ -250,15 +246,8 @@ int f2fs_issue_flush(struct f2fs_sb_info *sbi) return blkdev_issue_flush(sbi->sb->s_bdev, GFP_KERNEL, NULL); init_completion(&cmd.wait); - cmd.next = NULL; - spin_lock(&fcc->issue_lock); - if (fcc->issue_list) - fcc->issue_tail->next = &cmd; - else - fcc->issue_list = &cmd; - fcc->issue_tail = &cmd; - spin_unlock(&fcc->issue_lock); + llist_add(&cmd.llnode, &fcc->issue_list); if (!fcc->dispatch_list) wake_up(&fcc->flush_wait_queue); @@ -277,8 +266,8 @@ int create_flush_cmd_control(struct f2fs_sb_info *sbi) fcc = kzalloc(sizeof(struct flush_cmd_control), GFP_KERNEL); if (!fcc) return -ENOMEM; - spin_lock_init(&fcc->issue_lock); init_waitqueue_head(&fcc->flush_wait_queue); + init_llist_head(&fcc->issue_list); SM_I(sbi)->cmd_control_info = fcc; fcc->f2fs_issue_flush = kthread_run(issue_flush_thread, sbi, "f2fs_flush-%u:%u", MAJOR(dev), MINOR(dev)); -- 2.20.1