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f2fs: use lock-less list(llist) to simplify the flush cmd management

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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 <guz.fnst@cn.fujitsu.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Gu Zheng
2014-09-05 18:31:00 +08:00
committed by Jaegeuk Kim
parent 184a5cd2ce
commit 721bd4d5c3
2 changed files with 12 additions and 25 deletions
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29
fs/f2fs/segment.c
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@@ -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));