diff options
author | Tejun Heo <tj@kernel.org> | 2015-05-22 17:13:58 -0400 |
---|---|---|
committer | Jens Axboe <axboe@fb.com> | 2015-06-02 08:33:36 -0600 |
commit | cc395d7f1f7b9c740ab6d367ef1f6eb248595dff (patch) | |
tree | a99a691af5b57da0f323f9e50ecf68be0d97ff01 /fs | |
parent | ac7b19a34f332fdf8b13aac8708b14188fd1fbd2 (diff) | |
download | linux-cc395d7f1f7b9c740ab6d367ef1f6eb248595dff.tar.bz2 |
writeback: implement bdi_wait_for_completion()
If the completion of a wb_writeback_work can be waited upon by setting
its ->done to a struct completion and waiting on it; however, for
cgroup writeback support, it's necessary to issue multiple work items
to multiple bdi_writebacks and wait for the completion of all.
This patch implements wb_completion which can wait for multiple work
items and replaces the struct completion with it. It can be defined
using DEFINE_WB_COMPLETION_ONSTACK(), used for multiple work items and
waited for by wb_wait_for_completion().
Nobody currently issues multiple work items and this patch doesn't
introduce any behavior changes.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/fs-writeback.c | 58 |
1 files changed, 46 insertions, 12 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 22f1def4e63a..d7d4a1bcdd2f 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -34,6 +34,10 @@ */ #define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_CACHE_SHIFT - 10)) +struct wb_completion { + atomic_t cnt; +}; + /* * Passed into wb_writeback(), essentially a subset of writeback_control */ @@ -51,10 +55,23 @@ struct wb_writeback_work { enum wb_reason reason; /* why was writeback initiated? */ struct list_head list; /* pending work list */ - struct completion *done; /* set if the caller waits */ + struct wb_completion *done; /* set if the caller waits */ }; /* + * If one wants to wait for one or more wb_writeback_works, each work's + * ->done should be set to a wb_completion defined using the following + * macro. Once all work items are issued with wb_queue_work(), the caller + * can wait for the completion of all using wb_wait_for_completion(). Work + * items which are waited upon aren't freed automatically on completion. + */ +#define DEFINE_WB_COMPLETION_ONSTACK(cmpl) \ + struct wb_completion cmpl = { \ + .cnt = ATOMIC_INIT(1), \ + } + + +/* * If an inode is constantly having its pages dirtied, but then the * updates stop dirtytime_expire_interval seconds in the past, it's * possible for the worst case time between when an inode has its @@ -161,17 +178,34 @@ static void wb_queue_work(struct bdi_writeback *wb, trace_writeback_queue(wb->bdi, work); spin_lock_bh(&wb->work_lock); - if (!test_bit(WB_registered, &wb->state)) { - if (work->done) - complete(work->done); + if (!test_bit(WB_registered, &wb->state)) goto out_unlock; - } + if (work->done) + atomic_inc(&work->done->cnt); list_add_tail(&work->list, &wb->work_list); mod_delayed_work(bdi_wq, &wb->dwork, 0); out_unlock: spin_unlock_bh(&wb->work_lock); } +/** + * wb_wait_for_completion - wait for completion of bdi_writeback_works + * @bdi: bdi work items were issued to + * @done: target wb_completion + * + * Wait for one or more work items issued to @bdi with their ->done field + * set to @done, which should have been defined with + * DEFINE_WB_COMPLETION_ONSTACK(). This function returns after all such + * work items are completed. Work items which are waited upon aren't freed + * automatically on completion. + */ +static void wb_wait_for_completion(struct backing_dev_info *bdi, + struct wb_completion *done) +{ + atomic_dec(&done->cnt); /* put down the initial count */ + wait_event(bdi->wb_waitq, !atomic_read(&done->cnt)); +} + #ifdef CONFIG_CGROUP_WRITEBACK /** @@ -1143,7 +1177,7 @@ static long wb_do_writeback(struct bdi_writeback *wb) set_bit(WB_writeback_running, &wb->state); while ((work = get_next_work_item(wb)) != NULL) { - struct completion *done = work->done; + struct wb_completion *done = work->done; trace_writeback_exec(wb->bdi, work); @@ -1151,8 +1185,8 @@ static long wb_do_writeback(struct bdi_writeback *wb) if (work->auto_free) kfree(work); - if (done) - complete(done); + if (done && atomic_dec_and_test(&done->cnt)) + wake_up_all(&wb->bdi->wb_waitq); } /* @@ -1518,7 +1552,7 @@ void writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr, enum wb_reason reason) { - DECLARE_COMPLETION_ONSTACK(done); + DEFINE_WB_COMPLETION_ONSTACK(done); struct wb_writeback_work work = { .sb = sb, .sync_mode = WB_SYNC_NONE, @@ -1533,7 +1567,7 @@ void writeback_inodes_sb_nr(struct super_block *sb, return; WARN_ON(!rwsem_is_locked(&sb->s_umount)); wb_queue_work(&bdi->wb, &work); - wait_for_completion(&done); + wb_wait_for_completion(bdi, &done); } EXPORT_SYMBOL(writeback_inodes_sb_nr); @@ -1600,7 +1634,7 @@ EXPORT_SYMBOL(try_to_writeback_inodes_sb); */ void sync_inodes_sb(struct super_block *sb) { - DECLARE_COMPLETION_ONSTACK(done); + DEFINE_WB_COMPLETION_ONSTACK(done); struct wb_writeback_work work = { .sb = sb, .sync_mode = WB_SYNC_ALL, @@ -1618,7 +1652,7 @@ void sync_inodes_sb(struct super_block *sb) WARN_ON(!rwsem_is_locked(&sb->s_umount)); wb_queue_work(&bdi->wb, &work); - wait_for_completion(&done); + wb_wait_for_completion(bdi, &done); wait_sb_inodes(sb); } |