Hi Yuan,
On 10/08/2013 04:30 PM, Yuan Zhong wrote:
> Previously, do_checkpoint() will call congestion_wait() for waiting the pages
> (previous submitted node/meta/data pages) to be written back.
> Because congestion_wait() will set a regular period (e.g. HZ / 50 ) for
> waiting.
> For this reason, there is a situation that after the pages have been written
> back, but the checkpoint thread still wait for congestion_wait to exit.
How do you confirm this issue? I suspect that the block-core does not have a
wake-up mechanism
when the back device is uncongested.
> This is a problem here, especially, when sync a large number of small files
> or dirs.
> In order to avoid this, a wait_list is introduced, the checkpoint thread will
> be dropped into the wait_list if the pages have not been written back, and
> will be waked up by contrast.
Please pay some attention to the mail form, this mail is out of format in my
mail client.
Regards,
Gu
>
> Signed-off-by: Yuan Zhong <yuan.mark.zh...@samsung.com>
> ---
> fs/f2fs/checkpoint.c | 3 +--
> fs/f2fs/f2fs.h | 19 +++++++++++++++++++
> fs/f2fs/segment.c | 1 +
> fs/f2fs/super.c | 1 +
> 4 files changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index ca39442..5d69ae0 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -758,8 +758,7 @@ static void do_checkpoint(struct f2fs_sb_info *sbi, bool
> is_umount)
> f2fs_put_page(cp_page, 1);
>
> /* wait for previous submitted node/meta pages writeback */
> - while (get_pages(sbi, F2FS_WRITEBACK))
> - congestion_wait(BLK_RW_ASYNC, HZ / 50);
> + f2fs_writeback_wait(sbi);
>
> filemap_fdatawait_range(sbi->node_inode->i_mapping, 0, LONG_MAX);
> filemap_fdatawait_range(sbi->meta_inode->i_mapping, 0, LONG_MAX);
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 7fd99d8..4b0d70e 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -18,6 +18,8 @@
> #include <linux/crc32.h>
> #include <linux/magic.h>
> #include <linux/kobject.h>
> +#include <linux/wait.h>
> +#include <linux/sched.h>
>
> /*
> * For mount options
> @@ -368,6 +370,7 @@ struct f2fs_sb_info {
> struct mutex fs_lock[NR_GLOBAL_LOCKS]; /* blocking FS operations */
> struct mutex node_write; /* locking node writes */
> struct mutex writepages; /* mutex for writepages() */
> + wait_queue_head_t writeback_wqh; /* wait_queue for writeback */
> unsigned char next_lock_num; /* round-robin global locks */
> int por_doing; /* recovery is doing or not */
> int on_build_free_nids; /* build_free_nids is doing */
> @@ -961,6 +964,22 @@ static inline int f2fs_readonly(struct super_block *sb)
> return sb->s_flags & MS_RDONLY;
> }
>
> +static inline void f2fs_writeback_wait(struct f2fs_sb_info *sbi)
> +{
> + DEFINE_WAIT(wait);
> +
> + prepare_to_wait(&sbi->writeback_wqh, &wait, TASK_UNINTERRUPTIBLE);
> + if (get_pages(sbi, F2FS_WRITEBACK))
> + io_schedule();
> + finish_wait(&sbi->writeback_wqh, &wait);
> +}
> +
> +static inline void f2fs_writeback_wake(struct f2fs_sb_info *sbi)
> +{
> + if (!get_pages(sbi, F2FS_WRITEBACK))
> + wake_up_all(&sbi->writeback_wqh);
> +}
> +
> /*
> * file.c
> */
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index bd79bbe..0708aa9 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -597,6 +597,7 @@ static void f2fs_end_io_write(struct bio *bio, int err)
>
> if (p->is_sync)
> complete(p->wait);
> + f2fs_writeback_wake(p->sbi);
> kfree(p);
> bio_put(bio);
> }
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 094ccc6..3ac6d85 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -835,6 +835,7 @@ static int f2fs_fill_super(struct super_block *sb, void
> *data, int silent)
> mutex_init(&sbi->gc_mutex);
> mutex_init(&sbi->writepages);
> mutex_init(&sbi->cp_mutex);
> + init_waitqueue_head(&sbi->writeback_wqh);
> for (i = 0; i < NR_GLOBAL_LOCKS; i++)
> mutex_init(&sbi->fs_lock[i]);
>
> mutex_init(&sbi->node_write);N‹§²æìr¸›yúèšØb²X¬¶Ç§vØ^–)Þº{.nÇ+‰·¥Š{±‘êçzX§¶›¡Ü¨}©ž²Æ
>
> zÚ&j:+v‰¨¾«‘êçzZ+€Ê+zf£¢·hšˆ§~††Ûiÿûàz¹ ®w¥¢¸?™¨èÚ&¢)ߢf”ù^jÇ«y§m…á@A«a¶Úÿ
> 0¶ìh®å’i
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