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Date: Mon, 02 Dec 2013 09:29:44 +0800
From: Gu Zheng <guz.fnst@...fujitsu.com>
To: Jaegeuk Kim <jaegeuk.kim@...sung.com>
CC: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [PATCH] f2fs: remove the own bi_private allocation
On 11/30/2013 09:48 AM, Jaegeuk Kim wrote:
> Previously f2fs allocates its own bi_private data structure all the time even
> though we don't use it. But, can we remove this bi_private allocation?
>
> This patch removes such the additional bi_private allocation.
>
> 1. Retrieve f2fs_sb_info from its page->mapping->host->i_sb.
> - This removes the usecases of bi_private in end_io.
>
> 2. Use bi_private only when we really need it.
> - The bi_private is used only when the checkpoint procedure is conducted.
> - When conducting the checkpoint, f2fs submits a META_FLUSH bio to wait its bio
> completion.
> - Since we have no dependancies to remove bi_private now, let's just use
> bi_private pointer as the completion pointer.
Cool, looks good to me.:)
>
> Signed-off-by: Jaegeuk Kim <jaegeuk.kim@...sung.com>
Reviewed-by: Gu Zheng <guz.fnst@...fujitsu.com>
> ---
> fs/f2fs/segment.c | 43 ++++++++++++++++---------------------------
> fs/f2fs/segment.h | 7 -------
> 2 files changed, 16 insertions(+), 34 deletions(-)
>
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 0387863..0db4027 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -791,7 +791,7 @@ static void f2fs_end_io_write(struct bio *bio, int err)
> {
> const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
> struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
> - struct bio_private *p = bio->bi_private;
> + struct f2fs_sb_info *sbi = F2FS_SB(bvec->bv_page->mapping->host->i_sb);
>
> do {
> struct page *page = bvec->bv_page;
> @@ -802,21 +802,21 @@ static void f2fs_end_io_write(struct bio *bio, int err)
> SetPageError(page);
> if (page->mapping)
> set_bit(AS_EIO, &page->mapping->flags);
> - set_ckpt_flags(p->sbi->ckpt, CP_ERROR_FLAG);
> - p->sbi->sb->s_flags |= MS_RDONLY;
> +
> + set_ckpt_flags(sbi->ckpt, CP_ERROR_FLAG);
> + sbi->sb->s_flags |= MS_RDONLY;
> }
> end_page_writeback(page);
> - dec_page_count(p->sbi, F2FS_WRITEBACK);
> + dec_page_count(sbi, F2FS_WRITEBACK);
> } while (bvec >= bio->bi_io_vec);
>
> - if (p->is_sync)
> - complete(p->wait);
> + if (bio->bi_private)
> + complete(bio->bi_private);
>
> - if (!get_pages(p->sbi, F2FS_WRITEBACK) &&
> - !list_empty(&p->sbi->cp_wait.task_list))
> - wake_up(&p->sbi->cp_wait);
> + if (!get_pages(sbi, F2FS_WRITEBACK) &&
> + !list_empty(&sbi->cp_wait.task_list))
> + wake_up(&sbi->cp_wait);
>
> - kfree(p);
> bio_put(bio);
> }
>
> @@ -838,7 +838,6 @@ static void do_submit_bio(struct f2fs_sb_info *sbi,
> int rw = sync ? WRITE_SYNC : WRITE;
> enum page_type btype = PAGE_TYPE_OF_BIO(type);
> struct f2fs_bio_info *io = &sbi->write_io[btype];
> - struct bio_private *p;
>
> if (!io->bio)
> return;
> @@ -851,18 +850,16 @@ static void do_submit_bio(struct f2fs_sb_info *sbi,
>
> trace_f2fs_submit_write_bio(sbi->sb, rw, btype, io->bio);
>
> - p = io->bio->bi_private;
> - p->sbi = sbi;
> - io->bio->bi_end_io = f2fs_end_io_write;
> -
> + /*
> + * META_FLUSH is only from the checkpoint procedure, and we should wait
> + * this metadata bio for FS consistency.
> + */
> if (type == META_FLUSH) {
> DECLARE_COMPLETION_ONSTACK(wait);
> - p->is_sync = true;
> - p->wait = &wait;
> + io->bio->bi_private = &wait;
> submit_bio(rw, io->bio);
> wait_for_completion(&wait);
> } else {
> - p->is_sync = false;
> submit_bio(rw, io->bio);
> }
> io->bio = NULL;
> @@ -897,18 +894,10 @@ static void submit_write_page(struct f2fs_sb_info *sbi, struct page *page,
> do_submit_bio(sbi, type, false);
> alloc_new:
> if (io->bio == NULL) {
> - struct bio_private *priv;
> -retry:
> - priv = kmalloc(sizeof(struct bio_private), GFP_NOFS);
> - if (!priv) {
> - cond_resched();
> - goto retry;
> - }
> -
> bio_blocks = MAX_BIO_BLOCKS(max_hw_blocks(sbi));
> io->bio = f2fs_bio_alloc(bdev, bio_blocks);
> io->bio->bi_sector = SECTOR_FROM_BLOCK(sbi, blk_addr);
> - io->bio->bi_private = priv;
> + io->bio->bi_end_io = f2fs_end_io_write;
> /*
> * The end_io will be assigned at the sumbission phase.
> * Until then, let bio_add_page() merge consecutive IOs as much
> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> index 7fea2ee..26812fc 100644
> --- a/fs/f2fs/segment.h
> +++ b/fs/f2fs/segment.h
> @@ -92,13 +92,6 @@
> #define MAX_BIO_BLOCKS(max_hw_blocks) \
> (min((int)max_hw_blocks, BIO_MAX_PAGES))
>
> -/* during checkpoint, bio_private is used to synchronize the last bio */
> -struct bio_private {
> - struct f2fs_sb_info *sbi;
> - bool is_sync;
> - struct completion *wait;
> -};
> -
> /*
> * indicate a block allocation direction: RIGHT and LEFT.
> * RIGHT means allocating new sections towards the end of volume.
--
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