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Date: Wed, 31 Jul 2013 19:06:35 +0900
From: Jaegeuk Kim <jaegeuk.kim@...sung.com>
To: Gu Zheng <guz.fnst@...fujitsu.com>
Cc: f2fs <linux-f2fs-devel@...ts.sourceforge.net>,
fsdevel <linux-fsdevel@...r.kernel.org>,
linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] f2fs: add a wait step when submit bio with
{READ,WRITE}_SYNC
2013-07-31 (수), 09:59 +0800, Gu Zheng:
> Hi Kim,
>
> On 07/30/2013 08:29 PM, Jaegeuk Kim wrote:
>
> > Hi Gu,
> >
> > The original read flow was to avoid redandunt lock/unlock_page() calls.
>
> Right, this can gain better read performance. But is the wait step after
> submitting bio with READ_SYNC needless too?
Correct, the READ_SYNC is also used for IO priority.
The basic read policy here is that the caller should lock the page only
when it wants to manipulate there-in data.
Otherwise, we don't need to unnecessary lock and unlocks.
Thanks,
>
> > And we should not wait for WRITE_SYNC, since it is just for write
> > priority, not for synchronization of the file system.
>
> Got it, thanks for your explanation.:)
>
> Best regards,
> Gu
>
> > Thanks,
> >
> > 2013-07-30 (화), 18:06 +0800, Gu Zheng:
> >> When we submit bio with READ_SYNC or WRITE_SYNC, we need to wait a
> >> moment for the io completion, current codes only find_data_page() follows the
> >> rule, other places missing this step, so add it.
> >>
> >> Further more, moving the PageUptodate check into f2fs_readpage() to clean up
> >> the codes.
> >>
> >> Signed-off-by: Gu Zheng <guz.fnst@...fujitsu.com>
> >> ---
> >> fs/f2fs/checkpoint.c | 1 -
> >> fs/f2fs/data.c | 39 +++++++++++++++++----------------------
> >> fs/f2fs/node.c | 1 -
> >> fs/f2fs/recovery.c | 2 --
> >> fs/f2fs/segment.c | 2 +-
> >> 5 files changed, 18 insertions(+), 27 deletions(-)
> >>
> >> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> >> index fe91773..e376a42 100644
> >> --- a/fs/f2fs/checkpoint.c
> >> +++ b/fs/f2fs/checkpoint.c
> >> @@ -64,7 +64,6 @@ repeat:
> >> if (f2fs_readpage(sbi, page, index, READ_SYNC))
> >> goto repeat;
> >>
> >> - lock_page(page);
> >> if (page->mapping != mapping) {
> >> f2fs_put_page(page, 1);
> >> goto repeat;
> >> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> >> index 19cd7c6..b048936 100644
> >> --- a/fs/f2fs/data.c
> >> +++ b/fs/f2fs/data.c
> >> @@ -216,13 +216,11 @@ struct page *find_data_page(struct inode *inode, pgoff_t index, bool sync)
> >>
> >> err = f2fs_readpage(sbi, page, dn.data_blkaddr,
> >> sync ? READ_SYNC : READA);
> >> - if (sync) {
> >> - wait_on_page_locked(page);
> >> - if (!PageUptodate(page)) {
> >> - f2fs_put_page(page, 0);
> >> - return ERR_PTR(-EIO);
> >> - }
> >> - }
> >> + if (err)
> >> + return ERR_PTR(err);
> >> +
> >> + if (sync)
> >> + unlock_page(page);
> >> return page;
> >> }
> >>
> >> @@ -267,11 +265,6 @@ repeat:
> >> if (err)
> >> return ERR_PTR(err);
> >>
> >> - lock_page(page);
> >> - if (!PageUptodate(page)) {
> >> - f2fs_put_page(page, 1);
> >> - return ERR_PTR(-EIO);
> >> - }
> >> if (page->mapping != mapping) {
> >> f2fs_put_page(page, 1);
> >> goto repeat;
> >> @@ -325,11 +318,7 @@ repeat:
> >> err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
> >> if (err)
> >> return ERR_PTR(err);
> >> - lock_page(page);
> >> - if (!PageUptodate(page)) {
> >> - f2fs_put_page(page, 1);
> >> - return ERR_PTR(-EIO);
> >> - }
> >> +
> >> if (page->mapping != mapping) {
> >> f2fs_put_page(page, 1);
> >> goto repeat;
> >> @@ -399,6 +388,16 @@ int f2fs_readpage(struct f2fs_sb_info *sbi, struct page *page,
> >>
> >> submit_bio(type, bio);
> >> up_read(&sbi->bio_sem);
> >> +
> >> + if (type == READ_SYNC) {
> >> + wait_on_page_locked(page);
> >> + lock_page(page);
> >> + if (!PageUptodate(page)) {
> >> + f2fs_put_page(page, 1);
> >> + return -EIO;
> >> + }
> >> + }
> >> +
> >> return 0;
> >> }
> >>
> >> @@ -679,11 +678,7 @@ repeat:
> >> err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
> >> if (err)
> >> return err;
> >> - lock_page(page);
> >> - if (!PageUptodate(page)) {
> >> - f2fs_put_page(page, 1);
> >> - return -EIO;
> >> - }
> >> +
> >> if (page->mapping != mapping) {
> >> f2fs_put_page(page, 1);
> >> goto repeat;
> >> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> >> index f5172e2..f061554 100644
> >> --- a/fs/f2fs/node.c
> >> +++ b/fs/f2fs/node.c
> >> @@ -1534,7 +1534,6 @@ int restore_node_summary(struct f2fs_sb_info *sbi,
> >> if (f2fs_readpage(sbi, page, addr, READ_SYNC))
> >> goto out;
> >>
> >> - lock_page(page);
> >> rn = F2FS_NODE(page);
> >> sum_entry->nid = rn->footer.nid;
> >> sum_entry->version = 0;
> >> diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
> >> index 639eb34..ec68183 100644
> >> --- a/fs/f2fs/recovery.c
> >> +++ b/fs/f2fs/recovery.c
> >> @@ -140,8 +140,6 @@ static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head *head)
> >> if (err)
> >> goto out;
> >>
> >> - lock_page(page);
> >> -
> >> if (cp_ver != cpver_of_node(page))
> >> break;
> >>
> >> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> >> index 9b74ae2..bcd19db 100644
> >> --- a/fs/f2fs/segment.c
> >> +++ b/fs/f2fs/segment.c
> >> @@ -639,7 +639,7 @@ static void do_submit_bio(struct f2fs_sb_info *sbi,
> >>
> >> trace_f2fs_do_submit_bio(sbi->sb, btype, sync, sbi->bio[btype]);
> >>
> >> - if (type == META_FLUSH) {
> >> + if ((type == META_FLUSH) || (rw & WRITE_SYNC)) {
> >> DECLARE_COMPLETION_ONSTACK(wait);
> >> p->is_sync = true;
> >> p->wait = &wait;
> >
>
>
> --
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--
Jaegeuk Kim
Samsung
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