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Date: Fri, 07 Feb 2014 16:01:15 +0800
From: Chao Yu <chao2.yu@...sung.com>
To: jaegeuk.kim@...sung.com
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net
Subject: RE: [f2fs-dev] [PATCH] f2fs: introduce ra_meta_pages to readahead
CP/NAT/SIT pages
Hi Kim,
> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk.kim@...sung.com]
> Sent: Friday, February 07, 2014 2:58 PM
> To: Chao Yu
> Cc: linux-fsdevel@...r.kernel.org; linux-kernel@...r.kernel.org;
> linux-f2fs-devel@...ts.sourceforge.net
> Subject: Re: [f2fs-dev] [PATCH] f2fs: introduce ra_meta_pages to readahead CP/NAT/SIT pages
>
> Hi Chao,
>
> Sorry for the delay.
> When I tested this patch, a deadlock was occurred, so I couldn't afford
> to look inside in more detail.
> When I see again, there is a bug wrt blkno.
> Please see below.
You're right, and your code could fix this deadloop bug.
Thanks for the test and review. :)
I will send patch v2 later.
>
> 2014-01-28 (화), 10:28 +0800, Chao Yu:
> > This patch help us to cleanup the readahead code by merging ra_{sit,nat}_pages
> > function into ra_meta_pages.
> > Additionally the new function is used to readahead cp block in
> > recover_orphan_inodes.
> >
> > Signed-off-by: Chao Yu <chao2.yu@...sung.com>
> > ---
> > fs/f2fs/checkpoint.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++
> > fs/f2fs/f2fs.h | 10 +++++++
> > fs/f2fs/node.c | 38 +-----------------------
> > fs/f2fs/segment.c | 43 +---------------------------
> > 4 files changed, 90 insertions(+), 79 deletions(-)
> >
> > diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> > index 293d048..a1986c3 100644
> > --- a/fs/f2fs/checkpoint.c
> > +++ b/fs/f2fs/checkpoint.c
> > @@ -75,6 +75,82 @@ out:
> > return page;
> > }
> >
> > +inline int get_max_meta_blks(struct f2fs_sb_info *sbi, int type)
> > +{
> > + switch (type) {
> > + case META_NAT:
> > + return NM_I(sbi)->max_nid / NAT_ENTRY_PER_BLOCK;
> > + case META_SIT:
> > + return SIT_BLK_CNT(sbi);
> > + case META_CP:
> > + return 0;
> > + default:
> > + BUG();
> > + }
> > +}
> > +
> > +/*
> > + * Readahead CP/NAT/SIT pages
> > + */
> > +int ra_meta_pages(struct f2fs_sb_info *sbi, int start, int nrpages, int type)
> > +{
> > + struct address_space *mapping = sbi->meta_inode->i_mapping;
>
> We don't need to do this. Instead, we can use META_MAPPING(sbi) below.
>
> > + struct page *page;
> > + block_t blk_addr, prev_blk_addr = 0;
> > + int blkno = start;
> > + int max_blks = get_max_meta_blks(sbi, type);
>
> block_t prev_blk_addr = 0;
> struct page *page;
> int blkno = start;
> int max_blks = get_max_meta_blks(sbi, type);
>
> > + struct f2fs_io_info fio = {
> > + .type = META,
> > + .rw = READ_SYNC | REQ_META | REQ_PRIO
> > + };
> > +
> > + for (blkno = start; blkno < start + nrpages; blkno++) {
>
> for (; nrpages-- > 0; blkno++) {
> block_t blk_addr;
>
> --> In the case of META_NAT, blkno becomes 0 if it hits max_blks.
> So, we should not use *blkno < start + nrpages*.
>
> > +
> > + switch (type) {
> > + case META_NAT:
> > + /* get nat block addr */
> > + if (unlikely(blkno >= max_blks))
> > + blkno = 0;
> > + blk_addr = current_nat_addr(sbi,
> > + blkno * NAT_ENTRY_PER_BLOCK);
> > + break;
> > + case META_SIT:
> > + /* get sit block addr */
> > + if (unlikely(blkno >= max_blks))
> > + goto out;
> > + blk_addr = current_sit_addr(sbi,
> > + blkno * SIT_ENTRY_PER_BLOCK);
> > + if (blkno != start && prev_blk_addr + 1 != blk_addr)
> > + goto out;
> > + prev_blk_addr = blk_addr;
> > + break;
> > + case META_CP:
> > + /* get cp block addr */
> > + blk_addr = blkno;
> > + break;
> > + default:
> > + BUG();
> > + }
> > +
> > + page = grab_cache_page(mapping, blk_addr);
>
> page = grab_cache_page(META_MAPPING(sbi), blk_addr);
>
> > + if (!page)
> > + continue;
> > + if (PageUptodate(page)) {
> > + mark_page_accessed(page);
> > + f2fs_put_page(page, 1);
> > + continue;
> > + }
> > +
> > + f2fs_submit_page_mbio(sbi, page, blk_addr, &fio);
> > + mark_page_accessed(page);
> > + f2fs_put_page(page, 0);
> > + }
> > +out:
> > + f2fs_submit_merged_bio(sbi, META, READ);
> > + return blkno - start;
> > +}
> > +
> > static int f2fs_write_meta_page(struct page *page,
> > struct writeback_control *wbc)
> > {
> > @@ -285,6 +361,8 @@ void recover_orphan_inodes(struct f2fs_sb_info *sbi)
> > start_blk = __start_cp_addr(sbi) + 1;
> > orphan_blkaddr = __start_sum_addr(sbi) - 1;
> >
> > + ra_meta_pages(sbi, start_blk, orphan_blkaddr, META_CP);
> > +
> > for (i = 0; i < orphan_blkaddr; i++) {
> > struct page *page = get_meta_page(sbi, start_blk + i);
> > struct f2fs_orphan_block *orphan_blk;
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > index af51a0b..69ffc1b 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -88,6 +88,15 @@ enum {
> > SIT_BITMAP
> > };
> >
> > +/*
> > + * For CP/NAT/SIT readahead
> > + */
> > +enum {
> > + META_CP,
> > + META_NAT,
> > + META_SIT
> > +};
> > +
> > /* for the list of orphan inodes */
> > struct orphan_inode_entry {
> > struct list_head list; /* list head */
> > @@ -1158,6 +1167,7 @@ void destroy_segment_manager_caches(void);
> > */
> > struct page *grab_meta_page(struct f2fs_sb_info *, pgoff_t);
> > struct page *get_meta_page(struct f2fs_sb_info *, pgoff_t);
> > +int ra_meta_pages(struct f2fs_sb_info *, int, int, int);
> > long sync_meta_pages(struct f2fs_sb_info *, enum page_type, long);
> > int acquire_orphan_inode(struct f2fs_sb_info *);
> > void release_orphan_inode(struct f2fs_sb_info *);
> > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> > index b0649b7..2f7ae6f 100644
> > --- a/fs/f2fs/node.c
> > +++ b/fs/f2fs/node.c
> > @@ -82,42 +82,6 @@ static struct page *get_next_nat_page(struct f2fs_sb_info *sbi, nid_t nid)
> > return dst_page;
> > }
> >
> > -/*
> > - * Readahead NAT pages
> > - */
> > -static void ra_nat_pages(struct f2fs_sb_info *sbi, int nid)
> > -{
> > - struct address_space *mapping = META_MAPPING(sbi);
> > - struct f2fs_nm_info *nm_i = NM_I(sbi);
> > - struct page *page;
> > - pgoff_t index;
> > - int i;
> > - struct f2fs_io_info fio = {
> > - .type = META,
> > - .rw = READ_SYNC | REQ_META | REQ_PRIO
> > - };
> > -
> > -
> > - for (i = 0; i < FREE_NID_PAGES; i++, nid += NAT_ENTRY_PER_BLOCK) {
> > - if (unlikely(nid >= nm_i->max_nid))
> > - nid = 0;
> > - index = current_nat_addr(sbi, nid);
> > -
> > - page = grab_cache_page(mapping, index);
> > - if (!page)
> > - continue;
> > - if (PageUptodate(page)) {
> > - mark_page_accessed(page);
> > - f2fs_put_page(page, 1);
> > - continue;
> > - }
> > - f2fs_submit_page_mbio(sbi, page, index, &fio);
> > - mark_page_accessed(page);
> > - f2fs_put_page(page, 0);
> > - }
> > - f2fs_submit_merged_bio(sbi, META, READ);
> > -}
> > -
> > static struct nat_entry *__lookup_nat_cache(struct f2fs_nm_info *nm_i, nid_t n)
> > {
> > return radix_tree_lookup(&nm_i->nat_root, n);
> > @@ -1413,7 +1377,7 @@ static void build_free_nids(struct f2fs_sb_info *sbi)
> > return;
> >
> > /* readahead nat pages to be scanned */
> > - ra_nat_pages(sbi, nid);
> > + ra_meta_pages(sbi, NAT_BLOCK_OFFSET(nid), FREE_NID_PAGES, META_NAT);
> >
> > while (1) {
> > struct page *page = get_current_nat_page(sbi, nid);
> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > index 7caac5f..4c2b35b 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -1583,47 +1583,6 @@ static int build_curseg(struct f2fs_sb_info *sbi)
> > return restore_curseg_summaries(sbi);
> > }
> >
> > -static int ra_sit_pages(struct f2fs_sb_info *sbi, int start, int nrpages)
> > -{
> > - struct address_space *mapping = META_MAPPING(sbi);
> > - struct page *page;
> > - block_t blk_addr, prev_blk_addr = 0;
> > - int sit_blk_cnt = SIT_BLK_CNT(sbi);
> > - int blkno = start;
> > - struct f2fs_io_info fio = {
> > - .type = META,
> > - .rw = READ_SYNC | REQ_META | REQ_PRIO
> > - };
> > -
> > - for (; blkno < start + nrpages && blkno < sit_blk_cnt; blkno++) {
> > -
> > - blk_addr = current_sit_addr(sbi, blkno * SIT_ENTRY_PER_BLOCK);
> > -
> > - if (blkno != start && prev_blk_addr + 1 != blk_addr)
> > - break;
> > - prev_blk_addr = blk_addr;
> > -repeat:
> > - page = grab_cache_page(mapping, blk_addr);
> > - if (!page) {
> > - cond_resched();
> > - goto repeat;
> > - }
> > - if (PageUptodate(page)) {
> > - mark_page_accessed(page);
> > - f2fs_put_page(page, 1);
> > - continue;
> > - }
> > -
> > - f2fs_submit_page_mbio(sbi, page, blk_addr, &fio);
> > -
> > - mark_page_accessed(page);
> > - f2fs_put_page(page, 0);
> > - }
> > -
> > - f2fs_submit_merged_bio(sbi, META, READ);
> > - return blkno - start;
> > -}
> > -
> > static void build_sit_entries(struct f2fs_sb_info *sbi)
> > {
> > struct sit_info *sit_i = SIT_I(sbi);
> > @@ -1635,7 +1594,7 @@ static void build_sit_entries(struct f2fs_sb_info *sbi)
> > int nrpages = MAX_BIO_BLOCKS(max_hw_blocks(sbi));
> >
> > do {
> > - readed = ra_sit_pages(sbi, start_blk, nrpages);
> > + readed = ra_meta_pages(sbi, start_blk, nrpages, META_SIT);
> >
> > start = start_blk * sit_i->sents_per_block;
> > end = (start_blk + readed) * sit_i->sents_per_block;
>
> --
> Jaegeuk Kim
> Samsung
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