RE: [f2fs-dev] [PATCH 07/10] f2fs: use meta_inode cache to improve roll-forward speed

From: Chao Yu
Date: Sun Sep 21 2014 - 22:37:21 EST

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Hi Jaegeuk,

> -----Original Message-----
> From: Jaegeuk Kim [mailto:jaegeuk@xxxxxxxxxx]
> Sent: Monday, September 15, 2014 6:14 AM
> To: linux-kernel@xxxxxxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx;
> linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: Jaegeuk Kim
> Subject: [f2fs-dev] [PATCH 07/10] f2fs: use meta_inode cache to improve roll-forward speed
>
> Previously, all the dnode pages should be read during the roll-forward recovery.
> Even worsely, whole the chain was traversed twice.
> This patch removes that redundant and costly read operations by using page cache
> of meta_inode and readahead function as well.
>
> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> ---
> fs/f2fs/checkpoint.c | 11 ++++++++--
> fs/f2fs/f2fs.h | 5 +++--
> fs/f2fs/recovery.c | 59 +++++++++++++++++++++++++---------------------------
> fs/f2fs/segment.h | 5 +++--
> 4 files changed, 43 insertions(+), 37 deletions(-)
>
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index 7262d99..d1ed889 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -82,6 +82,8 @@ static inline int get_max_meta_blks(struct f2fs_sb_info *sbi, int type)
> case META_SSA:
> case META_CP:
> return 0;
> + case META_POR:
> + return SM_I(sbi)->main_blkaddr + sbi->user_block_count;

Here we will skip virtual over-provision segments, so better to use TOTAL_BLKS(sbi).

> default:
> BUG();
> }
> @@ -90,11 +92,11 @@ static inline int get_max_meta_blks(struct f2fs_sb_info *sbi, int type)
> /*
> * Readahead CP/NAT/SIT/SSA pages
> */
> -int ra_meta_pages(struct f2fs_sb_info *sbi, int start, int nrpages, int type)
> +int ra_meta_pages(struct f2fs_sb_info *sbi, block_t start, int nrpages, int type)
> {
> block_t prev_blk_addr = 0;
> struct page *page;
> - int blkno = start;
> + block_t blkno = start;
> int max_blks = get_max_meta_blks(sbi, type);
>
> struct f2fs_io_info fio = {
> @@ -128,6 +130,11 @@ int ra_meta_pages(struct f2fs_sb_info *sbi, int start, int nrpages, int
> type)
> /* get ssa/cp block addr */
> blk_addr = blkno;
> break;
> + case META_POR:
> + if (unlikely(blkno >= max_blks))
> + goto out;
> + blk_addr = blkno;
> + break;

The real modification in patch which is merged to dev of f2fs is as following:

- /* get ssa/cp block addr */
+ case META_POR:
+ if (blkno >= max_blks || blkno < min_blks)
+ goto out;

IMHO, it's better to verify boundary separately for META_{SSA,CP,POR} with unlikely.
How do you think?

> default:
> BUG();
> }
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 4f84d2a..48d7d46 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -103,7 +103,8 @@ enum {
> META_CP,
> META_NAT,
> META_SIT,
> - META_SSA
> + META_SSA,
> + META_POR,
> };
>
> /* for the list of ino */
> @@ -1291,7 +1292,7 @@ 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);
> +int ra_meta_pages(struct f2fs_sb_info *, block_t, int, int);
> long sync_meta_pages(struct f2fs_sb_info *, enum page_type, long);
> void add_dirty_inode(struct f2fs_sb_info *, nid_t, int type);
> void remove_dirty_inode(struct f2fs_sb_info *, nid_t, int type);
> diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
> index 3736728..6f7fbfa 100644
> --- a/fs/f2fs/recovery.c
> +++ b/fs/f2fs/recovery.c
> @@ -173,7 +173,7 @@ static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head
> *head)
> {
> unsigned long long cp_ver = cur_cp_version(F2FS_CKPT(sbi));
> struct curseg_info *curseg;
> - struct page *page;
> + struct page *page = NULL;
> block_t blkaddr;
> int err = 0;
>
> @@ -181,20 +181,19 @@ static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head
> *head)
> curseg = CURSEG_I(sbi, CURSEG_WARM_NODE);
> blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);
>
> - /* read node page */
> - page = alloc_page(GFP_F2FS_ZERO);
> - if (!page)
> - return -ENOMEM;
> - lock_page(page);
> -
> while (1) {
> struct fsync_inode_entry *entry;
>
> - err = f2fs_submit_page_bio(sbi, page, blkaddr, READ_SYNC);
> - if (err)
> - return err;
> + if (blkaddr < SM_I(sbi)->main_blkaddr ||
> + blkaddr > TOTAL_BLKS(sbi))

blkaddr >= TOTAL_BLKS(sbi) ?

> + break;
>
> - lock_page(page);
> + page = get_meta_page(sbi, blkaddr);
> + if (IS_ERR(page))
> + return PTR_ERR(page);
> +
> + ra_meta_pages(sbi, next_blkaddr_of_node(page),
> + MAX_BIO_BLOCKS(max_hw_blocks(sbi)), META_POR);

In first round we readahead [0,n] pages, then in second round we readahead [1,n+1] pages,
but as [1,n] pages is already uptodate, so we will readahead only one page, the same for the
following rounds. It's low efficiency.

So how about modify in find_fsync_dnodes/recover_data like this:

block_t blkaddr, ra_start_blk;
int err = 0;

/* get node pages in the current segment */
curseg = CURSEG_I(sbi, CURSEG_WARM_NODE);
blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);
ra_start_blk = blkaddr;

while (1) {
struct fsync_inode_entry *entry;

if (blkaddr < SM_I(sbi)->main_blkaddr ||
blkaddr > TOTAL_BLKS(sbi))
return 0;

if (ra_start_blk == blkaddr) {
ra_meta_pages(sbi, ra_start_blk, MAX_BIO_BLOCKS(sbi),
META_POR);
ra_start_blk += MAX_BIO_BLOCKS(sbi);
}

page = get_meta_page(sbi, blkaddr);

Thanks,
Yu

>
> if (cp_ver != cpver_of_node(page))
> break;
> @@ -243,11 +242,9 @@ static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head
> *head)
> next:
> /* check next segment */
> blkaddr = next_blkaddr_of_node(page);
> + f2fs_put_page(page, 1);
> }
> -
> - unlock_page(page);
> - __free_pages(page, 0);
> -
> + f2fs_put_page(page, 1);
> return err;
> }
>
> @@ -427,7 +424,7 @@ static int recover_data(struct f2fs_sb_info *sbi,
> {
> unsigned long long cp_ver = cur_cp_version(F2FS_CKPT(sbi));
> struct curseg_info *curseg;
> - struct page *page;
> + struct page *page = NULL;
> int err = 0;
> block_t blkaddr;
>
> @@ -435,21 +432,19 @@ static int recover_data(struct f2fs_sb_info *sbi,
> curseg = CURSEG_I(sbi, type);
> blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);
>
> - /* read node page */
> - page = alloc_page(GFP_F2FS_ZERO);
> - if (!page)
> - return -ENOMEM;
> -
> - lock_page(page);
> -
> while (1) {
> struct fsync_inode_entry *entry;
>
> - err = f2fs_submit_page_bio(sbi, page, blkaddr, READ_SYNC);
> - if (err)
> - return err;
> + if (blkaddr < SM_I(sbi)->main_blkaddr ||
> + blkaddr > TOTAL_BLKS(sbi))
> + break;
>
> - lock_page(page);
> + page = get_meta_page(sbi, blkaddr);
> + if (IS_ERR(page))
> + return PTR_ERR(page);
> +
> + ra_meta_pages(sbi, next_blkaddr_of_node(page),
> + MAX_BIO_BLOCKS(max_hw_blocks(sbi)), META_POR);
>
> if (cp_ver != cpver_of_node(page))
> break;
> @@ -477,11 +472,9 @@ static int recover_data(struct f2fs_sb_info *sbi,
> next:
> /* check next segment */
> blkaddr = next_blkaddr_of_node(page);
> + f2fs_put_page(page, 1);
> }
> -
> - unlock_page(page);
> - __free_pages(page, 0);
> -
> + f2fs_put_page(page, 1);
> if (!err)
> allocate_new_segments(sbi);
> return err;
> @@ -527,6 +520,10 @@ out:
> destroy_fsync_dnodes(&inode_list);
> kmem_cache_destroy(fsync_entry_slab);
>
> + /* truncate meta pages to be used by the recovery */
> + truncate_inode_pages_range(META_MAPPING(sbi),
> + SM_I(sbi)->main_blkaddr << PAGE_CACHE_SHIFT, -1);
> +
> if (err) {
> truncate_inode_pages_final(NODE_MAPPING(sbi));
> truncate_inode_pages_final(META_MAPPING(sbi));
> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> index 013aed2..c6f37f2 100644
> --- a/fs/f2fs/segment.h
> +++ b/fs/f2fs/segment.h
> @@ -87,6 +87,7 @@
> (BITS_TO_LONGS(nr) * sizeof(unsigned long))
> #define TOTAL_SEGS(sbi) (SM_I(sbi)->main_segments)
> #define TOTAL_SECS(sbi) (sbi->total_sections)
> +#define TOTAL_BLKS(sbi) (SM_I(sbi)->segment_count << sbi->log_blocks_per_seg)
>
> #define SECTOR_FROM_BLOCK(sbi, blk_addr) \
> (((sector_t)blk_addr) << (sbi)->log_sectors_per_block)
> @@ -553,7 +554,7 @@ static inline void check_seg_range(struct f2fs_sb_info *sbi, unsigned int
> segno)
> static inline void verify_block_addr(struct f2fs_sb_info *sbi, block_t blk_addr)
> {
> struct f2fs_sm_info *sm_info = SM_I(sbi);
> - block_t total_blks = sm_info->segment_count << sbi->log_blocks_per_seg;
> + block_t total_blks = TOTAL_BLKS(sbi);
> block_t start_addr = sm_info->seg0_blkaddr;
> block_t end_addr = start_addr + total_blks - 1;
> BUG_ON(blk_addr < start_addr);
> @@ -606,7 +607,7 @@ static inline void check_seg_range(struct f2fs_sb_info *sbi, unsigned int
> segno)
> static inline void verify_block_addr(struct f2fs_sb_info *sbi, block_t blk_addr)
> {
> struct f2fs_sm_info *sm_info = SM_I(sbi);
> - block_t total_blks = sm_info->segment_count << sbi->log_blocks_per_seg;
> + block_t total_blks = TOTAL_BLKS(sbi);
> block_t start_addr = sm_info->seg0_blkaddr;
> block_t end_addr = start_addr + total_blks - 1;
>
> --
> 1.8.5.2 (Apple Git-48)
>
>
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Next message: Namhyung Kim: "[PATCH v3] perf tools: Fix build-id matching on vmlinux"
Previous message: nick: "Re: FIX ME in oxu210p-hcd.c"
Next in thread: Jaegeuk Kim: "Re: [f2fs-dev] [PATCH 07/10] f2fs: use meta_inode cache to improve roll-forward speed"
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