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Subject[PATCH v2] f2fs: adjust readahead block number during recovery
Date
In a fragmented image, entries in dnode block list may locate in
incontiguous physical block address space, however, in recovery flow,
we will always readahead BIO_MAX_VECS size blocks, so in such case,
current readahead policy is low efficient, let's adjust readahead
window size dynamically based on consecutiveness of dnode blocks.

Signed-off-by: Chao Yu <chao@kernel.org>
---
v2:
- fix wrong parameter of min_t/max_t in adjust_por_ra_blocks().
fs/f2fs/checkpoint.c | 8 ++++++--
fs/f2fs/f2fs.h | 6 +++++-
fs/f2fs/recovery.c | 27 ++++++++++++++++++++++++---
3 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 57a2d9164bee..203a1577942d 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -282,18 +282,22 @@ int f2fs_ra_meta_pages(struct f2fs_sb_info *sbi, block_t start, int nrpages,
return blkno - start;
}

-void f2fs_ra_meta_pages_cond(struct f2fs_sb_info *sbi, pgoff_t index)
+void f2fs_ra_meta_pages_cond(struct f2fs_sb_info *sbi, pgoff_t index,
+ unsigned int ra_blocks)
{
struct page *page;
bool readahead = false;

+ if (ra_blocks == RECOVERY_MIN_RA_BLOCKS)
+ return;
+
page = find_get_page(META_MAPPING(sbi), index);
if (!page || !PageUptodate(page))
readahead = true;
f2fs_put_page(page, 0);

if (readahead)
- f2fs_ra_meta_pages(sbi, index, BIO_MAX_VECS, META_POR, true);
+ f2fs_ra_meta_pages(sbi, index, ra_blocks, META_POR, true);
}

static int __f2fs_write_meta_page(struct page *page,
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 5af415208488..1fa6b3f98a71 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -590,6 +590,9 @@ enum {
/* number of extent info in extent cache we try to shrink */
#define EXTENT_CACHE_SHRINK_NUMBER 128

+#define RECOVERY_MAX_RA_BLOCKS BIO_MAX_VECS
+#define RECOVERY_MIN_RA_BLOCKS 1
+
struct rb_entry {
struct rb_node rb_node; /* rb node located in rb-tree */
union {
@@ -3655,7 +3658,8 @@ bool f2fs_is_valid_blkaddr(struct f2fs_sb_info *sbi,
block_t blkaddr, int type);
int f2fs_ra_meta_pages(struct f2fs_sb_info *sbi, block_t start, int nrpages,
int type, bool sync);
-void f2fs_ra_meta_pages_cond(struct f2fs_sb_info *sbi, pgoff_t index);
+void f2fs_ra_meta_pages_cond(struct f2fs_sb_info *sbi, pgoff_t index,
+ unsigned int ra_blocks);
long f2fs_sync_meta_pages(struct f2fs_sb_info *sbi, enum page_type type,
long nr_to_write, enum iostat_type io_type);
void f2fs_add_ino_entry(struct f2fs_sb_info *sbi, nid_t ino, int type);
diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
index f69b685fb2b2..013e99c6671d 100644
--- a/fs/f2fs/recovery.c
+++ b/fs/f2fs/recovery.c
@@ -346,6 +346,19 @@ static int recover_inode(struct inode *inode, struct page *page)
return 0;
}

+static unsigned int adjust_por_ra_blocks(struct f2fs_sb_info *sbi,
+ unsigned int ra_blocks, unsigned int blkaddr,
+ unsigned int next_blkaddr)
+{
+ if (blkaddr + 1 == next_blkaddr)
+ ra_blocks = min_t(unsigned int, RECOVERY_MAX_RA_BLOCKS,
+ ra_blocks * 2);
+ else if (next_blkaddr % sbi->blocks_per_seg)
+ ra_blocks = max_t(unsigned int, RECOVERY_MIN_RA_BLOCKS,
+ ra_blocks / 2);
+ return ra_blocks;
+}
+
static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head *head,
bool check_only)
{
@@ -353,6 +366,7 @@ static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head *head,
struct page *page = NULL;
block_t blkaddr;
unsigned int loop_cnt = 0;
+ unsigned int ra_blocks = RECOVERY_MAX_RA_BLOCKS;
unsigned int free_blocks = MAIN_SEGS(sbi) * sbi->blocks_per_seg -
valid_user_blocks(sbi);
int err = 0;
@@ -427,11 +441,14 @@ static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head *head,
break;
}

+ ra_blocks = adjust_por_ra_blocks(sbi, ra_blocks, blkaddr,
+ next_blkaddr_of_node(page));
+
/* check next segment */
blkaddr = next_blkaddr_of_node(page);
f2fs_put_page(page, 1);

- f2fs_ra_meta_pages_cond(sbi, blkaddr);
+ f2fs_ra_meta_pages_cond(sbi, blkaddr, ra_blocks);
}
return err;
}
@@ -707,6 +724,7 @@ static int recover_data(struct f2fs_sb_info *sbi, struct list_head *inode_list,
struct page *page = NULL;
int err = 0;
block_t blkaddr;
+ unsigned int ra_blocks = RECOVERY_MAX_RA_BLOCKS;

/* get node pages in the current segment */
curseg = CURSEG_I(sbi, CURSEG_WARM_NODE);
@@ -718,8 +736,6 @@ static int recover_data(struct f2fs_sb_info *sbi, struct list_head *inode_list,
if (!f2fs_is_valid_blkaddr(sbi, blkaddr, META_POR))
break;

- f2fs_ra_meta_pages_cond(sbi, blkaddr);
-
page = f2fs_get_tmp_page(sbi, blkaddr);
if (IS_ERR(page)) {
err = PTR_ERR(page);
@@ -762,9 +778,14 @@ static int recover_data(struct f2fs_sb_info *sbi, struct list_head *inode_list,
if (entry->blkaddr == blkaddr)
list_move_tail(&entry->list, tmp_inode_list);
next:
+ ra_blocks = adjust_por_ra_blocks(sbi, ra_blocks, blkaddr,
+ next_blkaddr_of_node(page));
+
/* check next segment */
blkaddr = next_blkaddr_of_node(page);
f2fs_put_page(page, 1);
+
+ f2fs_ra_meta_pages_cond(sbi, blkaddr, ra_blocks);
}
if (!err)
f2fs_allocate_new_segments(sbi);
--
2.32.0
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