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Subject[PATCH 1/2] f2fs: check the largest extent at look-up time
Date
Because of the extent shrinker or other -ENOMEM scenarios, it cannot guarantee
that the largest extent would be cached in the tree all the time.

Instead of relying on extent_tree, we can simply check the cached one in extent
tree accordingly.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
---
fs/f2fs/data.c | 16 ++++++++++++++--
include/trace/events/f2fs.h | 12 ++++++------
2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index b6c28bb..8f059e0 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -511,12 +511,22 @@ static bool f2fs_lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
struct extent_tree *et = F2FS_I(inode)->extent_tree;
struct extent_node *en;
+ bool ret = false;

f2fs_bug_on(sbi, !et);

trace_f2fs_lookup_extent_tree_start(inode, pgofs);

read_lock(&et->lock);
+
+ if (et->largest.fofs <= pgofs &&
+ et->largest.fofs + et->largest.len > pgofs) {
+ *ei = et->largest;
+ ret = true;
+ stat_inc_read_hit(sbi->sb);
+ goto out;
+ }
+
en = __lookup_extent_tree(et, pgofs);
if (en) {
*ei = en->ei;
@@ -525,13 +535,15 @@ static bool f2fs_lookup_extent_tree(struct inode *inode, pgoff_t pgofs,
list_move_tail(&en->list, &sbi->extent_list);
et->cached_en = en;
spin_unlock(&sbi->extent_lock);
+ ret = true;
stat_inc_read_hit(sbi->sb);
}
+out:
stat_inc_total_hit(sbi->sb);
read_unlock(&et->lock);

- trace_f2fs_lookup_extent_tree_end(inode, pgofs, en);
- return en ? true : false;
+ trace_f2fs_lookup_extent_tree_end(inode, pgofs, ei);
+ return ret;
}

/* return true, if on-disk extent should be updated */
diff --git a/include/trace/events/f2fs.h b/include/trace/events/f2fs.h
index 04856a2..a019465 100644
--- a/include/trace/events/f2fs.h
+++ b/include/trace/events/f2fs.h
@@ -1099,11 +1099,11 @@ TRACE_EVENT(f2fs_lookup_extent_tree_start,
TRACE_EVENT_CONDITION(f2fs_lookup_extent_tree_end,

TP_PROTO(struct inode *inode, unsigned int pgofs,
- struct extent_node *en),
+ struct extent_info *ei),

- TP_ARGS(inode, pgofs, en),
+ TP_ARGS(inode, pgofs, ei),

- TP_CONDITION(en),
+ TP_CONDITION(ei),

TP_STRUCT__entry(
__field(dev_t, dev)
@@ -1118,9 +1118,9 @@ TRACE_EVENT_CONDITION(f2fs_lookup_extent_tree_end,
__entry->dev = inode->i_sb->s_dev;
__entry->ino = inode->i_ino;
__entry->pgofs = pgofs;
- __entry->fofs = en->ei.fofs;
- __entry->blk = en->ei.blk;
- __entry->len = en->ei.len;
+ __entry->fofs = ei->fofs;
+ __entry->blk = ei->blk;
+ __entry->len = ei->len;
),

TP_printk("dev = (%d,%d), ino = %lu, pgofs = %u, "
--
2.1.1


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