f2fs: check the largest extent at look-up time

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.

Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index be0945cd9808c91ef469be665042fd34dc4349d2..cdc1c2b781b8e6985d6c1aa8538360c3c625ebf0 100644 (file)
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -512,12 +512,22 @@ 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;
@@ -526,13 +536,15 @@ 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 04856a2d8c82d7d8579ba65125942b02a7820359..a01946514b5ac567b248fc86ad1b44d4d9581dc8 100644 (file)
--- 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, "