ext4: cache all of an extent tree's leaf block upon reading
When we read in an extent tree leaf block from disk, arrange to have
all of its entries cached. In nearly all cases the in-memory
representation will be more compact than the on-disk representation in
the buffer cache, and it allows us to get the information without
having to traverse the extent tree for successive extents.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
index ded2615..1dc5df0 100644
--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -419,7 +419,7 @@
unsigned short ee_len;
int depth, ee_status, es_status;
- path = ext4_ext_find_extent(inode, es->es_lblk, NULL);
+ path = ext4_ext_find_extent(inode, es->es_lblk, NULL, EXT4_EX_NOCACHE);
if (IS_ERR(path))
return;
@@ -684,6 +684,41 @@
}
/*
+ * ext4_es_cache_extent() inserts information into the extent status
+ * tree if and only if there isn't information about the range in
+ * question already.
+ */
+void ext4_es_cache_extent(struct inode *inode, ext4_lblk_t lblk,
+ ext4_lblk_t len, ext4_fsblk_t pblk,
+ unsigned int status)
+{
+ struct extent_status *es;
+ struct extent_status newes;
+ ext4_lblk_t end = lblk + len - 1;
+
+ newes.es_lblk = lblk;
+ newes.es_len = len;
+ ext4_es_store_pblock(&newes, pblk);
+ ext4_es_store_status(&newes, status);
+ trace_ext4_es_cache_extent(inode, &newes);
+
+ if (!len)
+ return;
+
+ BUG_ON(end < lblk);
+
+ write_lock(&EXT4_I(inode)->i_es_lock);
+
+ es = __es_tree_search(&EXT4_I(inode)->i_es_tree.root, lblk);
+ if (es && ((es->es_lblk <= lblk) || (es->es_lblk <= end)))
+ goto out;
+
+ __es_insert_extent(inode, &newes);
+out:
+ write_unlock(&EXT4_I(inode)->i_es_lock);
+}
+
+/*
* ext4_es_lookup_extent() looks up an extent in extent status tree.
*
* ext4_es_lookup_extent is called by ext4_map_blocks/ext4_da_map_blocks.