ext4: lookup block mapping in extent status tree
After tracking all extent status, we already have a extent cache in
memory. Every time we want to lookup a block mapping, we can first
try to lookup it in extent status tree to avoid a potential disk I/O.
A new function called ext4_es_lookup_extent is defined to finish this
work. When we try to lookup a block mapping, we always call
ext4_map_blocks and/or ext4_da_map_blocks. So in these functions we
first try to lookup a block mapping in extent status tree.
A new flag EXT4_GET_BLOCKS_NO_PUT_HOLE is used in ext4_da_map_blocks
in order not to put a hole into extent status tree because this hole
will be converted to delayed extent in the tree immediately.
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Jan kara <jack@suse.cz>
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index be0b1b3..b9d7a23 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2167,6 +2167,9 @@
block,
le32_to_cpu(ex->ee_block),
ext4_ext_get_actual_len(ex));
+ if (!ext4_find_delalloc_range(inode, lblock, lblock + len - 1))
+ ext4_es_insert_extent(inode, lblock, len, ~0,
+ EXTENT_STATUS_HOLE);
} else if (block >= le32_to_cpu(ex->ee_block)
+ ext4_ext_get_actual_len(ex)) {
ext4_lblk_t next;
@@ -2180,6 +2183,9 @@
block);
BUG_ON(next == lblock);
len = next - lblock;
+ if (!ext4_find_delalloc_range(inode, lblock, lblock + len - 1))
+ ext4_es_insert_extent(inode, lblock, len, ~0,
+ EXTENT_STATUS_HOLE);
} else {
lblock = len = 0;
BUG();
@@ -4018,7 +4024,8 @@
* put just found gap into cache to speed up
* subsequent requests
*/
- ext4_ext_put_gap_in_cache(inode, path, map->m_lblk);
+ if ((flags & EXT4_GET_BLOCKS_NO_PUT_HOLE) == 0)
+ ext4_ext_put_gap_in_cache(inode, path, map->m_lblk);
goto out2;
}