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/ext4.h b/fs/ext4/ext4.h
index 5c31d6a..329e7fb 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -579,6 +579,8 @@
#define EXT4_GET_BLOCKS_KEEP_SIZE 0x0080
/* Do not take i_data_sem locking in ext4_map_blocks */
#define EXT4_GET_BLOCKS_NO_LOCK 0x0100
+ /* Do not put hole in extent cache */
+#define EXT4_GET_BLOCKS_NO_PUT_HOLE 0x0200
/*
* Flags used by ext4_free_blocks
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;
}
diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
index 76f4351..eeb8931 100644
--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -461,6 +461,66 @@
return err;
}
+/*
+ * 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.
+ *
+ * Return: 1 on found, 0 on not
+ */
+int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk,
+ struct extent_status *es)
+{
+ struct ext4_es_tree *tree;
+ struct extent_status *es1 = NULL;
+ struct rb_node *node;
+ int found = 0;
+
+ trace_ext4_es_lookup_extent_enter(inode, lblk);
+ es_debug("lookup extent in block %u\n", lblk);
+
+ tree = &EXT4_I(inode)->i_es_tree;
+ read_lock(&EXT4_I(inode)->i_es_lock);
+
+ /* find extent in cache firstly */
+ es->es_lblk = es->es_len = es->es_pblk = 0;
+ if (tree->cache_es) {
+ es1 = tree->cache_es;
+ if (in_range(lblk, es1->es_lblk, es1->es_len)) {
+ es_debug("%u cached by [%u/%u)\n",
+ lblk, es1->es_lblk, es1->es_len);
+ found = 1;
+ goto out;
+ }
+ }
+
+ node = tree->root.rb_node;
+ while (node) {
+ es1 = rb_entry(node, struct extent_status, rb_node);
+ if (lblk < es1->es_lblk)
+ node = node->rb_left;
+ else if (lblk > ext4_es_end(es1))
+ node = node->rb_right;
+ else {
+ found = 1;
+ break;
+ }
+ }
+
+out:
+ if (found) {
+ BUG_ON(!es1);
+ es->es_lblk = es1->es_lblk;
+ es->es_len = es1->es_len;
+ es->es_pblk = es1->es_pblk;
+ }
+
+ read_unlock(&EXT4_I(inode)->i_es_lock);
+
+ trace_ext4_es_lookup_extent_exit(inode, es, found);
+ return found;
+}
+
static int __es_remove_extent(struct ext4_es_tree *tree, ext4_lblk_t lblk,
ext4_lblk_t end)
{
diff --git a/fs/ext4/extents_status.h b/fs/ext4/extents_status.h
index 3f69d09..8ffc90c 100644
--- a/fs/ext4/extents_status.h
+++ b/fs/ext4/extents_status.h
@@ -53,6 +53,8 @@
ext4_lblk_t len);
extern void ext4_es_find_delayed_extent(struct inode *inode, ext4_lblk_t lblk,
struct extent_status *es);
+extern int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk,
+ struct extent_status *es);
static inline int ext4_es_is_written(struct extent_status *es)
{
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 576b586b..95a0c62 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -507,12 +507,33 @@
int ext4_map_blocks(handle_t *handle, struct inode *inode,
struct ext4_map_blocks *map, int flags)
{
+ struct extent_status es;
int retval;
map->m_flags = 0;
ext_debug("ext4_map_blocks(): inode %lu, flag %d, max_blocks %u,"
"logical block %lu\n", inode->i_ino, flags, map->m_len,
(unsigned long) map->m_lblk);
+
+ /* Lookup extent status tree firstly */
+ if (ext4_es_lookup_extent(inode, map->m_lblk, &es)) {
+ if (ext4_es_is_written(&es) || ext4_es_is_unwritten(&es)) {
+ map->m_pblk = ext4_es_pblock(&es) +
+ map->m_lblk - es.es_lblk;
+ map->m_flags |= ext4_es_is_written(&es) ?
+ EXT4_MAP_MAPPED : EXT4_MAP_UNWRITTEN;
+ retval = es.es_len - (map->m_lblk - es.es_lblk);
+ if (retval > map->m_len)
+ retval = map->m_len;
+ map->m_len = retval;
+ } else if (ext4_es_is_delayed(&es) || ext4_es_is_hole(&es)) {
+ retval = 0;
+ } else {
+ BUG_ON(1);
+ }
+ goto found;
+ }
+
/*
* Try to see if we can get the block without requesting a new
* file system block.
@@ -544,6 +565,7 @@
if (!(flags & EXT4_GET_BLOCKS_NO_LOCK))
up_read((&EXT4_I(inode)->i_data_sem));
+found:
if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
int ret = check_block_validity(inode, map);
if (ret != 0)
@@ -1743,6 +1765,7 @@
struct ext4_map_blocks *map,
struct buffer_head *bh)
{
+ struct extent_status es;
int retval;
sector_t invalid_block = ~((sector_t) 0xffff);
@@ -1753,6 +1776,42 @@
ext_debug("ext4_da_map_blocks(): inode %lu, max_blocks %u,"
"logical block %lu\n", inode->i_ino, map->m_len,
(unsigned long) map->m_lblk);
+
+ /* Lookup extent status tree firstly */
+ if (ext4_es_lookup_extent(inode, iblock, &es)) {
+
+ if (ext4_es_is_hole(&es)) {
+ retval = 0;
+ down_read((&EXT4_I(inode)->i_data_sem));
+ goto add_delayed;
+ }
+
+ /*
+ * Delayed extent could be allocated by fallocate.
+ * So we need to check it.
+ */
+ if (ext4_es_is_delayed(&es) && !ext4_es_is_unwritten(&es)) {
+ map_bh(bh, inode->i_sb, invalid_block);
+ set_buffer_new(bh);
+ set_buffer_delay(bh);
+ return 0;
+ }
+
+ map->m_pblk = ext4_es_pblock(&es) + iblock - es.es_lblk;
+ retval = es.es_len - (iblock - es.es_lblk);
+ if (retval > map->m_len)
+ retval = map->m_len;
+ map->m_len = retval;
+ if (ext4_es_is_written(&es))
+ map->m_flags |= EXT4_MAP_MAPPED;
+ else if (ext4_es_is_unwritten(&es))
+ map->m_flags |= EXT4_MAP_UNWRITTEN;
+ else
+ BUG_ON(1);
+
+ return retval;
+ }
+
/*
* Try to see if we can get the block without requesting a new
* file system block.
@@ -1771,10 +1830,13 @@
map->m_flags |= EXT4_MAP_FROM_CLUSTER;
retval = 0;
} else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
- retval = ext4_ext_map_blocks(NULL, inode, map, 0);
+ retval = ext4_ext_map_blocks(NULL, inode, map,
+ EXT4_GET_BLOCKS_NO_PUT_HOLE);
else
- retval = ext4_ind_map_blocks(NULL, inode, map, 0);
+ retval = ext4_ind_map_blocks(NULL, inode, map,
+ EXT4_GET_BLOCKS_NO_PUT_HOLE);
+add_delayed:
if (retval == 0) {
int ret;
/*