ext4: refine extent status tree

This commit refines the extent status tree code.

1) A prefix 'es_' is added to to the extent status tree structure
members.

2) Refactored es_remove_extent() so that __es_remove_extent() can be
used by es_insert_extent() to remove the old extent entry(-ies) before
inserting a new one.

3) Rename extent_status_end() to ext4_es_end()

4) ext4_es_can_be_merged() is define to check whether two extents can
be merged or not.

5) Update and clarified comments.

Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>

1 files changed, 11 insertions, 10 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index b6b54d658dc2..37f94a751ad7 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3528,13 +3528,14 @@ static int ext4_find_delalloc_range(struct inode *inode,
 {
         struct extent_status es;
 
-        es.start = lblk_start;
-        ext4_es_find_extent(inode, &es);
-        if (es.len == 0)
+        es.es_lblk = lblk_start;
+        (void)ext4_es_find_extent(inode, &es);
+        if (es.es_len == 0)
                 return 0; /* there is no delay extent in this tree */
-        else if (es.start <= lblk_start && lblk_start < es.start + es.len)
+        else if (es.es_lblk <= lblk_start &&
+                 lblk_start < es.es_lblk + es.es_len)
                 return 1;
-        else if (lblk_start <= es.start && es.start <= lblk_end)
+        else if (lblk_start <= es.es_lblk && es.es_lblk <= lblk_end)
                 return 1;
         else
                 return 0;
@@ -4569,7 +4570,7 @@ static int ext4_find_delayed_extent(struct inode *inode,
         struct extent_status es;
         ext4_lblk_t next_del;
 
-        es.start = newex->ec_block;
+        es.es_lblk = newex->ec_block;
         next_del = ext4_es_find_extent(inode, &es);
 
         if (newex->ec_start == 0) {
@@ -4577,18 +4578,18 @@ static int ext4_find_delayed_extent(struct inode *inode,
                  * No extent in extent-tree contains block @newex->ec_start,
                  * then the block may stay in 1)a hole or 2)delayed-extent.
                  */
-                if (es.len == 0)
+                if (es.es_len == 0)
                         /* A hole found. */
                         return 0;
 
-                if (es.start > newex->ec_block) {
+                if (es.es_lblk > newex->ec_block) {
                         /* A hole found. */
-                        newex->ec_len = min(es.start - newex->ec_block,
+                        newex->ec_len = min(es.es_lblk - newex->ec_block,
                                             newex->ec_len);
                         return 0;
                 }
 
-                newex->ec_len = es.start + es.len - newex->ec_block;
+                newex->ec_len = es.es_lblk + es.es_len - newex->ec_block;
         }
 
         return next_del;