ext4: add a function merging extents right and left
1) Rename ext4_ext_try_to_merge() to ext4_ext_try_to_merge_right().
2) Add a new function ext4_ext_try_to_merge() which tries to merge
an extent both left and right.
3) Use the new function in ext4_ext_convert_unwritten_endio() and
ext4_ext_insert_extent().
Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Tested-by: Allison Henderson <achender@linux.vnet.ibm.com>
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 4890d6f..23a98b6 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -1563,7 +1563,7 @@
* Returns 0 if the extents (ex and ex+1) were _not_ merged and returns
* 1 if they got merged.
*/
-static int ext4_ext_try_to_merge(struct inode *inode,
+static int ext4_ext_try_to_merge_right(struct inode *inode,
struct ext4_ext_path *path,
struct ext4_extent *ex)
{
@@ -1603,6 +1603,31 @@
}
/*
+ * This function tries to merge the @ex extent to neighbours in the tree.
+ * return 1 if merge left else 0.
+ */
+static int ext4_ext_try_to_merge(struct inode *inode,
+ struct ext4_ext_path *path,
+ struct ext4_extent *ex) {
+ struct ext4_extent_header *eh;
+ unsigned int depth;
+ int merge_done = 0;
+ int ret = 0;
+
+ depth = ext_depth(inode);
+ BUG_ON(path[depth].p_hdr == NULL);
+ eh = path[depth].p_hdr;
+
+ if (ex > EXT_FIRST_EXTENT(eh))
+ merge_done = ext4_ext_try_to_merge_right(inode, path, ex - 1);
+
+ if (!merge_done)
+ ret = ext4_ext_try_to_merge_right(inode, path, ex);
+
+ return ret;
+}
+
+/*
* check if a portion of the "newext" extent overlaps with an
* existing extent.
*
@@ -3039,6 +3064,7 @@
ext4_ext_dirty(handle, inode, path + depth);
return err;
}
+
static int ext4_convert_unwritten_extents_endio(handle_t *handle,
struct inode *inode,
struct ext4_ext_path *path)
@@ -3047,46 +3073,27 @@
struct ext4_extent_header *eh;
int depth;
int err = 0;
- int ret = 0;
depth = ext_depth(inode);
eh = path[depth].p_hdr;
ex = path[depth].p_ext;
+ ext_debug("ext4_convert_unwritten_extents_endio: inode %lu, logical"
+ "block %llu, max_blocks %u\n", inode->i_ino,
+ (unsigned long long)le32_to_cpu(ex->ee_block),
+ ext4_ext_get_actual_len(ex));
+
err = ext4_ext_get_access(handle, inode, path + depth);
if (err)
goto out;
/* first mark the extent as initialized */
ext4_ext_mark_initialized(ex);
- /*
- * We have to see if it can be merged with the extent
- * on the left.
+ /* note: ext4_ext_correct_indexes() isn't needed here because
+ * borders are not changed
*/
- if (ex > EXT_FIRST_EXTENT(eh)) {
- /*
- * To merge left, pass "ex - 1" to try_to_merge(),
- * since it merges towards right _only_.
- */
- ret = ext4_ext_try_to_merge(inode, path, ex - 1);
- if (ret) {
- err = ext4_ext_correct_indexes(handle, inode, path);
- if (err)
- goto out;
- depth = ext_depth(inode);
- ex--;
- }
- }
- /*
- * Try to Merge towards right.
- */
- ret = ext4_ext_try_to_merge(inode, path, ex);
- if (ret) {
- err = ext4_ext_correct_indexes(handle, inode, path);
- if (err)
- goto out;
- depth = ext_depth(inode);
- }
+ ext4_ext_try_to_merge(inode, path, ex);
+
/* Mark modified extent as dirty */
err = ext4_ext_dirty(handle, inode, path + depth);
out: