When a large flex_bg file system is resized, the number of groups to be
added may be small, and a large amount of memory that will not be used will
be allocated. Therefore, resize_bg can be set to the size after the number
of new_group_data to be used is aligned upwards to the power of 2. This
does not affect the disk layout after online resize and saves some memory.
Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
---
fs/ext4/resize.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index e168a9f59600..4d4a5a32e310 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -235,8 +235,10 @@ struct ext4_new_flex_group_data {
*
* Returns NULL on failure otherwise address of the allocated structure.
*/
-static struct ext4_new_flex_group_data *alloc_flex_gd(unsigned int flexbg_size)
+static struct ext4_new_flex_group_data *alloc_flex_gd(unsigned int flexbg_size,
+ ext4_group_t o_group, ext4_group_t n_group)
{
+ ext4_group_t last_group;
struct ext4_new_flex_group_data *flex_gd;
flex_gd = kmalloc(sizeof(*flex_gd), GFP_NOFS);
@@ -248,6 +250,14 @@ static struct ext4_new_flex_group_data *alloc_flex_gd(unsigned int flexbg_size)
else
flex_gd->resize_bg = flexbg_size;
+ /* Avoid allocating large 'groups' array if not needed */
+ last_group = o_group | (flex_gd->resize_bg - 1);
+ if (n_group <= last_group)
+ flex_gd->resize_bg = 1 << fls(n_group - o_group + 1);
+ else if (n_group - last_group < flex_gd->resize_bg)
+ flex_gd->resize_bg = 1 << max(fls(last_group - o_group + 1),
+ fls(n_group - last_group));
+
flex_gd->groups = kmalloc_array(flex_gd->resize_bg,
sizeof(struct ext4_new_group_data),
GFP_NOFS);
@@ -2131,7 +2141,7 @@ int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
if (err)
goto out;
- flex_gd = alloc_flex_gd(flexbg_size);
+ flex_gd = alloc_flex_gd(flexbg_size, o_group, n_group);
if (flex_gd == NULL) {
err = -ENOMEM;
goto out;
--
2.31.1
