2021-02-09 20:47:23

by harshad shirwadkar

[permalink] [raw]
Subject: [PATCH v2 3/5] ext4: add MB_NUM_ORDERS macro

A few arrays in mballoc.c use the total number of valid orders as
their size. Currently, this value is set as "sb->s_blocksize_bits +
2". This makes code harder to read. So, instead add a new macro
MB_NUM_ORDERS(sb) to make the code more readable.

Signed-off-by: Harshad Shirwadkar <[email protected]>
Reviewed-by: Andreas Dilger <[email protected]>
---
fs/ext4/mballoc.c | 15 ++++++++-------
fs/ext4/mballoc.h | 5 +++++
2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index fffd0770e930..b7f25120547d 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -756,7 +756,7 @@ mb_set_largest_free_order(struct super_block *sb, struct ext4_group_info *grp)

grp->bb_largest_free_order = -1; /* uninit */

- bits = sb->s_blocksize_bits + 1;
+ bits = MB_NUM_ORDERS(sb) - 1;
for (i = bits; i >= 0; i--) {
if (grp->bb_counters[i] > 0) {
grp->bb_largest_free_order = i;
@@ -1928,7 +1928,7 @@ void ext4_mb_simple_scan_group(struct ext4_allocation_context *ac,
int max;

BUG_ON(ac->ac_2order <= 0);
- for (i = ac->ac_2order; i <= sb->s_blocksize_bits + 1; i++) {
+ for (i = ac->ac_2order; i < MB_NUM_ORDERS(sb); i++) {
if (grp->bb_counters[i] == 0)
continue;

@@ -2314,13 +2314,13 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac)
* We also support searching for power-of-two requests only for
* requests upto maximum buddy size we have constructed.
*/
- if (i >= sbi->s_mb_order2_reqs && i <= sb->s_blocksize_bits + 2) {
+ if (i >= sbi->s_mb_order2_reqs && i <= MB_NUM_ORDERS(sb)) {
/*
* This should tell if fe_len is exactly power of 2
*/
if ((ac->ac_g_ex.fe_len & (~(1 << (i - 1)))) == 0)
ac->ac_2order = array_index_nospec(i - 1,
- sb->s_blocksize_bits + 2);
+ MB_NUM_ORDERS(sb));
}

/* if stream allocation is enabled, use global goal */
@@ -2850,7 +2850,7 @@ int ext4_mb_init(struct super_block *sb)
unsigned max;
int ret;

- i = (sb->s_blocksize_bits + 2) * sizeof(*sbi->s_mb_offsets);
+ i = MB_NUM_ORDERS(sb) * sizeof(*sbi->s_mb_offsets);

sbi->s_mb_offsets = kmalloc(i, GFP_KERNEL);
if (sbi->s_mb_offsets == NULL) {
@@ -2858,7 +2858,7 @@ int ext4_mb_init(struct super_block *sb)
goto out;
}

- i = (sb->s_blocksize_bits + 2) * sizeof(*sbi->s_mb_maxs);
+ i = MB_NUM_ORDERS(sb) * sizeof(*sbi->s_mb_maxs);
sbi->s_mb_maxs = kmalloc(i, GFP_KERNEL);
if (sbi->s_mb_maxs == NULL) {
ret = -ENOMEM;
@@ -2884,7 +2884,8 @@ int ext4_mb_init(struct super_block *sb)
offset_incr = offset_incr >> 1;
max = max >> 1;
i++;
- } while (i <= sb->s_blocksize_bits + 1);
+ } while (i < MB_NUM_ORDERS(sb));
+

spin_lock_init(&sbi->s_md_lock);
sbi->s_mb_free_pending = 0;
diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h
index 7597330dbdf8..02861406932f 100644
--- a/fs/ext4/mballoc.h
+++ b/fs/ext4/mballoc.h
@@ -78,6 +78,11 @@
*/
#define MB_DEFAULT_MAX_INODE_PREALLOC 512

+/*
+ * Number of valid buddy orders
+ */
+#define MB_NUM_ORDERS(sb) ((sb)->s_blocksize_bits + 2)
+
struct ext4_free_data {
/* this links the free block information from sb_info */
struct list_head efd_list;
--
2.30.0.478.g8a0d178c01-goog


Subject: Re: [PATCH v2 3/5] ext4: add MB_NUM_ORDERS macro

Hello Harshad,

I believe there are two places yet there number could be changed to the macros

fs/ext4/mballoc.c <<ext4_mb_init_cache>>
(sb->s_blocksize_bits+2));

fs/ext4/mballoc.c <<ext4_mb_good_group>>
if (ac->ac_2order > ac->ac_sb->s_blocksize_bits+1)

Best regards,
Artem Blagodarenko

> On 9 Feb 2021, at 23:28, Harshad Shirwadkar <[email protected]> wrote:
>
> A few arrays in mballoc.c use the total number of valid orders as
> their size. Currently, this value is set as "sb->s_blocksize_bits +
> 2". This makes code harder to read. So, instead add a new macro
> MB_NUM_ORDERS(sb) to make the code more readable.
>
> Signed-off-by: Harshad Shirwadkar <[email protected]>
> Reviewed-by: Andreas Dilger <[email protected]>
> ---
> fs/ext4/mballoc.c | 15 ++++++++-------
> fs/ext4/mballoc.h | 5 +++++
> 2 files changed, 13 insertions(+), 7 deletions(-)
>
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index fffd0770e930..b7f25120547d 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -756,7 +756,7 @@ mb_set_largest_free_order(struct super_block *sb, struct ext4_group_info *grp)
>
> grp->bb_largest_free_order = -1; /* uninit */
>
> - bits = sb->s_blocksize_bits + 1;
> + bits = MB_NUM_ORDERS(sb) - 1;
> for (i = bits; i >= 0; i--) {
> if (grp->bb_counters[i] > 0) {
> grp->bb_largest_free_order = i;
> @@ -1928,7 +1928,7 @@ void ext4_mb_simple_scan_group(struct ext4_allocation_context *ac,
> int max;
>
> BUG_ON(ac->ac_2order <= 0);
> - for (i = ac->ac_2order; i <= sb->s_blocksize_bits + 1; i++) {
> + for (i = ac->ac_2order; i < MB_NUM_ORDERS(sb); i++) {
> if (grp->bb_counters[i] == 0)
> continue;
>
> @@ -2314,13 +2314,13 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac)
> * We also support searching for power-of-two requests only for
> * requests upto maximum buddy size we have constructed.
> */
> - if (i >= sbi->s_mb_order2_reqs && i <= sb->s_blocksize_bits + 2) {
> + if (i >= sbi->s_mb_order2_reqs && i <= MB_NUM_ORDERS(sb)) {
> /*
> * This should tell if fe_len is exactly power of 2
> */
> if ((ac->ac_g_ex.fe_len & (~(1 << (i - 1)))) == 0)
> ac->ac_2order = array_index_nospec(i - 1,
> - sb->s_blocksize_bits + 2);
> + MB_NUM_ORDERS(sb));
> }
>
> /* if stream allocation is enabled, use global goal */
> @@ -2850,7 +2850,7 @@ int ext4_mb_init(struct super_block *sb)
> unsigned max;
> int ret;
>
> - i = (sb->s_blocksize_bits + 2) * sizeof(*sbi->s_mb_offsets);
> + i = MB_NUM_ORDERS(sb) * sizeof(*sbi->s_mb_offsets);
>
> sbi->s_mb_offsets = kmalloc(i, GFP_KERNEL);
> if (sbi->s_mb_offsets == NULL) {
> @@ -2858,7 +2858,7 @@ int ext4_mb_init(struct super_block *sb)
> goto out;
> }
>
> - i = (sb->s_blocksize_bits + 2) * sizeof(*sbi->s_mb_maxs);
> + i = MB_NUM_ORDERS(sb) * sizeof(*sbi->s_mb_maxs);
> sbi->s_mb_maxs = kmalloc(i, GFP_KERNEL);
> if (sbi->s_mb_maxs == NULL) {
> ret = -ENOMEM;
> @@ -2884,7 +2884,8 @@ int ext4_mb_init(struct super_block *sb)
> offset_incr = offset_incr >> 1;
> max = max >> 1;
> i++;
> - } while (i <= sb->s_blocksize_bits + 1);
> + } while (i < MB_NUM_ORDERS(sb));
> +
>
> spin_lock_init(&sbi->s_md_lock);
> sbi->s_mb_free_pending = 0;
> diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h
> index 7597330dbdf8..02861406932f 100644
> --- a/fs/ext4/mballoc.h
> +++ b/fs/ext4/mballoc.h
> @@ -78,6 +78,11 @@
> */
> #define MB_DEFAULT_MAX_INODE_PREALLOC 512
>
> +/*
> + * Number of valid buddy orders
> + */
> +#define MB_NUM_ORDERS(sb) ((sb)->s_blocksize_bits + 2)
> +
> struct ext4_free_data {
> /* this links the free block information from sb_info */
> struct list_head efd_list;
> --
> 2.30.0.478.g8a0d178c01-goog
>