2018-12-21 21:00:49

by Nikolay Borisov

[permalink] [raw]
Subject: [PATCH] mm: Define VM_(MAX|MIN)_READAHEAD via sizes.h constants

All users of the aformentioned macros convert them to kbytes by
multplying. Instead, directly define the macros via the aptly named
SZ_16K/SZ_128K ones. Also remove the now redundant comments explaining
that VM_* are defined in kbytes it's obvious. No functional changes.

Signed-off-by: Nikolay Borisov <[email protected]>
---

I guess it makes sense for this to land via Andrew's mmotm tree?

block/blk-core.c | 3 +--
fs/9p/vfs_super.c | 2 +-
fs/afs/super.c | 2 +-
fs/btrfs/disk-io.c | 2 +-
fs/fuse/inode.c | 2 +-
include/linux/mm.h | 5 +++--
6 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index deb56932f8c4..d28b2eeec07e 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1031,8 +1031,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id,
if (!q->stats)
goto fail_stats;

- q->backing_dev_info->ra_pages =
- (VM_MAX_READAHEAD * 1024) / PAGE_SIZE;
+ q->backing_dev_info->ra_pages = VM_MAX_READAHEAD / PAGE_SIZE;
q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK;
q->backing_dev_info->name = "block";
q->node = node_id;
diff --git a/fs/9p/vfs_super.c b/fs/9p/vfs_super.c
index 48ce50484e80..5c9f757410ae 100644
--- a/fs/9p/vfs_super.c
+++ b/fs/9p/vfs_super.c
@@ -92,7 +92,7 @@ v9fs_fill_super(struct super_block *sb, struct v9fs_session_info *v9ses,
return ret;

if (v9ses->cache)
- sb->s_bdi->ra_pages = (VM_MAX_READAHEAD * 1024)/PAGE_SIZE;
+ sb->s_bdi->ra_pages = VM_MAX_READAHEAD / PAGE_SIZE;

sb->s_flags |= SB_ACTIVE | SB_DIRSYNC;
if (!v9ses->cache)
diff --git a/fs/afs/super.c b/fs/afs/super.c
index dcd07fe99871..d1f3af74481a 100644
--- a/fs/afs/super.c
+++ b/fs/afs/super.c
@@ -399,7 +399,7 @@ static int afs_fill_super(struct super_block *sb,
ret = super_setup_bdi(sb);
if (ret)
return ret;
- sb->s_bdi->ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_SIZE;
+ sb->s_bdi->ra_pages = VM_MAX_READAHEAD / PAGE_SIZE;

/* allocate the root inode and dentry */
if (as->dyn_root) {
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 6d776717d8b3..d84e7283d24b 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2900,7 +2900,7 @@ int open_ctree(struct super_block *sb,
sb->s_bdi->congested_fn = btrfs_congested_fn;
sb->s_bdi->congested_data = fs_info;
sb->s_bdi->capabilities |= BDI_CAP_CGROUP_WRITEBACK;
- sb->s_bdi->ra_pages = VM_MAX_READAHEAD * SZ_1K / PAGE_SIZE;
+ sb->s_bdi->ra_pages = VM_MAX_READAHEAD / PAGE_SIZE;
sb->s_bdi->ra_pages *= btrfs_super_num_devices(disk_super);
sb->s_bdi->ra_pages = max(sb->s_bdi->ra_pages, SZ_4M / PAGE_SIZE);

diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 568abed20eb2..25766e9035b1 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1009,7 +1009,7 @@ static int fuse_bdi_init(struct fuse_conn *fc, struct super_block *sb)
if (err)
return err;

- sb->s_bdi->ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_SIZE;
+ sb->s_bdi->ra_pages = VM_MAX_READAHEAD / PAGE_SIZE;
/* fuse does it's own writeback accounting */
sb->s_bdi->capabilities = BDI_CAP_NO_ACCT_WB | BDI_CAP_STRICTLIMIT;

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 5411de93a363..e2085eaceae9 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -26,6 +26,7 @@
#include <linux/page_ref.h>
#include <linux/memremap.h>
#include <linux/overflow.h>
+#include <linux/sizes.h>

struct mempolicy;
struct anon_vma;
@@ -2396,8 +2397,8 @@ int __must_check write_one_page(struct page *page);
void task_dirty_inc(struct task_struct *tsk);

/* readahead.c */
-#define VM_MAX_READAHEAD 128 /* kbytes */
-#define VM_MIN_READAHEAD 16 /* kbytes (includes current page) */
+#define VM_MAX_READAHEAD SZ_128K
+#define VM_MIN_READAHEAD SZ_16K /* includes current page */

int force_page_cache_readahead(struct address_space *mapping, struct file *filp,
pgoff_t offset, unsigned long nr_to_read);
--
2.17.1



2018-12-21 21:37:59

by Matthew Wilcox

[permalink] [raw]
Subject: Re: [PATCH] mm: Define VM_(MAX|MIN)_READAHEAD via sizes.h constants

On Fri, Dec 21, 2018 at 02:53:14PM +0200, Nikolay Borisov wrote:
> All users of the aformentioned macros convert them to kbytes by
> multplying. Instead, directly define the macros via the aptly named
> SZ_16K/SZ_128K ones. Also remove the now redundant comments explaining
> that VM_* are defined in kbytes it's obvious. No functional changes.

Actually, all users of these constants convert them to pages!

> + q->backing_dev_info->ra_pages = VM_MAX_READAHEAD / PAGE_SIZE;
> + sb->s_bdi->ra_pages = VM_MAX_READAHEAD / PAGE_SIZE;
> + sb->s_bdi->ra_pages = VM_MAX_READAHEAD / PAGE_SIZE;
> + sb->s_bdi->ra_pages = VM_MAX_READAHEAD / PAGE_SIZE;
> + sb->s_bdi->ra_pages = VM_MAX_READAHEAD / PAGE_SIZE;

> -#define VM_MAX_READAHEAD 128 /* kbytes */
> -#define VM_MIN_READAHEAD 16 /* kbytes (includes current page) */
> +#define VM_MAX_READAHEAD SZ_128K
> +#define VM_MIN_READAHEAD SZ_16K /* includes current page */

So perhaps:

#define VM_MAX_READAHEAD (SZ_128K / PAGE_SIZE)

VM_MIN_READAHEAD isn't used, so just delete it?

2018-12-22 00:15:55

by Nikolay Borisov

[permalink] [raw]
Subject: Re: [PATCH] mm: Define VM_(MAX|MIN)_READAHEAD via sizes.h constants



On 21.12.18 г. 15:24 ч., Matthew Wilcox wrote:
> On Fri, Dec 21, 2018 at 02:53:14PM +0200, Nikolay Borisov wrote:
>> All users of the aformentioned macros convert them to kbytes by
>> multplying. Instead, directly define the macros via the aptly named
>> SZ_16K/SZ_128K ones. Also remove the now redundant comments explaining
>> that VM_* are defined in kbytes it's obvious. No functional changes.
>
> Actually, all users of these constants convert them to pages!
>
>> + q->backing_dev_info->ra_pages = VM_MAX_READAHEAD / PAGE_SIZE;
>> + sb->s_bdi->ra_pages = VM_MAX_READAHEAD / PAGE_SIZE;
>> + sb->s_bdi->ra_pages = VM_MAX_READAHEAD / PAGE_SIZE;
>> + sb->s_bdi->ra_pages = VM_MAX_READAHEAD / PAGE_SIZE;
>> + sb->s_bdi->ra_pages = VM_MAX_READAHEAD / PAGE_SIZE;
>
>> -#define VM_MAX_READAHEAD 128 /* kbytes */
>> -#define VM_MIN_READAHEAD 16 /* kbytes (includes current page) */
>> +#define VM_MAX_READAHEAD SZ_128K
>> +#define VM_MIN_READAHEAD SZ_16K /* includes current page */
>
> So perhaps:
>
> #define VM_MAX_READAHEAD (SZ_128K / PAGE_SIZE)
>
> VM_MIN_READAHEAD isn't used, so just delete it?

I thought about that but didn't know if people will complain that some
times in the future we might need it.

>