On Fri, Jun 13, 2025 at 08:19:39PM +0800, Matthew Wilcox (Oracle) wrote:
> Retrieve a folio from the page cache instead of a page. Removes a
> hidden call to compound_head(). Then be sure to call folio_put()
> instead of put_page() to release it. That doesn't save any calls
> to compound_head(), just moves them around.
>
> Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Hi Matthew,
Overall the patch is fine to me. I will reply you after doing some basic
testing.
Thanks.
Coly Li
> ---
> drivers/md/bcache/super.c | 22 +++++++++++-----------
> 1 file changed, 11 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> index 1efb768b2890..83c786a5cc47 100644
> --- a/drivers/md/bcache/super.c
> +++ b/drivers/md/bcache/super.c
> @@ -168,14 +168,14 @@ static const char *read_super(struct cache_sb *sb,
> struct block_device *bdev,
> {
> const char *err;
> struct cache_sb_disk *s;
> - struct page *page;
> + struct folio *folio;
> unsigned int i;
>
> - page = read_cache_page_gfp(bdev->bd_mapping,
> - SB_OFFSET >> PAGE_SHIFT, GFP_KERNEL);
> - if (IS_ERR(page))
> + folio = mapping_read_folio_gfp(bdev->bd_mapping,
> + SB_OFFSET >> PAGE_SHIFT, GFP_KERNEL);
> + if (IS_ERR(folio))
> return "IO error";
> - s = page_address(page) + offset_in_page(SB_OFFSET);
> + s = folio_address(folio) + offset_in_folio(folio, SB_OFFSET);
>
> sb->offset = le64_to_cpu(s->offset);
> sb->version = le64_to_cpu(s->version);
> @@ -272,7 +272,7 @@ static const char *read_super(struct cache_sb *sb, struct
> block_device *bdev,
> *res = s;
> return NULL;
> err:
> - put_page(page);
> + folio_put(folio);
> return err;
> }
>
> @@ -1366,7 +1366,7 @@ static CLOSURE_CALLBACK(cached_dev_free)
> mutex_unlock(&bch_register_lock);
>
> if (dc->sb_disk)
> - put_page(virt_to_page(dc->sb_disk));
> + folio_put(virt_to_folio(dc->sb_disk));
>
> if (dc->bdev_file)
> fput(dc->bdev_file);
> @@ -2215,7 +2215,7 @@ void bch_cache_release(struct kobject *kobj)
> free_fifo(&ca->free[i]);
>
> if (ca->sb_disk)
> - put_page(virt_to_page(ca->sb_disk));
> + folio_put(virt_to_folio(ca->sb_disk));
>
> if (ca->bdev_file)
> fput(ca->bdev_file);
> @@ -2592,7 +2592,7 @@ static ssize_t register_bcache(struct kobject *k,
> struct kobj_attribute *attr,
> if (!holder) {
> ret = -ENOMEM;
> err = "cannot allocate memory";
> - goto out_put_sb_page;
> + goto out_put_sb_folio;
> }
>
> /* Now reopen in exclusive mode with proper holder */
> @@ -2666,8 +2666,8 @@ static ssize_t register_bcache(struct kobject *k,
> struct kobj_attribute *attr,
>
> out_free_holder:
> kfree(holder);
> -out_put_sb_page:
> - put_page(virt_to_page(sb_disk));
> +out_put_sb_folio:
> + folio_put(virt_to_folio(sb_disk));
> out_blkdev_put:
> if (bdev_file)
> fput(bdev_file);
> --
> 2.47.2
>
