bcache: switch from pages to folios in read_super()

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) <willy@infradead.org>
Signed-off-by: Coly Li <colyli@kernel.org>
Acked-back: Coly Li <colyli@kernel.org>
Link: https://lore.kernel.org/r/20250702024848.343370-1-colyli@kernel.org
[axboe: commit message massaging]
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 2ea490b9d370f2f0ad5e3627185460cdfd22d208..1492c8552255cb5e18690e94d7ffd754d9322932 100644 (file)
--- 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);
@@ -2216,7 +2216,7 @@ 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);
@@ -2593,7 +2593,7 @@ 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 */
@@ -2667,8 +2667,8 @@ async_done:
 
 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);