From: Yu Kuai <yuku...@huawei.com>

On the one hand covert to use folio while reading bdev inode, on the
other hand prevent to access bd_inode directly.

Signed-off-by: Yu Kuai <yuku...@huawei.com>
---
 drivers/mtd/devices/block2mtd.c | 81 +++++++++++++++------------------
 1 file changed, 36 insertions(+), 45 deletions(-)

diff --git a/drivers/mtd/devices/block2mtd.c b/drivers/mtd/devices/block2mtd.c
index aa44a23ec045..cf201bf73184 100644
--- a/drivers/mtd/devices/block2mtd.c
+++ b/drivers/mtd/devices/block2mtd.c
@@ -46,40 +46,34 @@ struct block2mtd_dev {
 /* Static info about the MTD, used in cleanup_module */
 static LIST_HEAD(blkmtd_device_list);
 
-
-static struct page *page_read(struct address_space *mapping, pgoff_t index)
-{
-       return read_mapping_page(mapping, index, NULL);
-}
-
 /* erase a specified part of the device */
 static int _block2mtd_erase(struct block2mtd_dev *dev, loff_t to, size_t len)
 {
-       struct address_space *mapping =
-                               dev->bdev_handle->bdev->bd_inode->i_mapping;
-       struct page *page;
+       struct block_device *bdev = dev->bdev_handle->bdev;
+       struct folio *folio;
        pgoff_t index = to >> PAGE_SHIFT;       // page index
        int pages = len >> PAGE_SHIFT;
        u_long *p;
        u_long *max;
 
        while (pages) {
-               page = page_read(mapping, index);
-               if (IS_ERR(page))
-                       return PTR_ERR(page);
+               folio = bdev_read_folio(bdev, index << PAGE_SHIFT);
+               if (IS_ERR(folio))
+                       return PTR_ERR(folio);
 
-               max = page_address(page) + PAGE_SIZE;
-               for (p=page_address(page); p<max; p++)
+               max = folio_address(folio) + folio_size(folio);
+               for (p = folio_address(folio); p < max; p++)
                        if (*p != -1UL) {
-                               lock_page(page);
-                               memset(page_address(page), 0xff, PAGE_SIZE);
-                               set_page_dirty(page);
-                               unlock_page(page);
-                               balance_dirty_pages_ratelimited(mapping);
+                               folio_lock(folio);
+                               memset(folio_address(folio), 0xff,
+                                      folio_size(folio));
+                               folio_mark_dirty(folio);
+                               folio_unlock(folio);
+                               bdev_balance_dirty_pages_ratelimited(bdev);
                                break;
                        }
 
-               put_page(page);
+               folio_put(folio);
                pages--;
                index++;
        }
@@ -106,9 +100,7 @@ static int block2mtd_read(struct mtd_info *mtd, loff_t 
from, size_t len,
                size_t *retlen, u_char *buf)
 {
        struct block2mtd_dev *dev = mtd->priv;
-       struct address_space *mapping =
-                               dev->bdev_handle->bdev->bd_inode->i_mapping;
-       struct page *page;
+       struct folio *folio;
        pgoff_t index = from >> PAGE_SHIFT;
        int offset = from & (PAGE_SIZE-1);
        int cpylen;
@@ -120,12 +112,13 @@ static int block2mtd_read(struct mtd_info *mtd, loff_t 
from, size_t len,
                        cpylen = len;   // this page
                len = len - cpylen;
 
-               page = page_read(mapping, index);
-               if (IS_ERR(page))
-                       return PTR_ERR(page);
+               folio = bdev_read_folio(dev->bdev_handle->bdev,
+                                       index << PAGE_SHIFT);
+               if (IS_ERR(folio))
+                       return PTR_ERR(folio);
 
-               memcpy(buf, page_address(page) + offset, cpylen);
-               put_page(page);
+               memcpy(buf, folio_address(folio) + offset, cpylen);
+               folio_put(folio);
 
                if (retlen)
                        *retlen += cpylen;
@@ -141,9 +134,8 @@ static int block2mtd_read(struct mtd_info *mtd, loff_t 
from, size_t len,
 static int _block2mtd_write(struct block2mtd_dev *dev, const u_char *buf,
                loff_t to, size_t len, size_t *retlen)
 {
-       struct page *page;
-       struct address_space *mapping =
-                               dev->bdev_handle->bdev->bd_inode->i_mapping;
+       struct block_device *bdev = dev->bdev_handle->bdev;
+       struct folio *folio;
        pgoff_t index = to >> PAGE_SHIFT;       // page index
        int offset = to & ~PAGE_MASK;   // page offset
        int cpylen;
@@ -155,18 +147,18 @@ static int _block2mtd_write(struct block2mtd_dev *dev, 
const u_char *buf,
                        cpylen = len;                   // this page
                len = len - cpylen;
 
-               page = page_read(mapping, index);
-               if (IS_ERR(page))
-                       return PTR_ERR(page);
+               folio = bdev_read_folio(bdev, index << PAGE_SHIFT);
+               if (IS_ERR(folio))
+                       return PTR_ERR(folio);
 
-               if (memcmp(page_address(page)+offset, buf, cpylen)) {
-                       lock_page(page);
-                       memcpy(page_address(page) + offset, buf, cpylen);
-                       set_page_dirty(page);
-                       unlock_page(page);
-                       balance_dirty_pages_ratelimited(mapping);
+               if (memcmp(folio_address(folio) + offset, buf, cpylen)) {
+                       folio_lock(folio);
+                       memcpy(folio_address(folio) + offset, buf, cpylen);
+                       folio_mark_dirty(folio);
+                       folio_unlock(folio);
+                       bdev_balance_dirty_pages_ratelimited(bdev);
                }
-               put_page(page);
+               folio_put(folio);
 
                if (retlen)
                        *retlen += cpylen;
@@ -211,8 +203,7 @@ static void block2mtd_free_device(struct block2mtd_dev *dev)
        kfree(dev->mtd.name);
 
        if (dev->bdev_handle) {
-               invalidate_mapping_pages(
-                       dev->bdev_handle->bdev->bd_inode->i_mapping, 0, -1);
+               invalidate_bdev(dev->bdev_handle->bdev);
                bdev_release(dev->bdev_handle);
        }
 
@@ -295,7 +286,7 @@ static struct block2mtd_dev *add_device(char *devname, int 
erase_size,
                goto err_free_block2mtd;
        }
 
-       if ((long)bdev->bd_inode->i_size % erase_size) {
+       if (bdev_nr_bytes(bdev) % erase_size) {
                pr_err("erasesize must be a divisor of device size\n");
                goto err_free_block2mtd;
        }
@@ -313,7 +304,7 @@ static struct block2mtd_dev *add_device(char *devname, int 
erase_size,
 
        dev->mtd.name = name;
 
-       dev->mtd.size = bdev->bd_inode->i_size & PAGE_MASK;
+       dev->mtd.size = bdev_nr_bytes(bdev) & PAGE_MASK;
        dev->mtd.erasesize = erase_size;
        dev->mtd.writesize = 1;
        dev->mtd.writebufsize = PAGE_SIZE;
-- 
2.39.2


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