[PATCH 10/17] mtd: convert page_read to read_kmap_page

Nate Diller
2007-04-12T02:53:06Z

Replace page_read() with read_kmap_page()/__read_kmap_page(). This probably
fixes behaviour on highmem systems, since page_address() was being used
without kmap(). Also eliminate the need to re-take the page lock during
writes to the page.

Signed-off-by: Nate Diller <nate.diller@gmail.com>

---

diff -urpN -X dontdiff linux-2.6.21-rc5-mm4/drivers/mtd/devices/block2mtd.c linux-2.6.21-rc5-mm4-test/drivers/mtd/devices/block2mtd.c
--- linux-2.6.21-rc5-mm4/drivers/mtd/devices/block2mtd.c 2007-04-05 17:14:24.000000000 -0700
+++ linux-2.6.21-rc5-mm4-test/drivers/mtd/devices/block2mtd.c 2007-04-06 01:59:19.000000000 -0700
@@ -39,12 +39,6 @@ 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, int 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)
{
@@ -56,23 +50,19 @@ static int _block2mtd_erase(struct block
u_long *max;

while (pages) {
- page = page_read(mapping, index);
- if (!page)
- return -ENOMEM;
+ page = __read_kmap_page(mapping, index);
if (IS_ERR(page))
return PTR_ERR(page);

max = page_address(page) + PAGE_SIZE;
for (p=page_address(page); p<max; p++)
if (*p != -1UL) {
- lock_page(page);
memset(page_address(page), 0xff, PAGE_SIZE);
set_page_dirty(page);
- unlock_page(page);
break;
}

- page_cache_release(page);
+ put_locked_page(page);
pages--;
index++;
}
@@ -125,14 +115,12 @@ static int block2mtd_read(struct mtd_inf
cpylen = len; // this page
len = len - cpylen;

- page = page_read(dev->blkdev->bd_inode->i_mapping, index);
- if (!page)
- return -ENOMEM;
+ page = read_kmap_page(dev->blkdev->bd_inode->i_mapping, index);
if (IS_ERR(page))
return PTR_ERR(page);

memcpy(buf, page_address(page) + offset, cpylen);
- page_cache_release(page);
+ put_kmapped_page(page);

if (retlen)
*retlen += cpylen;
@@ -163,19 +151,15 @@ static int _block2mtd_write(struct block
cpylen = len; // this page
len = len - cpylen;

- page = page_read(mapping, index);
- if (!page)
- return -ENOMEM;
+ page = __read_kmap_page(mapping, index);
if (IS_ERR(page))
return PTR_ERR(page);

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);
}
- page_cache_release(page);
+ put_locked_page(page);

if (retlen)
*retlen += cpylen;