[PATCH -next RFC 09/14] cramfs: use bdev apis in cramfs_blkdev_read()

Yu Kuai
2023-12-05T12:39:19Z

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

Also do some cleanup that there is no need for two for loop, and remove
local array pages.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
fs/cramfs/inode.c | 35 ++++++++++++-----------------------
1 file changed, 12 insertions(+), 23 deletions(-)

diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
index 60dbfa0f8805..46ff4e5506fd 100644
--- a/fs/cramfs/inode.c
+++ b/fs/cramfs/inode.c
@@ -183,9 +183,6 @@ static int next_buffer;
static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
unsigned int len)
{
- struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
- struct file_ra_state ra = {};
- struct page *pages[BLKS_PER_BUF];
unsigned i, blocknr, buffer;
unsigned long devsize;
char *data;
@@ -214,37 +211,29 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
devsize = bdev_nr_bytes(sb->s_bdev) >> PAGE_SHIFT;

/* Ok, read in BLKS_PER_BUF pages completely first. */
- file_ra_state_init(&ra, mapping);
- page_cache_sync_readahead(mapping, &ra, NULL, blocknr, BLKS_PER_BUF);
-
- for (i = 0; i < BLKS_PER_BUF; i++) {
- struct page *page = NULL;
-
- if (blocknr + i < devsize) {
- page = read_mapping_page(mapping, blocknr + i, NULL);
- /* synchronous error? */
- if (IS_ERR(page))
- page = NULL;
- }
- pages[i] = page;
- }
+ bdev_sync_readahead(sb->s_bdev, NULL, NULL, blocknr, BLKS_PER_BUF);

buffer = next_buffer;
next_buffer = NEXT_BUFFER(buffer);
buffer_blocknr[buffer] = blocknr;
buffer_dev[buffer] = sb;
-
data = read_buffers[buffer];
+
for (i = 0; i < BLKS_PER_BUF; i++) {
- struct page *page = pages[i];
+ struct folio *folio = NULL;
+
+ if (blocknr + i < devsize)
+ folio = bdev_read_folio(sb->s_bdev, blocknr + i);

- if (page) {
- memcpy_from_page(data, page, 0, PAGE_SIZE);
- put_page(page);
- } else
+ if (IS_ERR_OR_NULL(folio)) {
memset(data, 0, PAGE_SIZE);
+ } else {
+ memcpy_from_folio(data, folio, 0, PAGE_SIZE);
+ folio_put(folio);
+ }
data += PAGE_SIZE;
}
+
return read_buffers[buffer] + offset;
}