[PATCH 02/15] fs: Introduce i_blocks_per_page

Matthew Wilcox
2019-09-25T00:53:08Z

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

This helper is useful for both large pages in the page cache and for
supporting block size larger than page size. Convert some example
users (we have a few different ways of writing this idiom).

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
fs/iomap/buffered-io.c | 4 ++--
fs/jfs/jfs_metapage.c | 2 +-
fs/xfs/xfs_aops.c | 8 ++++----
include/linux/pagemap.h | 13 +++++++++++++
4 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index e25901ae3ff4..0e76a4b6d98a 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -24,7 +24,7 @@ iomap_page_create(struct inode *inode, struct page *page)
{
struct iomap_page *iop = to_iomap_page(page);

- if (iop || i_blocksize(inode) == PAGE_SIZE)
+ if (iop || i_blocks_per_page(inode, page) <= 1)
return iop;

iop = kmalloc(sizeof(*iop), GFP_NOFS | __GFP_NOFAIL);
@@ -128,7 +128,7 @@ iomap_set_range_uptodate(struct page *page, unsigned off, unsigned len)
bool uptodate = true;

if (iop) {
- for (i = 0; i < PAGE_SIZE / i_blocksize(inode); i++) {
+ for (i = 0; i < i_blocks_per_page(inode, page); i++) {
if (i >= first && i <= last)
set_bit(i, iop->uptodate);
else if (!test_bit(i, iop->uptodate))
diff --git a/fs/jfs/jfs_metapage.c b/fs/jfs/jfs_metapage.c
index a2f5338a5ea1..176580f54af9 100644
--- a/fs/jfs/jfs_metapage.c
+++ b/fs/jfs/jfs_metapage.c
@@ -473,7 +473,7 @@ static int metapage_readpage(struct file *fp, struct page *page)
struct inode *inode = page->mapping->host;
struct bio *bio = NULL;
int block_offset;
- int blocks_per_page = PAGE_SIZE >> inode->i_blkbits;
+ int blocks_per_page = i_blocks_per_page(inode, page);
sector_t page_start; /* address of page in fs blocks */
sector_t pblock;
int xlen;
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index f16d5f196c6b..102cfd8a97d6 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -68,7 +68,7 @@ xfs_finish_page_writeback(
mapping_set_error(inode->i_mapping, -EIO);
}

- ASSERT(iop || i_blocksize(inode) == PAGE_SIZE);
+ ASSERT(iop || i_blocks_per_page(inode, bvec->bv_page) <= 1);
ASSERT(!iop || atomic_read(&iop->write_count) > 0);

if (!iop || atomic_dec_and_test(&iop->write_count))
@@ -839,7 +839,7 @@ xfs_aops_discard_page(
page, ip->i_ino, offset);

error = xfs_bmap_punch_delalloc_range(ip, start_fsb,
- PAGE_SIZE / i_blocksize(inode));
+ i_blocks_per_page(inode, page));
if (error && !XFS_FORCED_SHUTDOWN(mp))
xfs_alert(mp, "page discard unable to remove delalloc mapping.");
out_invalidate:
@@ -877,7 +877,7 @@ xfs_writepage_map(
uint64_t file_offset; /* file offset of page */
int error = 0, count = 0, i;

- ASSERT(iop || i_blocksize(inode) == PAGE_SIZE);
+ ASSERT(iop || i_blocks_per_page(inode, page) <= 1);
ASSERT(!iop || atomic_read(&iop->write_count) == 0);

/*
@@ -886,7 +886,7 @@ xfs_writepage_map(
* one.
*/
for (i = 0, file_offset = page_offset(page);
- i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset;
+ i < i_blocks_per_page(inode, page) && file_offset < end_offset;
i++, file_offset += len) {
if (iop && !test_bit(i, iop->uptodate))
continue;
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 37a4d9e32cd3..750770a2c685 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -636,4 +636,17 @@ static inline unsigned long dir_pages(struct inode *inode)
PAGE_SHIFT;
}

+/**
+ * i_blocks_per_page - How many blocks fit in this page.
+ * @inode: The inode which contains the blocks.
+ * @page: The (potentially large) page.
+ *
+ * Context: Any context.
+ * Return: The number of filesystem blocks covered by this page.
+ */
+static inline
+unsigned int i_blocks_per_page(struct inode *inode, struct page *page)
+{
+ return page_size(page) >> inode->i_blkbits;
+}
#endif /* _LINUX_PAGEMAP_H */
--
2.23.0