[PATCH v4 09/36] fs: Introduce i_blocks_per_page

Matthew Wilcox
2020-05-15T13:17:21Z

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>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
fs/iomap/buffered-io.c | 8 ++++----
fs/jfs/jfs_metapage.c | 2 +-
fs/xfs/xfs_aops.c | 2 +-
include/linux/pagemap.h | 16 ++++++++++++++++
4 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 890c8fcda4f3..4bc37bf8d057 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -46,7 +46,7 @@ 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);
@@ -152,7 +152,7 @@ iomap_iop_set_range_uptodate(struct page *page, unsigned off, unsigned len)
unsigned int i;

spin_lock_irqsave(&iop->uptodate_lock, flags);
- 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))
@@ -1090,7 +1090,7 @@ iomap_finish_page_writeback(struct inode *inode, struct page *page,
mapping_set_error(inode->i_mapping, -EIO);
}

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

if (!iop || atomic_dec_and_test(&iop->write_count))
@@ -1386,7 +1386,7 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
int error = 0, count = 0, i;
LIST_HEAD(submit_list);

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

/*
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 1fd4fb7a607c..5b25f5ee84dc 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -544,7 +544,7 @@ xfs_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:
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index cacd5a30cb9d..1a0bb387948c 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -850,4 +850,20 @@ static inline int page_mkwrite_check_truncate(struct page *page,
return offset;
}

+/**
+ * i_blocks_per_page - How many blocks fit in this page.
+ * @inode: The inode which contains the blocks.
+ * @page: The (potentially large) page.
+ *
+ * If the block size is larger than the size of this page, will return
+ * zero,
+ *
+ * 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 thp_size(page) >> inode->i_blkbits;
+}
#endif /* _LINUX_PAGEMAP_H */
--
2.26.2