[PATCH v2 15/25] iomap: Support large pages in iomap_adjust_read_range

Matthew Wilcox
2020-02-12T04:19:51Z

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

Pass the struct page instead of the iomap_page so we can determine the
size of the page. Introduce offset_in_this_page() and use thp_size()
instead of PAGE_SIZE.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
fs/iomap/buffered-io.c | 16 +++++++++-------
include/linux/mm.h | 2 ++
2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 5e5a6b038fc3..e522039f627f 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -83,15 +83,16 @@ iomap_page_release(struct page *page)
* Calculate the range inside the page that we actually need to read.
*/
static void
-iomap_adjust_read_range(struct inode *inode, struct iomap_page *iop,
+iomap_adjust_read_range(struct inode *inode, struct page *page,
loff_t *pos, loff_t length, unsigned *offp, unsigned *lenp)
{
+ struct iomap_page *iop = to_iomap_page(page);
loff_t orig_pos = *pos;
loff_t isize = i_size_read(inode);
unsigned block_bits = inode->i_blkbits;
unsigned block_size = (1 << block_bits);
- unsigned poff = offset_in_page(*pos);
- unsigned plen = min_t(loff_t, PAGE_SIZE - poff, length);
+ unsigned poff = offset_in_this_page(page, *pos);
+ unsigned plen = min_t(loff_t, thp_size(page) - poff, length);
unsigned first = poff >> block_bits;
unsigned last = (poff + plen - 1) >> block_bits;

@@ -129,7 +130,8 @@ iomap_adjust_read_range(struct inode *inode, struct iomap_page *iop,
* page cache for blocks that are entirely outside of i_size.
*/
if (orig_pos <= isize && orig_pos + length > isize) {
- unsigned end = offset_in_page(isize - 1) >> block_bits;
+ unsigned end = offset_in_this_page(page, isize - 1) >>
+ block_bits;

if (first <= end && last > end)
plen -= (last - end) * block_size;
@@ -256,7 +258,7 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
}

/* zero post-eof blocks as the page may be mapped */
- iomap_adjust_read_range(inode, iop, &pos, length, &poff, &plen);
+ iomap_adjust_read_range(inode, page, &pos, length, &poff, &plen);
if (plen == 0)
goto done;

@@ -547,7 +549,6 @@ static int
__iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags,
struct page *page, struct iomap *srcmap)
{
- struct iomap_page *iop = iomap_page_create(inode, page);
loff_t block_size = i_blocksize(inode);
loff_t block_start = pos & ~(block_size - 1);
loff_t block_end = (pos + len + block_size - 1) & ~(block_size - 1);
@@ -556,9 +557,10 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags,

if (PageUptodate(page))
return 0;
+ iomap_page_create(inode, page);

do {
- iomap_adjust_read_range(inode, iop, &block_start,
+ iomap_adjust_read_range(inode, page, &block_start,
block_end - block_start, &poff, &plen);
if (plen == 0)
break;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 52269e56c514..b4bf86590096 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1387,6 +1387,8 @@ static inline void clear_page_pfmemalloc(struct page *page)
extern void pagefault_out_of_memory(void);

#define offset_in_page(p) ((unsigned long)(p) & ~PAGE_MASK)
+#define offset_in_this_page(page, p) \
+ ((unsigned long)(p) & (thp_size(page) - 1))

/*
* Flags passed to show_mem() and show_free_areas() to suppress output in
--
2.25.0