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From:   Matthew Wilcox <willy@infradead.org>
To:     linux-fsdevel@vger.kernel.org
Cc:     "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: [PATCH v6 23/51] iomap: Support THPs in iomap_adjust_read_range
Date:   Wed, 10 Jun 2020 13:13:17 -0700
Message-Id: <20200610201345.13273-24-willy@infradead.org>
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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.  Use offset_in_thp() instead of offset_in_page() and
use thp_size() instead of PAGE_SIZE.  Convert the arguments to be size_t
instead of unsigned int, in case pages ever get larger than 2^31 bytes.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 fs/iomap/buffered-io.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 1a398af42ed2..1b450e966822 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -77,16 +77,16 @@ 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,
-		loff_t *pos, loff_t length, unsigned *offp, unsigned *lenp)
+static void iomap_adjust_read_range(struct inode *inode, struct page *page,
+		loff_t *pos, loff_t length, size_t *offp, size_t *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);
+	size_t poff = offset_in_thp(page, *pos);
+	size_t plen = min_t(loff_t, thp_size(page) - poff, length);
 	unsigned first = poff >> block_bits;
 	unsigned last = (poff + plen - 1) >> block_bits;
 
@@ -124,7 +124,7 @@ 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_thp(page, isize - 1) >> block_bits;
 
 		if (first <= end && last > end)
 			plen -= (last - end) * block_size;
@@ -241,7 +241,7 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 	struct iomap_page *iop = iomap_page_create(inode, page);
 	bool same_page = false, is_contig = false;
 	loff_t orig_pos = pos;
-	unsigned poff, plen;
+	size_t poff, plen;
 	sector_t sector;
 
 	if (iomap->type == IOMAP_INLINE) {
@@ -251,7 +251,7 @@ 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;
 
@@ -560,18 +560,19 @@ 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);
-	unsigned from = offset_in_page(pos), to = from + len, poff, plen;
+	unsigned from = offset_in_page(pos), to = from + len;
+	size_t poff, plen;
 	int status;
 
 	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;
-- 
2.26.2