linux-kernel - [PATCH 01/11] fs: Make page_mkwrite_check

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Message-Id: <20200824151700.16097-2-willy@infradead.org>
Date:   Mon, 24 Aug 2020 16:16:50 +0100
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        "Darrick J . Wong" <darrick.wong@...cle.com>,
        linux-block@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 01/11] fs: Make page_mkwrite_check_truncate thp-aware

If the page is compound, check the last index in the page and return
the appropriate size.  Change the return type to ssize_t in case we ever
support pages larger than 2GB.

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
---
 include/linux/pagemap.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 853733286138..50b176b65911 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -876,22 +876,22 @@ static inline unsigned long dir_pages(struct inode *inode)
  * @page: the page to check
  * @inode: the inode to check the page against
  *
- * Returns the number of bytes in the page up to EOF,
+ * Return: The number of bytes in the page up to EOF,
  * or -EFAULT if the page was truncated.
  */
-static inline int page_mkwrite_check_truncate(struct page *page,
+static inline ssize_t page_mkwrite_check_truncate(struct page *page,
 					      struct inode *inode)
 {
 	loff_t size = i_size_read(inode);
 	pgoff_t index = size >> PAGE_SHIFT;
-	int offset = offset_in_page(size);
+	unsigned long offset = offset_in_thp(page, size);
 
 	if (page->mapping != inode->i_mapping)
 		return -EFAULT;
 
 	/* page is wholly inside EOF */
-	if (page->index < index)
-		return PAGE_SIZE;
+	if (page->index + thp_nr_pages(page) - 1 < index)
+		return thp_size(page);
 	/* page is wholly past EOF */
 	if (page->index > index || !offset)
 		return -EFAULT;
-- 
2.28.0