linux-kernel - [PATCH v2 11/25] fs: Make page_mkwrite_check

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Message-Id: <20200212041845.25879-12-willy@infradead.org>
Date:   Tue, 11 Feb 2020 20:18:31 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     linux-fsdevel@...r.kernel.org, linux-mm@...ck.org
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 11/25] fs: Make page_mkwrite_check_truncate thp-aware

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

If the page is compound, check the appropriate indices and return the
appropriate sizes.

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
---
 include/linux/pagemap.h | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index aa925295347c..2ec33aabdbf6 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -732,17 +732,18 @@ static inline int 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);
+	pgoff_t first_index = size >> PAGE_SHIFT;
+	pgoff_t last_index = first_index + hpage_nr_pages(page) - 1;
+	unsigned long offset = offset_in_this_page(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 < first_index)
+		return thp_size(page);
 	/* page is wholly past EOF */
-	if (page->index > index || !offset)
+	if (page->index > last_index || !offset)
 		return -EFAULT;
 	/* page is partially inside EOF */
 	return offset;
-- 
2.25.0