linux-kernel - [PATCH 1/4] fs/sysv: Use the offset_in

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Date:   Sat, 31 Dec 2022 08:57:14 +0100
From:   "Fabio M. De Francesco" <fmdefrancesco@...il.com>
To:     Christoph Hellwig <hch@...radead.org>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Cc:     "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: [PATCH 1/4] fs/sysv: Use the offset_in_page() helper

Use the offset_in_page() helper because it is more suitable than doing
explicit subtractions between pointers to directory entries and kernel
virtual addresses of mapped pages.

Cc: Ira Weiny <ira.weiny@...el.com>
Suggested-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
---
 fs/sysv/dir.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/fs/sysv/dir.c b/fs/sysv/dir.c
index 88e38cd8f5c9..685379bc9d64 100644
--- a/fs/sysv/dir.c
+++ b/fs/sysv/dir.c
@@ -206,8 +206,7 @@ int sysv_add_link(struct dentry *dentry, struct inode *inode)
 	return -EINVAL;
 
 got_it:
-	pos = page_offset(page) +
-			(char*)de - (char*)page_address(page);
+	pos = page_offset(page) + offset_in_page(de);
 	lock_page(page);
 	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
 	if (err)
@@ -230,8 +229,7 @@ int sysv_add_link(struct dentry *dentry, struct inode *inode)
 int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page)
 {
 	struct inode *inode = page->mapping->host;
-	char *kaddr = (char*)page_address(page);
-	loff_t pos = page_offset(page) + (char *)de - kaddr;
+	loff_t pos = page_offset(page) + offset_in_page(de);
 	int err;
 
 	lock_page(page);
@@ -328,8 +326,7 @@ void sysv_set_link(struct sysv_dir_entry *de, struct page *page,
 	struct inode *inode)
 {
 	struct inode *dir = page->mapping->host;
-	loff_t pos = page_offset(page) +
-			(char *)de-(char*)page_address(page);
+	loff_t pos = page_offset(page) + offset_in_page(de);
 	int err;
 
 	lock_page(page);
-- 
2.39.0