vfs: introduce file_modified() helper
The combination of file_remove_privs() and file_update_mtime() is
quite common in filesystem ->write_iter() methods.
Modelled after the helper file_accessed(), introduce file_modified()
and use it from generic_remap_file_range_prep().
Note that the order of calling file_remove_privs() before
file_update_mtime() in the helper was matched to the more common order by
filesystems and not the current order in generic_remap_file_range_prep().
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
diff --git a/fs/inode.c b/fs/inode.c
index df6542e..4348cfb 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -1899,6 +1899,26 @@ int file_update_time(struct file *file)
}
EXPORT_SYMBOL(file_update_time);
+/* Caller must hold the file's inode lock */
+int file_modified(struct file *file)
+{
+ int err;
+
+ /*
+ * Clear the security bits if the process is not being run by root.
+ * This keeps people from modifying setuid and setgid binaries.
+ */
+ err = file_remove_privs(file);
+ if (err)
+ return err;
+
+ if (unlikely(file->f_mode & FMODE_NOCMTIME))
+ return 0;
+
+ return file_update_time(file);
+}
+EXPORT_SYMBOL(file_modified);
+
int inode_needs_sync(struct inode *inode)
{
if (IS_SYNC(inode))