From: Matthew Wilcox (Oracle) <willy@infradead.org>
Date: Sat, 3 Oct 2020 02:55:22 +0000 (+0100)
Subject: fs: Allow a NULL pos pointer to __kernel_write
X-Git-Tag: howlett/maple_spf/20210104~745^2~1
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=4c207ef48269377236cd38979197c5e1631c8c16;p=users%2Fjedix%2Flinux-maple.git

fs: Allow a NULL pos pointer to __kernel_write

Linus prefers that callers be allowed to pass in a NULL pointer for ppos
like new_sync_write().

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---

diff --git a/fs/read_write.c b/fs/read_write.c
index 8c61f67453e3d..516eb51af70e2 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -544,11 +544,12 @@ ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t
 		return warn_unsupported(file, "write");
 
 	init_sync_kiocb(&kiocb, file);
-	kiocb.ki_pos = *pos;
+	kiocb.ki_pos = pos ? *pos : 0;
 	iov_iter_kvec(&iter, WRITE, &iov, 1, iov.iov_len);
 	ret = file->f_op->write_iter(&kiocb, &iter);
 	if (ret > 0) {
-		*pos = kiocb.ki_pos;
+		if (pos)
+			*pos = kiocb.ki_pos;
 		fsnotify_modify(file);
 		add_wchar(current, ret);
 	}