linux-kernel - [RFC PATCH 35/37] pipe_zero(): we don't need no stinkin' kmap

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Date:   Sun,  6 Jun 2021 19:10:49 +0000
From:   Al Viro <viro@...iv.linux.org.uk>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        David Sterba <dsterba@...e.com>,
        Miklos Szeredi <miklos@...redi.hu>,
        Anton Altaparmakov <anton@...era.com>,
        David Howells <dhowells@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        Pavel Begunkov <asml.silence@...il.com>
Subject: [RFC PATCH 35/37] pipe_zero(): we don't need no stinkin' kmap_atomic()...

	FWIW, memcpy_to_page() itself almost certainly ought to
use kmap_local_page()...

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
 lib/iov_iter.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 56d2606a47e4..7471fb181643 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -908,7 +908,9 @@ static size_t pipe_zero(size_t bytes, struct iov_iter *i)
 
 	do {
 		size_t chunk = min_t(size_t, n, PAGE_SIZE - off);
-		memzero_page(pipe->bufs[i_head & p_mask].page, off, chunk);
+		char *p = kmap_local_page(pipe->bufs[i_head & p_mask].page);
+		memset(p + off, 0, chunk);
+		kunmap_local(p);
 		i->head = i_head;
 		i->iov_offset = off + chunk;
 		n -= chunk;
-- 
2.11.0