From 0044d1fa1a86b9844df8ca37309b82865279fe15 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 13 Oct 2021 16:24:15 +0800 Subject: [PATCH] copy_page_to_iter(): fix ITER_DISCARD case stable inclusion from stable-5.10.50 commit b6df9e43d52deed1e3bb9a58b6ab3329049a945e bugzilla: 174522 https://gitee.com/openeuler/kernel/issues/I4DNFY Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b6df9e43d52deed1e3bb9a58b6ab3329049a945e -------------------------------- commit a506abc7b644d71966a75337d5a534f531b3cdc4 upstream. we need to advance the iterator... Cc: stable@vger.kernel.org Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman Signed-off-by: Chen Jun Acked-by: Weilong Chen Signed-off-by: Chen Jun Signed-off-by: Zheng Zengkai --- lib/iov_iter.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/lib/iov_iter.c b/lib/iov_iter.c index f0b2ccb1bb01..018ac4b1aa3c 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -922,9 +922,12 @@ size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes, size_t wanted = copy_to_iter(kaddr + offset, bytes, i); kunmap_atomic(kaddr); return wanted; - } else if (unlikely(iov_iter_is_discard(i))) + } else if (unlikely(iov_iter_is_discard(i))) { + if (unlikely(i->count < bytes)) + bytes = i->count; + i->count -= bytes; return bytes; - else if (likely(!iov_iter_is_pipe(i))) + } else if (likely(!iov_iter_is_pipe(i))) return copy_page_to_iter_iovec(page, offset, bytes, i); else return copy_page_to_iter_pipe(page, offset, bytes, i); -- GitLab