linux-kernel - [PATCH 11/29] iov_iter: Split copy_from_iter

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Date:   Sat, 21 Nov 2020 14:14:48 +0000
From:   David Howells <dhowells@...hat.com>
To:     Pavel Begunkov <asml.silence@...il.com>,
        Matthew Wilcox <willy@...radead.org>,
        Jens Axboe <axboe@...nel.dk>,
        Alexander Viro <viro@...iv.linux.org.uk>
Cc:     dhowells@...hat.com,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 11/29] iov_iter: Split copy_from_iter_flushcache()

Split copy_from_iter_flushcache() by type.

Signed-off-by: David Howells <dhowells@...hat.com>
---

 lib/iov_iter.c |   42 +++++++++++++++++++++++++-----------------
 1 file changed, 25 insertions(+), 17 deletions(-)

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index c57c2171f730..6b4739d7dd9a 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1000,7 +1000,7 @@ static size_t kvec_copy_from_iter_nocache(void *addr, size_t bytes, struct iov_i
 
 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
 /**
- * _copy_from_iter_flushcache - write destination through cpu cache
+ * copy_from_iter_flushcache - write destination through cpu cache
  * @addr: destination kernel address
  * @bytes: total transfer length
  * @iter: source iterator
@@ -1013,22 +1013,30 @@ static size_t kvec_copy_from_iter_nocache(void *addr, size_t bytes, struct iov_i
  * bypass the cache for the ITER_IOVEC case, and on some archs may use
  * instructions that strand dirty-data in the cache.
  */
-static size_t xxx_copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
+static size_t iovec_copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
 {
 	char *to = addr;
-	if (unlikely(iov_iter_is_pipe(i))) {
-		WARN_ON(1);
-		return 0;
-	}
-	iterate_and_advance(i, bytes, v,
+	iterate_and_advance_iovec(i, bytes, v,
 		__copy_from_user_flushcache((to += v.iov_len) - v.iov_len,
-					 v.iov_base, v.iov_len),
+					    v.iov_base, v.iov_len));
+	return bytes;
+}
+
+static size_t bvec_copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
+{
+	char *to = addr;
+	iterate_and_advance_bvec(i, bytes, v,
 		memcpy_page_flushcache((to += v.bv_len) - v.bv_len, v.bv_page,
-				 v.bv_offset, v.bv_len),
-		memcpy_flushcache((to += v.iov_len) - v.iov_len, v.iov_base,
-			v.iov_len)
-	)
+				 v.bv_offset, v.bv_len));
+	return bytes;
+}
 
+static size_t kvec_copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
+{
+	char *to = addr;
+	iterate_and_advance_kvec(i, bytes, v,
+		memcpy_flushcache((to += v.iov_len) - v.iov_len, v.iov_base,
+			v.iov_len));
 	return bytes;
 }
 #endif
@@ -2020,7 +2028,7 @@ static const struct iov_iter_ops iovec_iter_ops = {
 	.copy_from_iter_nocache		= iovec_copy_from_iter_nocache,
 	.copy_from_iter_full_nocache	= xxx_copy_from_iter_full_nocache,
 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
-	.copy_from_iter_flushcache	= xxx_copy_from_iter_flushcache,
+	.copy_from_iter_flushcache	= iovec_copy_from_iter_flushcache,
 #endif
 #ifdef CONFIG_ARCH_HAS_COPY_MC
 	.copy_mc_to_iter		= iovec_copy_mc_to_iter,
@@ -2054,7 +2062,7 @@ static const struct iov_iter_ops kvec_iter_ops = {
 	.copy_from_iter_nocache		= kvec_copy_from_iter_nocache,
 	.copy_from_iter_full_nocache	= xxx_copy_from_iter_full_nocache,
 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
-	.copy_from_iter_flushcache	= xxx_copy_from_iter_flushcache,
+	.copy_from_iter_flushcache	= kvec_copy_from_iter_flushcache,
 #endif
 #ifdef CONFIG_ARCH_HAS_COPY_MC
 	.copy_mc_to_iter		= kvec_copy_mc_to_iter,
@@ -2088,7 +2096,7 @@ static const struct iov_iter_ops bvec_iter_ops = {
 	.copy_from_iter_nocache		= bvec_copy_from_iter_nocache,
 	.copy_from_iter_full_nocache	= xxx_copy_from_iter_full_nocache,
 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
-	.copy_from_iter_flushcache	= xxx_copy_from_iter_flushcache,
+	.copy_from_iter_flushcache	= bvec_copy_from_iter_flushcache,
 #endif
 #ifdef CONFIG_ARCH_HAS_COPY_MC
 	.copy_mc_to_iter		= bvec_copy_mc_to_iter,
@@ -2122,7 +2130,7 @@ static const struct iov_iter_ops pipe_iter_ops = {
 	.copy_from_iter_nocache		= no_copy_from_iter,
 	.copy_from_iter_full_nocache	= xxx_copy_from_iter_full_nocache,
 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
-	.copy_from_iter_flushcache	= xxx_copy_from_iter_flushcache,
+	.copy_from_iter_flushcache	= no_copy_from_iter,
 #endif
 #ifdef CONFIG_ARCH_HAS_COPY_MC
 	.copy_mc_to_iter		= pipe_copy_mc_to_iter,
@@ -2156,7 +2164,7 @@ static const struct iov_iter_ops discard_iter_ops = {
 	.copy_from_iter_nocache		= no_copy_from_iter,
 	.copy_from_iter_full_nocache	= xxx_copy_from_iter_full_nocache,
 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
-	.copy_from_iter_flushcache	= xxx_copy_from_iter_flushcache,
+	.copy_from_iter_flushcache	= no_copy_from_iter,
 #endif
 #ifdef CONFIG_ARCH_HAS_COPY_MC
 	.copy_mc_to_iter		= discard_copy_to_iter,