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Subject: [PATCH 28/29] iov_iter: Split iov_iter_for_each_range()
From:   David Howells <dhowells@redhat.com>
To:     Pavel Begunkov <asml.silence@gmail.com>,
        Matthew Wilcox <willy@infradead.org>,
        Jens Axboe <axboe@kernel.dk>,
        Alexander Viro <viro@zeniv.linux.org.uk>
Cc:     dhowells@redhat.com,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org
Date:   Sat, 21 Nov 2020 14:17:00 +0000
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In-Reply-To: <160596800145.154728.7192318545120181269.stgit@warthog.procyon.org.uk>
References: <160596800145.154728.7192318545120181269.stgit@warthog.procyon.org.uk>
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Split iov_iter_for_each_range() by type.

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

 lib/iov_iter.c |   41 +++++++++++++++++++++++++++++++----------
 1 file changed, 31 insertions(+), 10 deletions(-)

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index ca0e94596eda..db798966823e 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -2282,7 +2282,7 @@ int import_single_range(int rw, void __user *buf, size_t len,
 }
 EXPORT_SYMBOL(import_single_range);
 
-static int xxx_for_each_range(struct iov_iter *i, size_t bytes,
+static int bvec_for_each_range(struct iov_iter *i, size_t bytes,
 			    int (*f)(struct kvec *vec, void *context),
 			    void *context)
 {
@@ -2291,18 +2291,39 @@ static int xxx_for_each_range(struct iov_iter *i, size_t bytes,
 	if (!bytes)
 		return 0;
 
-	iterate_all_kinds(i, bytes, v, -EINVAL, ({
+	iterate_over_bvec(i, bytes, v, ({
 		w.iov_base = kmap(v.bv_page) + v.bv_offset;
 		w.iov_len = v.bv_len;
 		err = f(&w, context);
 		kunmap(v.bv_page);
-		err;}), ({
+		err;
+	}));
+	return err;
+}
+
+static int kvec_for_each_range(struct iov_iter *i, size_t bytes,
+			    int (*f)(struct kvec *vec, void *context),
+			    void *context)
+{
+	struct kvec w;
+	int err = -EINVAL;
+	if (!bytes)
+		return 0;
+
+	iterate_over_kvec(i, bytes, v, ({
 		w = v;
-		err = f(&w, context);})
-	)
+		err = f(&w, context);
+	}));
 	return err;
 }
 
+static int no_for_each_range(struct iov_iter *i, size_t bytes,
+			    int (*f)(struct kvec *vec, void *context),
+			    void *context)
+{
+	return !bytes ? 0 : -EINVAL;
+}
+
 static const struct iov_iter_ops iovec_iter_ops = {
 	.type				= ITER_IOVEC,
 	.copy_from_user_atomic		= iovec_copy_from_user_atomic,
@@ -2334,7 +2355,7 @@ static const struct iov_iter_ops iovec_iter_ops = {
 	.get_pages_alloc		= iovec_get_pages_alloc,
 	.npages				= iovec_npages,
 	.dup_iter			= iovec_kvec_dup_iter,
-	.for_each_range			= xxx_for_each_range,
+	.for_each_range			= no_for_each_range,
 };
 
 static const struct iov_iter_ops kvec_iter_ops = {
@@ -2368,7 +2389,7 @@ static const struct iov_iter_ops kvec_iter_ops = {
 	.get_pages_alloc		= no_get_pages_alloc,
 	.npages				= kvec_npages,
 	.dup_iter			= iovec_kvec_dup_iter,
-	.for_each_range			= xxx_for_each_range,
+	.for_each_range			= kvec_for_each_range,
 };
 
 static const struct iov_iter_ops bvec_iter_ops = {
@@ -2402,7 +2423,7 @@ static const struct iov_iter_ops bvec_iter_ops = {
 	.get_pages_alloc		= bvec_get_pages_alloc,
 	.npages				= bvec_npages,
 	.dup_iter			= bvec_dup_iter,
-	.for_each_range			= xxx_for_each_range,
+	.for_each_range			= bvec_for_each_range,
 };
 
 static const struct iov_iter_ops pipe_iter_ops = {
@@ -2436,7 +2457,7 @@ static const struct iov_iter_ops pipe_iter_ops = {
 	.get_pages_alloc		= pipe_get_pages_alloc,
 	.npages				= pipe_npages,
 	.dup_iter			= no_dup_iter,
-	.for_each_range			= xxx_for_each_range,
+	.for_each_range			= no_for_each_range,
 };
 
 static const struct iov_iter_ops discard_iter_ops = {
@@ -2470,5 +2491,5 @@ static const struct iov_iter_ops discard_iter_ops = {
 	.get_pages_alloc		= no_get_pages_alloc,
 	.npages				= discard_npages,
 	.dup_iter			= discard_dup_iter,
-	.for_each_range			= xxx_for_each_range,
+	.for_each_range			= no_for_each_range,
 };