linux-kernel - [PATCH 4.4 088/118] fix iov_iter_fault_in

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Message-Id: <20160922172943.082643350@linuxfoundation.org>
Date:   Thu, 22 Sep 2016 19:29:48 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.4 088/118] fix iov_iter_fault_in_readable()

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Al Viro <viro@...IV.linux.org.uk>

commit d4690f1e1cdabb4d61207b6787b1605a0dc0aeab upstream.

... by turning it into what used to be multipages counterpart

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 include/linux/uio.h |    2 +-
 lib/iov_iter.c      |   24 ++----------------------
 2 files changed, 3 insertions(+), 23 deletions(-)

--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -76,7 +76,7 @@ size_t iov_iter_copy_from_user_atomic(st
 		struct iov_iter *i, unsigned long offset, size_t bytes);
 void iov_iter_advance(struct iov_iter *i, size_t bytes);
 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
-int iov_iter_fault_in_multipages_readable(struct iov_iter *i, size_t bytes);
+#define iov_iter_fault_in_multipages_readable iov_iter_fault_in_readable
 size_t iov_iter_single_seg_count(const struct iov_iter *i);
 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
 			 struct iov_iter *i);
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -298,33 +298,13 @@ done:
 }
 
 /*
- * Fault in the first iovec of the given iov_iter, to a maximum length
- * of bytes. Returns 0 on success, or non-zero if the memory could not be
- * accessed (ie. because it is an invalid address).
- *
- * writev-intensive code may want this to prefault several iovecs -- that
- * would be possible (callers must not rely on the fact that _only_ the
- * first iovec will be faulted with the current implementation).
- */
-int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
-{
-	if (!(i->type & (ITER_BVEC|ITER_KVEC))) {
-		char __user *buf = i->iov->iov_base + i->iov_offset;
-		bytes = min(bytes, i->iov->iov_len - i->iov_offset);
-		return fault_in_pages_readable(buf, bytes);
-	}
-	return 0;
-}
-EXPORT_SYMBOL(iov_iter_fault_in_readable);
-
-/*
  * Fault in one or more iovecs of the given iov_iter, to a maximum length of
  * bytes.  For each iovec, fault in each page that constitutes the iovec.
  *
  * Return 0 on success, or non-zero if the memory could not be accessed (i.e.
  * because it is an invalid address).
  */
-int iov_iter_fault_in_multipages_readable(struct iov_iter *i, size_t bytes)
+int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
 {
 	size_t skip = i->iov_offset;
 	const struct iovec *iov;
@@ -341,7 +321,7 @@ int iov_iter_fault_in_multipages_readabl
 	}
 	return 0;
 }
-EXPORT_SYMBOL(iov_iter_fault_in_multipages_readable);
+EXPORT_SYMBOL(iov_iter_fault_in_readable);
 
 void iov_iter_init(struct iov_iter *i, int direction,
 			const struct iovec *iov, unsigned long nr_segs,