linux-kernel - [PATCH v2] fs/ceph: use pipe_get_pages

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Message-ID: <20200825012034.1962362-1-jhubbard@nvidia.com>
Date:   Mon, 24 Aug 2020 18:20:34 -0700
From:   John Hubbard <jhubbard@...dia.com>
To:     <willy@...radead.org>, <jlayton@...nel.org>
CC:     <akpm@...ux-foundation.org>, <axboe@...nel.dk>,
        <ceph-devel@...r.kernel.org>, <hch@...radead.org>,
        <idryomov@...il.com>, <jhubbard@...dia.com>,
        <linux-block@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        <linux-xfs@...r.kernel.org>, <viro@...iv.linux.org.uk>
Subject: [PATCH v2] fs/ceph: use pipe_get_pages_alloc() for pipe

This reduces, by one, the number of callers of iov_iter_get_pages().
That's helpful because these calls are being audited and converted over
to use iov_iter_pin_user_pages(), where applicable. And this one here is
already known by the caller to be only for ITER_PIPE, so let's just
simplify it now.

Signed-off-by: John Hubbard <jhubbard@...dia.com>
---

OK, here's a v2 that does EXPORT_SYMBOL_GPL, instead of EXPORT_SYMBOL,
that's the only change from v1. That should help give this patch a
clear bill of passage. :)

thanks,
John Hubbard
NVIDIA

 fs/ceph/file.c      | 3 +--
 include/linux/uio.h | 3 ++-
 lib/iov_iter.c      | 6 +++---
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index d51c3f2fdca0..d3d7dd957390 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -879,8 +879,7 @@ static ssize_t ceph_sync_read(struct kiocb *iocb, struct iov_iter *to,
 		more = len < iov_iter_count(to);
 
 		if (unlikely(iov_iter_is_pipe(to))) {
-			ret = iov_iter_get_pages_alloc(to, &pages, len,
-						       &page_off);
+			ret = pipe_get_pages_alloc(to, &pages, len, &page_off);
 			if (ret <= 0) {
 				ceph_osdc_put_request(req);
 				ret = -ENOMEM;
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 3835a8a8e9ea..270a4dcf5453 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -226,7 +226,8 @@ ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
 			size_t maxsize, size_t *start);
 int iov_iter_npages(const struct iov_iter *i, int maxpages);
-
+ssize_t pipe_get_pages_alloc(struct iov_iter *i, struct page ***pages,
+			     size_t maxsize, size_t *start);
 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
 
 static inline size_t iov_iter_count(const struct iov_iter *i)
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 5e40786c8f12..6290998df480 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1355,9 +1355,8 @@ static struct page **get_pages_array(size_t n)
 	return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL);
 }
 
-static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
-		   struct page ***pages, size_t maxsize,
-		   size_t *start)
+ssize_t pipe_get_pages_alloc(struct iov_iter *i, struct page ***pages,
+			     size_t maxsize, size_t *start)
 {
 	struct page **p;
 	unsigned int iter_head, npages;
@@ -1387,6 +1386,7 @@ static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
 		kvfree(p);
 	return n;
 }
+EXPORT_SYMBOL_GPL(pipe_get_pages_alloc);
 
 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
 		   struct page ***pages, size_t maxsize,
-- 
2.28.0