From: John Hubbard <jhubbard@nvidia.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
Christoph Hellwig <hch@infradead.org>,
Ilya Dryomov <idryomov@gmail.com>, Jens Axboe <axboe@kernel.dk>,
Jeff Layton <jlayton@kernel.org>, <linux-xfs@vger.kernel.org>,
<linux-fsdevel@vger.kernel.org>, <linux-block@vger.kernel.org>,
<ceph-devel@vger.kernel.org>, <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
John Hubbard <jhubbard@nvidia.com>
Subject: [PATCH 1/5] iov_iter: introduce iov_iter_pin_user_pages*() routines
Date: Fri, 21 Aug 2020 21:20:55 -0700 [thread overview]
Message-ID: <20200822042059.1805541-2-jhubbard@nvidia.com> (raw)
In-Reply-To: <20200822042059.1805541-1-jhubbard@nvidia.com>
The new routines are:
iov_iter_pin_user_pages()
iov_iter_pin_user_pages_alloc()
and those correspond to these pre-existing routines:
iov_iter_get_pages()
iov_iter_get_pages_alloc()
Unlike the iov_iter_get_pages*() routines, the
iov_iter_pin_user_pages*() routines assert that only ITER_IOVEC items
are passed in. They then call pin_user_pages_fast(), instead of
get_user_pages_fast().
Why: In order to incrementally change Direct IO callers from calling
get_user_pages_fast() and put_page(), over to calling
pin_user_pages_fast() and unpin_user_page(), there need to be mid-level
routines that specifically call one or the other systems, for both page
acquisition and page release.
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
include/linux/uio.h | 5 +++
lib/iov_iter.c | 80 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 85 insertions(+)
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 3835a8a8e9ea..29b0504a27cc 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -229,6 +229,11 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages);
const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
+ssize_t iov_iter_pin_user_pages(struct iov_iter *i, struct page **pages,
+ size_t maxsize, unsigned int maxpages, size_t *start);
+ssize_t iov_iter_pin_user_pages_alloc(struct iov_iter *i, struct page ***pages,
+ size_t maxsize, size_t *start);
+
static inline size_t iov_iter_count(const struct iov_iter *i)
{
return i->count;
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 5e40786c8f12..d818b16d136b 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1309,6 +1309,44 @@ static ssize_t pipe_get_pages(struct iov_iter *i,
return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, start);
}
+ssize_t iov_iter_pin_user_pages(struct iov_iter *i,
+ struct page **pages, size_t maxsize, unsigned int maxpages,
+ size_t *start)
+{
+ size_t skip = i->iov_offset;
+ const struct iovec *iov;
+ struct iovec v;
+
+ if (WARN_ON_ONCE(!iter_is_iovec(i)))
+ return -EFAULT;
+
+ if (unlikely(!maxsize))
+ return 0;
+ maxsize = min(maxsize, i->count);
+
+ iterate_iovec(i, maxsize, v, iov, skip, ({
+ unsigned long addr = (unsigned long)v.iov_base;
+ size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
+ int n;
+ int res;
+
+ if (len > maxpages * PAGE_SIZE)
+ len = maxpages * PAGE_SIZE;
+ addr &= ~(PAGE_SIZE - 1);
+ n = DIV_ROUND_UP(len, PAGE_SIZE);
+
+ res = pin_user_pages_fast(addr, n,
+ iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0,
+ pages);
+ if (unlikely(res < 0))
+ return res;
+ return (res == n ? len : res * PAGE_SIZE) - *start;
+ 0;
+ }))
+ return 0;
+}
+EXPORT_SYMBOL(iov_iter_pin_user_pages);
+
ssize_t iov_iter_get_pages(struct iov_iter *i,
struct page **pages, size_t maxsize, unsigned maxpages,
size_t *start)
@@ -1388,6 +1426,48 @@ static ssize_t pipe_get_pages_alloc(struct iov_iter *i,
return n;
}
+ssize_t iov_iter_pin_user_pages_alloc(struct iov_iter *i,
+ struct page ***pages, size_t maxsize,
+ size_t *start)
+{
+ struct page **p;
+ size_t skip = i->iov_offset;
+ const struct iovec *iov;
+ struct iovec v;
+
+ if (WARN_ON_ONCE(!iter_is_iovec(i)))
+ return -EFAULT;
+
+ if (unlikely(!maxsize))
+ return 0;
+ maxsize = min(maxsize, i->count);
+
+ iterate_iovec(i, maxsize, v, iov, skip, ({
+ unsigned long addr = (unsigned long)v.iov_base;
+ size_t len = v.iov_len + (*start = addr & (PAGE_SIZE - 1));
+ int n;
+ int res;
+
+ addr &= ~(PAGE_SIZE - 1);
+ n = DIV_ROUND_UP(len, PAGE_SIZE);
+ p = get_pages_array(n);
+ if (!p)
+ return -ENOMEM;
+
+ res = pin_user_pages_fast(addr, n,
+ iov_iter_rw(i) != WRITE ? FOLL_WRITE : 0, p);
+ if (unlikely(res < 0)) {
+ kvfree(p);
+ return res;
+ }
+ *pages = p;
+ return (res == n ? len : res * PAGE_SIZE) - *start;
+ 0;
+ }))
+ return 0;
+}
+EXPORT_SYMBOL(iov_iter_pin_user_pages_alloc);
+
ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
struct page ***pages, size_t maxsize,
size_t *start)
--
2.28.0
next prev parent reply other threads:[~2020-08-22 4:21 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-22 4:20 [PATCH 0/5] bio: Direct IO: convert to pin_user_pages_fast() John Hubbard
2020-08-22 4:20 ` John Hubbard [this message]
2020-08-22 4:20 ` [PATCH 2/5] mm/gup: introduce pin_user_page() John Hubbard
2020-08-22 4:20 ` [PATCH 3/5] bio: convert get_user_pages_fast() --> pin_user_pages_fast() John Hubbard
2020-08-22 4:20 ` [PATCH 4/5] bio: introduce BIO_FOLL_PIN flag John Hubbard
2020-08-23 6:25 ` Christoph Hellwig
2020-08-23 6:57 ` John Hubbard
2020-08-24 7:36 ` John Hubbard
2020-08-24 9:20 ` Jens Axboe
2020-08-24 14:42 ` Christoph Hellwig
2020-08-27 3:25 ` [bio] 37abbdc72e: WARNING:at_block/bio.c:#bio_release_pages kernel test robot
2020-08-27 3:59 ` John Hubbard
2020-08-22 4:20 ` [PATCH 5/5] fs/ceph: use pipe_get_pages_alloc() for pipe John Hubbard
2020-08-24 10:53 ` Jeff Layton
2020-08-24 17:54 ` John Hubbard
2020-08-24 18:47 ` Jeff Layton
2020-08-24 18:54 ` Matthew Wilcox
2020-08-24 19:02 ` John Hubbard
2020-08-25 1:20 ` [PATCH v2] " John Hubbard
2020-08-25 16:22 ` Jeff Layton
2020-08-25 1:54 ` [PATCH 0/5] bio: Direct IO: convert to pin_user_pages_fast() Al Viro
2020-08-25 2:07 ` Al Viro
2020-08-25 2:13 ` John Hubbard
2020-08-25 2:07 ` John Hubbard
2020-08-25 2:22 ` Al Viro
2020-08-25 2:27 ` John Hubbard
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