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Sat, 29 Aug 2020 01:08:55 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Sat, 29 Aug 2020 01:08:55 -0700 Received: from HQMAIL105.nvidia.com (172.20.187.12) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Sat, 29 Aug 2020 08:08:54 +0000 Received: from hqnvemgw03.nvidia.com (10.124.88.68) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Sat, 29 Aug 2020 08:08:54 +0000 Received: from sandstorm.nvidia.com (Not Verified[10.2.50.252]) by hqnvemgw03.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Sat, 29 Aug 2020 01:08:54 -0700 From: John Hubbard To: Andrew Morton CC: Alexander Viro , Christoph Hellwig , Ilya Dryomov , Jens Axboe , , , , , LKML , John Hubbard Subject: [PATCH v2 2/3] iov_iter: introduce iov_iter_pin_user_pages*() routines Date: Sat, 29 Aug 2020 01:08:52 -0700 Message-ID: <20200829080853.20337-3-jhubbard@nvidia.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200829080853.20337-1-jhubbard@nvidia.com> References: <20200829080853.20337-1-jhubbard@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1598688521; bh=Vy/aicbsaikOMN7ktN/NsGfhFPk9fOg1k934MsKFztI=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:X-NVConfidentiality: Content-Transfer-Encoding:Content-Type; b=IkHoOYwMr+a3rkYodr7JMkibHrLP5gB6QnWW58BFLudMDnkVIVKMkG3++1GuG+rml nTlpsQtrq34EDfvVMEOmS30XkqnbTeEBJA1401I/Suloe8fnOTn2AiDbinkuNajMlR iMRgDyIgGlxp9X+SJc2JrIbSvsjEejN66a6JV0fNVz7uYLlbHlIM8olv9XW87WswZ1 7sezpbZfoH1N69FsPFNqYttCo43H+hplqf5TXajBOd0ziKnLHbFZrMOvw2v0mNraep CYVJAlxCAIX/ZGsZ80xzC9r0bGFnG5CDSpXp+kSNvH+AryxkoJIoCtfm9V5mhECa1M BP4yGPU1yiOlA== X-Rspamd-Queue-Id: 4FED618038E67 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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() Also, pipe_get_pages() and related are changed so as to pass down a "use_pup" (use pin_user_page() instead of get_page()) bool argument. Unlike the iov_iter_get_pages*() routines, the iov_iter_pin_user_pages*() routines assert that only ITER_IOVEC or ITER_PIPE items are passed in. They then call pin_user_page*(), instead of get_user_pages_fast() or get_page(). 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 --- include/linux/uio.h | 5 ++ lib/iov_iter.c | 110 ++++++++++++++++++++++++++++++++++++++++---- 2 files changed, 107 insertions(+), 8 deletions(-) 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..f25555eb3279 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -1269,7 +1269,8 @@ static inline ssize_t __pipe_get_pages(struct iov_iter *i, size_t maxsize, struct page **pages, int iter_head, - size_t *start) + size_t *start, + bool use_pup) { struct pipe_inode_info *pipe = i->pipe; unsigned int p_mask = pipe->ring_size - 1; @@ -1280,7 +1281,11 @@ static inline ssize_t __pipe_get_pages(struct iov_iter *i, maxsize = n; n += *start; while (n > 0) { - get_page(*pages++ = pipe->bufs[iter_head & p_mask].page); + if (use_pup) + pin_user_page(*pages++ = pipe->bufs[iter_head & p_mask].page); + else + get_page(*pages++ = pipe->bufs[iter_head & p_mask].page); + iter_head++; n -= PAGE_SIZE; } @@ -1290,7 +1295,7 @@ static inline ssize_t __pipe_get_pages(struct iov_iter *i, static ssize_t pipe_get_pages(struct iov_iter *i, struct page **pages, size_t maxsize, unsigned maxpages, - size_t *start) + size_t *start, bool use_pup) { unsigned int iter_head, npages; size_t capacity; @@ -1306,8 +1311,51 @@ static ssize_t pipe_get_pages(struct iov_iter *i, npages = pipe_space_for_user(iter_head, i->pipe->tail, i->pipe); capacity = min(npages, maxpages) * PAGE_SIZE - *start; - return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, start); + return __pipe_get_pages(i, min(maxsize, capacity), pages, iter_head, + start, use_pup); +} + +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 (unlikely(iov_iter_is_pipe(i))) + return pipe_get_pages(i, pages, maxsize, maxpages, start, true); + if (unlikely(iov_iter_is_discard(i))) + return -EFAULT; + 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, @@ -1317,7 +1365,7 @@ ssize_t iov_iter_get_pages(struct iov_iter *i, maxsize = i->count; if (unlikely(iov_iter_is_pipe(i))) - return pipe_get_pages(i, pages, maxsize, maxpages, start); + return pipe_get_pages(i, pages, maxsize, maxpages, start, false); if (unlikely(iov_iter_is_discard(i))) return -EFAULT; @@ -1357,7 +1405,7 @@ static struct page **get_pages_array(size_t n) static ssize_t pipe_get_pages_alloc(struct iov_iter *i, struct page ***pages, size_t maxsize, - size_t *start) + size_t *start, bool use_pup) { struct page **p; unsigned int iter_head, npages; @@ -1380,7 +1428,7 @@ static ssize_t pipe_get_pages_alloc(struct iov_iter *i, p = get_pages_array(npages); if (!p) return -ENOMEM; - n = __pipe_get_pages(i, maxsize, p, iter_head, start); + n = __pipe_get_pages(i, maxsize, p, iter_head, start, use_pup); if (n > 0) *pages = p; else @@ -1388,6 +1436,52 @@ 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 (unlikely(iov_iter_is_pipe(i))) + return pipe_get_pages_alloc(i, pages, maxsize, start, true); + if (unlikely(iov_iter_is_discard(i))) + return -EFAULT; + 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) @@ -1398,7 +1492,7 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, maxsize = i->count; if (unlikely(iov_iter_is_pipe(i))) - return pipe_get_pages_alloc(i, pages, maxsize, start); + return pipe_get_pages_alloc(i, pages, maxsize, start, false); if (unlikely(iov_iter_is_discard(i))) return -EFAULT;