From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f47.google.com (mail-wg0-f47.google.com [74.125.82.47]) by kanga.kvack.org (Postfix) with ESMTP id 8AA016B0036 for ; Wed, 10 Sep 2014 05:51:24 -0400 (EDT) Received: by mail-wg0-f47.google.com with SMTP id y10so3848690wgg.6 for ; Wed, 10 Sep 2014 02:51:24 -0700 (PDT) Received: from mail-we0-x233.google.com (mail-we0-x233.google.com [2a00:1450:400c:c03::233]) by mx.google.com with ESMTPS id f18si1622159wiw.99.2014.09.10.02.51.22 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 10 Sep 2014 02:51:22 -0700 (PDT) Received: by mail-we0-f179.google.com with SMTP id u56so4242414wes.10 for ; Wed, 10 Sep 2014 02:51:22 -0700 (PDT) Date: Wed, 10 Sep 2014 11:51:15 +0200 From: Miklos Szeredi Subject: Re: [PATCH 0/2] fuse: fix regression in fuse_get_user_pages() Message-ID: <20140910095115.GA7441@tucsk.piliscsaba.szeredi.hu> References: <20140903100826.23218.95122.stgit@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140903100826.23218.95122.stgit@localhost.localdomain> Sender: owner-linux-mm@kvack.org List-ID: To: Maxim Patlasov Cc: viro@zeniv.linux.org.uk, fuse-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, werner.baumann@onlinehome.de On Wed, Sep 03, 2014 at 02:10:23PM +0400, Maxim Patlasov wrote: > Hi, > > The patchset fixes a regression introduced by the following commits: > > c7f3888ad7f0 ("switch iov_iter_get_pages() to passing maximal number of pages") > c9c37e2e6378 ("fuse: switch to iov_iter_get_pages()") > Hmm, instead of reverting to passing maxbytes *instead* of maxpages, I think the right fix is to *add* the maxbytes argument. Just maxbytes alone doesn't have enough information in it. E.g. 4096 contiguous bytes could occupy 1 or 2 pages, depending on the starting offset. So how about the following (untested) patch? Thanks, Miklos diff --git a/fs/direct-io.c b/fs/direct-io.c index c3116404ab49..e181b6b2e297 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -158,7 +158,7 @@ static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio) { ssize_t ret; - ret = iov_iter_get_pages(sdio->iter, dio->pages, DIO_PAGES, + ret = iov_iter_get_pages(sdio->iter, dio->pages, LONG_MAX, DIO_PAGES, &sdio->from); if (ret < 0 && sdio->blocks_available && (dio->rw & WRITE)) { diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 912061ac4baf..caa8d95b24e8 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -1305,6 +1305,7 @@ static int fuse_get_user_pages(struct fuse_req *req, struct iov_iter *ii, size_t start; ssize_t ret = iov_iter_get_pages(ii, &req->pages[req->num_pages], + *nbytesp - nbytes, req->max_pages - req->num_pages, &start); if (ret < 0) diff --git a/include/linux/uio.h b/include/linux/uio.h index 48d64e6ab292..290fbf0b6b8a 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -84,7 +84,7 @@ unsigned long iov_iter_alignment(const struct iov_iter *i); void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov, unsigned long nr_segs, size_t count); ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages, - unsigned maxpages, size_t *start); + size_t maxsize, unsigned maxpages, size_t *start); 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); diff --git a/mm/iov_iter.c b/mm/iov_iter.c index ab88dc0ea1d3..9a09f2034fcc 100644 --- a/mm/iov_iter.c +++ b/mm/iov_iter.c @@ -310,7 +310,7 @@ void iov_iter_init(struct iov_iter *i, int direction, EXPORT_SYMBOL(iov_iter_init); static ssize_t get_pages_iovec(struct iov_iter *i, - struct page **pages, unsigned maxpages, + struct page **pages, size_t maxsize, unsigned maxpages, size_t *start) { size_t offset = i->iov_offset; @@ -323,6 +323,8 @@ static ssize_t get_pages_iovec(struct iov_iter *i, len = iov->iov_len - offset; if (len > i->count) len = i->count; + if (len > maxsize) + len = maxsize; addr = (unsigned long)iov->iov_base + offset; len += *start = addr & (PAGE_SIZE - 1); if (len > maxpages * PAGE_SIZE) @@ -588,13 +590,15 @@ static unsigned long alignment_bvec(const struct iov_iter *i) } static ssize_t get_pages_bvec(struct iov_iter *i, - struct page **pages, unsigned maxpages, + struct page **pages, size_t maxsize, unsigned maxpages, size_t *start) { const struct bio_vec *bvec = i->bvec; size_t len = bvec->bv_len - i->iov_offset; if (len > i->count) len = i->count; + if (len > maxsize) + len = maxsize; /* can't be more than PAGE_SIZE */ *start = bvec->bv_offset + i->iov_offset; @@ -711,13 +715,13 @@ unsigned long iov_iter_alignment(const struct iov_iter *i) EXPORT_SYMBOL(iov_iter_alignment); ssize_t iov_iter_get_pages(struct iov_iter *i, - struct page **pages, unsigned maxpages, + struct page **pages, size_t maxsize, unsigned maxpages, size_t *start) { if (i->type & ITER_BVEC) - return get_pages_bvec(i, pages, maxpages, start); + return get_pages_bvec(i, pages, maxsize, maxpages, start); else - return get_pages_iovec(i, pages, maxpages, start); + return get_pages_iovec(i, pages, maxsize, maxpages, start); } EXPORT_SYMBOL(iov_iter_get_pages); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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