From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ralph Campbell Subject: [RFC PATCH v3 1/2] ext4/xfs: add page refcount helper Date: Thu, 1 Oct 2020 11:17:14 -0700 Message-ID: <20201001181715.17416-2-rcampbell@nvidia.com> References: <20201001181715.17416-1-rcampbell@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20201001181715.17416-1-rcampbell@nvidia.com> To: linux-mm@kvack.org, kvm-ppc@vger.kernel.org, nouveau@lists.freedesktop.org, linux-kernel@vger.kernel.org Cc: Dan Williams , Ira Weiny , Matthew Wilcox , Jerome Glisse , John Hubbard , Alistair Popple , Christoph Hellwig , Jason Gunthorpe , Bharata B Rao , Zi Yan , "Kirill A . Shutemov" , Yang Shi , Paul Mackerras , Ben Skeggs , Andrew Morton , Ralph Campbell List-Id: nouveau.vger.kernel.org There are several places where ZONE_DEVICE struct pages assume a reference count =3D=3D 1 means the page is idle and free. Instead of open coding this= , add a helper function to hide this detail. Signed-off-by: Ralph Campbell --- fs/dax.c | 4 ++-- fs/ext4/inode.c | 5 +---- fs/xfs/xfs_file.c | 4 +--- include/linux/dax.h | 10 ++++++++++ 4 files changed, 14 insertions(+), 9 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 5b47834f2e1b..85c63f735909 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -358,7 +358,7 @@ static void dax_disassociate_entry(void *entry, struct = address_space *mapping, for_each_mapped_pfn(entry, pfn) { struct page *page =3D pfn_to_page(pfn); =20 - WARN_ON_ONCE(trunc && page_ref_count(page) > 1); + WARN_ON_ONCE(trunc && !dax_layout_is_idle_page(page)); WARN_ON_ONCE(page->mapping && page->mapping !=3D mapping); page->mapping =3D NULL; page->index =3D 0; @@ -372,7 +372,7 @@ static struct page *dax_busy_page(void *entry) for_each_mapped_pfn(entry, pfn) { struct page *page =3D pfn_to_page(pfn); =20 - if (page_ref_count(page) > 1) + if (!dax_layout_is_idle_page(page)) return page; } return NULL; diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index bf596467c234..4c3b80e68121 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3926,10 +3926,7 @@ int ext4_break_layouts(struct inode *inode) if (!page) return 0; =20 - error =3D ___wait_var_event(&page->_refcount, - atomic_read(&page->_refcount) =3D=3D 1, - TASK_INTERRUPTIBLE, 0, 0, - ext4_wait_dax_page(ei)); + error =3D dax_wait_page(ei, page, ext4_wait_dax_page); } while (error =3D=3D 0); =20 return error; diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 3d1b95124744..a5304aaeaa3a 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -749,9 +749,7 @@ xfs_break_dax_layouts( return 0; =20 *retry =3D true; - return ___wait_var_event(&page->_refcount, - atomic_read(&page->_refcount) =3D=3D 1, TASK_INTERRUPTIBLE, - 0, 0, xfs_wait_dax_page(inode)); + return dax_wait_page(inode, page, xfs_wait_dax_page); } =20 int diff --git a/include/linux/dax.h b/include/linux/dax.h index b52f084aa643..f906cf4db1cc 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -243,6 +243,16 @@ static inline bool dax_mapping(struct address_space *m= apping) return mapping->host && IS_DAX(mapping->host); } =20 +static inline bool dax_layout_is_idle_page(struct page *page) +{ + return page_ref_count(page) =3D=3D 1; +} + +#define dax_wait_page(_inode, _page, _wait_cb) \ + ___wait_var_event(&(_page)->_refcount, \ + dax_layout_is_idle_page(_page), \ + TASK_INTERRUPTIBLE, 0, 0, _wait_cb(_inode)) + #ifdef CONFIG_DEV_DAX_HMEM_DEVICES void hmem_register_device(int target_nid, struct resource *r); #else --=20 2.20.1