From: Ralph Campbell <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 <dan.j.williams@intel.com>,
Ira Weiny <ira.weiny@intel.com>,
Matthew Wilcox <willy@infradead.org>,
Jerome Glisse <jglisse@redhat.com>,
John Hubbard <jhubbard@nvidia.com>,
Alistair Popple <apopple@nvidia.com>,
Christoph Hellwig <hch@lst.de>, Jason Gunthorpe <jgg@nvidia.com>,
"Bharata B Rao" <bharata@linux.ibm.com>, Zi Yan <ziy@nvidia.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Yang Shi <yang.shi@linux.alibaba.com>,
Paul Mackerras <paulus@ozlabs.org>,
Ben Skeggs <bskeggs@redhat.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
Ralph Campbell <rcampbell@nvidia.com>
Subject: [RFC PATCH v3 1/2] ext4/xfs: add page refcount helper
Date: Thu, 1 Oct 2020 11:17:14 -0700 [thread overview]
Message-ID: <20201001181715.17416-2-rcampbell@nvidia.com> (raw)
In-Reply-To: <20201001181715.17416-1-rcampbell@nvidia.com>
There are several places where ZONE_DEVICE struct pages assume a reference
count == 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 <rcampbell@nvidia.com>
---
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 = pfn_to_page(pfn);
- 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 != mapping);
page->mapping = NULL;
page->index = 0;
@@ -372,7 +372,7 @@ static struct page *dax_busy_page(void *entry)
for_each_mapped_pfn(entry, pfn) {
struct page *page = pfn_to_page(pfn);
- 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;
- error = ___wait_var_event(&page->_refcount,
- atomic_read(&page->_refcount) == 1,
- TASK_INTERRUPTIBLE, 0, 0,
- ext4_wait_dax_page(ei));
+ error = dax_wait_page(ei, page, ext4_wait_dax_page);
} while (error == 0);
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;
*retry = true;
- return ___wait_var_event(&page->_refcount,
- atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE,
- 0, 0, xfs_wait_dax_page(inode));
+ return dax_wait_page(inode, page, xfs_wait_dax_page);
}
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 *mapping)
return mapping->host && IS_DAX(mapping->host);
}
+static inline bool dax_layout_is_idle_page(struct page *page)
+{
+ return page_ref_count(page) == 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
--
2.20.1
next prev parent reply other threads:[~2020-10-01 18:17 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-01 18:17 [RFC PATCH v3 0/2] mm: remove extra ZONE_DEVICE struct page refcount Ralph Campbell
2020-10-01 18:17 ` Ralph Campbell [this message]
2020-10-02 5:56 ` [RFC PATCH v3 1/2] ext4/xfs: add page refcount helper Christoph Hellwig
2020-10-05 16:29 ` Ralph Campbell
2020-10-01 18:17 ` [RFC PATCH v3 2/2] mm: remove extra ZONE_DEVICE struct page refcount Ralph Campbell
2020-10-02 5:59 ` Christoph Hellwig
2020-10-05 16:40 ` Ralph Campbell
2020-10-08 5:17 ` Ram Pai
2020-10-08 16:45 ` Ralph Campbell
2020-10-05 16:56 ` [RFC PATCH v3 0/2] " Matthew Wilcox
2020-10-05 18:24 ` Dan Williams
2021-05-13 13:15 ` Matthew Wilcox
2021-05-13 17:35 ` Ralph Campbell
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