diff mbox series

[v6,01/13] ext4/xfs: add page refcount helper

Message ID 20210813063150.2938-2-alex.sierra@amd.com (mailing list archive)
State New
Headers show
Series Support DEVICE_GENERIC memory in migrate_vma_* | expand

Commit Message

Sierra Guiza, Alejandro (Alex) Aug. 13, 2021, 6:31 a.m. UTC 
From: Ralph Campbell <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.

v3:
[AS]: rename dax_layout_is_idle_page func to dax_page_unused

v4:
[AS]: This ref count functionality was missing on fuse/dax.c.

Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Alex Sierra <alex.sierra@amd.com>
---
 fs/dax.c            |  4 ++--
 fs/ext4/inode.c     |  5 +----
 fs/fuse/dax.c       |  4 +---
 fs/xfs/xfs_file.c   |  4 +---
 include/linux/dax.h | 10 ++++++++++
 5 files changed, 15 insertions(+), 12 deletions(-)

Comments

Christoph Hellwig Aug. 15, 2021, 9:01 a.m. UTC | #1 
On Fri, Aug 13, 2021 at 01:31:38AM -0500, Alex Sierra wrote:
> From: Ralph Campbell <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.
> 
> v3:
> [AS]: rename dax_layout_is_idle_page func to dax_page_unused
> 
> v4:
> [AS]: This ref count functionality was missing on fuse/dax.c.

These per-patch changelog goes under the "---", otherwise they totally
mess up the logs when commited to git.  Same for the other patches in
this series.

But the changes itself looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>
diff mbox series

Patch

diff --git a/fs/dax.c b/fs/dax.c
index 62352cbcf0f4..c387d09e3e5a 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -369,7 +369,7 @@  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_page_unused(page));
 		WARN_ON_ONCE(page->mapping && page->mapping != mapping);
 		page->mapping = NULL;
 		page->index = 0;
@@ -383,7 +383,7 @@  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_page_unused(page))
 			return page;
 	}
 	return NULL;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index fe6045a46599..05ffe6875cb1 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3971,10 +3971,7 @@  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/fuse/dax.c b/fs/fuse/dax.c
index ff99ab2a3c43..2b1f190ba78a 100644
--- a/fs/fuse/dax.c
+++ b/fs/fuse/dax.c
@@ -677,9 +677,7 @@  static int __fuse_dax_break_layouts(struct inode *inode, bool *retry,
 		return 0;
 
 	*retry = true;
-	return ___wait_var_event(&page->_refcount,
-			atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE,
-			0, 0, fuse_wait_dax_page(inode));
+	return dax_wait_page(inode, page, fuse_wait_dax_page);
 }
 
 /* dmap_end == 0 leads to unmapping of whole file */
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 396ef36dcd0a..182057281086 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -840,9 +840,7 @@  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..8b5da1d60dbc 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_page_unused(struct page *page)
+{
+	return page_ref_count(page) == 1;
+}
+
+#define dax_wait_page(_inode, _page, _wait_cb)				\
+	___wait_var_event(&(_page)->_refcount,				\
+		dax_page_unused(_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