In preparation for device-dax to use the same mapping machinery as
fsdax, add support for device-dax compound pages.
Presently this is handled by dax_set_mapping() which is careful to only
update page->mapping for head pages. However, it does that by looking at
properties in the 'struct dev_dax' instance associated with the page.
Switch to just checking PageHead() directly.
Cc: Matthew Wilcox <wi...@infradead.org>
Cc: Jan Kara <j...@suse.cz>
Cc: "Darrick J. Wong" <djw...@kernel.org>
Cc: Jason Gunthorpe <j...@nvidia.com>
Cc: Christoph Hellwig <h...@lst.de>
Cc: John Hubbard <jhubb...@nvidia.com>
Signed-off-by: Dan Williams <dan.j.willi...@intel.com>
---
drivers/dax/Kconfig | 1 +
drivers/dax/mapping.c | 18 ++++++++++++++++++
2 files changed, 19 insertions(+)
diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig
index 3ed4da3935e5..2dcc8744277d 100644
--- a/drivers/dax/Kconfig
+++ b/drivers/dax/Kconfig
@@ -10,6 +10,7 @@ if DAX
config DEV_DAX
tristate "Device DAX: direct access mapping device"
depends on TRANSPARENT_HUGEPAGE
+ depends on !FS_DAX_LIMITED
help
Support raw access to differentiated (persistence, bandwidth,
latency...) memory via an mmap(2) capable character
diff --git a/drivers/dax/mapping.c b/drivers/dax/mapping.c
index 0810af7d9503..6bd38ddba2cb 100644
--- a/drivers/dax/mapping.c
+++ b/drivers/dax/mapping.c
@@ -351,6 +351,8 @@ static vm_fault_t dax_associate_entry(void *entry,
for_each_mapped_pfn(entry, pfn) {
struct page *page = pfn_to_page(pfn);
+ page = compound_head(page);
+
if (flags & DAX_COW) {
dax_mapping_set_cow(page);
} else {
@@ -358,6 +360,13 @@ static vm_fault_t dax_associate_entry(void *entry,
page->mapping = mapping;
page->index = index + i++;
}
+
+ /*
+ * page->mapping and page->index are only manipulated on
+ * head pages
+ */
+ if (PageHead(page))
+ break;
}
return 0;
@@ -380,6 +389,8 @@ static void dax_disassociate_entry(void *entry, struct
address_space *mapping,
for_each_mapped_pfn(entry, pfn) {
page = pfn_to_page(pfn);
+ page = compound_head(page);
+
WARN_ON_ONCE(trunc && page_maybe_dma_pinned(page));
if (dax_mapping_is_cow(page->mapping)) {
/* keep the CoW flag if this page is still shared */
@@ -389,6 +400,13 @@ static void dax_disassociate_entry(void *entry, struct
address_space *mapping,
WARN_ON_ONCE(page->mapping && page->mapping != mapping);
page->mapping = NULL;
page->index = 0;
+
+ /*
+ * page->mapping and page->index are only manipulated on
+ * head pages
+ */
+ if (PageHead(page))
+ break;
}
}
