In preparation for requesting folios from a pgmap, rework
for_each_mapped_pfn() to operate in terms of folios.
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: "Darrick J. Wong" <djwong@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
.clang-format | 1 +
fs/dax.c | 102 ++++++++++++++++++++++++++++++---------------------
include/linux/dax.h | 5 +++
3 files changed, 66 insertions(+), 42 deletions(-)
diff --git a/.clang-format b/.clang-format
index 1247d54f9e49..767651ddc50c 100644
--- a/.clang-format
+++ b/.clang-format
@@ -136,6 +136,7 @@ ForEachMacros:
- 'data__for_each_file'
- 'data__for_each_file_new'
- 'data__for_each_file_start'
+ - 'dax_for_each_folio'
- 'device_for_each_child_node'
- 'displayid_iter_for_each'
- 'dma_fence_array_for_each'
diff --git a/fs/dax.c b/fs/dax.c
index 1f6c1abfe0c9..d03c7a952d02 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -327,18 +327,41 @@ static unsigned long dax_entry_size(void *entry)
return PAGE_SIZE;
}
-static unsigned long dax_end_pfn(void *entry)
+/*
+ * Until fsdax constructs compound folios it needs to be prepared to
+ * support multiple folios per entry where each folio is a single page
+ */
+static struct folio *dax_entry_to_folio(void *entry, int idx)
{
- return dax_to_pfn(entry) + dax_entry_size(entry) / PAGE_SIZE;
+ unsigned long pfn, size = dax_entry_size(entry);
+ struct page *page;
+ struct folio *folio;
+
+ if (!size)
+ return NULL;
+
+ pfn = dax_to_pfn(entry);
+ page = pfn_to_page(pfn);
+ folio = page_folio(page);
+
+ /*
+ * Are there multiple folios per entry, and has the iterator
+ * passed the end of that set?
+ */
+ if (idx >= size / folio_size(folio))
+ return NULL;
+
+ VM_WARN_ON_ONCE(!IS_ALIGNED(size, folio_size(folio)));
+
+ return page_folio(page + idx);
}
/*
- * Iterate through all mapped pfns represented by an entry, i.e. skip
- * 'empty' and 'zero' entries.
+ * Iterate through all folios associated with a given entry
*/
-#define for_each_mapped_pfn(entry, pfn) \
- for (pfn = dax_to_pfn(entry); \
- pfn < dax_end_pfn(entry); pfn++)
+#define dax_for_each_folio(entry, folio, i) \
+ for (i = 0, folio = dax_entry_to_folio(entry, i); folio; \
+ folio = dax_entry_to_folio(entry, ++i))
static inline bool dax_mapping_is_cow(struct address_space *mapping)
{
@@ -348,18 +371,18 @@ static inline bool dax_mapping_is_cow(struct address_space *mapping)
/*
* Set the page->mapping with FS_DAX_MAPPING_COW flag, increase the refcount.
*/
-static inline void dax_mapping_set_cow(struct page *page)
+static inline void dax_mapping_set_cow(struct folio *folio)
{
- if ((uintptr_t)page->mapping != PAGE_MAPPING_DAX_COW) {
+ if ((uintptr_t)folio->mapping != PAGE_MAPPING_DAX_COW) {
/*
- * Reset the index if the page was already mapped
+ * Reset the index if the folio was already mapped
* regularly before.
*/
- if (page->mapping)
- page->index = 1;
- page->mapping = (void *)PAGE_MAPPING_DAX_COW;
+ if (folio->mapping)
+ folio->index = 1;
+ folio->mapping = (void *)PAGE_MAPPING_DAX_COW;
}
- page->index++;
+ folio->index++;
}
/*
@@ -370,48 +393,45 @@ static inline void dax_mapping_set_cow(struct page *page)
static void dax_associate_entry(void *entry, struct address_space *mapping,
struct vm_area_struct *vma, unsigned long address, bool cow)
{
- unsigned long size = dax_entry_size(entry), pfn, index;
- int i = 0;
+ unsigned long size = dax_entry_size(entry), index;
+ struct folio *folio;
+ int i;
if (IS_ENABLED(CONFIG_FS_DAX_LIMITED))
return;
index = linear_page_index(vma, address & ~(size - 1));
- for_each_mapped_pfn(entry, pfn) {
- struct page *page = pfn_to_page(pfn);
-
+ dax_for_each_folio(entry, folio, i)
if (cow) {
- dax_mapping_set_cow(page);
+ dax_mapping_set_cow(folio);
} else {
- WARN_ON_ONCE(page->mapping);
- page->mapping = mapping;
- page->index = index + i++;
+ WARN_ON_ONCE(folio->mapping);
+ folio->mapping = mapping;
+ folio->index = index + i;
}
- }
}
static void dax_disassociate_entry(void *entry, struct address_space *mapping,
bool trunc)
{
- unsigned long pfn;
+ struct folio *folio;
+ int i;
if (IS_ENABLED(CONFIG_FS_DAX_LIMITED))
return;
- for_each_mapped_pfn(entry, pfn) {
- struct page *page = pfn_to_page(pfn);
-
- if (dax_mapping_is_cow(page->mapping)) {
- /* keep the CoW flag if this page is still shared */
- if (page->index-- > 0)
+ dax_for_each_folio(entry, folio, i) {
+ if (dax_mapping_is_cow(folio->mapping)) {
+ /* keep the CoW flag if this folio is still shared */
+ if (folio->index-- > 0)
continue;
} else {
WARN_ON_ONCE(trunc && !dax_is_zapped(entry));
- WARN_ON_ONCE(trunc && !dax_page_idle(page));
- WARN_ON_ONCE(page->mapping && page->mapping != mapping);
+ WARN_ON_ONCE(trunc && !dax_folio_idle(folio));
+ WARN_ON_ONCE(folio->mapping && folio->mapping != mapping);
}
- page->mapping = NULL;
- page->index = 0;
+ folio->mapping = NULL;
+ folio->index = 0;
}
}
@@ -673,20 +693,18 @@ static void *dax_zap_entry(struct xa_state *xas, void *entry)
static struct page *dax_zap_pages(struct xa_state *xas, void *entry)
{
struct page *ret = NULL;
- unsigned long pfn;
+ struct folio *folio;
bool zap;
+ int i;
if (!dax_entry_size(entry))
return NULL;
zap = !dax_is_zapped(entry);
- for_each_mapped_pfn(entry, pfn) {
- struct page *page = pfn_to_page(pfn);
-
- if (!ret && !dax_page_idle(page))
- ret = page;
- }
+ dax_for_each_folio(entry, folio, i)
+ if (!ret && !dax_folio_idle(folio))
+ ret = folio_page(folio, 0);
if (zap)
dax_zap_entry(xas, entry);
diff --git a/include/linux/dax.h b/include/linux/dax.h
index f6acb4ed73cb..12e15ca11bff 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -222,6 +222,11 @@ static inline bool dax_page_idle(struct page *page)
return page_ref_count(page) == 1;
}
+static inline bool dax_folio_idle(struct folio *folio)
+{
+ return dax_page_idle(folio_page(folio, 0));
+}
+
#if IS_ENABLED(CONFIG_DAX)
int dax_read_lock(void);
void dax_read_unlock(int id);
