filesystem-dax: Set page->index

In support of enabling memory_failure() handling for filesystem-dax
mappings, set ->index to the pgoff of the page. The rmap implementation
requires ->index to bound the search through the vma interval tree. The
index is set and cleared at dax_associate_entry() and
dax_disassociate_entry() time respectively.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

diff --git a/fs/dax.c b/fs/dax.c
index 641192808bb69054a634b6f5b229c2ca25f308bf..4de11ed463cea1b99b5a6bd2f5dc4df93212f9c2 100644 (file)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -319,18 +319,27 @@ static unsigned long dax_radix_end_pfn(void *entry)
        for (pfn = dax_radix_pfn(entry); \
                        pfn < dax_radix_end_pfn(entry); pfn++)
 
-static void dax_associate_entry(void *entry, struct address_space *mapping)
+/*
+ * TODO: for reflink+dax we need a way to associate a single page with
+ * multiple address_space instances at different linear_page_index()
+ * offsets.
+ */
+static void dax_associate_entry(void *entry, struct address_space *mapping,
+               struct vm_area_struct *vma, unsigned long address)
 {
-       unsigned long pfn;
+       unsigned long size = dax_entry_size(entry), pfn, index;
+       int i = 0;
 
        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);
 
                WARN_ON_ONCE(page->mapping);
                page->mapping = mapping;
+               page->index = index + i++;
        }
 }
 
@@ -348,6 +357,7 @@ static void dax_disassociate_entry(void *entry, struct address_space *mapping,
                WARN_ON_ONCE(trunc && page_ref_count(page) > 1);
                WARN_ON_ONCE(page->mapping && page->mapping != mapping);
                page->mapping = NULL;
+               page->index = 0;
        }
 }
 
@@ -701,7 +711,7 @@ static void *dax_insert_mapping_entry(struct address_space *mapping,
        new_entry = dax_radix_locked_entry(pfn, flags);
        if (dax_entry_size(entry) != dax_entry_size(new_entry)) {
                dax_disassociate_entry(entry, mapping, false);
-               dax_associate_entry(new_entry, mapping);
+               dax_associate_entry(new_entry, mapping, vmf->vma, vmf->address);
        }
 
        if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {