mm: convert DAX lock/unlock page to lock/unlock folio

The one caller of DAX lock/unlock page already calls compound_head(), so
use page_folio() instead, then use a folio throughout the DAX code to
remove uses of page->mapping and page->index.

[jane.chu@oracle.com: add comment to mf_generic_kill_procss(), simplify mf_generic_kill_procs:folio initialization]
Link: https://lkml.kernel.org/r/20230908222336.186313-1-jane.chu@oracle.com
Link: https://lkml.kernel.org/r/20230822231314.349200-1-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Jane Chu <jane.chu@oracle.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Jane Chu <jane.chu@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/dax.c b/fs/dax.c
index 8fafecbe42b1596afecd2afb97c2c86aa05c6d2f..3380b43cb6bbbd1289901a3e29edc903abe6156e 100644 (file)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -412,23 +412,23 @@ static struct page *dax_busy_page(void *entry)
        return NULL;
 }
 
-/*
- * dax_lock_page - Lock the DAX entry corresponding to a page
- * @page: The page whose entry we want to lock
+/**
+ * dax_lock_folio - Lock the DAX entry corresponding to a folio
+ * @folio: The folio whose entry we want to lock
  *
  * Context: Process context.
- * Return: A cookie to pass to dax_unlock_page() or 0 if the entry could
+ * Return: A cookie to pass to dax_unlock_folio() or 0 if the entry could
  * not be locked.
  */
-dax_entry_t dax_lock_page(struct page *page)
+dax_entry_t dax_lock_folio(struct folio *folio)
 {
        XA_STATE(xas, NULL, 0);
        void *entry;
 
-       /* Ensure page->mapping isn't freed while we look at it */
+       /* Ensure folio->mapping isn't freed while we look at it */
        rcu_read_lock();
        for (;;) {
-               struct address_space *mapping = READ_ONCE(page->mapping);
+               struct address_space *mapping = READ_ONCE(folio->mapping);
 
                entry = NULL;
                if (!mapping || !dax_mapping(mapping))
@@ -447,11 +447,11 @@ dax_entry_t dax_lock_page(struct page *page)
 
                xas.xa = &mapping->i_pages;
                xas_lock_irq(&xas);
-               if (mapping != page->mapping) {
+               if (mapping != folio->mapping) {
                        xas_unlock_irq(&xas);
                        continue;
                }
-               xas_set(&xas, page->index);
+               xas_set(&xas, folio->index);
                entry = xas_load(&xas);
                if (dax_is_locked(entry)) {
                        rcu_read_unlock();
@@ -467,10 +467,10 @@ dax_entry_t dax_lock_page(struct page *page)
        return (dax_entry_t)entry;
 }
 
-void dax_unlock_page(struct page *page, dax_entry_t cookie)
+void dax_unlock_folio(struct folio *folio, dax_entry_t cookie)
 {
-       struct address_space *mapping = page->mapping;
-       XA_STATE(xas, &mapping->i_pages, page->index);
+       struct address_space *mapping = folio->mapping;
+       XA_STATE(xas, &mapping->i_pages, folio->index);
 
        if (S_ISCHR(mapping->host->i_mode))
                return;

diff --git a/include/linux/dax.h b/include/linux/dax.h
index 22cd9902345d74484b5a882a283e16d559369a10..b463502b16e17fbc08ff3a982a9597f5d70cb06b 100644 (file)
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -159,8 +159,8 @@ int dax_writeback_mapping_range(struct address_space *mapping,
 
 struct page *dax_layout_busy_page(struct address_space *mapping);
 struct page *dax_layout_busy_page_range(struct address_space *mapping, loff_t start, loff_t end);
-dax_entry_t dax_lock_page(struct page *page);
-void dax_unlock_page(struct page *page, dax_entry_t cookie);
+dax_entry_t dax_lock_folio(struct folio *folio);
+void dax_unlock_folio(struct folio *folio, dax_entry_t cookie);
 dax_entry_t dax_lock_mapping_entry(struct address_space *mapping,
                unsigned long index, struct page **page);
 void dax_unlock_mapping_entry(struct address_space *mapping,
@@ -182,14 +182,14 @@ static inline int dax_writeback_mapping_range(struct address_space *mapping,
        return -EOPNOTSUPP;
 }
 
-static inline dax_entry_t dax_lock_page(struct page *page)
+static inline dax_entry_t dax_lock_folio(struct folio *folio)
 {
-       if (IS_DAX(page->mapping->host))
+       if (IS_DAX(folio->mapping->host))
                return ~0UL;
        return 0;
 }
 
-static inline void dax_unlock_page(struct page *page, dax_entry_t cookie)
+static inline void dax_unlock_folio(struct folio *folio, dax_entry_t cookie)
 {
 }
 

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 4d6e43c88489a0ef1755656a7512577902374496..660c21859118e3fa1d156df7df11e79831e8de2a 100644 (file)
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1713,20 +1713,23 @@ static void unmap_and_kill(struct list_head *to_kill, unsigned long pfn,
        kill_procs(to_kill, flags & MF_MUST_KILL, false, pfn, flags);
 }
 
+/*
+ * Only dev_pagemap pages get here, such as fsdax when the filesystem
+ * either do not claim or fails to claim a hwpoison event, or devdax.
+ * The fsdax pages are initialized per base page, and the devdax pages
+ * could be initialized either as base pages, or as compound pages with
+ * vmemmap optimization enabled. Devdax is simplistic in its dealing with
+ * hwpoison, such that, if a subpage of a compound page is poisoned,
+ * simply mark the compound head page is by far sufficient.
+ */
 static int mf_generic_kill_procs(unsigned long long pfn, int flags,
                struct dev_pagemap *pgmap)
 {
-       struct page *page = pfn_to_page(pfn);
+       struct folio *folio = pfn_folio(pfn);
        LIST_HEAD(to_kill);
        dax_entry_t cookie;
        int rc = 0;
 
-       /*
-        * Pages instantiated by device-dax (not filesystem-dax)
-        * may be compound pages.
-        */
-       page = compound_head(page);
-
        /*
         * Prevent the inode from being freed while we are interrogating
         * the address_space, typically this would be handled by
@@ -1734,11 +1737,11 @@ static int mf_generic_kill_procs(unsigned long long pfn, int flags,
         * also prevents changes to the mapping of this pfn until
         * poison signaling is complete.
         */
-       cookie = dax_lock_page(page);
+       cookie = dax_lock_folio(folio);
        if (!cookie)
                return -EBUSY;
 
-       if (hwpoison_filter(page)) {
+       if (hwpoison_filter(&folio->page)) {
                rc = -EOPNOTSUPP;
                goto unlock;
        }
@@ -1760,7 +1763,7 @@ static int mf_generic_kill_procs(unsigned long long pfn, int flags,
         * Use this flag as an indication that the dax page has been
         * remapped UC to prevent speculative consumption of poison.
         */
-       SetPageHWPoison(page);
+       SetPageHWPoison(&folio->page);
 
        /*
         * Unlike System-RAM there is no possibility to swap in a
@@ -1769,11 +1772,11 @@ static int mf_generic_kill_procs(unsigned long long pfn, int flags,
         * SIGBUS (i.e. MF_MUST_KILL)
         */
        flags |= MF_ACTION_REQUIRED | MF_MUST_KILL;
-       collect_procs(page, &to_kill, true);
+       collect_procs(&folio->page, &to_kill, true);
 
-       unmap_and_kill(&to_kill, pfn, page->mapping, page->index, flags);
+       unmap_and_kill(&to_kill, pfn, folio->mapping, folio->index, flags);
 unlock:
-       dax_unlock_page(page, cookie);
+       dax_unlock_folio(folio, cookie);
        return rc;
 }