From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Try to allocate huge page if flags has AOP_FLAG_TRANSHUGE.
If, for some reason, it's not possible allocate a huge page at this
possition, it returns NULL. Caller should take care of fallback to
small pages.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
include/linux/fs.h | 1 +
include/linux/huge_mm.h | 3 +++
include/linux/pagemap.h | 9 ++++++++-
mm/filemap.c | 29 ++++++++++++++++++++++++-----
4 files changed, 36 insertions(+), 6 deletions(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 2c28271..a70b0ac 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -280,6 +280,7 @@ enum positive_aop_returns {
#define AOP_FLAG_NOFS 0x0004 /* used by filesystem to direct
* helper code (eg buffer layer)
* to clear GFP_FS from alloc */
+#define AOP_FLAG_TRANSHUGE 0x0008 /* allocate transhuge page */
/*
* oh the beauties of C type declarations.
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 88b44e2..74494a2 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -194,6 +194,9 @@ extern int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vm
#define HPAGE_CACHE_NR ({ BUILD_BUG(); 0; })
#define HPAGE_CACHE_INDEX_MASK ({ BUILD_BUG(); 0; })
+#define THP_WRITE_ALLOC ({ BUILD_BUG(); 0; })
+#define THP_WRITE_ALLOC_FAILED ({ BUILD_BUG(); 0; })
+
#define hpage_nr_pages(x) 1
#define transparent_hugepage_enabled(__vma) 0
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 2e86251..8feeecc 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -270,8 +270,15 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
int tag, unsigned int nr_pages, struct page **pages);
-struct page *grab_cache_page_write_begin(struct address_space *mapping,
+struct page *__grab_cache_page_write_begin(struct address_space *mapping,
pgoff_t index, unsigned flags);
+static inline struct page *grab_cache_page_write_begin(
+ struct address_space *mapping, pgoff_t index, unsigned flags)
+{
+ if (!transparent_hugepage_pagecache() && (flags & AOP_FLAG_TRANSHUGE))
+ return NULL;
+ return __grab_cache_page_write_begin(mapping, index, flags);
+}
/*
* Returns locked page at given index in given cache, creating it if needed.
diff --git a/mm/filemap.c b/mm/filemap.c
index 9ea46a4..e086ef0 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2309,25 +2309,44 @@ EXPORT_SYMBOL(generic_file_direct_write);
* Find or create a page at the given pagecache position. Return the locked
* page. This function is specifically for buffered writes.
*/
-struct page *grab_cache_page_write_begin(struct address_space *mapping,
- pgoff_t index, unsigned flags)
+struct page *__grab_cache_page_write_begin(struct address_space *mapping,
+ pgoff_t index, unsigned flags)
{
int status;
gfp_t gfp_mask;
struct page *page;
gfp_t gfp_notmask = 0;
+ bool thp = (flags & AOP_FLAG_TRANSHUGE) &&
+ IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE);
gfp_mask = mapping_gfp_mask(mapping);
if (mapping_cap_account_dirty(mapping))
gfp_mask |= __GFP_WRITE;
if (flags & AOP_FLAG_NOFS)
gfp_notmask = __GFP_FS;
+ if (thp) {
+ BUG_ON(index & HPAGE_CACHE_INDEX_MASK);
+ BUG_ON(!(gfp_mask & __GFP_COMP));
+ }
repeat:
page = find_lock_page(mapping, index);
- if (page)
+ if (page) {
+ if (thp && !PageTransHuge(page)) {
+ unlock_page(page);
+ page_cache_release(page);
+ return NULL;
+ }
goto found;
+ }
- page = __page_cache_alloc(gfp_mask & ~gfp_notmask);
+ if (thp) {
+ page = alloc_pages(gfp_mask & ~gfp_notmask, HPAGE_PMD_ORDER);
+ if (page)
+ count_vm_event(THP_WRITE_ALLOC);
+ else
+ count_vm_event(THP_WRITE_ALLOC_FAILED);
+ } else
+ page = __page_cache_alloc(gfp_mask & ~gfp_notmask);
if (!page)
return NULL;
status = add_to_page_cache_lru(page, mapping, index,
@@ -2342,7 +2361,7 @@ found:
wait_for_stable_page(page);
return page;
}
-EXPORT_SYMBOL(grab_cache_page_write_begin);
+EXPORT_SYMBOL(__grab_cache_page_write_begin);
static ssize_t generic_perform_write(struct file *file,
struct iov_iter *i, loff_t pos)
--
1.7.10.4
--
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