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Date: Fri, 9 Apr 2021 19:50:55 +0100
From: "Matthew Wilcox (Oracle)" <willy@...radead.org>
To: linux-mm@...ck.org
Cc: "Matthew Wilcox (Oracle)" <willy@...radead.org>,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-cachefs@...hat.com, linux-afs@...ts.infradead.org,
Christoph Hellwig <hch@....de>,
Jeff Layton <jlayton@...nel.org>
Subject: [PATCH v7 18/28] mm/filemap: Add lock_folio
This is like lock_page() but for use by callers who know they have a folio.
Convert __lock_page() to be __lock_folio(). This saves one call to
compound_head() per contended call to lock_page().
Saves 362 bytes of text; mostly from improved register allocation and
inlining decisions. __lock_folio is 59 bytes while __lock_page was 79.
Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Reviewed-by: Christoph Hellwig <hch@....de>
Acked-by: Jeff Layton <jlayton@...nel.org>
---
include/linux/pagemap.h | 24 +++++++++++++++++++-----
mm/filemap.c | 29 +++++++++++++++--------------
2 files changed, 34 insertions(+), 19 deletions(-)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index d94c9f8a451d..c59b19f1cb0f 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -714,7 +714,7 @@ static inline bool wake_page_match(struct wait_page_queue *wait_page,
return true;
}
-extern void __lock_page(struct page *page);
+void __lock_folio(struct folio *folio);
extern int __lock_page_killable(struct page *page);
extern int __lock_page_async(struct page *page, struct wait_page_queue *wait);
extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
@@ -722,13 +722,24 @@ extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
void unlock_page(struct page *page);
void unlock_folio(struct folio *folio);
+static inline bool trylock_folio(struct folio *folio)
+{
+ return likely(!test_and_set_bit_lock(PG_locked, folio_flags(folio, 0)));
+}
+
/*
* Return true if the page was successfully locked
*/
static inline int trylock_page(struct page *page)
{
- page = compound_head(page);
- return (likely(!test_and_set_bit_lock(PG_locked, &page->flags)));
+ return trylock_folio(page_folio(page));
+}
+
+static inline void lock_folio(struct folio *folio)
+{
+ might_sleep();
+ if (!trylock_folio(folio))
+ __lock_folio(folio);
}
/*
@@ -736,9 +747,12 @@ static inline int trylock_page(struct page *page)
*/
static inline void lock_page(struct page *page)
{
+ struct folio *folio;
might_sleep();
- if (!trylock_page(page))
- __lock_page(page);
+
+ folio = page_folio(page);
+ if (!trylock_folio(folio))
+ __lock_folio(folio);
}
/*
diff --git a/mm/filemap.c b/mm/filemap.c
index d1cf51274921..36289a9816b5 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1187,7 +1187,7 @@ static void wake_up_page(struct page *page, int bit)
*/
enum behavior {
EXCLUSIVE, /* Hold ref to page and take the bit when woken, like
- * __lock_page() waiting on then setting PG_locked.
+ * __lock_folio() waiting on then setting PG_locked.
*/
SHARED, /* Hold ref to page and check the bit when woken, like
* wait_on_page_writeback() waiting on PG_writeback.
@@ -1574,17 +1574,16 @@ void page_endio(struct page *page, bool is_write, int err)
EXPORT_SYMBOL_GPL(page_endio);
/**
- * __lock_page - get a lock on the page, assuming we need to sleep to get it
- * @__page: the page to lock
+ * __lock_folio - Get a lock on the folio, assuming we need to sleep to get it.
+ * @folio: The folio to lock
*/
-void __lock_page(struct page *__page)
+void __lock_folio(struct folio *folio)
{
- struct page *page = compound_head(__page);
- wait_queue_head_t *q = page_waitqueue(page);
- wait_on_page_bit_common(q, page, PG_locked, TASK_UNINTERRUPTIBLE,
+ wait_queue_head_t *q = page_waitqueue(&folio->page);
+ wait_on_page_bit_common(q, &folio->page, PG_locked, TASK_UNINTERRUPTIBLE,
EXCLUSIVE);
}
-EXPORT_SYMBOL(__lock_page);
+EXPORT_SYMBOL(__lock_folio);
int __lock_page_killable(struct page *__page)
{
@@ -1659,10 +1658,10 @@ int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
return 0;
}
} else {
- __lock_page(page);
+ __lock_folio(page_folio(page));
}
- return 1;
+ return 1;
}
/**
@@ -2806,7 +2805,9 @@ loff_t mapping_seek_hole_data(struct address_space *mapping, loff_t start,
static int lock_page_maybe_drop_mmap(struct vm_fault *vmf, struct page *page,
struct file **fpin)
{
- if (trylock_page(page))
+ struct folio *folio = page_folio(page);
+
+ if (trylock_folio(folio))
return 1;
/*
@@ -2819,7 +2820,7 @@ static int lock_page_maybe_drop_mmap(struct vm_fault *vmf, struct page *page,
*fpin = maybe_unlock_mmap_for_io(vmf, *fpin);
if (vmf->flags & FAULT_FLAG_KILLABLE) {
- if (__lock_page_killable(page)) {
+ if (__lock_page_killable(&folio->page)) {
/*
* We didn't have the right flags to drop the mmap_lock,
* but all fault_handlers only check for fatal signals
@@ -2831,11 +2832,11 @@ static int lock_page_maybe_drop_mmap(struct vm_fault *vmf, struct page *page,
return 0;
}
} else
- __lock_page(page);
+ __lock_folio(folio);
+
return 1;
}
-
/*
* Synchronous readahead happens when we don't even find a page in the page
* cache at all. We don't want to perform IO under the mmap sem, so if we have
--
2.30.2
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