[v14,025/138] mm/writeback: Add folio_wait_writeback()

Commit Message

Matthew Wilcox July 15, 2021, 3:35 a.m. UTC

wait_on_page_writeback_killable() only has one caller, so convert it to
call folio_wait_writeback_killable().  For the wait_on_page_writeback()
callers, add a compatibility wrapper around folio_wait_writeback().

Turning PageWriteback() into folio_test_writeback() eliminates a call
to compound_head() which saves 8 bytes and 15 bytes in the two
functions.  Unfortunately, that is more than offset by adding the
wait_on_page_writeback compatibility wrapper for a net increase in text
of 7 bytes.

Signed-off-by: Matthew Wilcox (Oracle) <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Acked-by: Jeff Layton <[e-mail]>
Acked-by: Kirill A. Shutemov <[e-mail]>
Acked-by: Vlastimil Babka <[e-mail]>
Reviewed-by: William Kucharski <[e-mail]>
---
 fs/afs/write.c          |  9 ++++----
 include/linux/pagemap.h |  3 ++-
 mm/folio-compat.c       |  6 ++++++
 mm/page-writeback.c     | 48 ++++++++++++++++++++++++++++-------------
 4 files changed, 46 insertions(+), 20 deletions(-)

Comments

Mike Rapoport July 20, 2021, 10:46 a.m. UTC | #1

On Thu, Jul 15, 2021 at 04:35:11AM +0100, Matthew Wilcox (Oracle) wrote:
> wait_on_page_writeback_killable() only has one caller, so convert it to
> call folio_wait_writeback_killable().  For the wait_on_page_writeback()
> callers, add a compatibility wrapper around folio_wait_writeback().
> 
> Turning PageWriteback() into folio_test_writeback() eliminates a call
> to compound_head() which saves 8 bytes and 15 bytes in the two
> functions.  Unfortunately, that is more than offset by adding the
> wait_on_page_writeback compatibility wrapper for a net increase in text
> of 7 bytes.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <[e-mail]>
> Reviewed-by: Christoph Hellwig <[e-mail]>
> Acked-by: Jeff Layton <[e-mail]>
> Acked-by: Kirill A. Shutemov <[e-mail]>
> Acked-by: Vlastimil Babka <[e-mail]>
> Reviewed-by: William Kucharski <[e-mail]>
> ---
>  fs/afs/write.c          |  9 ++++----
>  include/linux/pagemap.h |  3 ++-
>  mm/folio-compat.c       |  6 ++++++
>  mm/page-writeback.c     | 48 ++++++++++++++++++++++++++++-------------
>  4 files changed, 46 insertions(+), 20 deletions(-)

Acked-by: Mike Rapoport <[e-mail]>

David Howells Aug. 10, 2021, 3:37 p.m. UTC | #2

Matthew Wilcox (Oracle) <[e-mail]> wrote:

> wait_on_page_writeback_killable() only has one caller, so convert it to
> call folio_wait_writeback_killable().  For the wait_on_page_writeback()
> callers, add a compatibility wrapper around folio_wait_writeback().
> 
> Turning PageWriteback() into folio_test_writeback() eliminates a call
> to compound_head() which saves 8 bytes and 15 bytes in the two
> functions.  Unfortunately, that is more than offset by adding the
> wait_on_page_writeback compatibility wrapper for a net increase in text
> of 7 bytes.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <[e-mail]>
> Reviewed-by: Christoph Hellwig <[e-mail]>
> Acked-by: Jeff Layton <[e-mail]>
> Acked-by: Kirill A. Shutemov <[e-mail]>
> Acked-by: Vlastimil Babka <[e-mail]>
> Reviewed-by: William Kucharski <[e-mail]>

Reviewed-by: David Howells <[e-mail]>

Patch

diff --git a/fs/afs/write.c b/fs/afs/write.c
index 3104b62c2082..fb7d5c1cabde 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -839,7 +839,8 @@  int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
  */
 vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
 {
-	struct page *page = thp_head(vmf->page);
+	struct folio *folio = page_folio(vmf->page);
+	struct page *page = &folio->page;
 	struct file *file = vmf->vma->vm_file;
 	struct inode *inode = file_inode(file);
 	struct afs_vnode *vnode = AFS_FS_I(inode);
@@ -859,7 +860,7 @@  vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
 		goto out;
 #endif
 
-	if (wait_on_page_writeback_killable(page))
+	if (folio_wait_writeback_killable(folio))
 		goto out;
 
 	if (lock_page_killable(page) < 0)
@@ -869,8 +870,8 @@  vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
 	 * details the portion of the page we need to write back and we might
 	 * need to redirty the page if there's a problem.
 	 */
-	if (wait_on_page_writeback_killable(page) < 0) {
-		unlock_page(page);
+	if (folio_wait_writeback_killable(folio) < 0) {
+		folio_unlock(folio);
 		goto out;
 	}
 
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 66a019178550..0c5f53368fe9 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -767,7 +767,8 @@  static inline int wait_on_page_locked_killable(struct page *page)
 
 int put_and_wait_on_page_locked(struct page *page, int state);
 void wait_on_page_writeback(struct page *page);
-int wait_on_page_writeback_killable(struct page *page);
+void folio_wait_writeback(struct folio *folio);
+int folio_wait_writeback_killable(struct folio *folio);
 void end_page_writeback(struct page *page);
 void folio_end_writeback(struct folio *folio);
 void wait_for_stable_page(struct page *page);
diff --git a/mm/folio-compat.c b/mm/folio-compat.c
index 526843d03d58..41275dac7a92 100644
--- a/mm/folio-compat.c
+++ b/mm/folio-compat.c
@@ -23,3 +23,9 @@  void end_page_writeback(struct page *page)
 	return folio_end_writeback(page_folio(page));
 }
 EXPORT_SYMBOL(end_page_writeback);
+
+void wait_on_page_writeback(struct page *page)
+{
+	return folio_wait_writeback(page_folio(page));
+}
+EXPORT_SYMBOL_GPL(wait_on_page_writeback);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 9f63548f247c..c2c00e1533ad 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2830,33 +2830,51 @@  int __test_set_page_writeback(struct page *page, bool keep_write)
 }
 EXPORT_SYMBOL(__test_set_page_writeback);
 
-/*
- * Wait for a page to complete writeback
+/**
+ * folio_wait_writeback - Wait for a folio to finish writeback.
+ * @folio: The folio to wait for.
+ *
+ * If the folio is currently being written back to storage, wait for the
+ * I/O to complete.
+ *
+ * Context: Sleeps.  Must be called in process context and with
+ * no spinlocks held.  Caller should hold a reference on the folio.
+ * If the folio is not locked, writeback may start again after writeback
+ * has finished.
  */
-void wait_on_page_writeback(struct page *page)
+void folio_wait_writeback(struct folio *folio)
 {
-	while (PageWriteback(page)) {
-		trace_wait_on_page_writeback(page, page_mapping(page));
-		wait_on_page_bit(page, PG_writeback);
+	while (folio_test_writeback(folio)) {
+		trace_wait_on_page_writeback(&folio->page, folio_mapping(folio));
+		wait_on_page_bit(&folio->page, PG_writeback);
 	}
 }
-EXPORT_SYMBOL_GPL(wait_on_page_writeback);
+EXPORT_SYMBOL_GPL(folio_wait_writeback);
 
-/*
- * Wait for a page to complete writeback.  Returns -EINTR if we get a
- * fatal signal while waiting.
+/**
+ * folio_wait_writeback_killable - Wait for a folio to finish writeback.
+ * @folio: The folio to wait for.
+ *
+ * If the folio is currently being written back to storage, wait for the
+ * I/O to complete or a fatal signal to arrive.
+ *
+ * Context: Sleeps.  Must be called in process context and with
+ * no spinlocks held.  Caller should hold a reference on the folio.
+ * If the folio is not locked, writeback may start again after writeback
+ * has finished.
+ * Return: 0 on success, -EINTR if we get a fatal signal while waiting.
  */
-int wait_on_page_writeback_killable(struct page *page)
+int folio_wait_writeback_killable(struct folio *folio)
 {
-	while (PageWriteback(page)) {
-		trace_wait_on_page_writeback(page, page_mapping(page));
-		if (wait_on_page_bit_killable(page, PG_writeback))
+	while (folio_test_writeback(folio)) {
+		trace_wait_on_page_writeback(&folio->page, folio_mapping(folio));
+		if (wait_on_page_bit_killable(&folio->page, PG_writeback))
 			return -EINTR;
 	}
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(wait_on_page_writeback_killable);
+EXPORT_SYMBOL_GPL(folio_wait_writeback_killable);
 
 /**
  * wait_for_stable_page() - wait for writeback to finish, if necessary.