This replaces ->set_page_dirty(). It returns a bool instead of an int
and takes the address_space as a parameter instead of expecting the
implementations to retrieve the address_space from the page. This is
particularly important for filesystems which use FS_OPS for swap.
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
Documentation/filesystems/locking.rst | 15 ++++++++-------
Documentation/filesystems/vfs.rst | 16 ++++++++--------
include/linux/fs.h | 1 +
mm/page-writeback.c | 17 ++++++++++-------
mm/page_io.c | 5 ++++-
5 files changed, 31 insertions(+), 23 deletions(-)
diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst
index dee512efb458..72fa12dabd39 100644
--- a/Documentation/filesystems/locking.rst
+++ b/Documentation/filesystems/locking.rst
@@ -239,7 +239,7 @@ prototypes::
int (*writepage)(struct page *page, struct writeback_control *wbc);
int (*readpage)(struct file *, struct page *);
int (*writepages)(struct address_space *, struct writeback_control *);
- int (*set_page_dirty)(struct page *page);
+ bool (*dirty_folio)(struct address_space *, struct folio *folio);
void (*readahead)(struct readahead_control *);
int (*readpages)(struct file *filp, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages);
@@ -264,7 +264,7 @@ prototypes::
int (*swap_deactivate)(struct file *);
locking rules:
- All except set_page_dirty and freepage may block
+ All except dirty_folio and freepage may block
====================== ======================== ========= ===============
ops PageLocked(page) i_rwsem invalidate_lock
@@ -272,7 +272,7 @@ ops PageLocked(page) i_rwsem invalidate_lock
writepage: yes, unlocks (see below)
readpage: yes, unlocks shared
writepages:
-set_page_dirty no
+dirty_folio maybe
readahead: yes, unlocks shared
readpages: no shared
write_begin: locks the page exclusive
@@ -361,10 +361,11 @@ If nr_to_write is NULL, all dirty pages must be written.
writepages should _only_ write pages which are present on
mapping->io_pages.
-->set_page_dirty() is called from various places in the kernel
-when the target page is marked as needing writeback. It may be called
-under spinlock (it cannot block) and is sometimes called with the page
-not locked.
+->dirty_folio() is called from various places in the kernel when
+the target folio is marked as needing writeback. The folio cannot be
+truncated because either the caller holds the folio lock, or the caller
+has found the folio while holding the page table lock which will block
+truncation.
->bmap() is currently used by legacy ioctl() (FIBMAP) provided by some
filesystems and by the swapper. The latter will eventually go away. Please,
diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst
index c54ca4d88ed6..d16bee420326 100644
--- a/Documentation/filesystems/vfs.rst
+++ b/Documentation/filesystems/vfs.rst
@@ -658,7 +658,7 @@ pages, however the address_space has finer control of write sizes.
The read process essentially only requires 'readpage'. The write
process is more complicated and uses write_begin/write_end or
-set_page_dirty to write data into the address_space, and writepage and
+dirty_folio to write data into the address_space, and writepage and
writepages to writeback data to storage.
Adding and removing pages to/from an address_space is protected by the
@@ -724,7 +724,7 @@ cache in your filesystem. The following members are defined:
int (*writepage)(struct page *page, struct writeback_control *wbc);
int (*readpage)(struct file *, struct page *);
int (*writepages)(struct address_space *, struct writeback_control *);
- int (*set_page_dirty)(struct page *page);
+ bool (*dirty_folio)(struct address_space *, struct folio *);
void (*readahead)(struct readahead_control *);
int (*readpages)(struct file *filp, struct address_space *mapping,
struct list_head *pages, unsigned nr_pages);
@@ -793,13 +793,13 @@ cache in your filesystem. The following members are defined:
This will choose pages from the address space that are tagged as
DIRTY and will pass them to ->writepage.
-``set_page_dirty``
- called by the VM to set a page dirty. This is particularly
- needed if an address space attaches private data to a page, and
- that data needs to be updated when a page is dirtied. This is
+``dirty_folio``
+ called by the VM to mark a folio as dirty. This is particularly
+ needed if an address space attaches private data to a folio, and
+ that data needs to be updated when a folio is dirtied. This is
called, for example, when a memory mapped page gets modified.
- If defined, it should set the PageDirty flag, and the
- PAGECACHE_TAG_DIRTY tag in the radix tree.
+ If defined, it should set the folio dirty flag, and the
+ PAGECACHE_TAG_DIRTY search mark in i_pages.
``readahead``
Called by the VM to read pages associated with the address_space
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 055be40084f1..c3d5db8851ae 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -369,6 +369,7 @@ struct address_space_operations {
/* Set a page dirty. Return true if this dirtied it */
int (*set_page_dirty)(struct page *page);
+ bool (*dirty_folio)(struct address_space *, struct folio *);
/*
* Reads in the requested pages. Unlike ->readpage(), this is
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 91d163f8d36b..27a87ae4502c 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2616,7 +2616,7 @@ EXPORT_SYMBOL(folio_redirty_for_writepage);
* folio_mark_dirty - Mark a folio as being modified.
* @folio: The folio.
*
- * For folios with a mapping this should be done under the page lock
+ * For folios with a mapping this should be done with the folio lock held
* for the benefit of asynchronous memory errors who prefer a consistent
* dirty state. This rule can be broken in some special cases,
* but should be better not to.
@@ -2630,16 +2630,19 @@ bool folio_mark_dirty(struct folio *folio)
if (likely(mapping)) {
/*
* readahead/lru_deactivate_page could remain
- * PG_readahead/PG_reclaim due to race with end_page_writeback
- * About readahead, if the page is written, the flags would be
+ * PG_readahead/PG_reclaim due to race with folio_end_writeback
+ * About readahead, if the folio is written, the flags would be
* reset. So no problem.
- * About lru_deactivate_page, if the page is redirty, the flag
- * will be reset. So no problem. but if the page is used by readahead
- * it will confuse readahead and make it restart the size rampup
- * process. But it's a trivial problem.
+ * About lru_deactivate_page, if the folio is redirtied,
+ * the flag will be reset. So no problem. but if the
+ * folio is used by readahead it will confuse readahead
+ * and make it restart the size rampup process. But it's
+ * a trivial problem.
*/
if (folio_test_reclaim(folio))
folio_clear_reclaim(folio);
+ if (mapping->a_ops->dirty_folio)
+ return mapping->a_ops->dirty_folio(mapping, folio);
return mapping->a_ops->set_page_dirty(&folio->page);
}
if (!folio_test_dirty(folio)) {
diff --git a/mm/page_io.c b/mm/page_io.c
index 0bf8e40f4e57..24c975fb4e21 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -444,9 +444,12 @@ int swap_set_page_dirty(struct page *page)
if (data_race(sis->flags & SWP_FS_OPS)) {
struct address_space *mapping = sis->swap_file->f_mapping;
+ const struct address_space_operations *aops = mapping->a_ops;
VM_BUG_ON_PAGE(!PageSwapCache(page), page);
- return mapping->a_ops->set_page_dirty(page);
+ if (aops->dirty_folio)
+ return aops->dirty_folio(mapping, page_folio(page));
+ return aops->set_page_dirty(page);
} else {
return __set_page_dirty_no_writeback(page);
}
--
2.34.1
