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fs: Add aops->migrate_folio

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Provide a folio-based replacement for aops->migratepage.  Update the
documentation to document migrate_folio instead of migratepage.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Matthew Wilcox (Oracle) 2022-06-06 09:00:16 -04:00
parent 68f2736a85
commit 5490da4f06
5 changed files with 23 additions and 15 deletions
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5
Documentation/filesystems/locking.rst
View File

@ -252,7 +252,8 @@ prototypes::
bool (*release_folio)(struct folio *, gfp_t);
void (*free_folio)(struct folio *);
int (*direct_IO)(struct kiocb *, struct iov_iter *iter);
int (*migratepage)(struct address_space *, struct page *, struct page *);
int (*migrate_folio)(struct address_space *, struct folio *dst,
struct folio *src, enum migrate_mode);
int (*launder_folio)(struct folio *);
bool (*is_partially_uptodate)(struct folio *, size_t from, size_t count);
int (*error_remove_page)(struct address_space *, struct page *);
@ -278,7 +279,7 @@ invalidate_folio: yes exclusive
release_folio: yes
free_folio: yes
direct_IO:
migratepage: yes (both)
migrate_folio: yes (both)
launder_folio: yes
is_partially_uptodate: yes
error_remove_page: yes

14
Documentation/filesystems/vfs.rst
View File

@ -737,8 +737,8 @@ cache in your filesystem. The following members are defined:
bool (*release_folio)(struct folio *, gfp_t);
void (*free_folio)(struct folio *);
ssize_t (*direct_IO)(struct kiocb *, struct iov_iter *iter);
/* migrate the contents of a page to the specified target */
int (*migratepage) (struct page *, struct page *);
int (*migrate_folio)(struct mapping *, struct folio *dst,
struct folio *src, enum migrate_mode);
int (*launder_folio) (struct folio *);
bool (*is_partially_uptodate) (struct folio *, size_t from,
@ -926,12 +926,12 @@ cache in your filesystem. The following members are defined:
data directly between the storage and the application's address
space.
``migrate_page``
``migrate_folio``
This is used to compact the physical memory usage. If the VM
wants to relocate a page (maybe off a memory card that is
signalling imminent failure) it will pass a new page and an old
page to this function. migrate_page should transfer any private
data across and update any references that it has to the page.
wants to relocate a folio (maybe from a memory device that is
signalling imminent failure) it will pass a new folio and an old
folio to this function. migrate_folio should transfer any private
data across and update any references that it has to the folio.
``launder_folio``
Called before freeing a folio - it writes back the dirty folio.

4
include/linux/fs.h
View File

@ -362,9 +362,11 @@ struct address_space_operations {
void (*free_folio)(struct folio *folio);
ssize_t (*direct_IO)(struct kiocb *, struct iov_iter *iter);
/*
* migrate the contents of a page to the specified target. If
* migrate the contents of a folio to the specified target. If
* migrate_mode is MIGRATE_ASYNC, it must not block.
*/
int (*migrate_folio)(struct address_space *, struct folio *dst,
struct folio *src, enum migrate_mode);
int (*migratepage) (struct address_space *,
struct page *, struct page *, enum migrate_mode);
int (*launder_folio)(struct folio *);

4
mm/compaction.c
View File

@ -1042,7 +1042,9 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
goto isolate_fail_put;
mapping = page_mapping(page);
migrate_dirty = !mapping || mapping->a_ops->migratepage;
migrate_dirty = !mapping ||
mapping->a_ops->migrate_folio ||
mapping->a_ops->migratepage;
unlock_page(page);
if (!migrate_dirty)
goto isolate_fail_put;

11
mm/migrate.c
View File

@ -856,14 +856,17 @@ static int move_to_new_folio(struct folio *dst, struct folio *src,
if (!mapping)
rc = migrate_page(mapping, &dst->page, &src->page, mode);
else if (mapping->a_ops->migratepage)
else if (mapping->a_ops->migrate_folio)
/*
* Most pages have a mapping and most filesystems
* provide a migratepage callback. Anonymous pages
* Most folios have a mapping and most filesystems
* provide a migrate_folio callback. Anonymous folios
* are part of swap space which also has its own
* migratepage callback. This is the most common path
* migrate_folio callback. This is the most common path
* for page migration.
*/
rc = mapping->a_ops->migrate_folio(mapping, dst, src,
mode);
else if (mapping->a_ops->migratepage)
rc = mapping->a_ops->migratepage(mapping, &dst->page,
&src->page, mode);
else