The writepage callback is going away; filesystems must implement
migrate_folio or else dirty folios will not be migratable.
Signed-off-by: Matthew Wilcox (Oracle) <wi...@infradead.org>
---
mm/migrate.c | 60 ++++++----------------------------------------------
1 file changed, 7 insertions(+), 53 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index f3ee6d8d5e2e..6e2488e5dbe4 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -944,67 +944,21 @@ int filemap_migrate_folio(struct address_space *mapping,
}
EXPORT_SYMBOL_GPL(filemap_migrate_folio);
-/*
- * Writeback a folio to clean the dirty state
- */
-static int writeout(struct address_space *mapping, struct folio *folio)
-{
- struct writeback_control wbc = {
- .sync_mode = WB_SYNC_NONE,
- .nr_to_write = 1,
- .range_start = 0,
- .range_end = LLONG_MAX,
- .for_reclaim = 1
- };
- int rc;
-
- if (!mapping->a_ops->writepage)
- /* No write method for the address space */
- return -EINVAL;
-
- if (!folio_clear_dirty_for_io(folio))
- /* Someone else already triggered a write */
- return -EAGAIN;
-
- /*
- * A dirty folio may imply that the underlying filesystem has
- * the folio on some queue. So the folio must be clean for
- * migration. Writeout may mean we lose the lock and the
- * folio state is no longer what we checked for earlier.
- * At this point we know that the migration attempt cannot
- * be successful.
- */
- remove_migration_ptes(folio, folio, 0);
-
- rc = mapping->a_ops->writepage(&folio->page, &wbc);
-
- if (rc != AOP_WRITEPAGE_ACTIVATE)
- /* unlocked. Relock */
- folio_lock(folio);
-
- return (rc < 0) ? -EIO : -EAGAIN;
-}
-
/*
* Default handling if a filesystem does not provide a migration function.
*/
static int fallback_migrate_folio(struct address_space *mapping,
struct folio *dst, struct folio *src, enum migrate_mode mode)
{
- if (folio_test_dirty(src)) {
- /* Only writeback folios in full synchronous migration */
- switch (mode) {
- case MIGRATE_SYNC:
- break;
- default:
- return -EBUSY;
- }
- return writeout(mapping, src);
- }
+ WARN_ONCE(mapping->a_ops->writepages,
+ "%ps does not implement migrate_folio\n",
+ mapping->a_ops);
+ if (folio_test_dirty(src))
+ return -EBUSY;
/*
- * Buffers may be managed in a filesystem specific way.
- * We must have no buffers or drop them.
+ * Filesystem may have private data at folio->private that we
+ * can't migrate automatically.
*/
if (!filemap_release_folio(src, GFP_KERNEL))
return mode == MIGRATE_SYNC ? -EAGAIN : -EBUSY;
--
2.47.2
