[PATCH 1/7] shmem: provide a shmem_write_folio wrapper

[Christoph Hellwig <hch@lst.de>]

Provide a wrapper for the shmem abuses in drm to prepare for swap I/O
refactoring by keeping swap_iocb handling entirely contained in mm/.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Baoquan He <baoquan.he@linux.dev>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Chris Li <chrisl@kernel.org>
---
 drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 2 +-
 drivers/gpu/drm/ttm/ttm_backup.c          | 2 +-
 include/linux/shmem_fs.h                  | 5 +----
 mm/shmem.c                                | 7 ++++++-
 mm/swap.h                                 | 4 ++++
 5 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
index 06543ae60706..ef9440166295 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
@@ -325,7 +325,7 @@ void __shmem_writeback(size_t size, struct address_space *mapping)
 		if (folio_mapped(folio))
 			folio_redirty_for_writepage(&wbc, folio);
 		else
-			error = shmem_writeout(folio, NULL, NULL);
+			error = shmem_write_folio(folio);
 	}
 }
 
diff --git a/drivers/gpu/drm/ttm/ttm_backup.c b/drivers/gpu/drm/ttm/ttm_backup.c
index 81df4cb5606b..c5b813a563e7 100644
--- a/drivers/gpu/drm/ttm/ttm_backup.c
+++ b/drivers/gpu/drm/ttm/ttm_backup.c
@@ -117,7 +117,7 @@ ttm_backup_backup_page(struct file *backup, struct page *page,
 	if (writeback && !folio_mapped(to_folio) &&
 	    folio_clear_dirty_for_io(to_folio)) {
 		folio_set_reclaim(to_folio);
-		ret = shmem_writeout(to_folio, NULL, NULL);
+		ret = shmem_write_folio(to_folio);
 		if (!folio_test_writeback(to_folio))
 			folio_clear_reclaim(to_folio);
 		/*
diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index e729b9b0e38d..5663dff53186 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -12,8 +12,6 @@
 #include <linux/userfaultfd_k.h>
 #include <linux/bits.h>
 
-struct swap_iocb;
-
 /* inode in-kernel data */
 
 #ifdef CONFIG_TMPFS_QUOTA
@@ -123,8 +121,7 @@ static inline bool shmem_mapping(const struct address_space *mapping)
 void shmem_unlock_mapping(struct address_space *mapping);
 struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
 					pgoff_t index, gfp_t gfp_mask);
-int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
-		struct list_head *folio_list);
+int shmem_write_folio(struct folio *folio);
 void shmem_truncate_range(struct inode *inode, loff_t start, uoff_t end);
 int shmem_unuse(unsigned int type);
 
diff --git a/mm/shmem.c b/mm/shmem.c
index b51f83c970bb..6011a7f729ae 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1736,7 +1736,12 @@ int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
 	folio_mark_dirty(folio);
 	return AOP_WRITEPAGE_ACTIVATE;	/* Return with folio locked */
 }
-EXPORT_SYMBOL_GPL(shmem_writeout);
+
+int shmem_write_folio(struct folio *folio)
+{
+	return shmem_writeout(folio, NULL, NULL);
+}
+EXPORT_SYMBOL_GPL(shmem_write_folio);
 
 #if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS)
 static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
diff --git a/mm/swap.h b/mm/swap.h
index 77d2d14eda42..4f86ef338a60 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -473,4 +473,8 @@ static inline unsigned int folio_swap_flags(struct folio *folio)
 }
 
 #endif /* CONFIG_SWAP */
+
+int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
+		struct list_head *folio_list);
+
 #endif /* _MM_SWAP_H */
-- 
2.53.0