[PATCH 4/7] fs: Add filemap_symlink()

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

This is the equivalent of page_symlink() but takes a
buffered_write_operations structure.  It also doesn't handle GFP_NOFS
for you; if you need that, use memalloc_nofs_save() yourself.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 fs/namei.c              | 25 +++++++++++++++++++++++++
 include/linux/pagemap.h |  2 ++
 2 files changed, 27 insertions(+)

diff --git a/fs/namei.c b/fs/namei.c
index 37fb0a8aa09a..4352206b0408 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -5255,6 +5255,31 @@ int page_symlink(struct inode *inode, const char *symname, int len)
 }
 EXPORT_SYMBOL(page_symlink);
 
+int filemap_symlink(struct inode *inode, const char *symname, int len,
+		const struct buffered_write_operations *ops, void **fsdata)
+{
+	struct address_space *mapping = inode->i_mapping;
+	struct folio *folio;
+	int err;
+
+retry:
+	folio = ops->write_begin(NULL, mapping, 0, len-1, fsdata);
+	if (IS_ERR(folio))
+		return PTR_ERR(folio);
+
+	memcpy(folio_address(folio), symname, len-1);
+
+	err = ops->write_end(NULL, mapping, 0, len-1, len-1, folio, fsdata);
+	if (err < 0)
+		return err;
+	if (err < len-1)
+		goto retry;
+
+	mark_inode_dirty(inode);
+	return 0;
+}
+EXPORT_SYMBOL(filemap_symlink);
+
 const struct inode_operations page_symlink_inode_operations = {
 	.get_link	= page_get_link,
 };
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 2921c1cc6335..a7540f757368 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -39,6 +39,8 @@ ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);
 #define __generic_file_write_iter(kiocb, iter)		\
 	__filemap_write_iter(kiocb, iter, NULL, NULL)
 
+int filemap_symlink(struct inode *inode, const char *symname, int len,
+		const struct buffered_write_operations *bw, void **fsdata);
 unsigned long invalidate_mapping_pages(struct address_space *mapping,
 					pgoff_t start, pgoff_t end);
 
-- 
2.43.0