[RFC PATCH 16/18] ext4: impliment mmap iomap path

[Zhang Yi <yi.zhang@xxxxxxxxxxxxxxx>]

From: Zhang Yi <yi.zhang@xxxxxxxxxx>

Impliment mmap iomap path, direct use iomap_page_mkwrite() for the
.page_mkwrite() callback.

Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx>
---
 fs/ext4/ext4.h  |  1 +
 fs/ext4/file.c  |  6 ++++++
 fs/ext4/inode.c | 24 ++++++++++++++++++++++++
 3 files changed, 31 insertions(+)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 65373d53ba6a..6b3e34ea58ad 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3006,6 +3006,7 @@ extern int ext4_chunk_trans_blocks(struct inode *, int nrblocks);
 extern int ext4_zero_partial_blocks(handle_t *handle, struct inode *inode,
 			     loff_t lstart, loff_t lend);
 extern vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf);
+extern vm_fault_t ext4_iomap_page_mkwrite(struct vm_fault *vmf);
 extern qsize_t *ext4_get_reserved_space(struct inode *inode);
 extern int ext4_get_projid(struct inode *inode, kprojid_t *projid);
 extern void ext4_da_release_space(struct inode *inode, int to_free);
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 6830ea3a6c59..15fe65744cba 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -798,6 +798,12 @@ static const struct vm_operations_struct ext4_file_vm_ops = {
 	.page_mkwrite   = ext4_page_mkwrite,
 };
 
+static const struct vm_operations_struct ext4_iomap_file_vm_ops = {
+	.fault		= filemap_fault,
+	.map_pages	= filemap_map_pages,
+	.page_mkwrite   = ext4_iomap_page_mkwrite,
+};
+
 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	struct inode *inode = file->f_mapping->host;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index ca66afd61fb3..2efa898403f7 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3748,6 +3748,10 @@ const struct iomap_ops ext4_iomap_read_ops = {
 	.iomap_begin = ext4_iomap_buffered_io_begin,
 };
 
+const struct iomap_ops ext4_iomap_page_mkwrite_ops = {
+	.iomap_begin = ext4_iomap_buffered_io_begin,
+};
+
 static int ext4_iomap_read_folio(struct file *file, struct folio *folio)
 {
 	return iomap_read_folio(folio, &ext4_iomap_read_ops);
@@ -6698,3 +6702,23 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)
 	ext4_journal_stop(handle);
 	goto out;
 }
+
+vm_fault_t ext4_iomap_page_mkwrite(struct vm_fault *vmf)
+{
+	struct inode *inode = file_inode(vmf->vma->vm_file);
+	struct address_space *mapping = inode->i_mapping;
+	vm_fault_t ret;
+
+	if (unlikely(IS_IMMUTABLE(inode)))
+		return VM_FAULT_SIGBUS;
+
+	sb_start_pagefault(inode->i_sb);
+	file_update_time(vmf->vma->vm_file);
+
+	filemap_invalidate_lock_shared(mapping);
+	ret = iomap_page_mkwrite(vmf, &ext4_iomap_page_mkwrite_ops);
+	filemap_invalidate_unlock_shared(mapping);
+
+	sb_end_pagefault(inode->i_sb);
+	return ret;
+}
-- 
2.39.2