[PATCH v3 16/28] xfs: add bio_set and submit_io for ioend post-processing

[Andrey Albershteyn <aalbersh@redhat.com>]

The read IO path provides callout for configuring ioend. This allows
filesystem to add verification of completed BIOs. One of such tasks
is verification against fs-verity tree when pages were read. iomap
allows using custom bio_set with submit_bio() to add ioend
processing. The xfs_prepare_read_ioend() configures bio->bi_end_io
which places verification task in the workqueue. The task does
fs-verity verification and then call back to the iomap to finish IO.

This patch adds callouts implementation to verify pages with
fs-verity. Also implements folio operation .verify_folio for direct
folio verification by fs-verity.

Signed-off-by: Andrey Albershteyn <aalbersh@redhat.com>
---
 fs/xfs/xfs_aops.c  | 84 ++++++++++++++++++++++++++++++++++++++++++++--
 fs/xfs/xfs_aops.h  |  2 ++
 fs/xfs/xfs_linux.h |  1 +
 fs/xfs/xfs_super.c |  9 ++++-
 4 files changed, 93 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index b413a2dbcc18..fceb0c3de61f 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -26,6 +26,8 @@ struct xfs_writepage_ctx {
 	unsigned int		cow_seq;
 };
 
+static struct bio_set xfs_read_ioend_bioset;
+
 static inline struct xfs_writepage_ctx *
 XFS_WPC(struct iomap_writepage_ctx *ctx)
 {
@@ -548,19 +550,97 @@ xfs_vm_bmap(
 	return iomap_bmap(mapping, block, &xfs_read_iomap_ops);
 }
 
+static void
+xfs_read_work_end_io(
+	struct work_struct *work)
+{
+	struct iomap_read_ioend *ioend =
+		container_of(work, struct iomap_read_ioend, work);
+	struct bio *bio = &ioend->read_inline_bio;
+
+	fsverity_verify_bio(bio);
+	iomap_read_end_io(bio);
+	/*
+	 * The iomap_read_ioend has been freed by bio_put() in
+	 * iomap_read_end_io()
+	 */
+}
+
+static void
+xfs_read_end_io(
+	struct bio *bio)
+{
+	struct iomap_read_ioend *ioend =
+		container_of(bio, struct iomap_read_ioend, read_inline_bio);
+	struct xfs_inode	*ip = XFS_I(ioend->io_inode);
+
+	WARN_ON_ONCE(!queue_work(ip->i_mount->m_postread_workqueue,
+					&ioend->work));
+}
+
+static int
+xfs_verify_folio(
+	struct folio	*folio,
+	loff_t		pos,
+	unsigned int	len)
+{
+	if (fsverity_verify_blocks(folio, len, pos))
+		return 0;
+	return -EFSCORRUPTED;
+}
+
+int
+xfs_init_iomap_bioset(void)
+{
+	return bioset_init(&xfs_read_ioend_bioset,
+			   4 * (PAGE_SIZE / SECTOR_SIZE),
+			   offsetof(struct iomap_read_ioend, read_inline_bio),
+			   BIOSET_NEED_BVECS);
+}
+
+void
+xfs_free_iomap_bioset(void)
+{
+	bioset_exit(&xfs_read_ioend_bioset);
+}
+
+static void
+xfs_submit_read_bio(
+	const struct iomap_iter *iter,
+	struct bio *bio,
+	loff_t file_offset)
+{
+	struct iomap_read_ioend *ioend;
+
+	ioend = container_of(bio, struct iomap_read_ioend, read_inline_bio);
+	ioend->io_inode = iter->inode;
+	if (fsverity_active(ioend->io_inode)) {
+		INIT_WORK(&ioend->work, &xfs_read_work_end_io);
+		ioend->read_inline_bio.bi_end_io = &xfs_read_end_io;
+	}
+
+	submit_bio(bio);
+}
+
+static const struct iomap_readpage_ops xfs_readpage_ops = {
+	.verify_folio		= &xfs_verify_folio,
+	.submit_io		= &xfs_submit_read_bio,
+	.bio_set		= &xfs_read_ioend_bioset,
+};
+
 STATIC int
 xfs_vm_read_folio(
 	struct file		*unused,
 	struct folio		*folio)
 {
-	return iomap_read_folio(folio, &xfs_read_iomap_ops, NULL);
+	return iomap_read_folio(folio, &xfs_read_iomap_ops, &xfs_readpage_ops);
 }
 
 STATIC void
 xfs_vm_readahead(
 	struct readahead_control	*rac)
 {
-	iomap_readahead(rac, &xfs_read_iomap_ops, NULL);
+	iomap_readahead(rac, &xfs_read_iomap_ops, &xfs_readpage_ops);
 }
 
 static int
diff --git a/fs/xfs/xfs_aops.h b/fs/xfs/xfs_aops.h
index e0bd68419764..fa7c512b2717 100644
--- a/fs/xfs/xfs_aops.h
+++ b/fs/xfs/xfs_aops.h
@@ -10,5 +10,7 @@ extern const struct address_space_operations xfs_address_space_operations;
 extern const struct address_space_operations xfs_dax_aops;
 
 int	xfs_setfilesize(struct xfs_inode *ip, xfs_off_t offset, size_t size);
+int	xfs_init_iomap_bioset(void);
+void	xfs_free_iomap_bioset(void);
 
 #endif /* __XFS_AOPS_H__ */
diff --git a/fs/xfs/xfs_linux.h b/fs/xfs/xfs_linux.h
index e9d317a3dafe..ee213c6dfcaf 100644
--- a/fs/xfs/xfs_linux.h
+++ b/fs/xfs/xfs_linux.h
@@ -64,6 +64,7 @@ typedef __u32			xfs_nlink_t;
 #include <linux/xattr.h>
 #include <linux/mnt_idmapping.h>
 #include <linux/debugfs.h>
+#include <linux/fsverity.h>
 
 #include <asm/page.h>
 #include <asm/div64.h>
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 5e1ec5978176..3cdb642961f4 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -2375,11 +2375,17 @@ init_xfs_fs(void)
 	if (error)
 		goto out_remove_dbg_kobj;
 
-	error = register_filesystem(&xfs_fs_type);
+	error = xfs_init_iomap_bioset();
 	if (error)
 		goto out_qm_exit;
+
+	error = register_filesystem(&xfs_fs_type);
+	if (error)
+		goto out_iomap_bioset;
 	return 0;
 
+ out_iomap_bioset:
+	xfs_free_iomap_bioset();
  out_qm_exit:
 	xfs_qm_exit();
  out_remove_dbg_kobj:
@@ -2412,6 +2418,7 @@ init_xfs_fs(void)
 STATIC void __exit
 exit_xfs_fs(void)
 {
+	xfs_free_iomap_bioset();
 	xfs_qm_exit();
 	unregister_filesystem(&xfs_fs_type);
 #ifdef DEBUG
-- 
2.40.1