[PATCH v2 13/23] xfs: add iomap's readpage operations

[Andrey Albershteyn]

The read IO path provides callout for configuring ioend. This allows
filesystem to add verification of completed BIOs. 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 add 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 at redhat.com>
---
 fs/xfs/xfs_aops.c  | 45 +++++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/xfs_iomap.c | 11 +++++++++++
 fs/xfs/xfs_linux.h |  1 +
 3 files changed, 57 insertions(+)

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index daa0dd4768fb..2a3ab5afd665 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -548,6 +548,49 @@ 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 void
+xfs_prepare_read_ioend(
+	struct iomap_read_ioend	*ioend)
+{
+	if (!fsverity_active(ioend->io_inode))
+		return;
+
+	INIT_WORK(&ioend->work, &xfs_read_work_end_io);
+	ioend->read_inline_bio.bi_end_io = &xfs_read_end_io;
+}
+
+static const struct iomap_readpage_ops xfs_readpage_ops = {
+	.prepare_ioend		= &xfs_prepare_read_ioend,
+};
+
 STATIC int
 xfs_vm_read_folio(
 	struct file			*unused,
@@ -555,6 +598,7 @@ xfs_vm_read_folio(
 {
 	struct iomap_readpage_ctx	ctx = {
 		.cur_folio		= folio,
+		.ops			= &xfs_readpage_ops,
 	};
 
 	return iomap_read_folio(&ctx, &xfs_read_iomap_ops);
@@ -566,6 +610,7 @@ xfs_vm_readahead(
 {
 	struct iomap_readpage_ctx	ctx = {
 		.rac			= rac,
+		.ops			= &xfs_readpage_ops,
 	};
 
 	iomap_readahead(&ctx, &xfs_read_iomap_ops);
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 285885c308bd..e0f3c5d709f6 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -27,6 +27,7 @@
 #include "xfs_dquot_item.h"
 #include "xfs_dquot.h"
 #include "xfs_reflink.h"
+#include "xfs_verity.h"
 
 #define XFS_ALLOC_ALIGN(mp, off) \
 	(((off) >> mp->m_allocsize_log) << mp->m_allocsize_log)
@@ -83,8 +84,18 @@ xfs_iomap_valid(
 	return true;
 }
 
+static bool
+xfs_verify_folio(
+	struct folio	*folio,
+	loff_t		pos,
+	unsigned int	len)
+{
+	return fsverity_verify_folio(folio, len, pos);
+}
+
 static const struct iomap_folio_ops xfs_iomap_folio_ops = {
 	.iomap_valid		= xfs_iomap_valid,
+	.verify_folio		= xfs_verify_folio,
 };
 
 int
diff --git a/fs/xfs/xfs_linux.h b/fs/xfs/xfs_linux.h
index e88f18f85e4b..c574fbf4b67d 100644
--- a/fs/xfs/xfs_linux.h
+++ b/fs/xfs/xfs_linux.h
@@ -63,6 +63,7 @@ typedef __u32			xfs_nlink_t;
 #include <linux/rhashtable.h>
 #include <linux/xattr.h>
 #include <linux/mnt_idmapping.h>
+#include <linux/fsverity.h>
 
 #include <asm/page.h>
 #include <asm/div64.h>
-- 
2.38.4