[PATCH RFC 21/29] xfs: add writeback and iomap reading of Merkel tree pages

[Andrey Albershteyn <aalbersh@redhat.com>]

In the writeback path use unbound write interface, meaning that inode
size is not updated and none of the file size checks are applied.

In read path let iomap know that data is stored beyond EOF via flag.
This leads to skipping of post EOF zeroing.

Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
---
 fs/xfs/xfs_aops.c  | 21 ++++++++++++++-------
 fs/xfs/xfs_iomap.c |  9 +++++++--
 2 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 63151feb9c3f..02e2c04b36c1 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -22,6 +22,7 @@
 #include "xfs_icache.h"
 #include "xfs_zone_alloc.h"
 #include "xfs_rtgroup.h"
+#include "xfs_fsverity.h"
 
 struct xfs_writepage_ctx {
 	struct iomap_writepage_ctx ctx;
@@ -628,10 +629,12 @@ static const struct iomap_writeback_ops xfs_zoned_writeback_ops = {
 
 STATIC int
 xfs_vm_writepages(
-	struct address_space	*mapping,
-	struct writeback_control *wbc)
+	struct address_space		*mapping,
+	struct writeback_control	*wbc)
 {
-	struct xfs_inode	*ip = XFS_I(mapping->host);
+	struct xfs_inode		*ip = XFS_I(mapping->host);
+	struct xfs_writepage_ctx	wpc = { };
+
 
 	xfs_iflags_clear(ip, XFS_ITRUNCATED);
 
@@ -644,12 +647,16 @@ xfs_vm_writepages(
 		if (xc.open_zone)
 			xfs_open_zone_put(xc.open_zone);
 		return error;
-	} else {
-		struct xfs_writepage_ctx	wpc = { };
+	}
 
-		return iomap_writepages(mapping, wbc, &wpc.ctx,
-				&xfs_writeback_ops);
+	if (xfs_iflags_test(ip, XFS_VERITY_CONSTRUCTION)) {
+		wbc->range_start = XFS_FSVERITY_MTREE_OFFSET;
+		wbc->range_end = LLONG_MAX;
+		return iomap_writepages_unbound(mapping, wbc, &wpc.ctx,
+						&xfs_writeback_ops);
 	}
+
+	return iomap_writepages(mapping, wbc, &wpc.ctx, &xfs_writeback_ops);
 }
 
 STATIC int
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 00ec1a738b39..c8725508165c 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -2031,6 +2031,7 @@ xfs_read_iomap_begin(
 	bool			shared = false;
 	unsigned int		lockmode = XFS_ILOCK_SHARED;
 	u64			seq;
+	int			iomap_flags;
 
 	ASSERT(!(flags & (IOMAP_WRITE | IOMAP_ZERO)));
 
@@ -2050,8 +2051,12 @@ xfs_read_iomap_begin(
 	if (error)
 		return error;
 	trace_xfs_iomap_found(ip, offset, length, XFS_DATA_FORK, &imap);
-	return xfs_bmbt_to_iomap(ip, iomap, &imap, flags,
-				 shared ? IOMAP_F_SHARED : 0, seq);
+	iomap_flags = shared ? IOMAP_F_SHARED : 0;
+
+	if (fsverity_active(inode) && offset >= XFS_FSVERITY_MTREE_OFFSET)
+		iomap_flags |= IOMAP_F_BEYOND_EOF;
+
+	return xfs_bmbt_to_iomap(ip, iomap, &imap, flags, iomap_flags, seq);
 }
 
 const struct iomap_ops xfs_read_iomap_ops = {

-- 
2.50.0