[PATCH] btrfs-progs: zoned: open host-managed devices with O_DIRECT for read-only

On host-managed zoned devices the page cache is not coherent with the
on-disk contents, so all IO must use O_DIRECT. Both device-open paths only
added O_DIRECT for O_RDWR opens, so read-only tools like "btrfs check" used
buffered IO and could read stale zero pages for one mirror of duplicated
metadata, reporting a spurious

	checksum verify failed on <bytenr> wanted 0x00000000 found 0xb6bde3e4

even though both copies are intact on disk.

Drop the O_RDWR condition so host-managed zoned devices always use
O_DIRECT, matching btrfstune.

Signed-off-by: Johannes Thumshirn <[email protected]>
---
 kernel-shared/disk-io.c | 2 +-
 kernel-shared/volumes.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel-shared/disk-io.c b/kernel-shared/disk-io.c
index 7f87e567..8b9c6dca 100644
--- a/kernel-shared/disk-io.c
+++ b/kernel-shared/disk-io.c
@@ -1722,7 +1722,7 @@ struct btrfs_fs_info *open_ctree_fs_info(struct open_ctree_args *oca)
 	if (!(oca->flags & OPEN_CTREE_WRITES))
 		oflags = O_RDONLY;
 
-	if ((oflags & O_RDWR) && zoned_model(oca->filename) == ZONED_HOST_MANAGED)
+	if (zoned_model(oca->filename) == ZONED_HOST_MANAGED)
 		oflags |= O_DIRECT;
 
 	fp = open(oca->filename, oflags);
diff --git a/kernel-shared/volumes.c b/kernel-shared/volumes.c
index a54ea4dd..24971c09 100644
--- a/kernel-shared/volumes.c
+++ b/kernel-shared/volumes.c
@@ -697,7 +697,7 @@ int btrfs_open_devices(struct btrfs_fs_info *fs_info,
 			continue;
 		}
 
-		if ((flags & O_RDWR) && zoned_model(device->name) == ZONED_HOST_MANAGED)
+		if (zoned_model(device->name) == ZONED_HOST_MANAGED)
 			flags |= O_DIRECT;
 
 		fd = open(device->name, flags);
-- 
2.54.0