Userland uses this flag and resets it only when changing the fsid is
complete. Its not a good idea to mount the device anything in between,
so this patch fails the mount if SB SUPER_FLAG_CHANGING_FSID is set.
Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
cc: wqu@xxxxxxxx
---
fs/btrfs/disk-io.c | 7 ++++++-
include/uapi/linux/btrfs_tree.h | 1 +
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index a69e5944dc08..8b76faa77235 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -61,7 +61,8 @@
BTRFS_HEADER_FLAG_RELOC |\
BTRFS_SUPER_FLAG_ERROR |\
BTRFS_SUPER_FLAG_SEEDING |\
- BTRFS_SUPER_FLAG_METADUMP)
+ BTRFS_SUPER_FLAG_METADUMP |\
+ BTRFS_SUPER_FLAG_CHANGING_FSID)
static const struct extent_io_ops btree_extent_io_ops;
static void end_workqueue_fn(struct btrfs_work *work);
@@ -3906,6 +3907,10 @@ static int btrfs_check_super_valid(struct btrfs_fs_info *fs_info)
btrfs_err(fs_info, "no valid FS found");
ret = -EINVAL;
}
+ if (btrfs_super_flags(sb) & ~BTRFS_SUPER_FLAG_CHANGING_FSID) {
+ btrfs_err(fs_info, "SUPER_FLAG_CHANGING_FSID is set");
+ ret = -EINVAL;
+ }
if (btrfs_super_flags(sb) & ~BTRFS_SUPER_FLAG_SUPP)
btrfs_warn(fs_info, "unrecognized super flag: %llu",
btrfs_super_flags(sb) & ~BTRFS_SUPER_FLAG_SUPP);
diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index 38ab0e06259a..aff1356c2bb8 100644
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -457,6 +457,7 @@ struct btrfs_free_space_header {
#define BTRFS_SUPER_FLAG_SEEDING (1ULL << 32)
#define BTRFS_SUPER_FLAG_METADUMP (1ULL << 33)
#define BTRFS_SUPER_FLAG_METADUMP_V2 (1ULL << 34)
+#define BTRFS_SUPER_FLAG_CHANGING_FSID (1ULL << 35)
/*
--
2.15.0
--
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