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authorLi Zefan <lizf@cn.fujitsu.com>2011-03-28 02:01:25 +0000
committerChris Mason <chris.mason@oracle.com>2011-04-05 01:20:24 -0400
commit08fe4db170b4193603d9d31f40ebaf652d07ac9c (patch)
tree2d0d2abe40b77266600653e399d4973a679716a9 /fs/btrfs/root-tree.c
parentadae52b94e18afa1f84fab67df2a8a872c2f5533 (diff)
Btrfs: Fix uninitialized root flags for subvolumes
root_item->flags and root_item->byte_limit are not initialized when a subvolume is created. This bug is not revealed until we added readonly snapshot support - now you mount a btrfs filesystem and you may find the subvolumes in it are readonly. To work around this problem, we steal a bit from root_item->inode_item->flags, and use it to indicate if those fields have been properly initialized. When we read a tree root from disk, we check if the bit is set, and if not we'll set the flag and initialize the two fields of the root item. Reported-by: Andreas Philipp <philipp.andreas@gmail.com> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Tested-by: Andreas Philipp <philipp.andreas@gmail.com> cc: stable@kernel.org Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs/btrfs/root-tree.c')
-rw-r--r--fs/btrfs/root-tree.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index 29b2d7c930e..6928bff62da 100644
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -473,3 +473,21 @@ again:
btrfs_free_path(path);
return 0;
}
+
+/*
+ * Old btrfs forgets to init root_item->flags and root_item->byte_limit
+ * for subvolumes. To work around this problem, we steal a bit from
+ * root_item->inode_item->flags, and use it to indicate if those fields
+ * have been properly initialized.
+ */
+void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
+{
+ u64 inode_flags = le64_to_cpu(root_item->inode.flags);
+
+ if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
+ inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
+ root_item->inode.flags = cpu_to_le64(inode_flags);
+ root_item->flags = 0;
+ root_item->byte_limit = 0;
+ }
+}