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authorMiao Xie <miaox@cn.fujitsu.com>2013-06-06 03:28:03 +0000
committerJosef Bacik <jbacik@fusionio.com>2013-07-01 08:52:25 -0400
commit5bc7247ac47cf100309e4d7e24214889c46a1636 (patch)
tree2e28c383acea82994e54c330ba7345b436b69656 /fs/btrfs
parent8c2a1a3028d560cfb95f1c583e872c65ed2f0b3d (diff)
downloadlinux-next-5bc7247ac47cf100309e4d7e24214889c46a1636.tar.gz
Btrfs: fix broken nocow after balance
Balance will create reloc_root for each fs root, and it's going to record last_snapshot to filter shared blocks. The side effect of setting last_snapshot is to break nocow attributes of files. Since the extents are not shared by the relocation tree after the balance, we can recover the old last_snapshot safely if no one snapshoted the source tree. We fix the above problem by this way. Reported-by: Kyle Gates <kylegates@hotmail.com> Signed-off-by: Liu Bo <bo.li.liu@oracle.com> Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Diffstat (limited to 'fs/btrfs')
-rw-r--r--fs/btrfs/relocation.c44
1 files changed, 44 insertions, 0 deletions
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index aa559f1161df..4a404b44b0ad 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -1305,6 +1305,7 @@ static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
struct extent_buffer *eb;
struct btrfs_root_item *root_item;
struct btrfs_key root_key;
+ u64 last_snap = 0;
int ret;
root_item = kmalloc(sizeof(*root_item), GFP_NOFS);
@@ -1320,6 +1321,7 @@ static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
BTRFS_TREE_RELOC_OBJECTID);
BUG_ON(ret);
+ last_snap = btrfs_root_last_snapshot(&root->root_item);
btrfs_set_root_last_snapshot(&root->root_item,
trans->transid - 1);
} else {
@@ -1345,6 +1347,12 @@ static struct btrfs_root *create_reloc_root(struct btrfs_trans_handle *trans,
memset(&root_item->drop_progress, 0,
sizeof(struct btrfs_disk_key));
root_item->drop_level = 0;
+ /*
+ * abuse rtransid, it is safe because it is impossible to
+ * receive data into a relocation tree.
+ */
+ btrfs_set_root_rtransid(root_item, last_snap);
+ btrfs_set_root_otransid(root_item, trans->transid);
}
btrfs_tree_unlock(eb);
@@ -2272,8 +2280,12 @@ void free_reloc_roots(struct list_head *list)
static noinline_for_stack
int merge_reloc_roots(struct reloc_control *rc)
{
+ struct btrfs_trans_handle *trans;
struct btrfs_root *root;
struct btrfs_root *reloc_root;
+ u64 last_snap;
+ u64 otransid;
+ u64 objectid;
LIST_HEAD(reloc_roots);
int found = 0;
int ret = 0;
@@ -2307,12 +2319,44 @@ again:
} else {
list_del_init(&reloc_root->root_list);
}
+
+ /*
+ * we keep the old last snapshod transid in rtranid when we
+ * created the relocation tree.
+ */
+ last_snap = btrfs_root_rtransid(&reloc_root->root_item);
+ otransid = btrfs_root_otransid(&reloc_root->root_item);
+ objectid = reloc_root->root_key.offset;
+
ret = btrfs_drop_snapshot(reloc_root, rc->block_rsv, 0, 1);
if (ret < 0) {
if (list_empty(&reloc_root->root_list))
list_add_tail(&reloc_root->root_list,
&reloc_roots);
goto out;
+ } else if (!ret) {
+ /*
+ * recover the last snapshot tranid to avoid
+ * the space balance break NOCOW.
+ */
+ root = read_fs_root(rc->extent_root->fs_info,
+ objectid);
+ if (IS_ERR(root))
+ continue;
+
+ if (btrfs_root_refs(&root->root_item) == 0)
+ continue;
+
+ trans = btrfs_join_transaction(root);
+ BUG_ON(IS_ERR(trans));
+
+ /* Check if the fs/file tree was snapshoted or not. */
+ if (btrfs_root_last_snapshot(&root->root_item) ==
+ otransid - 1)
+ btrfs_set_root_last_snapshot(&root->root_item,
+ last_snap);
+
+ btrfs_end_transaction(trans, root);
}
}