Commit fb235dc06fac ("btrfs: qgroup: Move half of the qgroup accounting
time out of commit trans") makes btrfs_qgroup_extent_record::old_roots
populated at insert time.
It's OK for most cases as btrfs_qgroup_extent_record is inserted at
delayed ref head insert time, which has a less restrict lock context.
But later delayed subtree scan optimization will need to insert
btrfs_qgroup_extent_record with path write lock hold, where triggering a
backref walk can easily lead to dead lock.
So this patch introduces two new internal functions,
qgroup_trace_extent() and qgroup_trace_leaf_items(), with new @exec_post
parameter to info whether we need to initialize the backref walk right
now.
Also modifies btrfs_qgroup_account_extents() not to trigger kernel
warning.
Signed-off-by: Qu Wenruo <w...@suse.com>
---
fs/btrfs/qgroup.c | 51 +++++++++++++++++++++++++++++++++++++----------
1 file changed, 41 insertions(+), 10 deletions(-)
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 45868fd76209..6c674ac29b90 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -1580,8 +1580,16 @@ int btrfs_qgroup_trace_extent_post(struct btrfs_fs_info
*fs_info,
return 0;
}
-int btrfs_qgroup_trace_extent(struct btrfs_trans_handle *trans, u64 bytenr,
- u64 num_bytes, gfp_t gfp_flag)
+/*
+ * Insert qgroup extent record for extent at @bytenr, @num_bytes.
+ *
+ * @bytenr: bytenr of the extent
+ * @num_bytes: length of the extent
+ * @exec_post: whether to exec the post insert work
+ * will init backref walk if set to true.
+ */
+static int qgroup_trace_extent(struct btrfs_trans_handle *trans, u64 bytenr,
+ u64 num_bytes, gfp_t gfp_flag, bool exec_post)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_qgroup_extent_record *record;
@@ -1607,11 +1615,27 @@ int btrfs_qgroup_trace_extent(struct btrfs_trans_handle
*trans, u64 bytenr,
kfree(record);
return 0;
}
- return btrfs_qgroup_trace_extent_post(fs_info, record);
+ if (exec_post)
+ return btrfs_qgroup_trace_extent_post(fs_info, record);
+ return 0;
}
-int btrfs_qgroup_trace_leaf_items(struct btrfs_trans_handle *trans,
- struct extent_buffer *eb)
+int btrfs_qgroup_trace_extent(struct btrfs_trans_handle *trans, u64 bytenr,
+ u64 num_bytes, gfp_t gfp_flag)
+{
+ return qgroup_trace_extent(trans, bytenr, num_bytes, gfp_flag, true);
+}
+
+/*
+ * Insert qgroup extent record for leaf and all file extents in it
+ *
+ * @bytenr: bytenr of the leaf
+ * @num_bytes: length of the leaf
+ * @exec_post: whether to exec the post insert work
+ * will init backref walk if set to true.
+ */
+static int qgroup_trace_leaf_items(struct btrfs_trans_handle *trans,
+ struct extent_buffer *eb, bool exec_post)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
int nr = btrfs_header_nritems(eb);
@@ -1643,8 +1667,8 @@ int btrfs_qgroup_trace_leaf_items(struct
btrfs_trans_handle *trans,
num_bytes = btrfs_file_extent_disk_num_bytes(eb, fi);
- ret = btrfs_qgroup_trace_extent(trans, bytenr, num_bytes,
- GFP_NOFS);
+ ret = qgroup_trace_extent(trans, bytenr, num_bytes, GFP_NOFS,
+ exec_post);
if (ret)
return ret;
}
@@ -1652,6 +1676,12 @@ int btrfs_qgroup_trace_leaf_items(struct
btrfs_trans_handle *trans,
return 0;
}
+int btrfs_qgroup_trace_leaf_items(struct btrfs_trans_handle *trans,
+ struct extent_buffer *eb)
+{
+ return qgroup_trace_leaf_items(trans, eb, true);
+}
+
/*
* Walk up the tree from the bottom, freeing leaves and any interior
* nodes which have had all slots visited. If a node (leaf or
@@ -2558,10 +2588,11 @@ int btrfs_qgroup_account_extents(struct
btrfs_trans_handle *trans)
if (!ret) {
/*
- * Old roots should be searched when inserting qgroup
- * extent record
+ * Most record->old_roots should have been populated at
+ * insert time. Although we still allow some records
+ * without old_roots populated.
*/
- if (WARN_ON(!record->old_roots)) {
+ if (!record->old_roots) {
/* Search commit root to find old_roots */
ret = btrfs_find_all_roots(NULL, fs_info,
record->bytenr, 0,
--
2.19.1
