Cause we've added sub transaction, if it do not want to cow a block, we also
need to get new sub transid recorded. Thus we need to acquire write lock
ahead.
This is used for log code to find the most uptodate file extents.
Signed-off-by: Liu Bo <liubo2...@cn.fujitsu.com>
---
fs/btrfs/ctree.c | 52 ++++++++++++++++++++++++++++++++++++++++++----------
1 files changed, 42 insertions(+), 10 deletions(-)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 41d1d17..548246c 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -511,6 +511,33 @@ static noinline int __btrfs_cow_block(struct
btrfs_trans_handle *trans,
return 0;
}
+static inline void update_block_generation(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct extent_buffer *buf,
+ struct extent_buffer *parent,
+ int slot)
+{
+ /*
+ * If it does not need to cow this block, we still need to
+ * update the block's generation, for transid may have been
+ * changed during fsync.
+ */
+ if (btrfs_header_generation(buf) == trans->transid)
+ return;
+
+ if (buf == root->node) {
+ btrfs_set_header_generation(buf, trans->transid);
+ btrfs_mark_buffer_dirty(buf);
+ add_root_to_dirty_list(root);
+ } else {
+ btrfs_set_node_ptr_generation(parent, slot,
+ trans->transid);
+ btrfs_set_header_generation(buf, trans->transid);
+ btrfs_mark_buffer_dirty(parent);
+ btrfs_mark_buffer_dirty(buf);
+ }
+}
+
static inline int should_cow_block(struct btrfs_trans_handle *trans,
struct btrfs_root *root,
struct extent_buffer *buf)
@@ -551,6 +578,7 @@ noinline int btrfs_cow_block(struct btrfs_trans_handle
*trans,
}
if (!should_cow_block(trans, root, buf)) {
+ update_block_generation(trans, root, buf, parent, parent_slot);
*cow_ret = buf;
return 0;
}
@@ -1699,16 +1727,6 @@ again:
*/
if (cow) {
/*
- * if we don't really need to cow this block
- * then we don't want to set the path blocking,
- * so we test it here
- */
- if (!should_cow_block(trans, root, b))
- goto cow_done;
-
- btrfs_set_path_blocking(p);
-
- /*
* must have write locks on this node and the
* parent
*/
@@ -1718,6 +1736,20 @@ again:
goto again;
}
+ /*
+ * if we don't really need to cow this block
+ * then we don't want to set the path blocking,
+ * so we test it here
+ */
+ if (!should_cow_block(trans, root, b)) {
+ update_block_generation(trans, root, b,
+ p->nodes[level + 1],
+ p->slots[level + 1]);
+ goto cow_done;
+ }
+
+ btrfs_set_path_blocking(p);
+
err = btrfs_cow_block(trans, root, b,
p->nodes[level + 1],
p->slots[level + 1], &b);
--
1.6.5.2
--
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