Reorder the flags field in struct btrfs_header and record a flag on writeout
This allows detection of blocks that have already been written in the
running transaction so they can be recowed instead of modified again.
It is step one in trusting the transid field of the block pointers.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 70b6ddf..6ba5394 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -124,6 +124,7 @@
btrfs_set_header_bytenr(cow, cow->start);
btrfs_set_header_generation(cow, trans->transid);
btrfs_set_header_owner(cow, new_root_objectid);
+ btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN);
WARN_ON(btrfs_header_generation(buf) > trans->transid);
ret = btrfs_inc_ref(trans, new_root, buf);
@@ -183,6 +184,7 @@
btrfs_set_header_bytenr(cow, cow->start);
btrfs_set_header_generation(cow, trans->transid);
btrfs_set_header_owner(cow, root->root_key.objectid);
+ btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN);
WARN_ON(btrfs_header_generation(buf) > trans->transid);
if (btrfs_header_generation(buf) != trans->transid) {
@@ -245,11 +247,14 @@
}
header_trans = btrfs_header_generation(buf);
- if (header_trans == trans->transid) {
+ spin_lock(&root->fs_info->hash_lock);
+ if (header_trans == trans->transid &&
+ !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) {
*cow_ret = buf;
+ spin_unlock(&root->fs_info->hash_lock);
return 0;
}
-
+ spin_unlock(&root->fs_info->hash_lock);
search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
ret = __btrfs_cow_block(trans, root, buf, parent,
parent_slot, cow_ret, search_start, 0);
@@ -1494,6 +1499,7 @@
btrfs_set_header_bytenr(split, split->start);
btrfs_set_header_generation(split, trans->transid);
btrfs_set_header_owner(split, root->root_key.objectid);
+ btrfs_set_header_flags(split, 0);
write_extent_buffer(split, root->fs_info->fsid,
(unsigned long)btrfs_header_fsid(split),
BTRFS_FSID_SIZE);
