Btrfs: create special free space cache inode
In order to save free space cache, we need an inode to hold the data, and we
need a special item to point at the right inode for the right block group. So
first, create a special item that will point to the right inode, and the number
of extent entries we will have and the number of bitmaps we will have. We
truncate and pre-allocate space everytime to make sure it's uptodate.
This feature will be turned on as soon as you mount with -o space_cache, however
it is safe to boot into old kernels, they will just generate the cache the old
fashion way. When you boot back into a newer kernel we will notice that we
modified and not the cache and automatically discard the cache.
Signed-off-by: Josef Bacik <josef@redhat.com>
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 66e4c66..e7144c4 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -163,6 +163,7 @@
TRANS_START,
TRANS_JOIN,
TRANS_USERSPACE,
+ TRANS_JOIN_NOLOCK,
};
static int may_wait_transaction(struct btrfs_root *root, int type)
@@ -186,7 +187,8 @@
if (!h)
return ERR_PTR(-ENOMEM);
- mutex_lock(&root->fs_info->trans_mutex);
+ if (type != TRANS_JOIN_NOLOCK)
+ mutex_lock(&root->fs_info->trans_mutex);
if (may_wait_transaction(root, type))
wait_current_trans(root);
@@ -195,7 +197,8 @@
cur_trans = root->fs_info->running_transaction;
cur_trans->use_count++;
- mutex_unlock(&root->fs_info->trans_mutex);
+ if (type != TRANS_JOIN_NOLOCK)
+ mutex_unlock(&root->fs_info->trans_mutex);
h->transid = cur_trans->transid;
h->transaction = cur_trans;
@@ -224,9 +227,11 @@
}
}
- mutex_lock(&root->fs_info->trans_mutex);
+ if (type != TRANS_JOIN_NOLOCK)
+ mutex_lock(&root->fs_info->trans_mutex);
record_root_in_trans(h, root);
- mutex_unlock(&root->fs_info->trans_mutex);
+ if (type != TRANS_JOIN_NOLOCK)
+ mutex_unlock(&root->fs_info->trans_mutex);
if (!current->journal_info && type != TRANS_USERSPACE)
current->journal_info = h;
@@ -244,6 +249,12 @@
return start_transaction(root, 0, TRANS_JOIN);
}
+struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root,
+ int num_blocks)
+{
+ return start_transaction(root, 0, TRANS_JOIN_NOLOCK);
+}
+
struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
int num_blocks)
{
@@ -348,7 +359,7 @@
}
static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
- struct btrfs_root *root, int throttle)
+ struct btrfs_root *root, int throttle, int lock)
{
struct btrfs_transaction *cur_trans = trans->transaction;
struct btrfs_fs_info *info = root->fs_info;
@@ -376,18 +387,19 @@
btrfs_trans_release_metadata(trans, root);
- if (!root->fs_info->open_ioctl_trans &&
+ if (lock && !root->fs_info->open_ioctl_trans &&
should_end_transaction(trans, root))
trans->transaction->blocked = 1;
- if (cur_trans->blocked && !cur_trans->in_commit) {
+ if (lock && cur_trans->blocked && !cur_trans->in_commit) {
if (throttle)
return btrfs_commit_transaction(trans, root);
else
wake_up_process(info->transaction_kthread);
}
- mutex_lock(&info->trans_mutex);
+ if (lock)
+ mutex_lock(&info->trans_mutex);
WARN_ON(cur_trans != info->running_transaction);
WARN_ON(cur_trans->num_writers < 1);
cur_trans->num_writers--;
@@ -395,7 +407,8 @@
if (waitqueue_active(&cur_trans->writer_wait))
wake_up(&cur_trans->writer_wait);
put_transaction(cur_trans);
- mutex_unlock(&info->trans_mutex);
+ if (lock)
+ mutex_unlock(&info->trans_mutex);
if (current->journal_info == trans)
current->journal_info = NULL;
@@ -411,13 +424,19 @@
int btrfs_end_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
- return __btrfs_end_transaction(trans, root, 0);
+ return __btrfs_end_transaction(trans, root, 0, 1);
}
int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
- return __btrfs_end_transaction(trans, root, 1);
+ return __btrfs_end_transaction(trans, root, 1, 1);
+}
+
+int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root)
+{
+ return __btrfs_end_transaction(trans, root, 0, 0);
}
/*
@@ -966,6 +985,8 @@
super->root = root_item->bytenr;
super->generation = root_item->generation;
super->root_level = root_item->level;
+ if (super->cache_generation != 0 || btrfs_test_opt(root, SPACE_CACHE))
+ super->cache_generation = root_item->generation;
}
int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
