btrfs_start_transaction: wait for commits in progress to finish
btrfs_commit_transaction has to loop waiting for any writers in the
transaction to finish before it can proceed. btrfs_start_transaction
should be polite and not join a transaction that is in the process
of being finished off.
There are a few places that can't wait, basically the ones doing IO that
might be needed to finish the transaction. For them, btrfs_join_transaction
is added.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 86a5acc..0582390 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -62,6 +62,7 @@
init_waitqueue_head(&cur_trans->writer_wait);
init_waitqueue_head(&cur_trans->commit_wait);
cur_trans->in_commit = 0;
+ cur_trans->blocked = 0;
cur_trans->use_count = 1;
cur_trans->commit_done = 0;
cur_trans->start_time = get_seconds();
@@ -99,14 +100,36 @@
return 0;
}
-struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
- int num_blocks)
+struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
+ int num_blocks, int join)
{
struct btrfs_trans_handle *h =
kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
+ struct btrfs_transaction *cur_trans;
int ret;
mutex_lock(&root->fs_info->trans_mutex);
+ cur_trans = root->fs_info->running_transaction;
+ if (cur_trans && cur_trans->blocked && !join) {
+ DEFINE_WAIT(wait);
+ cur_trans->use_count++;
+ while(1) {
+ prepare_to_wait(&root->fs_info->transaction_wait, &wait,
+ TASK_UNINTERRUPTIBLE);
+ if (cur_trans->blocked) {
+ mutex_unlock(&root->fs_info->trans_mutex);
+ schedule();
+ mutex_lock(&root->fs_info->trans_mutex);
+ finish_wait(&root->fs_info->transaction_wait,
+ &wait);
+ } else {
+ finish_wait(&root->fs_info->transaction_wait,
+ &wait);
+ break;
+ }
+ }
+ put_transaction(cur_trans);
+ }
ret = join_transaction(root);
BUG_ON(ret);
@@ -123,6 +146,17 @@
return h;
}
+struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
+ int num_blocks)
+{
+ return start_transaction(root, num_blocks, 0);
+}
+struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
+ int num_blocks)
+{
+ return start_transaction(root, num_blocks, 1);
+}
+
static noinline int wait_for_commit(struct btrfs_root *root,
struct btrfs_transaction *commit)
{
@@ -156,7 +190,7 @@
if (waitqueue_active(&cur_trans->writer_wait))
wake_up(&cur_trans->writer_wait);
- if (cur_trans->in_commit && throttle) {
+ if (0 && cur_trans->in_commit && throttle) {
DEFINE_WAIT(wait);
mutex_unlock(&root->fs_info->trans_mutex);
prepare_to_wait(&root->fs_info->transaction_throttle, &wait,
@@ -617,6 +651,7 @@
printk("commit trans %Lu\n", trans->transid);
trans->transaction->in_commit = 1;
+ trans->transaction->blocked = 1;
cur_trans = trans->transaction;
if (cur_trans->list.prev != &root->fs_info->trans_list) {
prev_trans = list_entry(cur_trans->list.prev,
@@ -684,7 +719,9 @@
btrfs_copy_pinned(root, pinned_copy);
+ trans->transaction->blocked = 0;
wake_up(&root->fs_info->transaction_throttle);
+ wake_up(&root->fs_info->transaction_wait);
mutex_unlock(&root->fs_info->trans_mutex);
ret = btrfs_write_and_wait_transaction(trans, root);