Commit 89ce8a63 authored by Chris Mason's avatar Chris Mason

Add btrfs_end_transaction_throttle to force writers to wait for pending commits

The existing throttle mechanism was often not sufficient to prevent
new writers from coming in and making a given transaction run forever.
This adds an explicit wait at the end of most operations so they will
allow the current transaction to close.

There is no wait inside file_write, inode updates, or cow filling, all which
have different deadlock possibilities.

This is a temporary measure until better asynchronous commit support is
added.  This code leads to stalls as it waits for data=ordered
writeback, and it really needs to be fixed.
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 333db94c
......@@ -1672,24 +1672,6 @@ void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
set_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree, buf);
}
void btrfs_throttle(struct btrfs_root *root)
{
#if 0
struct backing_dev_info *bdi;
bdi = &root->fs_info->bdi;
if (atomic_read(&root->fs_info->throttles) &&
bdi_write_congested(bdi)) {
#if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,18)
congestion_wait(WRITE, HZ/20);
#else
blk_congestion_wait(WRITE, HZ/20);
#endif
}
#endif
}
void btrfs_btree_balance_dirty(struct btrfs_root *root, unsigned long nr)
{
/*
......
......@@ -70,7 +70,6 @@ int btrfs_clear_buffer_defrag_done(struct extent_buffer *buf);
int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid);
u32 btrfs_csum_data(struct btrfs_root *root, char *data, u32 seed, size_t len);
void btrfs_csum_final(u32 crc, char *result);
void btrfs_throttle(struct btrfs_root *root);
int btrfs_open_device(struct btrfs_device *dev);
int btrfs_verify_block_csum(struct btrfs_root *root,
struct extent_buffer *buf);
......
......@@ -934,7 +934,6 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
balance_dirty_pages_ratelimited_nr(inode->i_mapping, num_pages);
if (num_pages < (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
btrfs_btree_balance_dirty(root, 1);
btrfs_throttle(root);
cond_resched();
}
out:
......
......@@ -855,10 +855,9 @@ static int btrfs_unlink(struct inode *dir, struct dentry *dentry)
btrfs_del_ordered_inode(inode, 1);
}
btrfs_end_transaction(trans, root);
btrfs_end_transaction_throttle(trans, root);
fail:
btrfs_btree_balance_dirty(root, nr);
btrfs_throttle(root);
return ret;
}
......@@ -889,10 +888,9 @@ static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
}
nr = trans->blocks_used;
ret = btrfs_end_transaction(trans, root);
ret = btrfs_end_transaction_throttle(trans, root);
fail:
btrfs_btree_balance_dirty(root, nr);
btrfs_throttle(root);
if (ret && !err)
err = ret;
......@@ -1871,14 +1869,13 @@ static int btrfs_mknod(struct inode *dir, struct dentry *dentry,
btrfs_update_inode_block_group(trans, dir);
out_unlock:
nr = trans->blocks_used;
btrfs_end_transaction(trans, root);
btrfs_end_transaction_throttle(trans, root);
fail:
if (drop_inode) {
inode_dec_link_count(inode);
iput(inode);
}
btrfs_btree_balance_dirty(root, nr);
btrfs_throttle(root);
return err;
}
......@@ -1936,14 +1933,13 @@ static int btrfs_create(struct inode *dir, struct dentry *dentry,
btrfs_update_inode_block_group(trans, dir);
out_unlock:
nr = trans->blocks_used;
btrfs_end_transaction(trans, root);
btrfs_end_transaction_throttle(trans, root);
fail:
if (drop_inode) {
inode_dec_link_count(inode);
iput(inode);
}
btrfs_btree_balance_dirty(root, nr);
btrfs_throttle(root);
return err;
}
......@@ -1985,14 +1981,13 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
drop_inode = 1;
nr = trans->blocks_used;
btrfs_end_transaction(trans, root);
btrfs_end_transaction_throttle(trans, root);
fail:
if (drop_inode) {
inode_dec_link_count(inode);
iput(inode);
}
btrfs_btree_balance_dirty(root, nr);
btrfs_throttle(root);
return err;
}
......@@ -2055,13 +2050,12 @@ static int btrfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
out_fail:
nr = trans->blocks_used;
btrfs_end_transaction(trans, root);
btrfs_end_transaction_throttle(trans, root);
out_unlock:
if (drop_on_err)
iput(inode);
btrfs_btree_balance_dirty(root, nr);
btrfs_throttle(root);
return err;
}
......@@ -2587,10 +2581,9 @@ static void btrfs_truncate(struct inode *inode)
btrfs_update_inode(trans, root, inode);
nr = trans->blocks_used;
ret = btrfs_end_transaction(trans, root);
ret = btrfs_end_transaction_throttle(trans, root);
BUG_ON(ret);
btrfs_btree_balance_dirty(root, nr);
btrfs_throttle(root);
}
/*
......@@ -2912,14 +2905,13 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
out_unlock:
nr = trans->blocks_used;
btrfs_end_transaction(trans, root);
btrfs_end_transaction_throttle(trans, root);
out_fail:
if (drop_inode) {
inode_dec_link_count(inode);
iput(inode);
}
btrfs_btree_balance_dirty(root, nr);
btrfs_throttle(root);
return err;
}
......
......@@ -164,7 +164,6 @@ static noinline int create_subvol(struct btrfs_root *root, char *name,
ret = err;
fail_commit:
btrfs_btree_balance_dirty(root, nr);
btrfs_throttle(root);
return ret;
}
......@@ -206,7 +205,6 @@ static int create_snapshot(struct btrfs_root *root, char *name, int namelen)
fail_unlock:
btrfs_btree_balance_dirty(root, nr);
btrfs_throttle(root);
return ret;
}
......
......@@ -130,8 +130,27 @@ struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
return h;
}
int btrfs_end_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
static noinline int wait_for_commit(struct btrfs_root *root,
struct btrfs_transaction *commit)
{
DEFINE_WAIT(wait);
mutex_lock(&root->fs_info->trans_mutex);
while(!commit->commit_done) {
prepare_to_wait(&commit->commit_wait, &wait,
TASK_UNINTERRUPTIBLE);
if (commit->commit_done)
break;
mutex_unlock(&root->fs_info->trans_mutex);
schedule();
mutex_lock(&root->fs_info->trans_mutex);
}
mutex_unlock(&root->fs_info->trans_mutex);
finish_wait(&commit->commit_wait, &wait);
return 0;
}
static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root, int throttle)
{
struct btrfs_transaction *cur_trans;
......@@ -140,8 +159,18 @@ int btrfs_end_transaction(struct btrfs_trans_handle *trans,
WARN_ON(cur_trans != trans->transaction);
WARN_ON(cur_trans->num_writers < 1);
cur_trans->num_writers--;
if (waitqueue_active(&cur_trans->writer_wait))
wake_up(&cur_trans->writer_wait);
if (cur_trans->in_commit && throttle) {
int ret;
mutex_unlock(&root->fs_info->trans_mutex);
ret = wait_for_commit(root, cur_trans);
BUG_ON(ret);
mutex_lock(&root->fs_info->trans_mutex);
}
put_transaction(cur_trans);
mutex_unlock(&root->fs_info->trans_mutex);
memset(trans, 0, sizeof(*trans));
......@@ -149,6 +178,18 @@ int btrfs_end_transaction(struct btrfs_trans_handle *trans,
return 0;
}
int btrfs_end_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
return __btrfs_end_transaction(trans, root, 0);
}
int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
{
return __btrfs_end_transaction(trans, root, 1);
}
int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root)
......@@ -240,25 +281,6 @@ int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
return 0;
}
static noinline int wait_for_commit(struct btrfs_root *root,
struct btrfs_transaction *commit)
{
DEFINE_WAIT(wait);
mutex_lock(&root->fs_info->trans_mutex);
while(!commit->commit_done) {
prepare_to_wait(&commit->commit_wait, &wait,
TASK_UNINTERRUPTIBLE);
if (commit->commit_done)
break;
mutex_unlock(&root->fs_info->trans_mutex);
schedule();
mutex_lock(&root->fs_info->trans_mutex);
}
mutex_unlock(&root->fs_info->trans_mutex);
finish_wait(&commit->commit_wait, &wait);
return 0;
}
struct dirty_root {
struct list_head list;
struct btrfs_root *root;
......@@ -680,6 +702,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
root->fs_info->btree_inode->i_mapping, GFP_NOFS);
trans->transaction->in_commit = 1;
printk("trans %Lu in commit\n", trans->transid);
cur_trans = trans->transaction;
if (cur_trans->list.prev != &root->fs_info->trans_list) {
prev_trans = list_entry(cur_trans->list.prev,
......@@ -760,6 +783,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
kfree(pinned_copy);
cur_trans->commit_done = 1;
printk("trans %Lu done in commit\n", cur_trans->transid);
root->fs_info->last_trans_committed = cur_trans->transid;
wake_up(&cur_trans->commit_wait);
put_transaction(cur_trans);
......
......@@ -101,4 +101,6 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
int btrfs_write_ordered_inodes(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
#endif
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