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Btrfs: optimize how we account for space in truncate 

Currently we're starting and stopping a transaction for no real reason, so kill
that and just reserve enough space as if we can truncate all in one transaction.
Also use btrfs_block_rsv_check() for our reserve to minimize the amount of space
we may have to allocate for our slack space.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
This commit is contained in:
Josef Bacik 2011-08-08 13:46:15 -04:00
parent 13553e5221
commit 907cbcebd4
1 changed files with 29 additions and 29 deletions
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56
fs/btrfs/inode.c
View File

@ -6482,6 +6482,7 @@ static int btrfs_truncate(struct inode *inode)
struct btrfs_trans_handle *trans;
unsigned long nr;
u64 mask = root->sectorsize - 1;
u64 min_size = btrfs_calc_trans_metadata_size(root, 2);
ret = btrfs_truncate_page(inode->i_mapping, inode->i_size);
if (ret)
@ -6530,17 +6531,21 @@ static int btrfs_truncate(struct inode *inode)
if (!rsv)
return -ENOMEM;
trans = btrfs_start_transaction(root, 4);
/*
* 2 for the truncate slack space
* 1 for the orphan item we're going to add
* 1 for the orphan item deletion
* 1 for updating the inode.
*/
trans = btrfs_start_transaction(root, 5);
if (IS_ERR(trans)) {
err = PTR_ERR(trans);
goto out;
}
/*
* Reserve space for the truncate process. Truncate should be adding
* space, but if there are snapshots it may end up using space.
*/
ret = btrfs_truncate_reserve_metadata(trans, root, rsv);
/* Migrate the slack space for the truncate to our reserve */
ret = btrfs_block_rsv_migrate(&root->fs_info->trans_block_rsv, rsv,
min_size);
BUG_ON(ret);
ret = btrfs_orphan_add(trans, inode);
@ -6549,21 +6554,6 @@ static int btrfs_truncate(struct inode *inode)
goto out;
}
nr = trans->blocks_used;
btrfs_end_transaction(trans, root);
btrfs_btree_balance_dirty(root, nr);
/*
* Ok so we've already migrated our bytes over for the truncate, so here
* just reserve the one slot we need for updating the inode.
*/
trans = btrfs_start_transaction(root, 1);
if (IS_ERR(trans)) {
err = PTR_ERR(trans);
goto out;
}
trans->block_rsv = rsv;
/*
* setattr is responsible for setting the ordered_data_close flag,
* but that is only tested during the last file release. That
@ -6585,19 +6575,29 @@ static int btrfs_truncate(struct inode *inode)
btrfs_add_ordered_operation(trans, root, inode);
while (1) {
ret = btrfs_block_rsv_check(trans, root, rsv, min_size, 0);
if (ret) {
/*
* This can only happen with the original transaction we
* started above, every other time we shouldn't have a
* transaction started yet.
*/
if (ret == -EAGAIN)
goto end_trans;
err = ret;
break;
}
if (!trans) {
trans = btrfs_start_transaction(root, 3);
/* Just need the 1 for updating the inode */
trans = btrfs_start_transaction(root, 1);
if (IS_ERR(trans)) {
err = PTR_ERR(trans);
goto out;
}
ret = btrfs_truncate_reserve_metadata(trans, root,
rsv);
BUG_ON(ret);
}
trans->block_rsv = rsv;
}
ret = btrfs_truncate_inode_items(trans, root, inode,
inode->i_size,
@ -6613,7 +6613,7 @@ static int btrfs_truncate(struct inode *inode)
err = ret;
break;
}
end_trans:
nr = trans->blocks_used;
btrfs_end_transaction(trans, root);
trans = NULL;