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Btrfs: Use btrfs_join_transaction to avoid deadlocks during snapshot creation 

Snapshot creation happens at a specific time during transaction commit.  We
need to make sure the code called by snapshot creation doesn't wait
for the running transaction to commit.

This changes btrfs_delete_inode and finish_pending_snaps to use
btrfs_join_transaction instead of btrfs_start_transaction to avoid deadlocks.

It would be better if btrfs_delete_inode didn't use the join, but the
call path that triggers it is:

btrfs_commit_transaction->create_pending_snapshots->
create_pending_snapshot->btrfs_lookup_dentry->
fixup_tree_root_location->btrfs_read_fs_root->
btrfs_read_fs_root_no_name->btrfs_orphan_cleanup->iput

This will be fixed in a later patch by moving the orphan cleanup to the
cleaner thread.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Yan Zheng 2009-01-06 09:58:06 -05:00 committed by Chris Mason
parent 9ca03b997f
commit 180591bcfe
2 changed files with 2 additions and 2 deletions
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2
fs/btrfs/inode.c
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@ -2886,7 +2886,7 @@ void btrfs_delete_inode(struct inode *inode)
btrfs_wait_ordered_range(inode, 0, (u64)-1);
btrfs_i_size_write(inode, 0);
trans = btrfs_start_transaction(root, 1);
trans = btrfs_join_transaction(root, 1);
btrfs_set_trans_block_group(trans, inode);
ret = btrfs_truncate_inode_items(trans, root, inode, inode->i_size, 0);

2
fs/btrfs/transaction.c
View File

@ -800,7 +800,7 @@ static noinline int finish_pending_snapshot(struct btrfs_fs_info *fs_info,
parent_inode = pending->dentry->d_parent->d_inode;
parent_root = BTRFS_I(parent_inode)->root;
trans = btrfs_start_transaction(parent_root, 1);
trans = btrfs_join_transaction(parent_root, 1);
/*
* insert the directory item