From 8ca17f0f59529df9e2132ca594ff00c52a9bc556 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Fri, 27 May 2016 13:24:13 -0400 Subject: [PATCH] Btrfs: use FLUSH_LIMIT for relocation in reserve_metadata_bytes We used to allow you to set FLUSH_ALL and then just wouldn't do things like commit transactions or wait on ordered extents if we noticed you were in a transaction. However now that all the flushing for FLUSH_ALL is asynchronous we've lost the ability to tell, and we could end up deadlocking. So instead use FLUSH_LIMIT in reserve_metadata_bytes in relocation and then return -EAGAIN if we error out to preserve the previous behavior. I've also added an ASSERT() to catch anybody else who tries to do this. Thanks, Signed-off-by: Josef Bacik Signed-off-by: David Sterba --- fs/btrfs/extent-tree.c | 2 ++ fs/btrfs/relocation.c | 37 ++++++++++++++++++++----------------- 2 files changed, 22 insertions(+), 17 deletions(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index f3de211173ad..3a129c42658e 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -5135,6 +5135,8 @@ static int __reserve_metadata_bytes(struct btrfs_root *root, int ret = 0; ASSERT(orig_bytes); + ASSERT(!current->journal_info || flush != BTRFS_RESERVE_FLUSH_ALL); + spin_lock(&space_info->lock); ret = -ENOSPC; used = space_info->bytes_used + space_info->bytes_reserved + diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 23e16de52e23..fc067b07e31f 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -2604,25 +2604,28 @@ static int reserve_metadata_space(struct btrfs_trans_handle *trans, trans->block_rsv = rc->block_rsv; rc->reserved_bytes += num_bytes; + + /* + * We are under a transaction here so we can only do limited flushing. + * If we get an enospc just kick back -EAGAIN so we know to drop the + * transaction and try to refill when we can flush all the things. + */ ret = btrfs_block_rsv_refill(root, rc->block_rsv, num_bytes, - BTRFS_RESERVE_FLUSH_ALL); + BTRFS_RESERVE_FLUSH_LIMIT); if (ret) { - if (ret == -EAGAIN) { - tmp = rc->extent_root->nodesize * - RELOCATION_RESERVED_NODES; - while (tmp <= rc->reserved_bytes) - tmp <<= 1; - /* - * only one thread can access block_rsv at this point, - * so we don't need hold lock to protect block_rsv. - * we expand more reservation size here to allow enough - * space for relocation and we will return earlier in - * enospc case. - */ - rc->block_rsv->size = tmp + rc->extent_root->nodesize * - RELOCATION_RESERVED_NODES; - } - return ret; + tmp = rc->extent_root->nodesize * RELOCATION_RESERVED_NODES; + while (tmp <= rc->reserved_bytes) + tmp <<= 1; + /* + * only one thread can access block_rsv at this point, + * so we don't need hold lock to protect block_rsv. + * we expand more reservation size here to allow enough + * space for relocation and we will return eailer in + * enospc case. + */ + rc->block_rsv->size = tmp + rc->extent_root->nodesize * + RELOCATION_RESERVED_NODES; + return -EAGAIN; } return 0; -- 2.20.1