From 15d1ff8111aad85d8b40ee396758990d17a2caac Mon Sep 17 00:00:00 2001 From: Liu Bo Date: Thu, 29 Mar 2012 09:57:44 -0400 Subject: Btrfs: fix deadlock during allocating chunks This deadlock comes from xfstests 251. We'll hold the chunk_mutex throughout the whole of a chunk allocation. But if we find that we've used up system chunk space, we need to allocate a new system chunk, but this will lead to a recursion of chunk allocation and end up with a deadlock on chunk_mutex. So instead we need to allocate the system chunk first if we find we're in ENOSPC. Signed-off-by: Liu Bo Signed-off-by: Chris Mason --- fs/btrfs/extent-tree.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) (limited to 'fs/btrfs/extent-tree.c') diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 7c233407beee..a84420491c11 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -3445,6 +3445,50 @@ static int should_alloc_chunk(struct btrfs_root *root, return 1; } +static u64 get_system_chunk_thresh(struct btrfs_root *root, u64 type) +{ + u64 num_dev; + + if (type & BTRFS_BLOCK_GROUP_RAID10 || + type & BTRFS_BLOCK_GROUP_RAID0) + num_dev = root->fs_info->fs_devices->rw_devices; + else if (type & BTRFS_BLOCK_GROUP_RAID1) + num_dev = 2; + else + num_dev = 1; /* DUP or single */ + + /* metadata for updaing devices and chunk tree */ + return btrfs_calc_trans_metadata_size(root, num_dev + 1); +} + +static void check_system_chunk(struct btrfs_trans_handle *trans, + struct btrfs_root *root, u64 type) +{ + struct btrfs_space_info *info; + u64 left; + u64 thresh; + + info = __find_space_info(root->fs_info, BTRFS_BLOCK_GROUP_SYSTEM); + spin_lock(&info->lock); + left = info->total_bytes - info->bytes_used - info->bytes_pinned - + info->bytes_reserved - info->bytes_readonly; + spin_unlock(&info->lock); + + thresh = get_system_chunk_thresh(root, type); + if (left < thresh && btrfs_test_opt(root, ENOSPC_DEBUG)) { + printk(KERN_INFO "left=%llu, need=%llu, flags=%llu\n", + left, thresh, type); + dump_space_info(info, 0, 0); + } + + if (left < thresh) { + u64 flags; + + flags = btrfs_get_alloc_profile(root->fs_info->chunk_root, 0); + btrfs_alloc_chunk(trans, root, flags); + } +} + static int do_chunk_alloc(struct btrfs_trans_handle *trans, struct btrfs_root *extent_root, u64 alloc_bytes, u64 flags, int force) @@ -3515,6 +3559,12 @@ again: force_metadata_allocation(fs_info); } + /* + * Check if we have enough space in SYSTEM chunk because we may need + * to update devices. + */ + check_system_chunk(trans, extent_root, flags); + ret = btrfs_alloc_chunk(trans, extent_root, flags); if (ret < 0 && ret != -ENOSPC) goto out; -- cgit v1.2.2