From ae2e4728816510ae4e8ed2b732b34ea0aba05a34 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Fri, 27 May 2016 12:58:35 -0400 Subject: [PATCH] Btrfs: change how we calculate the global block rsv Traditionally we've calculated the global block rsv by guessing how much of the metadata used amount was the extent tree, and then taking the data size and figuring out how large the csum tree would have to be to hold that much data. This is imprecise and falls down on MIXED file systems as we can't trust the data used amount. This resulted in failures for xfstests generic/333 because it creates lots of clones, which explodes out the extent tree. Our global reserve calculations were woefully inaccurate in this case which meant we got into a situation where we did not have enough reserved to do our work. We know we only use the global block rsv for the extent, csum, and root trees, so just get the bytes used for these trees and use that as the basis of our global reserve. Since these are not reference counted trees the bytes_used value will be accurate. This fixed the transaction aborts seen with generic/333. Thanks, Signed-off-by: Josef Bacik Signed-off-by: David Sterba --- fs/btrfs/extent-tree.c | 45 +++++++++--------------------------------- 1 file changed, 9 insertions(+), 36 deletions(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 9ef8f99d5a2a..7c644f810816 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -5615,48 +5615,21 @@ void btrfs_block_rsv_release(struct btrfs_root *root, num_bytes); } -/* - * helper to calculate size of global block reservation. - * the desired value is sum of space used by extent tree, - * checksum tree and root tree - */ -static u64 calc_global_metadata_size(struct btrfs_fs_info *fs_info) -{ - struct btrfs_space_info *sinfo; - u64 num_bytes; - u64 meta_used; - u64 data_used; - int csum_size = btrfs_super_csum_size(fs_info->super_copy); - - sinfo = __find_space_info(fs_info, BTRFS_BLOCK_GROUP_DATA); - spin_lock(&sinfo->lock); - data_used = sinfo->bytes_used; - spin_unlock(&sinfo->lock); - - sinfo = __find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA); - spin_lock(&sinfo->lock); - if (sinfo->flags & BTRFS_BLOCK_GROUP_DATA) - data_used = 0; - meta_used = sinfo->bytes_used; - spin_unlock(&sinfo->lock); - - num_bytes = (data_used >> fs_info->sb->s_blocksize_bits) * - csum_size * 2; - num_bytes += div_u64(data_used + meta_used, 50); - - if (num_bytes * 3 > meta_used) - num_bytes = div_u64(meta_used, 3); - - return ALIGN(num_bytes, fs_info->extent_root->nodesize << 10); -} - static void update_global_block_rsv(struct btrfs_fs_info *fs_info) { struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv; struct btrfs_space_info *sinfo = block_rsv->space_info; u64 num_bytes; - num_bytes = calc_global_metadata_size(fs_info); + /* + * The global block rsv is based on the size of the extent tree, the + * checksum tree and the root tree. If the fs is empty we want to set + * it to a minimal amount for safety. + */ + num_bytes = btrfs_root_used(&fs_info->extent_root->root_item) + + btrfs_root_used(&fs_info->csum_root->root_item) + + btrfs_root_used(&fs_info->tree_root->root_item); + num_bytes = max_t(u64, num_bytes, SZ_16M); spin_lock(&sinfo->lock); spin_lock(&block_rsv->lock); -- 2.20.1