On Thu, Sep 03, 2015 at 12:44:26PM -0700, Omar Sandoval wrote:
> The free space tree is updated in tandem with the extent tree. There are
> only a handful of places where we need to hook in:
>
> 1. Block group creation
> 2. Block group deletion
> 3. Delayed refs (extent creation and deletion)
> 4. Block group caching
>
> Signed-off-by: Omar Sandoval <osan...@fb.com>
> ---
> fs/btrfs/extent-tree.c | 40 +++++++++++++++++++++++++++++++++++++---
> 1 file changed, 37 insertions(+), 3 deletions(-)
>
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index 418c0eca9bb4..1c007e858787 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -33,6 +33,7 @@
> #include "raid56.h"
> #include "locking.h"
> #include "free-space-cache.h"
> +#include "free-space-tree.h"
> #include "math.h"
> #include "sysfs.h"
> #include "qgroup.h"
> @@ -520,7 +521,10 @@ static noinline void caching_thread(struct btrfs_work
> *work)
> mutex_lock(&caching_ctl->mutex);
> down_read(&fs_info->commit_root_sem);
>
> - ret = load_extent_tree_free(caching_ctl);
> + if (btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
> + ret = load_free_space_tree(caching_ctl);
> + else
> + ret = load_extent_tree_free(caching_ctl);
>
> spin_lock(&block_group->lock);
> block_group->caching_ctl = NULL;
> @@ -626,8 +630,8 @@ static int cache_block_group(struct
> btrfs_block_group_cache *cache,
> }
> } else {
> /*
> - * We are not going to do the fast caching, set cached to the
> - * appropriate value and wakeup any waiters.
> + * We're either using the free space tree or no caching at all.
> + * Set cached to the appropriate value and wakeup any waiters.
> */
> spin_lock(&cache->lock);
> if (load_cache_only) {
> @@ -6385,6 +6389,13 @@ static int __btrfs_free_extent(struct
> btrfs_trans_handle *trans,
> }
> }
>
> + ret = add_to_free_space_tree(trans, root->fs_info, bytenr,
> + num_bytes);
> + if (ret) {
> + btrfs_abort_transaction(trans, extent_root, ret);
> + goto out;
> + }
> +
> ret = update_block_group(trans, root, bytenr, num_bytes, 0);
> if (ret) {
> btrfs_abort_transaction(trans, extent_root, ret);
> @@ -7328,6 +7339,11 @@ static int alloc_reserved_file_extent(struct
> btrfs_trans_handle *trans,
> btrfs_mark_buffer_dirty(path->nodes[0]);
> btrfs_free_path(path);
>
> + ret = remove_from_free_space_tree(trans, fs_info, ins->objectid,
> + ins->offset);
> + if (ret)
> + return ret;
> +
> ret = update_block_group(trans, root, ins->objectid, ins->offset, 1);
> if (ret) { /* -ENOENT, logic error */
> btrfs_err(fs_info, "update block group failed for %llu %llu",
> @@ -7409,6 +7425,11 @@ static int alloc_reserved_tree_block(struct
> btrfs_trans_handle *trans,
> btrfs_mark_buffer_dirty(leaf);
> btrfs_free_path(path);
>
> + ret = remove_from_free_space_tree(trans, fs_info, ins->objectid,
> + num_bytes);
> + if (ret)
> + return ret;
> +
> ret = update_block_group(trans, root, ins->objectid, root->nodesize,
> 1);
> if (ret) { /* -ENOENT, logic error */
> @@ -9279,6 +9300,8 @@ btrfs_create_block_group_cache(struct btrfs_root *root,
> u64 start, u64 size)
> cache->full_stripe_len = btrfs_full_stripe_len(root,
> &root->fs_info->mapping_tree,
> start);
> + set_free_space_tree_thresholds(cache);
> +
> atomic_set(&cache->count, 1);
> spin_lock_init(&cache->lock);
> init_rwsem(&cache->data_rwsem);
> @@ -9542,6 +9565,13 @@ int btrfs_make_block_group(struct btrfs_trans_handle
> *trans,
> add_new_free_space(cache, root->fs_info, chunk_offset,
> chunk_offset + size);
>
> + ret = add_block_group_free_space(trans, root->fs_info, cache);
> + if (ret) {
> + btrfs_remove_free_space_cache(cache);
> + btrfs_put_block_group(cache);
> + return ret;
> + }
> +
Crap, so this definitely isn't the right place to do this. If we end up
allocating a new block group while modifying the free space tree, we'll
call through here and deadlock on the free space tree. Instead, I think
I'll have to delay this until either the first time we attempt to modify
the free space tree for a block group or in
btrfs_create_pending_block_groups(), whichever happens first.
> free_excluded_extents(root, cache);
>
> /*
> @@ -9885,6 +9915,10 @@ int btrfs_remove_block_group(struct btrfs_trans_handle
> *trans,
>
> unlock_chunks(root);
>
> + ret = remove_block_group_free_space(trans, root->fs_info, block_group);
> + if (ret)
> + goto out;
> +
> btrfs_put_block_group(block_group);
> btrfs_put_block_group(block_group);
>
> --
> 2.5.1
>
--
Omar
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