The main balance function has two loops which are functionally identical in their looping mechanism, but which perform a different operation on the chunks they loop over. To avoid repeating code more than necessary, factor this loop out into a separate iterator function which takes a function parameter for the action to be performed.
Signed-off-by: Hugo Mills <h...@carfax.org.uk> --- fs/btrfs/volumes.c | 174 +++++++++++++++++++++++++++++---------------------- 1 files changed, 99 insertions(+), 75 deletions(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index f38b231..a81fd3c 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -2014,6 +2014,97 @@ static u64 div_factor(u64 num, int factor) return num; } +/* Define a type, and two functions which can be used for the two + * phases of the balance operation: one for counting chunks, and one + * for actually moving them. */ +typedef void (*balance_iterator_function)(struct btrfs_root *, + struct btrfs_balance_info *, + struct btrfs_path *, + struct btrfs_key *); + +static void balance_count_chunks(struct btrfs_root *chunk_root, + struct btrfs_balance_info *bal_info, + struct btrfs_path *path, + struct btrfs_key *key) +{ + spin_lock(&chunk_root->fs_info->balance_info_lock); + bal_info->expected++; + spin_unlock(&chunk_root->fs_info->balance_info_lock); +} + +static void balance_move_chunks(struct btrfs_root *chunk_root, + struct btrfs_balance_info *bal_info, + struct btrfs_path *path, + struct btrfs_key *key) +{ + int ret; + + ret = btrfs_relocate_chunk(chunk_root, + chunk_root->root_key.objectid, + key->objectid, + key->offset); + BUG_ON(ret && ret != -ENOSPC); + spin_lock(&chunk_root->fs_info->balance_info_lock); + bal_info->completed++; + spin_unlock(&chunk_root->fs_info->balance_info_lock); + printk(KERN_INFO "btrfs: balance: %u/%u block groups completed\n", + bal_info->completed, bal_info->expected); +} + +/* Iterate through all chunks, performing some function on each one. */ +static int balance_iterate_chunks(struct btrfs_root *chunk_root, + struct btrfs_balance_info *bal_info, + balance_iterator_function iterator_fn) +{ + int ret = 0; + struct btrfs_path *path; + struct btrfs_key key; + struct btrfs_key found_key; + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + + key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID; + key.offset = (u64)-1; + key.type = BTRFS_CHUNK_ITEM_KEY; + + while (!bal_info->cancel_pending) { + ret = btrfs_search_slot(NULL, chunk_root, &key, path, 0, 0); + if (ret < 0) + break; + /* + * this shouldn't happen, it means the last relocate + * failed + */ + if (ret == 0) + break; + + ret = btrfs_previous_item(chunk_root, path, 0, + BTRFS_CHUNK_ITEM_KEY); + if (ret) + break; + + btrfs_item_key_to_cpu(path->nodes[0], &found_key, + path->slots[0]); + if (found_key.objectid != key.objectid) + break; + + /* chunk zero is special */ + if (found_key.offset == 0) + break; + + /* Call the function to do the work for this chunk */ + btrfs_release_path(path); + iterator_fn(chunk_root, bal_info, path, &found_key); + + key.offset = found_key.offset - 1; + } + + btrfs_free_path(path); + return ret; +} + int btrfs_balance(struct btrfs_root *dev_root) { int ret; @@ -2021,11 +2112,8 @@ int btrfs_balance(struct btrfs_root *dev_root) struct btrfs_device *device; u64 old_size; u64 size_to_free; - struct btrfs_path *path; - struct btrfs_key key; struct btrfs_root *chunk_root = dev_root->fs_info->chunk_root; struct btrfs_trans_handle *trans; - struct btrfs_key found_key; struct btrfs_balance_info *bal_info; if (dev_root->fs_info->sb->s_flags & MS_RDONLY) @@ -2046,8 +2134,7 @@ int btrfs_balance(struct btrfs_root *dev_root) } spin_lock(&dev_root->fs_info->balance_info_lock); dev_root->fs_info->balance_info = bal_info; - bal_info->expected = -1; /* One less than actually counted, - because chunk 0 is special */ + bal_info->expected = 0; bal_info->completed = 0; bal_info->cancel_pending = 0; spin_unlock(&dev_root->fs_info->balance_info_lock); @@ -2076,86 +2163,23 @@ int btrfs_balance(struct btrfs_root *dev_root) } /* step two, count the chunks */ - path = btrfs_alloc_path(); - if (!path) { - ret = -ENOMEM; + ret = balance_iterate_chunks(chunk_root, bal_info, + balance_count_chunks); + if (ret) goto error; - } - - key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID; - key.offset = (u64)-1; - key.type = BTRFS_CHUNK_ITEM_KEY; - - ret = btrfs_search_slot(NULL, chunk_root, &key, path, 0, 0); - if (ret <= 0) { - printk(KERN_ERR "btrfs: Failed to find the last chunk.\n"); - BUG(); - } - - while (1) { - ret = btrfs_previous_item(chunk_root, path, 0, - BTRFS_CHUNK_ITEM_KEY); - if (ret) - break; - - spin_lock(&dev_root->fs_info->balance_info_lock); - bal_info->expected++; - spin_unlock(&dev_root->fs_info->balance_info_lock); - } - - btrfs_release_path(path); /* step three, relocate all the chunks */ - key.objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID; - key.offset = (u64)-1; - key.type = BTRFS_CHUNK_ITEM_KEY; - - while (!bal_info->cancel_pending) { - ret = btrfs_search_slot(NULL, chunk_root, &key, path, 0, 0); - if (ret < 0) - goto error; - - /* - * this shouldn't happen, it means the last relocate - * failed - */ - if (ret == 0) - break; - - ret = btrfs_previous_item(chunk_root, path, 0, - BTRFS_CHUNK_ITEM_KEY); - if (ret) - break; - - btrfs_item_key_to_cpu(path->nodes[0], &found_key, - path->slots[0]); - if (found_key.objectid != key.objectid) - break; - - /* chunk zero is special */ - if (found_key.offset == 0) - break; + ret = balance_iterate_chunks(chunk_root, bal_info, + balance_move_chunks); + if (ret) + goto error; - btrfs_release_path(path); - ret = btrfs_relocate_chunk(chunk_root, - chunk_root->root_key.objectid, - found_key.objectid, - found_key.offset); - BUG_ON(ret && ret != -ENOSPC); - key.offset = found_key.offset - 1; - spin_lock(&dev_root->fs_info->balance_info_lock); - bal_info->completed++; - spin_unlock(&dev_root->fs_info->balance_info_lock); - printk(KERN_INFO "btrfs: balance: %u/%u block groups completed\n", - bal_info->completed, bal_info->expected); - } ret = 0; if (bal_info->cancel_pending) { printk(KERN_INFO "btrfs: balance cancelled\n"); ret = -EINTR; } error: - btrfs_free_path(path); spin_lock(&dev_root->fs_info->balance_info_lock); kfree(dev_root->fs_info->balance_info); dev_root->fs_info->balance_info = NULL; -- 1.7.2.5 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html