diff options
| -rw-r--r-- | fs/btrfs/block-group.c | 516 | ||||
| -rw-r--r-- | fs/btrfs/block-group.h | 3 | ||||
| -rw-r--r-- | fs/btrfs/ctree.h | 3 | ||||
| -rw-r--r-- | fs/btrfs/extent-tree.c | 518 |
4 files changed, 519 insertions, 521 deletions
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c index a4b76e57680a..763bab380379 100644 --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -12,6 +12,7 @@ #include "ref-verify.h" #include "sysfs.h" #include "tree-log.h" +#include "delalloc-space.h" void btrfs_get_block_group(struct btrfs_block_group_cache *cache) { @@ -2003,3 +2004,518 @@ void btrfs_dec_block_group_ro(struct btrfs_block_group_cache *cache) spin_unlock(&cache->lock); spin_unlock(&sinfo->lock); } + +static int write_one_cache_group(struct btrfs_trans_handle *trans, + struct btrfs_path *path, + struct btrfs_block_group_cache *cache) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + int ret; + struct btrfs_root *extent_root = fs_info->extent_root; + unsigned long bi; + struct extent_buffer *leaf; + + ret = btrfs_search_slot(trans, extent_root, &cache->key, path, 0, 1); + if (ret) { + if (ret > 0) + ret = -ENOENT; + goto fail; + } + + leaf = path->nodes[0]; + bi = btrfs_item_ptr_offset(leaf, path->slots[0]); + write_extent_buffer(leaf, &cache->item, bi, sizeof(cache->item)); + btrfs_mark_buffer_dirty(leaf); +fail: + btrfs_release_path(path); + return ret; + +} + +static int cache_save_setup(struct btrfs_block_group_cache *block_group, + struct btrfs_trans_handle *trans, + struct btrfs_path *path) +{ + struct btrfs_fs_info *fs_info = block_group->fs_info; + struct btrfs_root *root = fs_info->tree_root; + struct inode *inode = NULL; + struct extent_changeset *data_reserved = NULL; + u64 alloc_hint = 0; + int dcs = BTRFS_DC_ERROR; + u64 num_pages = 0; + int retries = 0; + int ret = 0; + + /* + * If this block group is smaller than 100 megs don't bother caching the + * block group. + */ + if (block_group->key.offset < (100 * SZ_1M)) { + spin_lock(&block_group->lock); + block_group->disk_cache_state = BTRFS_DC_WRITTEN; + spin_unlock(&block_group->lock); + return 0; + } + + if (trans->aborted) + return 0; +again: + inode = lookup_free_space_inode(block_group, path); + if (IS_ERR(inode) && PTR_ERR(inode) != -ENOENT) { + ret = PTR_ERR(inode); + btrfs_release_path(path); + goto out; + } + + if (IS_ERR(inode)) { + BUG_ON(retries); + retries++; + + if (block_group->ro) + goto out_free; + + ret = create_free_space_inode(trans, block_group, path); + if (ret) + goto out_free; + goto again; + } + + /* + * We want to set the generation to 0, that way if anything goes wrong + * from here on out we know not to trust this cache when we load up next + * time. + */ + BTRFS_I(inode)->generation = 0; + ret = btrfs_update_inode(trans, root, inode); + if (ret) { + /* + * So theoretically we could recover from this, simply set the + * super cache generation to 0 so we know to invalidate the + * cache, but then we'd have to keep track of the block groups + * that fail this way so we know we _have_ to reset this cache + * before the next commit or risk reading stale cache. So to + * limit our exposure to horrible edge cases lets just abort the + * transaction, this only happens in really bad situations + * anyway. + */ + btrfs_abort_transaction(trans, ret); + goto out_put; + } + WARN_ON(ret); + + /* We've already setup this transaction, go ahead and exit */ + if (block_group->cache_generation == trans->transid && + i_size_read(inode)) { + dcs = BTRFS_DC_SETUP; + goto out_put; + } + + if (i_size_read(inode) > 0) { + ret = btrfs_check_trunc_cache_free_space(fs_info, + &fs_info->global_block_rsv); + if (ret) + goto out_put; + + ret = btrfs_truncate_free_space_cache(trans, NULL, inode); + if (ret) + goto out_put; + } + + spin_lock(&block_group->lock); + if (block_group->cached != BTRFS_CACHE_FINISHED || + !btrfs_test_opt(fs_info, SPACE_CACHE)) { + /* + * don't bother trying to write stuff out _if_ + * a) we're not cached, + * b) we're with nospace_cache mount option, + * c) we're with v2 space_cache (FREE_SPACE_TREE). + */ + dcs = BTRFS_DC_WRITTEN; + spin_unlock(&block_group->lock); + goto out_put; + } + spin_unlock(&block_group->lock); + + /* + * We hit an ENOSPC when setting up the cache in this transaction, just + * skip doing the setup, we've already cleared the cache so we're safe. + */ + if (test_bit(BTRFS_TRANS_CACHE_ENOSPC, &trans->transaction->flags)) { + ret = -ENOSPC; + goto out_put; + } + + /* + * Try to preallocate enough space based on how big the block group is. + * Keep in mind this has to include any pinned space which could end up + * taking up quite a bit since it's not folded into the other space + * cache. + */ + num_pages = div_u64(block_group->key.offset, SZ_256M); + if (!num_pages) + num_pages = 1; + + num_pages *= 16; + num_pages *= PAGE_SIZE; + + ret = btrfs_check_data_free_space(inode, &data_reserved, 0, num_pages); + if (ret) + goto out_put; + + ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, num_pages, + num_pages, num_pages, + &alloc_hint); + /* + * Our cache requires contiguous chunks so that we don't modify a bunch + * of metadata or split extents when writing the cache out, which means + * we can enospc if we are heavily fragmented in addition to just normal + * out of space conditions. So if we hit this just skip setting up any + * other block groups for this transaction, maybe we'll unpin enough + * space the next time around. + */ + if (!ret) + dcs = BTRFS_DC_SETUP; + else if (ret == -ENOSPC) + set_bit(BTRFS_TRANS_CACHE_ENOSPC, &trans->transaction->flags); + +out_put: + iput(inode); +out_free: + btrfs_release_path(path); +out: + spin_lock(&block_group->lock); + if (!ret && dcs == BTRFS_DC_SETUP) + block_group->cache_generation = trans->transid; + block_group->disk_cache_state = dcs; + spin_unlock(&block_group->lock); + + extent_changeset_free(data_reserved); + return ret; +} + +int btrfs_setup_space_cache(struct btrfs_trans_handle *trans) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + struct btrfs_block_group_cache *cache, *tmp; + struct btrfs_transaction *cur_trans = trans->transaction; + struct btrfs_path *path; + + if (list_empty(&cur_trans->dirty_bgs) || + !btrfs_test_opt(fs_info, SPACE_CACHE)) + return 0; + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + + /* Could add new block groups, use _safe just in case */ + list_for_each_entry_safe(cache, tmp, &cur_trans->dirty_bgs, + dirty_list) { + if (cache->disk_cache_state == BTRFS_DC_CLEAR) + cache_save_setup(cache, trans, path); + } + + btrfs_free_path(path); + return 0; +} + +/* + * Transaction commit does final block group cache writeback during a critical + * section where nothing is allowed to change the FS. This is required in + * order for the cache to actually match the block group, but can introduce a + * lot of latency into the commit. + * + * So, btrfs_start_dirty_block_groups is here to kick off block group cache IO. + * There's a chance we'll have to redo some of it if the block group changes + * again during the commit, but it greatly reduces the commit latency by + * getting rid of the easy block groups while we're still allowing others to + * join the commit. + */ +int btrfs_start_dirty_block_groups(struct btrfs_trans_handle *trans) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + struct btrfs_block_group_cache *cache; + struct btrfs_transaction *cur_trans = trans->transaction; + int ret = 0; + int should_put; + struct btrfs_path *path = NULL; + LIST_HEAD(dirty); + struct list_head *io = &cur_trans->io_bgs; + int num_started = 0; + int loops = 0; + + spin_lock(&cur_trans->dirty_bgs_lock); + if (list_empty(&cur_trans->dirty_bgs)) { + spin_unlock(&cur_trans->dirty_bgs_lock); + return 0; + } + list_splice_init(&cur_trans->dirty_bgs, &dirty); + spin_unlock(&cur_trans->dirty_bgs_lock); + +again: + /* Make sure all the block groups on our dirty list actually exist */ + btrfs_create_pending_block_groups(trans); + + if (!path) { + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + } + + /* + * cache_write_mutex is here only to save us from balance or automatic + * removal of empty block groups deleting this block group while we are + * writing out the cache + */ + mutex_lock(&trans->transaction->cache_write_mutex); + while (!list_empty(&dirty)) { + bool drop_reserve = true; + + cache = list_first_entry(&dirty, + struct btrfs_block_group_cache, + dirty_list); + /* + * This can happen if something re-dirties a block group that + * is already under IO. Just wait for it to finish and then do + * it all again + */ + if (!list_empty(&cache->io_list)) { + list_del_init(&cache->io_list); + btrfs_wait_cache_io(trans, cache, path); + btrfs_put_block_group(cache); + } + + + /* + * btrfs_wait_cache_io uses the cache->dirty_list to decide if + * it should update the cache_state. Don't delete until after + * we wait. + * + * Since we're not running in the commit critical section + * we need the dirty_bgs_lock to protect from update_block_group + */ + spin_lock(&cur_trans->dirty_bgs_lock); + list_del_init(&cache->dirty_list); + spin_unlock(&cur_trans->dirty_bgs_lock); + + should_put = 1; + + cache_save_setup(cache, trans, path); + + if (cache->disk_cache_state == BTRFS_DC_SETUP) { + cache->io_ctl.inode = NULL; + ret = btrfs_write_out_cache(trans, cache, path); + if (ret == 0 && cache->io_ctl.inode) { + num_started++; + should_put = 0; + + /* + * The cache_write_mutex is protecting the + * io_list, also refer to the definition of + * btrfs_transaction::io_bgs for more details + */ + list_add_tail(&cache->io_list, io); + } else { + /* + * If we failed to write the cache, the + * generation will be bad and life goes on + */ + ret = 0; + } + } + if (!ret) { + ret = write_one_cache_group(trans, path, cache); + /* + * Our block group might still be attached to the list + * of new block groups in the transaction handle of some + * other task (struct btrfs_trans_handle->new_bgs). This + * means its block group item isn't yet in the extent + * tree. If this happens ignore the error, as we will + * try again later in the critical section of the + * transaction commit. + */ + if (ret == -ENOENT) { + ret = 0; + spin_lock(&cur_trans->dirty_bgs_lock); + if (list_empty(&cache->dirty_list)) { + list_add_tail(&cache->dirty_list, + &cur_trans->dirty_bgs); + btrfs_get_block_group(cache); + drop_reserve = false; + } + spin_unlock(&cur_trans->dirty_bgs_lock); + } else if (ret) { + btrfs_abort_transaction(trans, ret); + } + } + + /* If it's not on the io list, we need to put the block group */ + if (should_put) + btrfs_put_block_group(cache); + if (drop_reserve) + btrfs_delayed_refs_rsv_release(fs_info, 1); + + if (ret) + break; + + /* + * Avoid blocking other tasks for too long. It might even save + * us from writing caches for block groups that are going to be + * removed. + */ + mutex_unlock(&trans->transaction->cache_write_mutex); + mutex_lock(&trans->transaction->cache_write_mutex); + } + mutex_unlock(&trans->transaction->cache_write_mutex); + + /* + * Go through delayed refs for all the stuff we've just kicked off + * and then loop back (just once) + */ + ret = btrfs_run_delayed_refs(trans, 0); + if (!ret && loops == 0) { + loops++; + spin_lock(&cur_trans->dirty_bgs_lock); + list_splice_init(&cur_trans->dirty_bgs, &dirty); + /* + * dirty_bgs_lock protects us from concurrent block group + * deletes too (not just cache_write_mutex). + */ + if (!list_empty(&dirty)) { + spin_unlock(&cur_trans->dirty_bgs_lock); + goto again; + } + spin_unlock(&cur_trans->dirty_bgs_lock); + } else if (ret < 0) { + btrfs_cleanup_dirty_bgs(cur_trans, fs_info); + } + + btrfs_free_path(path); + return ret; +} + +int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + struct btrfs_block_group_cache *cache; + struct btrfs_transaction *cur_trans = trans->transaction; + int ret = 0; + int should_put; + struct btrfs_path *path; + struct list_head *io = &cur_trans->io_bgs; + int num_started = 0; + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + + /* + * Even though we are in the critical section of the transaction commit, + * we can still have concurrent tasks adding elements to this + * transaction's list of dirty block groups. These tasks correspond to + * endio free space workers started when writeback finishes for a + * space cache, which run inode.c:btrfs_finish_ordered_io(), and can + * allocate new block groups as a result of COWing nodes of the root + * tree when updating the free space inode. The writeback for the space + * caches is triggered by an earlier call to + * btrfs_start_dirty_block_groups() and iterations of the following + * loop. + * Also we want to do the cache_save_setup first and then run the + * delayed refs to make sure we have the best chance at doing this all + * in one shot. + */ + spin_lock(&cur_trans->dirty_bgs_lock); + while (!list_empty(&cur_trans->dirty_bgs)) { + cache = list_first_entry(&cur_trans->dirty_bgs, + struct btrfs_block_group_cache, + dirty_list); + + /* + * This can happen if cache_save_setup re-dirties a block group + * that is already under IO. Just wait for it to finish and + * then do it all again + */ + if (!list_empty(&cache->io_list)) { + spin_unlock(&cur_trans->dirty_bgs_lock); + list_del_init(&cache->io_list); + btrfs_wait_cache_io(trans, cache, path); + btrfs_put_block_group(cache); + spin_lock(&cur_trans->dirty_bgs_lock); + } + + /* + * Don't remove from the dirty list until after we've waited on + * any pending IO + */ + list_del_init(&cache->dirty_list); + spin_unlock(&cur_trans->dirty_bgs_lock); + should_put = 1; + + cache_save_setup(cache, trans, path); + + if (!ret) + ret = btrfs_run_delayed_refs(trans, + (unsigned long) -1); + + if (!ret && cache->disk_cache_state == BTRFS_DC_SETUP) { + cache->io_ctl.inode = NULL; + ret = btrfs_write_out_cache(trans, cache, path); + if (ret == 0 && cache->io_ctl.inode) { + num_started++; + should_put = 0; + list_add_tail(&cache->io_list, io); + } else { + /* + * If we failed to write the cache, the + * generation will be bad and life goes on + */ + ret = 0; + } + } + if (!ret) { + ret = write_one_cache_group(trans, path, cache); + /* + * One of the free space endio workers might have + * created a new block group while updating a free space + * cache's inode (at inode.c:btrfs_finish_ordered_io()) + * and hasn't released its transaction handle yet, in + * which case the new block group is still attached to + * its transaction handle and its creation has not + * finished yet (no block group item in the extent tree + * yet, etc). If this is the case, wait for all free + * space endio workers to finish and retry. This is a + * a very rare case so no need for a more efficient and + * complex approach. + */ + if (ret == -ENOENT) { + wait_event(cur_trans->writer_wait, + atomic_read(&cur_trans->num_writers) == 1); + ret = write_one_cache_group(trans, path, cache); + } + if (ret) + btrfs_abort_transaction(trans, ret); + } + + /* If its not on the io list, we need to put the block group */ + if (should_put) + btrfs_put_block_group(cache); + btrfs_delayed_refs_rsv_release(fs_info, 1); + spin_lock(&cur_trans->dirty_bgs_lock); + } + spin_unlock(&cur_trans->dirty_bgs_lock); + + /* + * Refer to the definition of io_bgs member for details why it's safe + * to use it without any locking + */ + while (!list_empty(io)) { + cache = list_first_entry(io, struct btrfs_block_group_cache, + io_list); + list_del_init(&cache->io_list); + btrfs_wait_cache_io(trans, cache, path); + btrfs_put_block_group(cache); + } + + btrfs_free_path(path); + return ret; +} diff --git a/fs/btrfs/block-group.h b/fs/btrfs/block-group.h index a048a9408dec..749d34071f86 100644 --- a/fs/btrfs/block-group.h +++ b/fs/btrfs/block-group.h @@ -189,6 +189,9 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans, u64 bytes_used, void btrfs_create_pending_block_groups(struct btrfs_trans_handle *trans); int btrfs_inc_block_group_ro(struct btrfs_block_group_cache *cache); void btrfs_dec_block_group_ro(struct btrfs_block_group_cache *cache); +int btrfs_start_dirty_block_groups(struct btrfs_trans_handle *trans); +int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans); +int btrfs_setup_space_cache(struct btrfs_trans_handle *trans); static inline int btrfs_block_group_cache_done( struct btrfs_block_group_cache *cache) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index f97ad638983b..6b17573c2fe6 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -2523,9 +2523,6 @@ int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans); int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans, struct btrfs_ref *generic_ref); -int btrfs_start_dirty_block_groups(struct btrfs_trans_handle *trans); -int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans); -int btrfs_setup_space_cache(struct btrfs_trans_handle *trans); int btrfs_extent_readonly(struct btrfs_fs_info *fs_info, u64 bytenr); int btrfs_free_block_groups(struct btrfs_fs_info *info); void btrfs_get_block_group_trimming(struct btrfs_block_group_cache *cache); diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 519cf2cb5cef..0b78e5dcfe48 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -2511,524 +2511,6 @@ int btrfs_dec_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root, return __btrfs_mod_ref(trans, root, buf, full_backref, 0); } -static int write_one_cache_group(struct btrfs_trans_handle *trans, - struct btrfs_path *path, - struct btrfs_block_group_cache *cache) -{ - struct btrfs_fs_info *fs_info = trans->fs_info; - int ret; - struct btrfs_root *extent_root = fs_info->extent_root; - unsigned long bi; - struct extent_buffer *leaf; - - ret = btrfs_search_slot(trans, extent_root, &cache->key, path, 0, 1); - if (ret) { - if (ret > 0) - ret = -ENOENT; - goto fail; - } - - leaf = path->nodes[0]; - bi = btrfs_item_ptr_offset(leaf, path->slots[0]); - write_extent_buffer(leaf, &cache->item, bi, sizeof(cache->item)); - btrfs_mark_buffer_dirty(leaf); -fail: - btrfs_release_path(path); - return ret; - -} - -static int cache_save_setup(struct btrfs_block_group_cache *block_group, - struct btrfs_trans_handle *trans, - struct btrfs_path *path) -{ - struct btrfs_fs_info *fs_info = block_group->fs_info; - struct btrfs_root *root = fs_info->tree_root; - struct inode *inode = NULL; - struct extent_changeset *data_reserved = NULL; - u64 alloc_hint = 0; - int dcs = BTRFS_DC_ERROR; - u64 num_pages = 0; - int retries = 0; - int ret = 0; - - /* - * If this block group is smaller than 100 megs don't bother caching the - * block group. - */ - if (block_group->key.offset < (100 * SZ_1M)) { - spin_lock(&block_group->lock); - block_group->disk_cache_state = BTRFS_DC_WRITTEN; - spin_unlock(&block_group->lock); - return 0; - } - - if (trans->aborted) - return 0; -again: - inode = lookup_free_space_inode(block_group, path); - if (IS_ERR(inode) && PTR_ERR(inode) != -ENOENT) { - ret = PTR_ERR(inode); - btrfs_release_path(path); - goto out; - } - - if (IS_ERR(inode)) { - BUG_ON(retries); - retries++; - - if (block_group->ro) - goto out_free; - - ret = create_free_space_inode(trans, block_group, path); - if (ret) - goto out_free; - goto again; - } - - /* - * We want to set the generation to 0, that way if anything goes wrong - * from here on out we know not to trust this cache when we load up next - * time. - */ - BTRFS_I(inode)->generation = 0; - ret = btrfs_update_inode(trans, root, inode); - if (ret) { - /* - * So theoretically we could recover from this, simply set the - * super cache generation to 0 so we know to invalidate the - * cache, but then we'd have to keep track of the block groups - * that fail this way so we know we _have_ to reset this cache - * before the next commit or risk reading stale cache. So to - * limit our exposure to horrible edge cases lets just abort the - * transaction, this only happens in really bad situations - * anyway. - */ - btrfs_abort_transaction(trans, ret); - goto out_put; - } - WARN_ON(ret); - - /* We've already setup this transaction, go ahead and exit */ - if (block_group->cache_generation == trans->transid && - i_size_read(inode)) { - dcs = BTRFS_DC_SETUP; - goto out_put; - } - - if (i_size_read(inode) > 0) { - ret = btrfs_check_trunc_cache_free_space(fs_info, - &fs_info->global_block_rsv); - if (ret) - goto out_put; - - ret = btrfs_truncate_free_space_cache(trans, NULL, inode); - if (ret) - goto out_put; - } - - spin_lock(&block_group->lock); - if (block_group->cached != BTRFS_CACHE_FINISHED || - !btrfs_test_opt(fs_info, SPACE_CACHE)) { - /* - * don't bother trying to write stuff out _if_ - * a) we're not cached, - * b) we're with nospace_cache mount option, - * c) we're with v2 space_cache (FREE_SPACE_TREE). - */ - dcs = BTRFS_DC_WRITTEN; - spin_unlock(&block_group->lock); - goto out_put; - } - spin_unlock(&block_group->lock); - - /* - * We hit an ENOSPC when setting up the cache in this transaction, just - * skip doing the setup, we've already cleared the cache so we're safe. - */ - if (test_bit(BTRFS_TRANS_CACHE_ENOSPC, &trans->transaction->flags)) { - ret = -ENOSPC; - goto out_put; - } - - /* - * Try to preallocate enough space based on how big the block group is. - * Keep in mind this has to include any pinned space which could end up - * taking up quite a bit since it's not folded into the other space - * cache. - */ - num_pages = div_u64(block_group->key.offset, SZ_256M); - if (!num_pages) - num_pages = 1; - - num_pages *= 16; - num_pages *= PAGE_SIZE; - - ret = btrfs_check_data_free_space(inode, &data_reserved, 0, num_pages); - if (ret) - goto out_put; - - ret = btrfs_prealloc_file_range_trans(inode, trans, 0, 0, num_pages, - num_pages, num_pages, - &alloc_hint); - /* - * Our cache requires contiguous chunks so that we don't modify a bunch - * of metadata or split extents when writing the cache out, which means - * we can enospc if we are heavily fragmented in addition to just normal - * out of space conditions. So if we hit this just skip setting up any - * other block groups for this transaction, maybe we'll unpin enough - * space the next time around. - */ - if (!ret) - dcs = BTRFS_DC_SETUP; - else if (ret == -ENOSPC) - set_bit(BTRFS_TRANS_CACHE_ENOSPC, &trans->transaction->flags); - -out_put: - iput(inode); -out_free: - btrfs_release_path(path); -out: - spin_lock(&block_group->lock); - if (!ret && dcs == BTRFS_DC_SETUP) - block_group->cache_generation = trans->transid; - block_group->disk_cache_state = dcs; - spin_unlock(&block_group->lock); - - extent_changeset_free(data_reserved); - return ret; -} - -int btrfs_setup_space_cache(struct btrfs_trans_handle *trans) -{ - struct btrfs_fs_info *fs_info = trans->fs_info; - struct btrfs_block_group_cache *cache, *tmp; - struct btrfs_transaction *cur_trans = trans->transaction; - struct btrfs_path *path; - - if (list_empty(&cur_trans->dirty_bgs) || - !btrfs_test_opt(fs_info, SPACE_CACHE)) - return 0; - - path = btrfs_alloc_path(); - if (!path) - return -ENOMEM; - - /* Could add new block groups, use _safe just in case */ - list_for_each_entry_safe(cache, tmp, &cur_trans->dirty_bgs, - dirty_list) { - if (cache->disk_cache_state == BTRFS_DC_CLEAR) - cache_save_setup(cache, trans, path); - } - - btrfs_free_path(path); - return 0; -} - -/* - * transaction commit does final block group cache writeback during a - * critical section where nothing is allowed to change the FS. This is - * required in order for the cache to actually match the block group, - * but can introduce a lot of latency into the commit. - * - * So, btrfs_start_dirty_block_groups is here to kick off block group - * cache IO. There's a chance we'll have to redo some of it if the - * block group changes again during the commit, but it greatly reduces - * the commit latency by getting rid of the easy block groups while - * we're still allowing others to join the commit. - */ -int btrfs_start_dirty_block_groups(struct btrfs_trans_handle *trans) -{ - struct btrfs_fs_info *fs_info = trans->fs_info; - struct btrfs_block_group_cache *cache; - struct btrfs_transaction *cur_trans = trans->transaction; - int ret = 0; - int should_put; - struct btrfs_path *path = NULL; - LIST_HEAD(dirty); - struct list_head *io = &cur_trans->io_bgs; - int num_started = 0; - int loops = 0; - - spin_lock(&cur_trans->dirty_bgs_lock); - if (list_empty(&cur_trans->dirty_bgs)) { - spin_unlock(&cur_trans->dirty_bgs_lock); - return 0; - } - list_splice_init(&cur_trans->dirty_bgs, &dirty); - spin_unlock(&cur_trans->dirty_bgs_lock); - -again: - /* - * make sure all the block groups on our dirty list actually - * exist - */ - btrfs_create_pending_block_groups(trans); - - if (!path) { - path = btrfs_alloc_path(); - if (!path) - return -ENOMEM; - } - - /* - * cache_write_mutex is here only to save us from balance or automatic - * removal of empty block groups deleting this block group while we are - * writing out the cache - */ - mutex_lock(&trans->transaction->cache_write_mutex); - while (!list_empty(&dirty)) { - bool drop_reserve = true; - - cache = list_first_entry(&dirty, - struct btrfs_block_group_cache, - dirty_list); - /* - * this can happen if something re-dirties a block - * group that is already under IO. Just wait for it to - * finish and then do it all again - */ - if (!list_empty(&cache->io_list)) { - list_del_init(&cache->io_list); - btrfs_wait_cache_io(trans, cache, path); - btrfs_put_block_group(cache); - } - - - /* - * btrfs_wait_cache_io uses the cache->dirty_list to decide - * if it should update the cache_state. Don't delete - * until after we wait. - * - * Since we're not running in the commit critical section - * we need the dirty_bgs_lock to protect from update_block_group - */ - spin_lock(&cur_trans->dirty_bgs_lock); - list_del_init(&cache->dirty_list); - spin_unlock(&cur_trans->dirty_bgs_lock); - - should_put = 1; - - cache_save_setup(cache, trans, path); - - if (cache->disk_cache_state == BTRFS_DC_SETUP) { - cache->io_ctl.inode = NULL; - ret = btrfs_write_out_cache(trans, cache, path); - if (ret == 0 && cache->io_ctl.inode) { - num_started++; - should_put = 0; - - /* - * The cache_write_mutex is protecting the - * io_list, also refer to the definition of - * btrfs_transaction::io_bgs for more details - */ - list_add_tail(&cache->io_list, io); - } else { - /* - * if we failed to write the cache, the - * generation will be bad and life goes on - */ - ret = 0; - } - } - if (!ret) { - ret = write_one_cache_group(trans, path, cache); - /* - * Our block group might still be attached to the list - * of new block groups in the transaction handle of some - * other task (struct btrfs_trans_handle->new_bgs). This - * means its block group item isn't yet in the extent - * tree. If this happens ignore the error, as we will - * try again later in the critical section of the - * transaction commit. - */ - if (ret == -ENOENT) { - ret = 0; - spin_lock(&cur_trans->dirty_bgs_lock); - if (list_empty(&cache->dirty_list)) { - list_add_tail(&cache->dirty_list, - &cur_trans->dirty_bgs); - btrfs_get_block_group(cache); - drop_reserve = false; - } - spin_unlock(&cur_trans->dirty_bgs_lock); - } else if (ret) { - btrfs_abort_transaction(trans, ret); - } - } - - /* if it's not on the io list, we need to put the block group */ - if (should_put) - btrfs_put_block_group(cache); - if (drop_reserve) - btrfs_delayed_refs_rsv_release(fs_info, 1); - - if (ret) - break; - - /* - * Avoid blocking other tasks for too long. It might even save - * us from writing caches for block groups that are going to be - * removed. - */ - mutex_unlock(&trans->transaction->cache_write_mutex); - mutex_lock(&trans->transaction->cache_write_mutex); - } - mutex_unlock(&trans->transaction->cache_write_mutex); - - /* - * go through delayed refs for all the stuff we've just kicked off - * and then loop back (just once) - */ - ret = btrfs_run_delayed_refs(trans, 0); - if (!ret && loops == 0) { - loops++; - spin_lock(&cur_trans->dirty_bgs_lock); - list_splice_init(&cur_trans->dirty_bgs, &dirty); - /* - * dirty_bgs_lock protects us from concurrent block group - * deletes too (not just cache_write_mutex). - */ - if (!list_empty(&dirty)) { - spin_unlock(&cur_trans->dirty_bgs_lock); - goto again; - } - spin_unlock(&cur_trans->dirty_bgs_lock); - } else if (ret < 0) { - btrfs_cleanup_dirty_bgs(cur_trans, fs_info); - } - - btrfs_free_path(path); - return ret; -} - -int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans) -{ - struct btrfs_fs_info *fs_info = trans->fs_info; - struct btrfs_block_group_cache *cache; - struct btrfs_transaction *cur_trans = trans->transaction; - int ret = 0; - int should_put; - struct btrfs_path *path; - struct list_head *io = &cur_trans->io_bgs; - int num_started = 0; - - path = btrfs_alloc_path(); - if (!path) - return -ENOMEM; - - /* - * Even though we are in the critical section of the transaction commit, - * we can still have concurrent tasks adding elements to this - * transaction's list of dirty block groups. These tasks correspond to - * endio free space workers started when writeback finishes for a - * space cache, which run inode.c:btrfs_finish_ordered_io(), and can - * allocate new block groups as a result of COWing nodes of the root - * tree when updating the free space inode. The writeback for the space - * caches is triggered by an earlier call to - * btrfs_start_dirty_block_groups() and iterations of the following - * loop. - * Also we want to do the cache_save_setup first and then run the - * delayed refs to make sure we have the best chance at doing this all - * in one shot. - */ - spin_lock(&cur_trans->dirty_bgs_lock); - while (!list_empty(&cur_trans->dirty_bgs)) { - cache = list_first_entry(&cur_trans->dirty_bgs, - struct btrfs_block_group_cache, - dirty_list); - - /* - * this can happen if cache_save_setup re-dirties a block - * group that is already under IO. Just wait for it to - * finish and then do it all again - */ - if (!list_empty(&cache->io_list)) { - spin_unlock(&cur_trans->dirty_bgs_lock); - list_del_init(&cache->io_list); - btrfs_wait_cache_io(trans, cache, path); - btrfs_put_block_group(cache); - spin_lock(&cur_trans->dirty_bgs_lock); - } - - /* - * don't remove from the dirty list until after we've waited - * on any pending IO - */ - list_del_init(&cache->dirty_list); - spin_unlock(&cur_trans->dirty_bgs_lock); - should_put = 1; - - cache_save_setup(cache, trans, path); - - if (!ret) - ret = btrfs_run_delayed_refs(trans, - (unsigned long) -1); - - if (!ret && cache->disk_cache_state == BTRFS_DC_SETUP) { - cache->io_ctl.inode = NULL; - ret = btrfs_write_out_cache(trans, cache, path); - if (ret == 0 && cache->io_ctl.inode) { - num_started++; - should_put = 0; - list_add_tail(&cache->io_list, io); - } else { - /* - * if we failed to write the cache, the - * generation will be bad and life goes on - */ - ret = 0; - } - } - if (!ret) { - ret = write_one_cache_group(trans, path, cache); - /* - * One of the free space endio workers might have - * created a new block group while updating a free space - * cache's inode (at inode.c:btrfs_finish_ordered_io()) - * and hasn't released its transaction handle yet, in - * which case the new block group is still attached to - * its transaction handle and its creation has not - * finished yet (no block group item in the extent tree - * yet, etc). If this is the case, wait for all free - * space endio workers to finish and retry. This is a - * a very rare case so no need for a more efficient and - * complex approach. - */ - if (ret == -ENOENT) { - wait_event(cur_trans->writer_wait, - atomic_read(&cur_trans->num_writers) == 1); - ret = write_one_cache_group(trans, path, cache); - } - if (ret) - btrfs_abort_transaction(trans, ret); - } - - /* if its not on the io list, we need to put the block group */ - if (should_put) - btrfs_put_block_group(cache); - btrfs_delayed_refs_rsv_release(fs_info, 1); - spin_lock(&cur_trans->dirty_bgs_lock); - } - spin_unlock(&cur_trans->dirty_bgs_lock); - - /* - * Refer to the definition of io_bgs member for details why it's safe - * to use it without any locking - */ - while (!list_empty(io)) { - cache = list_first_entry(io, struct btrfs_block_group_cache, - io_list); - list_del_init(&cache->io_list); - btrfs_wait_cache_io(trans, cache, path); - btrfs_put_block_group(cache); - } - - btrfs_free_path(path); - return ret; -} - int btrfs_extent_readonly(struct btrfs_fs_info *fs_info, u64 bytenr) { struct btrfs_block_group_cache *block_group; |