From 66d7e7f09f77456fe68683247d77721032a00ee5 Mon Sep 17 00:00:00 2001 From: Arne Jansen Date: Mon, 12 Sep 2011 15:26:38 +0200 Subject: Btrfs: mark delayed refs as for cow Add a for_cow parameter to add_delayed_*_ref and pass the appropriate value from every call site. The for_cow parameter will later on be used to determine if a ref will change anything with respect to qgroups. Delayed refs coming from relocation are always counted as for_cow, as they don't change subvol quota. Also pass in the fs_info for later use. btrfs_find_all_roots() will use this as an optimization, as changes that are for_cow will not change anything with respect to which root points to a certain leaf. Thus, we don't need to add the current sequence number to those delayed refs. Signed-off-by: Arne Jansen Signed-off-by: Jan Schmidt --- fs/btrfs/delayed-ref.c | 50 +++++++++++++++++++++++++++++++------------------- 1 file changed, 31 insertions(+), 19 deletions(-) (limited to 'fs/btrfs/delayed-ref.c') diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c index 125cf76fcd08..3a0f0ab804f4 100644 --- a/fs/btrfs/delayed-ref.c +++ b/fs/btrfs/delayed-ref.c @@ -390,7 +390,8 @@ update_existing_head_ref(struct btrfs_delayed_ref_node *existing, * this does all the dirty work in terms of maintaining the correct * overall modification count. */ -static noinline int add_delayed_ref_head(struct btrfs_trans_handle *trans, +static noinline int add_delayed_ref_head(struct btrfs_fs_info *fs_info, + struct btrfs_trans_handle *trans, struct btrfs_delayed_ref_node *ref, u64 bytenr, u64 num_bytes, int action, int is_data) @@ -468,10 +469,12 @@ static noinline int add_delayed_ref_head(struct btrfs_trans_handle *trans, /* * helper to insert a delayed tree ref into the rbtree. */ -static noinline int add_delayed_tree_ref(struct btrfs_trans_handle *trans, +static noinline int add_delayed_tree_ref(struct btrfs_fs_info *fs_info, + struct btrfs_trans_handle *trans, struct btrfs_delayed_ref_node *ref, u64 bytenr, u64 num_bytes, u64 parent, - u64 ref_root, int level, int action) + u64 ref_root, int level, int action, + int for_cow) { struct btrfs_delayed_ref_node *existing; struct btrfs_delayed_tree_ref *full_ref; @@ -522,11 +525,12 @@ static noinline int add_delayed_tree_ref(struct btrfs_trans_handle *trans, /* * helper to insert a delayed data ref into the rbtree. */ -static noinline int add_delayed_data_ref(struct btrfs_trans_handle *trans, +static noinline int add_delayed_data_ref(struct btrfs_fs_info *fs_info, + struct btrfs_trans_handle *trans, struct btrfs_delayed_ref_node *ref, u64 bytenr, u64 num_bytes, u64 parent, u64 ref_root, u64 owner, u64 offset, - int action) + int action, int for_cow) { struct btrfs_delayed_ref_node *existing; struct btrfs_delayed_data_ref *full_ref; @@ -554,6 +558,7 @@ static noinline int add_delayed_data_ref(struct btrfs_trans_handle *trans, full_ref->root = ref_root; ref->type = BTRFS_EXTENT_DATA_REF_KEY; } + full_ref->objectid = owner; full_ref->offset = offset; @@ -580,10 +585,12 @@ static noinline int add_delayed_data_ref(struct btrfs_trans_handle *trans, * to make sure the delayed ref is eventually processed before this * transaction commits. */ -int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans, +int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info, + struct btrfs_trans_handle *trans, u64 bytenr, u64 num_bytes, u64 parent, u64 ref_root, int level, int action, - struct btrfs_delayed_extent_op *extent_op) + struct btrfs_delayed_extent_op *extent_op, + int for_cow) { struct btrfs_delayed_tree_ref *ref; struct btrfs_delayed_ref_head *head_ref; @@ -610,12 +617,13 @@ int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans, * insert both the head node and the new ref without dropping * the spin lock */ - ret = add_delayed_ref_head(trans, &head_ref->node, bytenr, num_bytes, - action, 0); + ret = add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr, + num_bytes, action, 0); BUG_ON(ret); - ret = add_delayed_tree_ref(trans, &ref->node, bytenr, num_bytes, - parent, ref_root, level, action); + ret = add_delayed_tree_ref(fs_info, trans, &ref->node, bytenr, + num_bytes, parent, ref_root, level, action, + for_cow); BUG_ON(ret); spin_unlock(&delayed_refs->lock); return 0; @@ -624,11 +632,13 @@ int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans, /* * add a delayed data ref. it's similar to btrfs_add_delayed_tree_ref. */ -int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans, +int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info, + struct btrfs_trans_handle *trans, u64 bytenr, u64 num_bytes, u64 parent, u64 ref_root, u64 owner, u64 offset, int action, - struct btrfs_delayed_extent_op *extent_op) + struct btrfs_delayed_extent_op *extent_op, + int for_cow) { struct btrfs_delayed_data_ref *ref; struct btrfs_delayed_ref_head *head_ref; @@ -655,18 +665,20 @@ int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans, * insert both the head node and the new ref without dropping * the spin lock */ - ret = add_delayed_ref_head(trans, &head_ref->node, bytenr, num_bytes, - action, 1); + ret = add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr, + num_bytes, action, 1); BUG_ON(ret); - ret = add_delayed_data_ref(trans, &ref->node, bytenr, num_bytes, - parent, ref_root, owner, offset, action); + ret = add_delayed_data_ref(fs_info, trans, &ref->node, bytenr, + num_bytes, parent, ref_root, owner, offset, + action, for_cow); BUG_ON(ret); spin_unlock(&delayed_refs->lock); return 0; } -int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans, +int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info, + struct btrfs_trans_handle *trans, u64 bytenr, u64 num_bytes, struct btrfs_delayed_extent_op *extent_op) { @@ -683,7 +695,7 @@ int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans, delayed_refs = &trans->transaction->delayed_refs; spin_lock(&delayed_refs->lock); - ret = add_delayed_ref_head(trans, &head_ref->node, bytenr, + ret = add_delayed_ref_head(fs_info, trans, &head_ref->node, bytenr, num_bytes, BTRFS_UPDATE_DELAYED_HEAD, extent_op->is_data); BUG_ON(ret); -- cgit v1.2.3 From eebe063b7f916087cd5c61de57b20a3a30894a96 Mon Sep 17 00:00:00 2001 From: Arne Jansen Date: Wed, 14 Sep 2011 14:01:24 +0200 Subject: Btrfs: always save ref_root in delayed refs For consistent backref walking and (later) qgroup calculation the information to which root a delayed ref belongs is useful even for shared refs. Signed-off-by: Arne Jansen Signed-off-by: Jan Schmidt --- fs/btrfs/delayed-ref.c | 18 ++++++++---------- fs/btrfs/delayed-ref.h | 12 ++++-------- 2 files changed, 12 insertions(+), 18 deletions(-) (limited to 'fs/btrfs/delayed-ref.c') diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c index 3a0f0ab804f4..babd37badb43 100644 --- a/fs/btrfs/delayed-ref.c +++ b/fs/btrfs/delayed-ref.c @@ -495,13 +495,12 @@ static noinline int add_delayed_tree_ref(struct btrfs_fs_info *fs_info, ref->in_tree = 1; full_ref = btrfs_delayed_node_to_tree_ref(ref); - if (parent) { - full_ref->parent = parent; + full_ref->parent = parent; + full_ref->root = ref_root; + if (parent) ref->type = BTRFS_SHARED_BLOCK_REF_KEY; - } else { - full_ref->root = ref_root; + else ref->type = BTRFS_TREE_BLOCK_REF_KEY; - } full_ref->level = level; trace_btrfs_delayed_tree_ref(ref, full_ref, action); @@ -551,13 +550,12 @@ static noinline int add_delayed_data_ref(struct btrfs_fs_info *fs_info, ref->in_tree = 1; full_ref = btrfs_delayed_node_to_data_ref(ref); - if (parent) { - full_ref->parent = parent; + full_ref->parent = parent; + full_ref->root = ref_root; + if (parent) ref->type = BTRFS_SHARED_DATA_REF_KEY; - } else { - full_ref->root = ref_root; + else ref->type = BTRFS_EXTENT_DATA_REF_KEY; - } full_ref->objectid = owner; full_ref->offset = offset; diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h index 8316bff18d30..a5fb2bc83732 100644 --- a/fs/btrfs/delayed-ref.h +++ b/fs/btrfs/delayed-ref.h @@ -98,19 +98,15 @@ struct btrfs_delayed_ref_head { struct btrfs_delayed_tree_ref { struct btrfs_delayed_ref_node node; - union { - u64 root; - u64 parent; - }; + u64 root; + u64 parent; int level; }; struct btrfs_delayed_data_ref { struct btrfs_delayed_ref_node node; - union { - u64 root; - u64 parent; - }; + u64 root; + u64 parent; u64 objectid; u64 offset; }; -- cgit v1.2.3 From 00f04b88791ff49dc64ada18819d40a5b0671709 Mon Sep 17 00:00:00 2001 From: Arne Jansen Date: Wed, 14 Sep 2011 12:37:00 +0200 Subject: Btrfs: add sequence numbers to delayed refs Sequence numbers are needed to reconstruct the backrefs of a given extent to a certain point in time. The total set of backrefs consist of the set of backrefs recorded on disk plus the enqueued delayed refs for it that existed at that moment. This patch also adds a list that records all delayed refs which are currently in the process of being added. When walking all refs of an extent in btrfs_find_all_roots(), we freeze the current state of delayed refs, honor anythinh up to this point and prevent processing newer delayed refs to assert consistency. Signed-off-by: Arne Jansen Signed-off-by: Jan Schmidt --- fs/btrfs/delayed-ref.c | 34 ++++++++++++++++++++++++ fs/btrfs/delayed-ref.h | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++ fs/btrfs/transaction.c | 4 +++ 3 files changed, 108 insertions(+) (limited to 'fs/btrfs/delayed-ref.c') diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c index babd37badb43..a405db0320e8 100644 --- a/fs/btrfs/delayed-ref.c +++ b/fs/btrfs/delayed-ref.c @@ -101,6 +101,11 @@ static int comp_entry(struct btrfs_delayed_ref_node *ref2, return -1; if (ref1->type > ref2->type) return 1; + /* merging of sequenced refs is not allowed */ + if (ref1->seq < ref2->seq) + return -1; + if (ref1->seq > ref2->seq) + return 1; if (ref1->type == BTRFS_TREE_BLOCK_REF_KEY || ref1->type == BTRFS_SHARED_BLOCK_REF_KEY) { return comp_tree_refs(btrfs_delayed_node_to_tree_ref(ref2), @@ -209,6 +214,24 @@ int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans, return 0; } +int btrfs_check_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs, + u64 seq) +{ + struct seq_list *elem; + + assert_spin_locked(&delayed_refs->lock); + if (list_empty(&delayed_refs->seq_head)) + return 0; + + elem = list_first_entry(&delayed_refs->seq_head, struct seq_list, list); + if (seq >= elem->seq) { + pr_debug("holding back delayed_ref %llu, lowest is %llu (%p)\n", + seq, elem->seq, delayed_refs); + return 1; + } + return 0; +} + int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans, struct list_head *cluster, u64 start) { @@ -438,6 +461,7 @@ static noinline int add_delayed_ref_head(struct btrfs_fs_info *fs_info, ref->action = 0; ref->is_head = 1; ref->in_tree = 1; + ref->seq = 0; head_ref = btrfs_delayed_node_to_head(ref); head_ref->must_insert_reserved = must_insert_reserved; @@ -479,6 +503,7 @@ static noinline int add_delayed_tree_ref(struct btrfs_fs_info *fs_info, struct btrfs_delayed_ref_node *existing; struct btrfs_delayed_tree_ref *full_ref; struct btrfs_delayed_ref_root *delayed_refs; + u64 seq = 0; if (action == BTRFS_ADD_DELAYED_EXTENT) action = BTRFS_ADD_DELAYED_REF; @@ -494,6 +519,10 @@ static noinline int add_delayed_tree_ref(struct btrfs_fs_info *fs_info, ref->is_head = 0; ref->in_tree = 1; + if (need_ref_seq(for_cow, ref_root)) + seq = inc_delayed_seq(delayed_refs); + ref->seq = seq; + full_ref = btrfs_delayed_node_to_tree_ref(ref); full_ref->parent = parent; full_ref->root = ref_root; @@ -534,6 +563,7 @@ static noinline int add_delayed_data_ref(struct btrfs_fs_info *fs_info, struct btrfs_delayed_ref_node *existing; struct btrfs_delayed_data_ref *full_ref; struct btrfs_delayed_ref_root *delayed_refs; + u64 seq = 0; if (action == BTRFS_ADD_DELAYED_EXTENT) action = BTRFS_ADD_DELAYED_REF; @@ -549,6 +579,10 @@ static noinline int add_delayed_data_ref(struct btrfs_fs_info *fs_info, ref->is_head = 0; ref->in_tree = 1; + if (need_ref_seq(for_cow, ref_root)) + seq = inc_delayed_seq(delayed_refs); + ref->seq = seq; + full_ref = btrfs_delayed_node_to_data_ref(ref); full_ref->parent = parent; full_ref->root = ref_root; diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h index a5fb2bc83732..174416f7882b 100644 --- a/fs/btrfs/delayed-ref.h +++ b/fs/btrfs/delayed-ref.h @@ -33,6 +33,9 @@ struct btrfs_delayed_ref_node { /* the size of the extent */ u64 num_bytes; + /* seq number to keep track of insertion order */ + u64 seq; + /* ref count on this data structure */ atomic_t refs; @@ -136,6 +139,20 @@ struct btrfs_delayed_ref_root { int flushing; u64 run_delayed_start; + + /* + * seq number of delayed refs. We need to know if a backref was being + * added before the currently processed ref or afterwards. + */ + u64 seq; + + /* + * seq_list holds a list of all seq numbers that are currently being + * added to the list. While walking backrefs (btrfs_find_all_roots, + * qgroups), which might take some time, no newer ref must be processed, + * as it might influence the outcome of the walk. + */ + struct list_head seq_head; }; static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref) @@ -171,6 +188,59 @@ int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans, struct btrfs_delayed_ref_head *head); int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans, struct list_head *cluster, u64 search_start); + +struct seq_list { + struct list_head list; + u64 seq; +}; + +static inline u64 inc_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs) +{ + assert_spin_locked(&delayed_refs->lock); + ++delayed_refs->seq; + return delayed_refs->seq; +} + +static inline void +btrfs_get_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs, + struct seq_list *elem) +{ + assert_spin_locked(&delayed_refs->lock); + elem->seq = delayed_refs->seq; + list_add_tail(&elem->list, &delayed_refs->seq_head); +} + +static inline void +btrfs_put_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs, + struct seq_list *elem) +{ + spin_lock(&delayed_refs->lock); + list_del(&elem->list); + spin_unlock(&delayed_refs->lock); +} + +int btrfs_check_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs, + u64 seq); + +/* + * delayed refs with a ref_seq > 0 must be held back during backref walking. + * this only applies to items in one of the fs-trees. for_cow items never need + * to be held back, so they won't get a ref_seq number. + */ +static inline int need_ref_seq(int for_cow, u64 rootid) +{ + if (for_cow) + return 0; + + if (rootid == BTRFS_FS_TREE_OBJECTID) + return 1; + + if ((s64)rootid >= (s64)BTRFS_FIRST_FREE_OBJECTID) + return 1; + + return 0; +} + /* * a node might live in a head or a regular ref, this lets you * test for the proper type to use. diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index a2bfedcbcabc..31a7393af64e 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -36,6 +36,8 @@ static noinline void put_transaction(struct btrfs_transaction *transaction) WARN_ON(atomic_read(&transaction->use_count) == 0); if (atomic_dec_and_test(&transaction->use_count)) { BUG_ON(!list_empty(&transaction->list)); + WARN_ON(transaction->delayed_refs.root.rb_node); + WARN_ON(!list_empty(&transaction->delayed_refs.seq_head)); memset(transaction, 0, sizeof(*transaction)); kmem_cache_free(btrfs_transaction_cachep, transaction); } @@ -108,8 +110,10 @@ loop: cur_trans->delayed_refs.num_heads = 0; cur_trans->delayed_refs.flushing = 0; cur_trans->delayed_refs.run_delayed_start = 0; + cur_trans->delayed_refs.seq = 1; spin_lock_init(&cur_trans->commit_lock); spin_lock_init(&cur_trans->delayed_refs.lock); + INIT_LIST_HEAD(&cur_trans->delayed_refs.seq_head); INIT_LIST_HEAD(&cur_trans->pending_snapshots); list_add_tail(&cur_trans->list, &root->fs_info->trans_list); -- cgit v1.2.3 From d1270cd91f308c9d22b2804720c36ccd32dbc35e Mon Sep 17 00:00:00 2001 From: Arne Jansen Date: Tue, 13 Sep 2011 15:16:43 +0200 Subject: Btrfs: put back delayed refs that are too new When processing a delayed ref, first check if there are still old refs in the process of being added. If so, put this ref back to the tree. To avoid looping on this ref, choose a newer one in the next loop. btrfs_find_ref_cluster has to take care of that. Signed-off-by: Arne Jansen Signed-off-by: Jan Schmidt --- fs/btrfs/delayed-ref.c | 43 +++++++++++++++++++++++++------------------ fs/btrfs/extent-tree.c | 27 ++++++++++++++++++++++----- 2 files changed, 47 insertions(+), 23 deletions(-) (limited to 'fs/btrfs/delayed-ref.c') diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c index a405db0320e8..ee181989d444 100644 --- a/fs/btrfs/delayed-ref.c +++ b/fs/btrfs/delayed-ref.c @@ -155,16 +155,22 @@ static struct btrfs_delayed_ref_node *tree_insert(struct rb_root *root, /* * find an head entry based on bytenr. This returns the delayed ref - * head if it was able to find one, or NULL if nothing was in that spot + * head if it was able to find one, or NULL if nothing was in that spot. + * If return_bigger is given, the next bigger entry is returned if no exact + * match is found. */ static struct btrfs_delayed_ref_node *find_ref_head(struct rb_root *root, u64 bytenr, - struct btrfs_delayed_ref_node **last) + struct btrfs_delayed_ref_node **last, + int return_bigger) { - struct rb_node *n = root->rb_node; + struct rb_node *n; struct btrfs_delayed_ref_node *entry; - int cmp; + int cmp = 0; +again: + n = root->rb_node; + entry = NULL; while (n) { entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node); WARN_ON(!entry->in_tree); @@ -187,6 +193,19 @@ static struct btrfs_delayed_ref_node *find_ref_head(struct rb_root *root, else return entry; } + if (entry && return_bigger) { + if (cmp > 0) { + n = rb_next(&entry->rb_node); + if (!n) + n = rb_first(root); + entry = rb_entry(n, struct btrfs_delayed_ref_node, + rb_node); + bytenr = entry->bytenr; + return_bigger = 0; + goto again; + } + return entry; + } return NULL; } @@ -246,20 +265,8 @@ int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans, node = rb_first(&delayed_refs->root); } else { ref = NULL; - find_ref_head(&delayed_refs->root, start, &ref); + find_ref_head(&delayed_refs->root, start + 1, &ref, 1); if (ref) { - struct btrfs_delayed_ref_node *tmp; - - node = rb_prev(&ref->rb_node); - while (node) { - tmp = rb_entry(node, - struct btrfs_delayed_ref_node, - rb_node); - if (tmp->bytenr < start) - break; - ref = tmp; - node = rb_prev(&ref->rb_node); - } node = &ref->rb_node; } else node = rb_first(&delayed_refs->root); @@ -748,7 +755,7 @@ btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr) struct btrfs_delayed_ref_root *delayed_refs; delayed_refs = &trans->transaction->delayed_refs; - ref = find_ref_head(&delayed_refs->root, bytenr, NULL); + ref = find_ref_head(&delayed_refs->root, bytenr, NULL, 0); if (ref) return btrfs_delayed_node_to_head(ref); return NULL; diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index dc8b9a834596..bbcca12fbbba 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -2236,6 +2236,28 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans, } } + /* + * locked_ref is the head node, so we have to go one + * node back for any delayed ref updates + */ + ref = select_delayed_ref(locked_ref); + + if (ref && ref->seq && + btrfs_check_delayed_seq(delayed_refs, ref->seq)) { + /* + * there are still refs with lower seq numbers in the + * process of being added. Don't run this ref yet. + */ + list_del_init(&locked_ref->cluster); + mutex_unlock(&locked_ref->mutex); + locked_ref = NULL; + delayed_refs->num_heads_ready++; + spin_unlock(&delayed_refs->lock); + cond_resched(); + spin_lock(&delayed_refs->lock); + continue; + } + /* * record the must insert reserved flag before we * drop the spin lock. @@ -2246,11 +2268,6 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans, extent_op = locked_ref->extent_op; locked_ref->extent_op = NULL; - /* - * locked_ref is the head node, so we have to go one - * node back for any delayed ref updates - */ - ref = select_delayed_ref(locked_ref); if (!ref) { /* All delayed refs have been processed, Go ahead * and send the head node to run_one_delayed_ref, -- cgit v1.2.3 From a168650c08300434e1456abe7b6451f1448230d3 Mon Sep 17 00:00:00 2001 From: Jan Schmidt Date: Mon, 12 Dec 2011 16:10:07 +0100 Subject: Btrfs: add waitqueue instead of doing busy waiting for more delayed refs Now that we may be holding back delayed refs for a limited period, we might end up having no runnable delayed refs. Without this commit, we'd do busy waiting in that thread until another (runnable) ref arives. Instead, we're detecting this situation and use a waitqueue, such that we only try to run more refs after a) another runnable ref was added or b) delayed refs are no longer held back Signed-off-by: Jan Schmidt --- fs/btrfs/delayed-ref.c | 8 +++++++ fs/btrfs/delayed-ref.h | 7 ++++++ fs/btrfs/extent-tree.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++++- fs/btrfs/transaction.c | 1 + 4 files changed, 74 insertions(+), 1 deletion(-) (limited to 'fs/btrfs/delayed-ref.c') diff --git a/fs/btrfs/delayed-ref.c b/fs/btrfs/delayed-ref.c index ee181989d444..66e4f29505a3 100644 --- a/fs/btrfs/delayed-ref.c +++ b/fs/btrfs/delayed-ref.c @@ -664,6 +664,9 @@ int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info, num_bytes, parent, ref_root, level, action, for_cow); BUG_ON(ret); + if (!need_ref_seq(for_cow, ref_root) && + waitqueue_active(&delayed_refs->seq_wait)) + wake_up(&delayed_refs->seq_wait); spin_unlock(&delayed_refs->lock); return 0; } @@ -712,6 +715,9 @@ int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info, num_bytes, parent, ref_root, owner, offset, action, for_cow); BUG_ON(ret); + if (!need_ref_seq(for_cow, ref_root) && + waitqueue_active(&delayed_refs->seq_wait)) + wake_up(&delayed_refs->seq_wait); spin_unlock(&delayed_refs->lock); return 0; } @@ -739,6 +745,8 @@ int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info, extent_op->is_data); BUG_ON(ret); + if (waitqueue_active(&delayed_refs->seq_wait)) + wake_up(&delayed_refs->seq_wait); spin_unlock(&delayed_refs->lock); return 0; } diff --git a/fs/btrfs/delayed-ref.h b/fs/btrfs/delayed-ref.h index 174416f7882b..d8f244d94925 100644 --- a/fs/btrfs/delayed-ref.h +++ b/fs/btrfs/delayed-ref.h @@ -153,6 +153,12 @@ struct btrfs_delayed_ref_root { * as it might influence the outcome of the walk. */ struct list_head seq_head; + + /* + * when the only refs we have in the list must not be processed, we want + * to wait for more refs to show up or for the end of backref walking. + */ + wait_queue_head_t seq_wait; }; static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref) @@ -216,6 +222,7 @@ btrfs_put_delayed_seq(struct btrfs_delayed_ref_root *delayed_refs, { spin_lock(&delayed_refs->lock); list_del(&elem->list); + wake_up(&delayed_refs->seq_wait); spin_unlock(&delayed_refs->lock); } diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index bbcca12fbbba..0a435e2e143e 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -2300,7 +2300,12 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans, ref->in_tree = 0; rb_erase(&ref->rb_node, &delayed_refs->root); delayed_refs->num_entries--; - + /* + * we modified num_entries, but as we're currently running + * delayed refs, skip + * wake_up(&delayed_refs->seq_wait); + * here. + */ spin_unlock(&delayed_refs->lock); ret = run_one_delayed_ref(trans, root, ref, extent_op, @@ -2317,6 +2322,23 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans, return count; } + +static void wait_for_more_refs(struct btrfs_delayed_ref_root *delayed_refs, + unsigned long num_refs) +{ + struct list_head *first_seq = delayed_refs->seq_head.next; + + spin_unlock(&delayed_refs->lock); + pr_debug("waiting for more refs (num %ld, first %p)\n", + num_refs, first_seq); + wait_event(delayed_refs->seq_wait, + num_refs != delayed_refs->num_entries || + delayed_refs->seq_head.next != first_seq); + pr_debug("done waiting for more refs (num %ld, first %p)\n", + delayed_refs->num_entries, delayed_refs->seq_head.next); + spin_lock(&delayed_refs->lock); +} + /* * this starts processing the delayed reference count updates and * extent insertions we have queued up so far. count can be @@ -2332,8 +2354,11 @@ int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans, struct btrfs_delayed_ref_node *ref; struct list_head cluster; int ret; + u64 delayed_start; int run_all = count == (unsigned long)-1; int run_most = 0; + unsigned long num_refs = 0; + int consider_waiting; if (root == root->fs_info->extent_root) root = root->fs_info->tree_root; @@ -2341,6 +2366,7 @@ int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans, delayed_refs = &trans->transaction->delayed_refs; INIT_LIST_HEAD(&cluster); again: + consider_waiting = 0; spin_lock(&delayed_refs->lock); if (count == 0) { count = delayed_refs->num_entries * 2; @@ -2357,11 +2383,35 @@ again: * of refs to process starting at the first one we are able to * lock */ + delayed_start = delayed_refs->run_delayed_start; ret = btrfs_find_ref_cluster(trans, &cluster, delayed_refs->run_delayed_start); if (ret) break; + if (delayed_start >= delayed_refs->run_delayed_start) { + if (consider_waiting == 0) { + /* + * btrfs_find_ref_cluster looped. let's do one + * more cycle. if we don't run any delayed ref + * during that cycle (because we can't because + * all of them are blocked) and if the number of + * refs doesn't change, we avoid busy waiting. + */ + consider_waiting = 1; + num_refs = delayed_refs->num_entries; + } else { + wait_for_more_refs(delayed_refs, num_refs); + /* + * after waiting, things have changed. we + * dropped the lock and someone else might have + * run some refs, built new clusters and so on. + * therefore, we restart staleness detection. + */ + consider_waiting = 0; + } + } + ret = run_clustered_refs(trans, root, &cluster); BUG_ON(ret < 0); @@ -2369,6 +2419,11 @@ again: if (count == 0) break; + + if (ret || delayed_refs->run_delayed_start == 0) { + /* refs were run, let's reset staleness detection */ + consider_waiting = 0; + } } if (run_all) { @@ -4933,6 +4988,8 @@ static noinline int check_ref_cleanup(struct btrfs_trans_handle *trans, rb_erase(&head->node.rb_node, &delayed_refs->root); delayed_refs->num_entries--; + if (waitqueue_active(&delayed_refs->seq_wait)) + wake_up(&delayed_refs->seq_wait); /* * we don't take a ref on the node because we're removing it from the diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 31a7393af64e..04c5c7c2c32f 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -111,6 +111,7 @@ loop: cur_trans->delayed_refs.flushing = 0; cur_trans->delayed_refs.run_delayed_start = 0; cur_trans->delayed_refs.seq = 1; + init_waitqueue_head(&cur_trans->delayed_refs.seq_wait); spin_lock_init(&cur_trans->commit_lock); spin_lock_init(&cur_trans->delayed_refs.lock); INIT_LIST_HEAD(&cur_trans->delayed_refs.seq_head); 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