/* * Copyright (C) 2009 Oracle. All rights reserved. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public * License v2 as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public * License along with this program; if not, write to the * Free Software Foundation, Inc., 59 Temple Place - Suite 330, * Boston, MA 021110-1307, USA. */ #include <linux/sched.h> #include <linux/slab.h> #include <linux/sort.h> #include "ctree.h" #include "delayed-ref.h" #include "transaction.h" /* * delayed back reference update tracking. For subvolume trees * we queue up extent allocations and backref maintenance for * delayed processing. This avoids deep call chains where we * add extents in the middle of btrfs_search_slot, and it allows * us to buffer up frequently modified backrefs in an rb tree instead * of hammering updates on the extent allocation tree. */ /* * compare two delayed tree backrefs with same bytenr and type */ static int comp_tree_refs(struct btrfs_delayed_tree_ref *ref2, struct btrfs_delayed_tree_ref *ref1) { if (ref1->node.type == BTRFS_TREE_BLOCK_REF_KEY) { if (ref1->root < ref2->root) return -1; if (ref1->root > ref2->root) return 1; } else { if (ref1->parent < ref2->parent) return -1; if (ref1->parent > ref2->parent) return 1; } return 0; } /* * compare two delayed data backrefs with same bytenr and type */ static int comp_data_refs(struct btrfs_delayed_data_ref *ref2, struct btrfs_delayed_data_ref *ref1) { if (ref1->node.type == BTRFS_EXTENT_DATA_REF_KEY) { if (ref1->root < ref2->root) return -1; if (ref1->root > ref2->root) return 1; if (ref1->objectid < ref2->objectid) return -1; if (ref1->objectid > ref2->objectid) return 1; if (ref1->offset < ref2->offset) return -1; if (ref1->offset > ref2->offset) return 1; } else { if (ref1->parent < ref2->parent) return -1; if (ref1->parent > ref2->parent) return 1; } return 0; } /* * entries in the rb tree are ordered by the byte number of the extent, * type of the delayed backrefs and content of delayed backrefs. */ static int comp_entry(struct btrfs_delayed_ref_node *ref2, struct btrfs_delayed_ref_node *ref1) { if (ref1->bytenr < ref2->bytenr) return -1; if (ref1->bytenr > ref2->bytenr) return 1; if (ref1->is_head && ref2->is_head) return 0; if (ref2->is_head) return -1; if (ref1->is_head) return 1; if (ref1->type < ref2->type) return -1; if (ref1->type > ref2->type) 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), btrfs_delayed_node_to_tree_ref(ref1)); } else if (ref1->type == BTRFS_EXTENT_DATA_REF_KEY || ref1->type == BTRFS_SHARED_DATA_REF_KEY) { return comp_data_refs(btrfs_delayed_node_to_data_ref(ref2), btrfs_delayed_node_to_data_ref(ref1)); } BUG(); return 0; } /* * insert a new ref into the rbtree. This returns any existing refs * for the same (bytenr,parent) tuple, or NULL if the new node was properly * inserted. */ static struct btrfs_delayed_ref_node *tree_insert(struct rb_root *root, struct rb_node *node) { struct rb_node **p = &root->rb_node; struct rb_node *parent_node = NULL; struct btrfs_delayed_ref_node *entry; struct btrfs_delayed_ref_node *ins; int cmp; ins = rb_entry(node, struct btrfs_delayed_ref_node, rb_node); while (*p) { parent_node = *p; entry = rb_entry(parent_node, struct btrfs_delayed_ref_node, rb_node); cmp = comp_entry(entry, ins); if (cmp < 0) p = &(*p)->rb_left; else if (cmp > 0) p = &(*p)->rb_right; else return entry; } rb_link_node(node, parent_node, p); rb_insert_color(node, root); return NULL; } /* * 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 */ static struct btrfs_delayed_ref_node *find_ref_head(struct rb_root *root, u64 bytenr, struct btrfs_delayed_ref_node **last) { struct rb_node *n = root->rb_node; struct btrfs_delayed_ref_node *entry; int cmp; while (n) { entry = rb_entry(n, struct btrfs_delayed_ref_node, rb_node); WARN_ON(!entry->in_tree); if (last) *last = entry; if (bytenr < entry->bytenr) cmp = -1; else if (bytenr > entry->bytenr) cmp = 1; else if (!btrfs_delayed_ref_is_head(entry)) cmp = 1; else cmp = 0; if (cmp < 0) n = n->rb_left; else if (cmp > 0) n = n->rb_right; else return entry; } return NULL; } int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans, struct btrfs_delayed_ref_head *head) { struct btrfs_delayed_ref_root *delayed_refs; delayed_refs = &trans->transaction->delayed_refs; assert_spin_locked(&delayed_refs->lock); if (mutex_trylock(&head->mutex)) return 0; atomic_inc(&head->node.refs); spin_unlock(&delayed_refs->lock); mutex_lock(&head->mutex); spin_lock(&delayed_refs->lock); if (!head->node.in_tree) { mutex_unlock(&head->mutex); btrfs_put_delayed_ref(&head->node); return -EAGAIN; } btrfs_put_delayed_ref(&head->node); return 0; } int btrfs_find_ref_cluster(struct btrfs_trans_handle *trans, struct list_head *cluster, u64 start) { int count = 0; struct btrfs_delayed_ref_root *delayed_refs; struct rb_node *node; struct btrfs_delayed_ref_node *ref; struct btrfs_delayed_ref_head *head; delayed_refs = &trans->transaction->delayed_refs; if (start == 0) { node = rb_first(&delayed_refs->root); } else { ref = NULL; find_ref_head(&delayed_refs->root, start, &ref); 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); } again: while (node && count < 32) { ref = rb_entry(node, struct btrfs_delayed_ref_node, rb_node); if (btrfs_delayed_ref_is_head(ref)) { head = btrfs_delayed_node_to_head(ref); if (list_empty(&head->cluster)) { list_add_tail(&head->cluster, cluster); delayed_refs->run_delayed_start = head->node.bytenr; count++; WARN_ON(delayed_refs->num_heads_ready == 0); delayed_refs->num_heads_ready--; } else if (count) { /* the goal of the clustering is to find extents * that are likely to end up in the same extent * leaf on disk. So, we don't want them spread * all over the tree. Stop now if we've hit * a head that was already in use */ break; } } node = rb_next(node); } if (count) { return 0; } else if (start) { /* * we've gone to the end of the rbtree without finding any * clusters. start from the beginning and try again */ start = 0; node = rb_first(&delayed_refs->root); goto again; } return 1; } /* * helper function to update an extent delayed ref in the * rbtree. existing and update must both have the same * bytenr and parent * * This may free existing if the update cancels out whatever * operation it was doing. */ static noinline void update_existing_ref(struct btrfs_trans_handle *trans, struct btrfs_delayed_ref_root *delayed_refs, struct btrfs_delayed_ref_node *existing, struct btrfs_delayed_ref_node *update) { if (update->action != existing->action) { /* * this is effectively undoing either an add or a * drop. We decrement the ref_mod, and if it goes * down to zero we just delete the entry without * every changing the extent allocation tree. */ existing->ref_mod--; if (existing->ref_mod == 0) { rb_erase(&existing->rb_node, &delayed_refs->root); existing->in_tree = 0; btrfs_put_delayed_ref(existing); delayed_refs->num_entries--; if (trans->delayed_ref_updates) trans->delayed_ref_updates--; } else { WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY || existing->type == BTRFS_SHARED_BLOCK_REF_KEY); } } else { WARN_ON(existing->type == BTRFS_TREE_BLOCK_REF_KEY || existing->type == BTRFS_SHARED_BLOCK_REF_KEY); /* * the action on the existing ref matches * the action on the ref we're trying to add. * Bump the ref_mod by one so the backref that * is eventually added/removed has the correct * reference count */ existing->ref_mod += update->ref_mod; } } /* * helper function to update the accounting in the head ref * existing and update must have the same bytenr */ static noinline void update_existing_head_ref(struct btrfs_delayed_ref_node *existing, struct btrfs_delayed_ref_node *update) { struct btrfs_delayed_ref_head *existing_ref; struct btrfs_delayed_ref_head *ref; existing_ref = btrfs_delayed_node_to_head(existing); ref = btrfs_delayed_node_to_head(update); BUG_ON(existing_ref->is_data != ref->is_data); if (ref->must_insert_reserved) { /* if the extent was freed and then * reallocated before the delayed ref * entries were processed, we can end up * with an existing head ref without * the must_insert_reserved flag set. * Set it again here */ existing_ref->must_insert_reserved = ref->must_insert_reserved; /* * update the num_bytes so we make sure the accounting * is done correctly */ existing->num_bytes = update->num_bytes; } if (ref->extent_op) { if (!existing_ref->extent_op) { existing_ref->extent_op = ref->extent_op; } else { if (ref->extent_op->update_key) { memcpy(&existing_ref->extent_op->key, &ref->extent_op->key, sizeof(ref->extent_op->key)); existing_ref->extent_op->update_key = 1; } if (ref->extent_op->update_flags) { existing_ref->extent_op->flags_to_set |= ref->extent_op->flags_to_set; existing_ref->extent_op->update_flags = 1; } kfree(ref->extent_op); } } /* * update the reference mod on the head to reflect this new operation */ existing->ref_mod += update->ref_mod; } /* * helper function to actually insert a head node into the rbtree. * 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, struct btrfs_delayed_ref_node *ref, u64 bytenr, u64 num_bytes, int action, int is_data) { struct btrfs_delayed_ref_node *existing; struct btrfs_delayed_ref_head *head_ref = NULL; struct btrfs_delayed_ref_root *delayed_refs; int count_mod = 1; int must_insert_reserved = 0; /* * the head node stores the sum of all the mods, so dropping a ref * should drop the sum in the head node by one. */ if (action == BTRFS_UPDATE_DELAYED_HEAD) count_mod = 0; else if (action == BTRFS_DROP_DELAYED_REF) count_mod = -1; /* * BTRFS_ADD_DELAYED_EXTENT means that we need to update * the reserved accounting when the extent is finally added, or * if a later modification deletes the delayed ref without ever * inserting the extent into the extent allocation tree. * ref->must_insert_reserved is the flag used to record * that accounting mods are required. * * Once we record must_insert_reserved, switch the action to * BTRFS_ADD_DELAYED_REF because other special casing is not required. */ if (action == BTRFS_ADD_DELAYED_EXTENT) must_insert_reserved = 1; else must_insert_reserved = 0; delayed_refs = &trans->transaction->delayed_refs; /* first set the basic ref node struct up */ atomic_set(&ref->refs, 1); ref->bytenr = bytenr; ref->num_bytes = num_bytes; ref->ref_mod = count_mod; ref->type = 0; ref->action = 0; ref->is_head = 1; ref->in_tree = 1; head_ref = btrfs_delayed_node_to_head(ref); head_ref->must_insert_reserved = must_insert_reserved; head_ref->is_data = is_data; INIT_LIST_HEAD(&head_ref->cluster); mutex_init(&head_ref->mutex); trace_btrfs_delayed_ref_head(ref, head_ref, action); existing = tree_insert(&delayed_refs->root, &ref->rb_node); if (existing) { update_existing_head_ref(existing, ref); /* * we've updated the existing ref, free the newly * allocated ref */ kfree(ref); } else { delayed_refs->num_heads++; delayed_refs->num_heads_ready++; delayed_refs->num_entries++; trans->delayed_ref_updates++; } return 0; } /* * helper to insert a delayed tree ref into the rbtree. */ static noinline int add_delayed_tree_ref(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) { struct btrfs_delayed_ref_node *existing; struct btrfs_delayed_tree_ref *full_ref; struct btrfs_delayed_ref_root *delayed_refs; if (action == BTRFS_ADD_DELAYED_EXTENT) action = BTRFS_ADD_DELAYED_REF; delayed_refs = &trans->transaction->delayed_refs; /* first set the basic ref node struct up */ atomic_set(&ref->refs, 1); ref->bytenr = bytenr; ref->num_bytes = num_bytes; ref->ref_mod = 1; ref->action = action; ref->is_head = 0; ref->in_tree = 1; full_ref = btrfs_delayed_node_to_tree_ref(ref); if (parent) { full_ref->parent = parent; ref->type = BTRFS_SHARED_BLOCK_REF_KEY; } else { full_ref->root = ref_root; ref->type = BTRFS_TREE_BLOCK_REF_KEY; } full_ref->level = level; trace_btrfs_delayed_tree_ref(ref, full_ref, action); existing = tree_insert(&delayed_refs->root, &ref->rb_node); if (existing) { update_existing_ref(trans, delayed_refs, existing, ref); /* * we've updated the existing ref, free the newly * allocated ref */ kfree(ref); } else { delayed_refs->num_entries++; trans->delayed_ref_updates++; } return 0; } /* * helper to insert a delayed data ref into the rbtree. */ static noinline int add_delayed_data_ref(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) { struct btrfs_delayed_ref_node *existing; struct btrfs_delayed_data_ref *full_ref; struct btrfs_delayed_ref_root *delayed_refs; if (action == BTRFS_ADD_DELAYED_EXTENT) action = BTRFS_ADD_DELAYED_REF; delayed_refs = &trans->transaction->delayed_refs; /* first set the basic ref node struct up */ atomic_set(&ref->refs, 1); ref->bytenr = bytenr; ref->num_bytes = num_bytes; ref->ref_mod = 1; ref->action = action; ref->is_head = 0; ref->in_tree = 1; full_ref = btrfs_delayed_node_to_data_ref(ref); if (parent) { full_ref->parent = parent; ref->type = BTRFS_SHARED_DATA_REF_KEY; } else { full_ref->root = ref_root; ref->type = BTRFS_EXTENT_DATA_REF_KEY; } full_ref->objectid = owner; full_ref->offset = offset; trace_btrfs_delayed_data_ref(ref, full_ref, action); existing = tree_insert(&delayed_refs->root, &ref->rb_node); if (existing) { update_existing_ref(trans, delayed_refs, existing, ref); /* * we've updated the existing ref, free the newly * allocated ref */ kfree(ref); } else { delayed_refs->num_entries++; trans->delayed_ref_updates++; } return 0; } /* * add a delayed tree ref. This does all of the accounting required * to make sure the delayed ref is eventually processed before this * transaction commits. */ int btrfs_add_delayed_tree_ref(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_tree_ref *ref; struct btrfs_delayed_ref_head *head_ref; struct btrfs_delayed_ref_root *delayed_refs; int ret; BUG_ON(extent_op && extent_op->is_data); ref = kmalloc(sizeof(*ref), GFP_NOFS); if (!ref) return -ENOMEM; head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS); if (!head_ref) { kfree(ref); return -ENOMEM; } head_ref->extent_op = extent_op; delayed_refs = &trans->transaction->delayed_refs; spin_lock(&delayed_refs->lock); /* * 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); BUG_ON(ret); ret = add_delayed_tree_ref(trans, &ref->node, bytenr, num_bytes, parent, ref_root, level, action); BUG_ON(ret); spin_unlock(&delayed_refs->lock); return 0; } /* * 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, 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_data_ref *ref; struct btrfs_delayed_ref_head *head_ref; struct btrfs_delayed_ref_root *delayed_refs; int ret; BUG_ON(extent_op && !extent_op->is_data); ref = kmalloc(sizeof(*ref), GFP_NOFS); if (!ref) return -ENOMEM; head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS); if (!head_ref) { kfree(ref); return -ENOMEM; } head_ref->extent_op = extent_op; delayed_refs = &trans->transaction->delayed_refs; spin_lock(&delayed_refs->lock); /* * 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); BUG_ON(ret); ret = add_delayed_data_ref(trans, &ref->node, bytenr, num_bytes, parent, ref_root, owner, offset, action); BUG_ON(ret); spin_unlock(&delayed_refs->lock); return 0; } int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans, u64 bytenr, u64 num_bytes, struct btrfs_delayed_extent_op *extent_op) { struct btrfs_delayed_ref_head *head_ref; struct btrfs_delayed_ref_root *delayed_refs; int ret; head_ref = kmalloc(sizeof(*head_ref), GFP_NOFS); if (!head_ref) return -ENOMEM; head_ref->extent_op = extent_op; delayed_refs = &trans->transaction->delayed_refs; spin_lock(&delayed_refs->lock); ret = add_delayed_ref_head(trans, &head_ref->node, bytenr, num_bytes, BTRFS_UPDATE_DELAYED_HEAD, extent_op->is_data); BUG_ON(ret); spin_unlock(&delayed_refs->lock); return 0; } /* * this does a simple search for the head node for a given extent. * It must be called with the delayed ref spinlock held, and it returns * the head node if any where found, or NULL if not. */ struct btrfs_delayed_ref_head * btrfs_find_delayed_ref_head(struct btrfs_trans_handle *trans, u64 bytenr) { struct btrfs_delayed_ref_node *ref; struct btrfs_delayed_ref_root *delayed_refs; delayed_refs = &trans->transaction->delayed_refs; ref = find_ref_head(&delayed_refs->root, bytenr, NULL); if (ref) return btrfs_delayed_node_to_head(ref); return NULL; }