diff options
Diffstat (limited to 'fs/btrfs/extent-io-tree.c')
-rw-r--r-- | fs/btrfs/extent-io-tree.c | 272 |
1 files changed, 180 insertions, 92 deletions
diff --git a/fs/btrfs/extent-io-tree.c b/fs/btrfs/extent-io-tree.c index ff8e117a1a..ea149be28d 100644 --- a/fs/btrfs/extent-io-tree.c +++ b/fs/btrfs/extent-io-tree.c @@ -105,32 +105,40 @@ void extent_io_tree_init(struct btrfs_fs_info *fs_info, lockdep_set_class(&tree->lock, &file_extent_tree_class); } +/* + * Empty an io tree, removing and freeing every extent state record from the + * tree. This should be called once we are sure no other task can access the + * tree anymore, so no tree updates happen after we empty the tree and there + * aren't any waiters on any extent state record (EXTENT_LOCKED bit is never + * set on any extent state when calling this function). + */ void extent_io_tree_release(struct extent_io_tree *tree) { + struct rb_root root; + struct extent_state *state; + struct extent_state *tmp; + spin_lock(&tree->lock); - /* - * Do a single barrier for the waitqueue_active check here, the state - * of the waitqueue should not change once extent_io_tree_release is - * called. - */ - smp_mb(); - while (!RB_EMPTY_ROOT(&tree->state)) { - struct rb_node *node; - struct extent_state *state; - - node = rb_first(&tree->state); - state = rb_entry(node, struct extent_state, rb_node); - rb_erase(&state->rb_node, &tree->state); + root = tree->state; + tree->state = RB_ROOT; + rbtree_postorder_for_each_entry_safe(state, tmp, &root, rb_node) { + /* Clear node to keep free_extent_state() happy. */ RB_CLEAR_NODE(&state->rb_node); + ASSERT(!(state->state & EXTENT_LOCKED)); /* - * btree io trees aren't supposed to have tasks waiting for - * changes in the flags of extent states ever. + * No need for a memory barrier here, as we are holding the tree + * lock and we only change the waitqueue while holding that lock + * (see wait_extent_bit()). */ ASSERT(!waitqueue_active(&state->wq)); free_extent_state(state); - cond_resched_lock(&tree->lock); } + /* + * Should still be empty even after a reschedule, no other task should + * be accessing the tree anymore. + */ + ASSERT(RB_EMPTY_ROOT(&tree->state)); spin_unlock(&tree->lock); } @@ -327,6 +335,36 @@ static void extent_io_tree_panic(struct extent_io_tree *tree, int err) "locking error: extent tree was modified by another thread while locked"); } +static void merge_prev_state(struct extent_io_tree *tree, struct extent_state *state) +{ + struct extent_state *prev; + + prev = prev_state(state); + if (prev && prev->end == state->start - 1 && prev->state == state->state) { + if (tree->inode) + btrfs_merge_delalloc_extent(tree->inode, state, prev); + state->start = prev->start; + rb_erase(&prev->rb_node, &tree->state); + RB_CLEAR_NODE(&prev->rb_node); + free_extent_state(prev); + } +} + +static void merge_next_state(struct extent_io_tree *tree, struct extent_state *state) +{ + struct extent_state *next; + + next = next_state(state); + if (next && next->start == state->end + 1 && next->state == state->state) { + if (tree->inode) + btrfs_merge_delalloc_extent(tree->inode, state, next); + state->end = next->end; + rb_erase(&next->rb_node, &tree->state); + RB_CLEAR_NODE(&next->rb_node); + free_extent_state(next); + } +} + /* * Utility function to look for merge candidates inside a given range. Any * extents with matching state are merged together into a single extent in the @@ -338,31 +376,11 @@ static void extent_io_tree_panic(struct extent_io_tree *tree, int err) */ static void merge_state(struct extent_io_tree *tree, struct extent_state *state) { - struct extent_state *other; - if (state->state & (EXTENT_LOCKED | EXTENT_BOUNDARY)) return; - other = prev_state(state); - if (other && other->end == state->start - 1 && - other->state == state->state) { - if (tree->inode) - btrfs_merge_delalloc_extent(tree->inode, state, other); - state->start = other->start; - rb_erase(&other->rb_node, &tree->state); - RB_CLEAR_NODE(&other->rb_node); - free_extent_state(other); - } - other = next_state(state); - if (other && other->start == state->end + 1 && - other->state == state->state) { - if (tree->inode) - btrfs_merge_delalloc_extent(tree->inode, state, other); - state->end = other->end; - rb_erase(&other->rb_node, &tree->state); - RB_CLEAR_NODE(&other->rb_node); - free_extent_state(other); - } + merge_prev_state(tree, state); + merge_next_state(tree, state); } static void set_state_bits(struct extent_io_tree *tree, @@ -384,19 +402,27 @@ static void set_state_bits(struct extent_io_tree *tree, * Insert an extent_state struct into the tree. 'bits' are set on the * struct before it is inserted. * - * This may return -EEXIST if the extent is already there, in which case the - * state struct is freed. + * Returns a pointer to the struct extent_state record containing the range + * requested for insertion, which may be the same as the given struct or it + * may be an existing record in the tree that was expanded to accommodate the + * requested range. In case of an extent_state different from the one that was + * given, the later can be freed or reused by the caller. + * + * On error it returns an error pointer. * * The tree lock is not taken internally. This is a utility function and * probably isn't what you want to call (see set/clear_extent_bit). */ -static int insert_state(struct extent_io_tree *tree, - struct extent_state *state, - u32 bits, struct extent_changeset *changeset) +static struct extent_state *insert_state(struct extent_io_tree *tree, + struct extent_state *state, + u32 bits, + struct extent_changeset *changeset) { struct rb_node **node; struct rb_node *parent = NULL; - const u64 end = state->end; + const u64 start = state->start - 1; + const u64 end = state->end + 1; + const bool try_merge = !(bits & (EXTENT_LOCKED | EXTENT_BOUNDARY)); set_state_bits(tree, state, bits, changeset); @@ -407,23 +433,42 @@ static int insert_state(struct extent_io_tree *tree, parent = *node; entry = rb_entry(parent, struct extent_state, rb_node); - if (end < entry->start) { + if (state->end < entry->start) { + if (try_merge && end == entry->start && + state->state == entry->state) { + if (tree->inode) + btrfs_merge_delalloc_extent(tree->inode, + state, entry); + entry->start = state->start; + merge_prev_state(tree, entry); + state->state = 0; + return entry; + } node = &(*node)->rb_left; - } else if (end > entry->end) { + } else if (state->end > entry->end) { + if (try_merge && entry->end == start && + state->state == entry->state) { + if (tree->inode) + btrfs_merge_delalloc_extent(tree->inode, + state, entry); + entry->end = state->end; + merge_next_state(tree, entry); + state->state = 0; + return entry; + } node = &(*node)->rb_right; } else { btrfs_err(tree->fs_info, "found node %llu %llu on insert of %llu %llu", - entry->start, entry->end, state->start, end); - return -EEXIST; + entry->start, entry->end, state->start, state->end); + return ERR_PTR(-EEXIST); } } rb_link_node(&state->rb_node, parent, node); rb_insert_color(&state->rb_node, &tree->state); - merge_state(tree, state); - return 0; + return state; } /* @@ -708,26 +753,13 @@ out: } -static void wait_on_state(struct extent_io_tree *tree, - struct extent_state *state) - __releases(tree->lock) - __acquires(tree->lock) -{ - DEFINE_WAIT(wait); - prepare_to_wait(&state->wq, &wait, TASK_UNINTERRUPTIBLE); - spin_unlock(&tree->lock); - schedule(); - spin_lock(&tree->lock); - finish_wait(&state->wq, &wait); -} - /* * Wait for one or more bits to clear on a range in the state tree. * The range [start, end] is inclusive. * The tree lock is taken by this function */ -void wait_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, u32 bits, - struct extent_state **cached_state) +static void wait_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, + u32 bits, struct extent_state **cached_state) { struct extent_state *state; @@ -758,9 +790,15 @@ process_node: goto out; if (state->state & bits) { + DEFINE_WAIT(wait); + start = state->start; refcount_inc(&state->refs); - wait_on_state(tree, state); + prepare_to_wait(&state->wq, &wait, TASK_UNINTERRUPTIBLE); + spin_unlock(&tree->lock); + schedule(); + spin_lock(&tree->lock); + finish_wait(&state->wq, &wait); free_extent_state(state); goto again; } @@ -847,10 +885,19 @@ bool find_first_extent_bit(struct extent_io_tree *tree, u64 start, if (state->end == start - 1 && extent_state_in_tree(state)) { while ((state = next_state(state)) != NULL) { if (state->state & bits) - goto got_it; + break; } + /* + * If we found the next extent state, clear cached_state + * so that we can cache the next extent state below and + * avoid future calls going over the same extent state + * again. If we haven't found any, clear as well since + * it's now useless. + */ free_extent_state(*cached_state); *cached_state = NULL; + if (state) + goto got_it; goto out; } free_extent_state(*cached_state); @@ -1133,6 +1180,8 @@ hit_next: */ if (state->start > start) { u64 this_end; + struct extent_state *inserted_state; + if (end < last_start) this_end = end; else @@ -1148,12 +1197,15 @@ hit_next: */ prealloc->start = start; prealloc->end = this_end; - err = insert_state(tree, prealloc, bits, changeset); - if (err) + inserted_state = insert_state(tree, prealloc, bits, changeset); + if (IS_ERR(inserted_state)) { + err = PTR_ERR(inserted_state); extent_io_tree_panic(tree, err); + } - cache_state(prealloc, cached_state); - prealloc = NULL; + cache_state(inserted_state, cached_state); + if (inserted_state == prealloc) + prealloc = NULL; start = this_end + 1; goto search_again; } @@ -1356,6 +1408,8 @@ hit_next: */ if (state->start > start) { u64 this_end; + struct extent_state *inserted_state; + if (end < last_start) this_end = end; else @@ -1373,11 +1427,14 @@ hit_next: */ prealloc->start = start; prealloc->end = this_end; - err = insert_state(tree, prealloc, bits, NULL); - if (err) + inserted_state = insert_state(tree, prealloc, bits, NULL); + if (IS_ERR(inserted_state)) { + err = PTR_ERR(inserted_state); extent_io_tree_panic(tree, err); - cache_state(prealloc, cached_state); - prealloc = NULL; + } + cache_state(inserted_state, cached_state); + if (inserted_state == prealloc) + prealloc = NULL; start = this_end + 1; goto search_again; } @@ -1640,15 +1697,46 @@ search: } /* - * Search a range in the state tree for a given mask. If 'filled' == 1, this - * returns 1 only if every extent in the tree has the bits set. Otherwise, 1 - * is returned if any bit in the range is found set. + * Check if the single @bit exists in the given range. + */ +bool test_range_bit_exists(struct extent_io_tree *tree, u64 start, u64 end, u32 bit) +{ + struct extent_state *state = NULL; + bool bitset = false; + + ASSERT(is_power_of_2(bit)); + + spin_lock(&tree->lock); + state = tree_search(tree, start); + while (state && start <= end) { + if (state->start > end) + break; + + if (state->state & bit) { + bitset = true; + break; + } + + /* If state->end is (u64)-1, start will overflow to 0 */ + start = state->end + 1; + if (start > end || start == 0) + break; + state = next_state(state); + } + spin_unlock(&tree->lock); + return bitset; +} + +/* + * Check if the whole range [@start,@end) contains the single @bit set. */ -int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end, - u32 bits, int filled, struct extent_state *cached) +bool test_range_bit(struct extent_io_tree *tree, u64 start, u64 end, u32 bit, + struct extent_state *cached) { struct extent_state *state = NULL; - int bitset = 0; + bool bitset = true; + + ASSERT(is_power_of_2(bit)); spin_lock(&tree->lock); if (cached && extent_state_in_tree(cached) && cached->start <= start && @@ -1657,35 +1745,35 @@ int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end, else state = tree_search(tree, start); while (state && start <= end) { - if (filled && state->start > start) { - bitset = 0; + if (state->start > start) { + bitset = false; break; } if (state->start > end) break; - if (state->state & bits) { - bitset = 1; - if (!filled) - break; - } else if (filled) { - bitset = 0; + if ((state->state & bit) == 0) { + bitset = false; break; } if (state->end == (u64)-1) break; + /* + * Last entry (if state->end is (u64)-1 and overflow happens), + * or next entry starts after the range. + */ start = state->end + 1; - if (start > end) + if (start > end || start == 0) break; state = next_state(state); } /* We ran out of states and were still inside of our range. */ - if (filled && !state) - bitset = 0; + if (!state) + bitset = false; spin_unlock(&tree->lock); return bitset; } |