From a717531942f488209dded30f6bc648167bcefa72 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Thu, 22 Jan 2009 09:23:10 -0500 Subject: Btrfs: do less aggressive btree readahead Just before reading a leaf, btrfs scans the node for blocks that are close by and reads them too. It tries to build up a large window of IO looking for blocks that are within a max distance from the top and bottom of the IO window. This patch changes things to just look for blocks within 64k of the target block. It will trigger less IO and make for lower latencies on the read size. Signed-off-by: Chris Mason --- fs/btrfs/ctree.c | 21 +++++---------------- 1 file changed, 5 insertions(+), 16 deletions(-) (limited to 'fs/btrfs/ctree.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 9e46c077681..2603ee539b7 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1210,8 +1210,7 @@ static noinline void reada_for_search(struct btrfs_root *root, struct btrfs_disk_key disk_key; u32 nritems; u64 search; - u64 lowest_read; - u64 highest_read; + u64 target; u64 nread = 0; int direction = path->reada; struct extent_buffer *eb; @@ -1235,8 +1234,7 @@ static noinline void reada_for_search(struct btrfs_root *root, return; } - highest_read = search; - lowest_read = search; + target = search; nritems = btrfs_header_nritems(node); nr = slot; @@ -1256,24 +1254,15 @@ static noinline void reada_for_search(struct btrfs_root *root, break; } search = btrfs_node_blockptr(node, nr); - if ((search >= lowest_read && search <= highest_read) || - (search < lowest_read && lowest_read - search <= 16384) || - (search > highest_read && search - highest_read <= 16384)) { + if ((search <= target && target - search <= 65536) || + (search > target && search - target <= 65536)) { readahead_tree_block(root, search, blocksize, btrfs_node_ptr_generation(node, nr)); nread += blocksize; } nscan++; - if (path->reada < 2 && (nread > (64 * 1024) || nscan > 32)) + if ((nread > 65536 || nscan > 32)) break; - - if (nread > (256 * 1024) || nscan > 128) - break; - - if (search < lowest_read) - lowest_read = search; - if (search > highest_read) - highest_read = search; } } -- cgit v1.2.3-70-g09d2 From c487685d7c18a8481900755aa5c56a7a74193101 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 4 Feb 2009 09:24:25 -0500 Subject: Btrfs: hash_lock is no longer needed Before metadata is written to disk, it is updated to reflect that writeout has begun. Once this update is done, the block must be cow'd before it can be modified again. This update was originally synchronized by using a per-fs spinlock. Today the buffers for the metadata blocks are locked before writeout begins, and everyone that tests the flag has the buffer locked as well. So, the per-fs spinlock (called hash_lock for no good reason) is no longer required. Signed-off-by: Chris Mason --- fs/btrfs/ctree.c | 7 +------ fs/btrfs/ctree.h | 1 - fs/btrfs/disk-io.c | 4 ---- 3 files changed, 1 insertion(+), 11 deletions(-) (limited to 'fs/btrfs/ctree.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 2603ee539b7..3b6e35aafc9 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -388,16 +388,14 @@ noinline int btrfs_cow_block(struct btrfs_trans_handle *trans, WARN_ON(1); } - spin_lock(&root->fs_info->hash_lock); if (btrfs_header_generation(buf) == trans->transid && btrfs_header_owner(buf) == root->root_key.objectid && !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) { *cow_ret = buf; - spin_unlock(&root->fs_info->hash_lock); WARN_ON(prealloc_dest); return 0; } - spin_unlock(&root->fs_info->hash_lock); + search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1); ret = __btrfs_cow_block(trans, root, buf, parent, parent_slot, cow_ret, search_start, 0, @@ -1376,14 +1374,11 @@ again: int wret; /* is a cow on this block not required */ - spin_lock(&root->fs_info->hash_lock); if (btrfs_header_generation(b) == trans->transid && btrfs_header_owner(b) == root->root_key.objectid && !btrfs_header_flag(b, BTRFS_HEADER_FLAG_WRITTEN)) { - spin_unlock(&root->fs_info->hash_lock); goto cow_done; } - spin_unlock(&root->fs_info->hash_lock); /* ok, we have to cow, is our old prealloc the right * size? diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index de103a8a815..f2b8d26b047 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -703,7 +703,6 @@ struct btrfs_fs_info { struct super_block *sb; struct inode *btree_inode; struct backing_dev_info bdi; - spinlock_t hash_lock; struct mutex trans_mutex; struct mutex tree_log_mutex; struct mutex transaction_kthread_mutex; diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 9c381004797..549271607c1 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1503,7 +1503,6 @@ struct btrfs_root *open_ctree(struct super_block *sb, INIT_LIST_HEAD(&fs_info->dead_roots); INIT_LIST_HEAD(&fs_info->hashers); INIT_LIST_HEAD(&fs_info->delalloc_inodes); - spin_lock_init(&fs_info->hash_lock); spin_lock_init(&fs_info->delalloc_lock); spin_lock_init(&fs_info->new_trans_lock); spin_lock_init(&fs_info->ref_cache_lock); @@ -2361,7 +2360,6 @@ int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid) int btree_lock_page_hook(struct page *page) { struct inode *inode = page->mapping->host; - struct btrfs_root *root = BTRFS_I(inode)->root; struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree; struct extent_buffer *eb; unsigned long len; @@ -2376,9 +2374,7 @@ int btree_lock_page_hook(struct page *page) goto out; btrfs_tree_lock(eb); - spin_lock(&root->fs_info->hash_lock); btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN); - spin_unlock(&root->fs_info->hash_lock); btrfs_tree_unlock(eb); free_extent_buffer(eb); out: -- cgit v1.2.3-70-g09d2 From b4ce94de9b4d64e8ab3cf155d13653c666e22b9b Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 4 Feb 2009 09:25:08 -0500 Subject: Btrfs: Change btree locking to use explicit blocking points Most of the btrfs metadata operations can be protected by a spinlock, but some operations still need to schedule. So far, btrfs has been using a mutex along with a trylock loop, most of the time it is able to avoid going for the full mutex, so the trylock loop is a big performance gain. This commit is step one for getting rid of the blocking locks entirely. btrfs_tree_lock takes a spinlock, and the code explicitly switches to a blocking lock when it starts an operation that can schedule. We'll be able get rid of the blocking locks in smaller pieces over time. Tracing allows us to find the most common cause of blocking, so we can start with the hot spots first. The basic idea is: btrfs_tree_lock() returns with the spin lock held btrfs_set_lock_blocking() sets the EXTENT_BUFFER_BLOCKING bit in the extent buffer flags, and then drops the spin lock. The buffer is still considered locked by all of the btrfs code. If btrfs_tree_lock gets the spinlock but finds the blocking bit set, it drops the spin lock and waits on a wait queue for the blocking bit to go away. Much of the code that needs to set the blocking bit finishes without actually blocking a good percentage of the time. So, an adaptive spin is still used against the blocking bit to avoid very high context switch rates. btrfs_clear_lock_blocking() clears the blocking bit and returns with the spinlock held again. btrfs_tree_unlock() can be called on either blocking or spinning locks, it does the right thing based on the blocking bit. ctree.c has a helper function to set/clear all the locked buffers in a path as blocking. Signed-off-by: Chris Mason --- fs/btrfs/ctree.c | 234 +++++++++++++++++++++++++++++++++++++++++++++++-- fs/btrfs/ctree.h | 4 + fs/btrfs/disk-io.c | 10 ++- fs/btrfs/extent-tree.c | 5 ++ fs/btrfs/extent_io.c | 18 ++-- fs/btrfs/extent_io.h | 16 +++- fs/btrfs/inode.c | 3 + fs/btrfs/locking.c | 208 +++++++++++++++++++++++++++++++++++++++---- fs/btrfs/locking.h | 6 ++ fs/btrfs/tree-defrag.c | 1 + fs/btrfs/tree-log.c | 4 + 11 files changed, 470 insertions(+), 39 deletions(-) (limited to 'fs/btrfs/ctree.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 3b6e35aafc9..3af777357ac 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -54,6 +54,31 @@ struct btrfs_path *btrfs_alloc_path(void) return path; } +/* + * set all locked nodes in the path to blocking locks. This should + * be done before scheduling + */ +noinline void btrfs_set_path_blocking(struct btrfs_path *p) +{ + int i; + for (i = 0; i < BTRFS_MAX_LEVEL; i++) { + if (p->nodes[i] && p->locks[i]) + btrfs_set_lock_blocking(p->nodes[i]); + } +} + +/* + * reset all the locked nodes in the patch to spinning locks. + */ +noinline void btrfs_clear_path_blocking(struct btrfs_path *p) +{ + int i; + for (i = 0; i < BTRFS_MAX_LEVEL; i++) { + if (p->nodes[i] && p->locks[i]) + btrfs_clear_lock_blocking(p->nodes[i]); + } +} + /* this also releases the path */ void btrfs_free_path(struct btrfs_path *p) { @@ -272,6 +297,8 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans, if (IS_ERR(cow)) return PTR_ERR(cow); + /* cow is set to blocking by btrfs_init_new_buffer */ + copy_extent_buffer(cow, buf, 0, 0, cow->len); btrfs_set_header_bytenr(cow, cow->start); btrfs_set_header_generation(cow, trans->transid); @@ -397,6 +424,11 @@ noinline int btrfs_cow_block(struct btrfs_trans_handle *trans, } search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1); + + if (parent) + btrfs_set_lock_blocking(parent); + btrfs_set_lock_blocking(buf); + ret = __btrfs_cow_block(trans, root, buf, parent, parent_slot, cow_ret, search_start, 0, prealloc_dest); @@ -502,6 +534,8 @@ int btrfs_realloc_node(struct btrfs_trans_handle *trans, if (parent_nritems == 1) return 0; + btrfs_set_lock_blocking(parent); + for (i = start_slot; i < end_slot; i++) { int close = 1; @@ -562,6 +596,7 @@ int btrfs_realloc_node(struct btrfs_trans_handle *trans, search_start = last_block; btrfs_tree_lock(cur); + btrfs_set_lock_blocking(cur); err = __btrfs_cow_block(trans, root, cur, parent, i, &cur, search_start, min(16 * blocksize, @@ -860,6 +895,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans, return 0; mid = path->nodes[level]; + WARN_ON(!path->locks[level]); WARN_ON(btrfs_header_generation(mid) != trans->transid); @@ -882,6 +918,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans, /* promote the child to a root */ child = read_node_slot(root, mid, 0); btrfs_tree_lock(child); + btrfs_set_lock_blocking(child); BUG_ON(!child); ret = btrfs_cow_block(trans, root, child, mid, 0, &child, 0); BUG_ON(ret); @@ -898,6 +935,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans, add_root_to_dirty_list(root); btrfs_tree_unlock(child); + path->locks[level] = 0; path->nodes[level] = NULL; clean_tree_block(trans, root, mid); @@ -922,6 +960,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans, left = read_node_slot(root, parent, pslot - 1); if (left) { btrfs_tree_lock(left); + btrfs_set_lock_blocking(left); wret = btrfs_cow_block(trans, root, left, parent, pslot - 1, &left, 0); if (wret) { @@ -932,6 +971,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans, right = read_node_slot(root, parent, pslot + 1); if (right) { btrfs_tree_lock(right); + btrfs_set_lock_blocking(right); wret = btrfs_cow_block(trans, root, right, parent, pslot + 1, &right, 0); if (wret) { @@ -1107,6 +1147,8 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans, u32 left_nr; btrfs_tree_lock(left); + btrfs_set_lock_blocking(left); + left_nr = btrfs_header_nritems(left); if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) { wret = 1; @@ -1153,7 +1195,10 @@ static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans, */ if (right) { u32 right_nr; + btrfs_tree_lock(right); + btrfs_set_lock_blocking(right); + right_nr = btrfs_header_nritems(right); if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) { wret = 1; @@ -1264,6 +1309,68 @@ static noinline void reada_for_search(struct btrfs_root *root, } } +/* + * returns -EAGAIN if it had to drop the path, or zero if everything was in + * cache + */ +static noinline int reada_for_balance(struct btrfs_root *root, + struct btrfs_path *path, int level) +{ + int slot; + int nritems; + struct extent_buffer *parent; + struct extent_buffer *eb; + u64 gen; + u64 block1 = 0; + u64 block2 = 0; + int ret = 0; + int blocksize; + + parent = path->nodes[level - 1]; + if (!parent) + return 0; + + nritems = btrfs_header_nritems(parent); + slot = path->slots[level]; + blocksize = btrfs_level_size(root, level); + + if (slot > 0) { + block1 = btrfs_node_blockptr(parent, slot - 1); + gen = btrfs_node_ptr_generation(parent, slot - 1); + eb = btrfs_find_tree_block(root, block1, blocksize); + if (eb && btrfs_buffer_uptodate(eb, gen)) + block1 = 0; + free_extent_buffer(eb); + } + if (slot < nritems) { + block2 = btrfs_node_blockptr(parent, slot + 1); + gen = btrfs_node_ptr_generation(parent, slot + 1); + eb = btrfs_find_tree_block(root, block2, blocksize); + if (eb && btrfs_buffer_uptodate(eb, gen)) + block2 = 0; + free_extent_buffer(eb); + } + if (block1 || block2) { + ret = -EAGAIN; + btrfs_release_path(root, path); + if (block1) + readahead_tree_block(root, block1, blocksize, 0); + if (block2) + readahead_tree_block(root, block2, blocksize, 0); + + if (block1) { + eb = read_tree_block(root, block1, blocksize, 0); + free_extent_buffer(eb); + } + if (block1) { + eb = read_tree_block(root, block2, blocksize, 0); + free_extent_buffer(eb); + } + } + return ret; +} + + /* * when we walk down the tree, it is usually safe to unlock the higher layers * in the tree. The exceptions are when our path goes through slot 0, because @@ -1314,6 +1421,32 @@ static noinline void unlock_up(struct btrfs_path *path, int level, } } +/* + * This releases any locks held in the path starting at level and + * going all the way up to the root. + * + * btrfs_search_slot will keep the lock held on higher nodes in a few + * corner cases, such as COW of the block at slot zero in the node. This + * ignores those rules, and it should only be called when there are no + * more updates to be done higher up in the tree. + */ +noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level) +{ + int i; + + if (path->keep_locks || path->lowest_level) + return; + + for (i = level; i < BTRFS_MAX_LEVEL; i++) { + if (!path->nodes[i]) + break; + if (!path->locks[i]) + break; + btrfs_tree_unlock(path->nodes[i]); + path->locks[i] = 0; + } +} + /* * look for key in the tree. path is filled in with nodes along the way * if key is found, we return zero and you can find the item in the leaf @@ -1385,6 +1518,7 @@ again: */ if (prealloc_block.objectid && prealloc_block.offset != b->len) { + btrfs_set_path_blocking(p); btrfs_free_reserved_extent(root, prealloc_block.objectid, prealloc_block.offset); @@ -1409,6 +1543,8 @@ again: goto again; } + btrfs_set_path_blocking(p); + wret = btrfs_cow_block(trans, root, b, p->nodes[level + 1], p->slots[level + 1], @@ -1430,6 +1566,22 @@ cow_done: if (!p->skip_locking) p->locks[level] = 1; + btrfs_clear_path_blocking(p); + + /* + * we have a lock on b and as long as we aren't changing + * the tree, there is no way to for the items in b to change. + * It is safe to drop the lock on our parent before we + * go through the expensive btree search on b. + * + * If cow is true, then we might be changing slot zero, + * which may require changing the parent. So, we can't + * drop the lock until after we know which slot we're + * operating on. + */ + if (!cow) + btrfs_unlock_up_safe(p, level + 1); + ret = check_block(root, p, level); if (ret) { ret = -1; @@ -1437,6 +1589,7 @@ cow_done: } ret = bin_search(b, key, level, &slot); + if (level != 0) { if (ret && slot > 0) slot -= 1; @@ -1444,7 +1597,16 @@ cow_done: if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >= BTRFS_NODEPTRS_PER_BLOCK(root) - 3) { - int sret = split_node(trans, root, p, level); + int sret; + + sret = reada_for_balance(root, p, level); + if (sret) + goto again; + + btrfs_set_path_blocking(p); + sret = split_node(trans, root, p, level); + btrfs_clear_path_blocking(p); + BUG_ON(sret > 0); if (sret) { ret = sret; @@ -1453,8 +1615,16 @@ cow_done: b = p->nodes[level]; slot = p->slots[level]; } else if (ins_len < 0) { - int sret = balance_level(trans, root, p, - level); + int sret; + + sret = reada_for_balance(root, p, level); + if (sret) + goto again; + + btrfs_set_path_blocking(p); + sret = balance_level(trans, root, p, level); + btrfs_clear_path_blocking(p); + if (sret) { ret = sret; goto done; @@ -1488,7 +1658,7 @@ cow_done: * of the btree by dropping locks before * we read. */ - if (level > 1) { + if (level > 0) { btrfs_release_path(NULL, p); if (tmp) free_extent_buffer(tmp); @@ -1503,6 +1673,7 @@ cow_done: free_extent_buffer(tmp); goto again; } else { + btrfs_set_path_blocking(p); if (tmp) free_extent_buffer(tmp); if (should_reada) @@ -1512,14 +1683,29 @@ cow_done: b = read_node_slot(root, b, slot); } } - if (!p->skip_locking) - btrfs_tree_lock(b); + if (!p->skip_locking) { + int lret; + + btrfs_clear_path_blocking(p); + lret = btrfs_try_spin_lock(b); + + if (!lret) { + btrfs_set_path_blocking(p); + btrfs_tree_lock(b); + btrfs_clear_path_blocking(p); + } + } } else { p->slots[level] = slot; if (ins_len > 0 && btrfs_leaf_free_space(root, b) < ins_len) { - int sret = split_leaf(trans, root, key, + int sret; + + btrfs_set_path_blocking(p); + sret = split_leaf(trans, root, key, p, ins_len, ret == 0); + btrfs_clear_path_blocking(p); + BUG_ON(sret > 0); if (sret) { ret = sret; @@ -1533,12 +1719,16 @@ cow_done: } ret = 1; done: + /* + * we don't really know what they plan on doing with the path + * from here on, so for now just mark it as blocking + */ + btrfs_set_path_blocking(p); if (prealloc_block.objectid) { btrfs_free_reserved_extent(root, prealloc_block.objectid, prealloc_block.offset); } - return ret; } @@ -1562,6 +1752,8 @@ int btrfs_merge_path(struct btrfs_trans_handle *trans, ret = btrfs_cow_block(trans, root, eb, NULL, 0, &eb, 0); BUG_ON(ret); + btrfs_set_lock_blocking(eb); + parent = eb; while (1) { level = btrfs_header_level(parent); @@ -1586,6 +1778,7 @@ int btrfs_merge_path(struct btrfs_trans_handle *trans, eb = read_tree_block(root, bytenr, blocksize, generation); btrfs_tree_lock(eb); + btrfs_set_lock_blocking(eb); } /* @@ -1610,6 +1803,7 @@ int btrfs_merge_path(struct btrfs_trans_handle *trans, eb = read_tree_block(root, bytenr, blocksize, generation); btrfs_tree_lock(eb); + btrfs_set_lock_blocking(eb); } ret = btrfs_cow_block(trans, root, eb, parent, slot, @@ -2156,6 +2350,8 @@ static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root right = read_node_slot(root, upper, slot + 1); btrfs_tree_lock(right); + btrfs_set_lock_blocking(right); + free_space = btrfs_leaf_free_space(root, right); if (free_space < data_size) goto out_unlock; @@ -2351,6 +2547,8 @@ static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root left = read_node_slot(root, path->nodes[1], slot - 1); btrfs_tree_lock(left); + btrfs_set_lock_blocking(left); + free_space = btrfs_leaf_free_space(root, left); if (free_space < data_size) { ret = 1; @@ -2809,6 +3007,12 @@ int btrfs_split_item(struct btrfs_trans_handle *trans, path->keep_locks = 0; BUG_ON(ret); + /* + * make sure any changes to the path from split_leaf leave it + * in a blocking state + */ + btrfs_set_path_blocking(path); + leaf = path->nodes[0]; BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item)); @@ -3338,6 +3542,7 @@ int btrfs_insert_empty_items(struct btrfs_trans_handle *trans, BUG(); } out: + btrfs_unlock_up_safe(path, 1); return ret; } @@ -3705,12 +3910,14 @@ find_next_key: */ if (slot >= nritems) { path->slots[level] = slot; + btrfs_set_path_blocking(path); sret = btrfs_find_next_key(root, path, min_key, level, cache_only, min_trans); if (sret == 0) { btrfs_release_path(root, path); goto again; } else { + btrfs_clear_path_blocking(path); goto out; } } @@ -3722,16 +3929,20 @@ find_next_key: unlock_up(path, level, 1); goto out; } + btrfs_set_path_blocking(path); cur = read_node_slot(root, cur, slot); btrfs_tree_lock(cur); + path->locks[level - 1] = 1; path->nodes[level - 1] = cur; unlock_up(path, level, 1); + btrfs_clear_path_blocking(path); } out: if (ret == 0) memcpy(min_key, &found_key, sizeof(found_key)); + btrfs_set_path_blocking(path); return ret; } @@ -3827,6 +4038,7 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path) if (ret < 0) return ret; + btrfs_set_path_blocking(path); nritems = btrfs_header_nritems(path->nodes[0]); /* * by releasing the path above we dropped all our locks. A balance @@ -3857,6 +4069,7 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path) free_extent_buffer(next); } + /* the path was set to blocking above */ if (level == 1 && (path->locks[1] || path->skip_locking) && path->reada) reada_for_search(root, path, level, slot, 0); @@ -3865,6 +4078,7 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path) if (!path->skip_locking) { WARN_ON(!btrfs_tree_locked(c)); btrfs_tree_lock(next); + btrfs_set_lock_blocking(next); } break; } @@ -3881,12 +4095,15 @@ int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path) path->locks[level] = 1; if (!level) break; + + btrfs_set_path_blocking(path); if (level == 1 && path->locks[1] && path->reada) reada_for_search(root, path, level, slot, 0); next = read_node_slot(root, next, 0); if (!path->skip_locking) { WARN_ON(!btrfs_tree_locked(path->nodes[level])); btrfs_tree_lock(next); + btrfs_set_lock_blocking(next); } } done: @@ -3911,6 +4128,7 @@ int btrfs_previous_item(struct btrfs_root *root, while (1) { if (path->slots[0] == 0) { + btrfs_set_path_blocking(path); ret = btrfs_prev_leaf(root, path); if (ret != 0) return ret; diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index f2b8d26b047..531db112c8b 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1835,6 +1835,10 @@ void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p); struct btrfs_path *btrfs_alloc_path(void); void btrfs_free_path(struct btrfs_path *p); void btrfs_init_path(struct btrfs_path *p); +void btrfs_set_path_blocking(struct btrfs_path *p); +void btrfs_clear_path_blocking(struct btrfs_path *p); +void btrfs_unlock_up_safe(struct btrfs_path *p, int level); + int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int slot, int nr); int btrfs_del_leaf(struct btrfs_trans_handle *trans, diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 549271607c1..5aebddd7119 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -799,7 +799,7 @@ struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr, ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid); if (ret == 0) - buf->flags |= EXTENT_UPTODATE; + set_bit(EXTENT_BUFFER_UPTODATE, &buf->bflags); else WARN_ON(1); return buf; @@ -813,6 +813,10 @@ int clean_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root, if (btrfs_header_generation(buf) == root->fs_info->running_transaction->transid) { WARN_ON(!btrfs_tree_locked(buf)); + + /* ugh, clear_extent_buffer_dirty can be expensive */ + btrfs_set_lock_blocking(buf); + clear_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree, buf); } @@ -2311,6 +2315,8 @@ void btrfs_mark_buffer_dirty(struct extent_buffer *buf) u64 transid = btrfs_header_generation(buf); struct inode *btree_inode = root->fs_info->btree_inode; + btrfs_set_lock_blocking(buf); + WARN_ON(!btrfs_tree_locked(buf)); if (transid != root->fs_info->generation) { printk(KERN_CRIT "btrfs transid mismatch buffer %llu, " @@ -2353,7 +2359,7 @@ int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid) int ret; ret = btree_read_extent_buffer_pages(root, buf, 0, parent_transid); if (ret == 0) - buf->flags |= EXTENT_UPTODATE; + set_bit(EXTENT_BUFFER_UPTODATE, &buf->bflags); return ret; } diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 7a22f2e6ec4..ed1e25d7248 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -3407,7 +3407,10 @@ struct extent_buffer *btrfs_init_new_buffer(struct btrfs_trans_handle *trans, btrfs_set_header_generation(buf, trans->transid); btrfs_tree_lock(buf); clean_tree_block(trans, root, buf); + + btrfs_set_lock_blocking(buf); btrfs_set_buffer_uptodate(buf); + if (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID) { set_extent_dirty(&root->dirty_log_pages, buf->start, buf->start + buf->len - 1, GFP_NOFS); @@ -3416,6 +3419,7 @@ struct extent_buffer *btrfs_init_new_buffer(struct btrfs_trans_handle *trans, buf->start + buf->len - 1, GFP_NOFS); } trans->blocks_used++; + /* this returns a buffer locked for blocking */ return buf; } @@ -3752,6 +3756,7 @@ static noinline int walk_down_subtree(struct btrfs_trans_handle *trans, next = read_tree_block(root, bytenr, blocksize, ptr_gen); btrfs_tree_lock(next); + btrfs_set_lock_blocking(next); ret = btrfs_lookup_extent_ref(trans, root, bytenr, blocksize, &refs); diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 2ea7f052722..dd5df53e045 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -2990,7 +2990,9 @@ static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree, eb = kmem_cache_zalloc(extent_buffer_cache, mask); eb->start = start; eb->len = len; - mutex_init(&eb->mutex); + spin_lock_init(&eb->lock); + init_waitqueue_head(&eb->lock_wq); + #if LEAK_DEBUG spin_lock_irqsave(&leak_lock, flags); list_add(&eb->leak_list, &buffers); @@ -3071,8 +3073,7 @@ struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree, unlock_page(p); } if (uptodate) - eb->flags |= EXTENT_UPTODATE; - eb->flags |= EXTENT_BUFFER_FILLED; + set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); spin_lock(&tree->buffer_lock); exists = buffer_tree_insert(tree, start, &eb->rb_node); @@ -3226,7 +3227,7 @@ int clear_extent_buffer_uptodate(struct extent_io_tree *tree, unsigned long num_pages; num_pages = num_extent_pages(eb->start, eb->len); - eb->flags &= ~EXTENT_UPTODATE; + clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); clear_extent_uptodate(tree, eb->start, eb->start + eb->len - 1, GFP_NOFS); @@ -3297,7 +3298,7 @@ int extent_buffer_uptodate(struct extent_io_tree *tree, struct page *page; int pg_uptodate = 1; - if (eb->flags & EXTENT_UPTODATE) + if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags)) return 1; ret = test_range_bit(tree, eb->start, eb->start + eb->len - 1, @@ -3333,7 +3334,7 @@ int read_extent_buffer_pages(struct extent_io_tree *tree, struct bio *bio = NULL; unsigned long bio_flags = 0; - if (eb->flags & EXTENT_UPTODATE) + if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags)) return 0; if (test_range_bit(tree, eb->start, eb->start + eb->len - 1, @@ -3364,7 +3365,7 @@ int read_extent_buffer_pages(struct extent_io_tree *tree, } if (all_uptodate) { if (start_i == 0) - eb->flags |= EXTENT_UPTODATE; + set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); goto unlock_exit; } @@ -3400,7 +3401,7 @@ int read_extent_buffer_pages(struct extent_io_tree *tree, } if (!ret) - eb->flags |= EXTENT_UPTODATE; + set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags); return ret; unlock_exit: @@ -3497,7 +3498,6 @@ int map_extent_buffer(struct extent_buffer *eb, unsigned long start, unmap_extent_buffer(eb, eb->map_token, km); eb->map_token = NULL; save = 1; - WARN_ON(!mutex_is_locked(&eb->mutex)); } err = map_private_extent_buffer(eb, start, min_len, token, map, map_start, map_len, km); diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h index e80c6d96b31..1f9df88afbf 100644 --- a/fs/btrfs/extent_io.h +++ b/fs/btrfs/extent_io.h @@ -22,6 +22,10 @@ /* flags for bio submission */ #define EXTENT_BIO_COMPRESSED 1 +/* these are bit numbers for test/set bit */ +#define EXTENT_BUFFER_UPTODATE 0 +#define EXTENT_BUFFER_BLOCKING 1 + /* * page->private values. Every page that is controlled by the extent * map has page->private set to one. @@ -95,11 +99,19 @@ struct extent_buffer { unsigned long map_start; unsigned long map_len; struct page *first_page; + unsigned long bflags; atomic_t refs; - int flags; struct list_head leak_list; struct rb_node rb_node; - struct mutex mutex; + + /* the spinlock is used to protect most operations */ + spinlock_t lock; + + /* + * when we keep the lock held while blocking, waiters go onto + * the wq + */ + wait_queue_head_t lock_wq; }; struct extent_map_tree; diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 4a79e1c5ebd..ebd7d6c37df 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -50,6 +50,7 @@ #include "tree-log.h" #include "ref-cache.h" #include "compression.h" +#include "locking.h" struct btrfs_iget_args { u64 ino; @@ -2021,6 +2022,7 @@ void btrfs_read_locked_inode(struct inode *inode) BTRFS_I(inode)->flags = btrfs_inode_flags(leaf, inode_item); alloc_group_block = btrfs_inode_block_group(leaf, inode_item); + BTRFS_I(inode)->block_group = btrfs_find_block_group(root, 0, alloc_group_block, 0); btrfs_free_path(path); @@ -2117,6 +2119,7 @@ noinline int btrfs_update_inode(struct btrfs_trans_handle *trans, goto failed; } + btrfs_unlock_up_safe(path, 1); leaf = path->nodes[0]; inode_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item); diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c index 39bae7761db..68fd9ccf180 100644 --- a/fs/btrfs/locking.c +++ b/fs/btrfs/locking.c @@ -26,45 +26,215 @@ #include "locking.h" /* - * locks the per buffer mutex in an extent buffer. This uses adaptive locks - * and the spin is not tuned very extensively. The spinning does make a big - * difference in almost every workload, but spinning for the right amount of - * time needs some help. - * - * In general, we want to spin as long as the lock holder is doing btree - * searches, and we should give up if they are in more expensive code. + * btrfs_header_level() isn't free, so don't call it when lockdep isn't + * on */ +#ifdef CONFIG_DEBUG_LOCK_ALLOC +static inline void spin_nested(struct extent_buffer *eb) +{ + spin_lock_nested(&eb->lock, BTRFS_MAX_LEVEL - btrfs_header_level(eb)); +} +#else +static inline void spin_nested(struct extent_buffer *eb) +{ + spin_lock(&eb->lock); +} +#endif -int btrfs_tree_lock(struct extent_buffer *eb) +/* + * Setting a lock to blocking will drop the spinlock and set the + * flag that forces other procs who want the lock to wait. After + * this you can safely schedule with the lock held. + */ +void btrfs_set_lock_blocking(struct extent_buffer *eb) { - int i; + if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) { + set_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags); + spin_unlock(&eb->lock); + } + /* exit with the spin lock released and the bit set */ +} - if (mutex_trylock(&eb->mutex)) - return 0; +/* + * clearing the blocking flag will take the spinlock again. + * After this you can't safely schedule + */ +void btrfs_clear_lock_blocking(struct extent_buffer *eb) +{ + if (test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) { + spin_nested(eb); + clear_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags); + smp_mb__after_clear_bit(); + } + /* exit with the spin lock held */ +} + +/* + * unfortunately, many of the places that currently set a lock to blocking + * don't end up blocking for every long, and often they don't block + * at all. For a dbench 50 run, if we don't spin one the blocking bit + * at all, the context switch rate can jump up to 400,000/sec or more. + * + * So, we're still stuck with this crummy spin on the blocking bit, + * at least until the most common causes of the short blocks + * can be dealt with. + */ +static int btrfs_spin_on_block(struct extent_buffer *eb) +{ + int i; for (i = 0; i < 512; i++) { cpu_relax(); - if (mutex_trylock(&eb->mutex)) + if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) + return 1; + if (need_resched()) + break; + } + return 0; +} + +/* + * This is somewhat different from trylock. It will take the + * spinlock but if it finds the lock is set to blocking, it will + * return without the lock held. + * + * returns 1 if it was able to take the lock and zero otherwise + * + * After this call, scheduling is not safe without first calling + * btrfs_set_lock_blocking() + */ +int btrfs_try_spin_lock(struct extent_buffer *eb) +{ + int i; + + spin_nested(eb); + if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) + return 1; + spin_unlock(&eb->lock); + + /* spin for a bit on the BLOCKING flag */ + for (i = 0; i < 2; i++) { + if (!btrfs_spin_on_block(eb)) + break; + + spin_nested(eb); + if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) + return 1; + spin_unlock(&eb->lock); + } + return 0; +} + +/* + * the autoremove wake function will return 0 if it tried to wake up + * a process that was already awake, which means that process won't + * count as an exclusive wakeup. The waitq code will continue waking + * procs until it finds one that was actually sleeping. + * + * For btrfs, this isn't quite what we want. We want a single proc + * to be notified that the lock is ready for taking. If that proc + * already happen to be awake, great, it will loop around and try for + * the lock. + * + * So, btrfs_wake_function always returns 1, even when the proc that we + * tried to wake up was already awake. + */ +static int btrfs_wake_function(wait_queue_t *wait, unsigned mode, + int sync, void *key) +{ + autoremove_wake_function(wait, mode, sync, key); + return 1; +} + +/* + * returns with the extent buffer spinlocked. + * + * This will spin and/or wait as required to take the lock, and then + * return with the spinlock held. + * + * After this call, scheduling is not safe without first calling + * btrfs_set_lock_blocking() + */ +int btrfs_tree_lock(struct extent_buffer *eb) +{ + DEFINE_WAIT(wait); + wait.func = btrfs_wake_function; + + while(1) { + spin_nested(eb); + + /* nobody is blocking, exit with the spinlock held */ + if (!test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) return 0; + + /* + * we have the spinlock, but the real owner is blocking. + * wait for them + */ + spin_unlock(&eb->lock); + + /* + * spin for a bit, and if the blocking flag goes away, + * loop around + */ + if (btrfs_spin_on_block(eb)) + continue; + + prepare_to_wait_exclusive(&eb->lock_wq, &wait, + TASK_UNINTERRUPTIBLE); + + if (test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) + schedule(); + + finish_wait(&eb->lock_wq, &wait); } - cpu_relax(); - mutex_lock_nested(&eb->mutex, BTRFS_MAX_LEVEL - btrfs_header_level(eb)); return 0; } +/* + * Very quick trylock, this does not spin or schedule. It returns + * 1 with the spinlock held if it was able to take the lock, or it + * returns zero if it was unable to take the lock. + * + * After this call, scheduling is not safe without first calling + * btrfs_set_lock_blocking() + */ int btrfs_try_tree_lock(struct extent_buffer *eb) { - return mutex_trylock(&eb->mutex); + if (spin_trylock(&eb->lock)) { + if (test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) { + /* + * we've got the spinlock, but the real owner is + * blocking. Drop the spinlock and return failure + */ + spin_unlock(&eb->lock); + return 0; + } + return 1; + } + /* someone else has the spinlock giveup */ + return 0; } int btrfs_tree_unlock(struct extent_buffer *eb) { - mutex_unlock(&eb->mutex); + /* + * if we were a blocking owner, we don't have the spinlock held + * just clear the bit and look for waiters + */ + if (test_and_clear_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags)) + smp_mb__after_clear_bit(); + else + spin_unlock(&eb->lock); + + if (waitqueue_active(&eb->lock_wq)) + wake_up(&eb->lock_wq); return 0; } int btrfs_tree_locked(struct extent_buffer *eb) { - return mutex_is_locked(&eb->mutex); + return test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags) || + spin_is_locked(&eb->lock); } /* @@ -75,12 +245,14 @@ int btrfs_path_lock_waiting(struct btrfs_path *path, int level) { int i; struct extent_buffer *eb; + for (i = level; i <= level + 1 && i < BTRFS_MAX_LEVEL; i++) { eb = path->nodes[i]; if (!eb) break; smp_mb(); - if (!list_empty(&eb->mutex.wait_list)) + if (spin_is_contended(&eb->lock) || + waitqueue_active(&eb->lock_wq)) return 1; } return 0; diff --git a/fs/btrfs/locking.h b/fs/btrfs/locking.h index bc1faef1251..d92e707f587 100644 --- a/fs/btrfs/locking.h +++ b/fs/btrfs/locking.h @@ -22,6 +22,12 @@ int btrfs_tree_lock(struct extent_buffer *eb); int btrfs_tree_unlock(struct extent_buffer *eb); int btrfs_tree_locked(struct extent_buffer *eb); + int btrfs_try_tree_lock(struct extent_buffer *eb); +int btrfs_try_spin_lock(struct extent_buffer *eb); + int btrfs_path_lock_waiting(struct btrfs_path *path, int level); + +void btrfs_set_lock_blocking(struct extent_buffer *eb); +void btrfs_clear_lock_blocking(struct extent_buffer *eb); #endif diff --git a/fs/btrfs/tree-defrag.c b/fs/btrfs/tree-defrag.c index 3e8358c3616..98d25fa4570 100644 --- a/fs/btrfs/tree-defrag.c +++ b/fs/btrfs/tree-defrag.c @@ -74,6 +74,7 @@ int btrfs_defrag_leaves(struct btrfs_trans_handle *trans, u32 nritems; root_node = btrfs_lock_root_node(root); + btrfs_set_lock_blocking(root_node); nritems = btrfs_header_nritems(root_node); root->defrag_max.objectid = 0; /* from above we know this is not a leaf */ diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 4f26f3ed0c8..20794290256 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -1615,6 +1615,7 @@ static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans, btrfs_tree_lock(next); clean_tree_block(trans, root, next); + btrfs_set_lock_blocking(next); btrfs_wait_tree_block_writeback(next); btrfs_tree_unlock(next); @@ -1661,6 +1662,7 @@ static noinline int walk_down_log_tree(struct btrfs_trans_handle *trans, next = path->nodes[*level]; btrfs_tree_lock(next); clean_tree_block(trans, root, next); + btrfs_set_lock_blocking(next); btrfs_wait_tree_block_writeback(next); btrfs_tree_unlock(next); @@ -1718,6 +1720,7 @@ static noinline int walk_up_log_tree(struct btrfs_trans_handle *trans, btrfs_tree_lock(next); clean_tree_block(trans, root, next); + btrfs_set_lock_blocking(next); btrfs_wait_tree_block_writeback(next); btrfs_tree_unlock(next); @@ -1790,6 +1793,7 @@ static int walk_log_tree(struct btrfs_trans_handle *trans, btrfs_tree_lock(next); clean_tree_block(trans, log, next); + btrfs_set_lock_blocking(next); btrfs_wait_tree_block_writeback(next); btrfs_tree_unlock(next); -- cgit v1.2.3-70-g09d2 From 4d081c41a4f98aecb5e86ef7d3e644cc7b52131f Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 4 Feb 2009 09:31:28 -0500 Subject: Btrfs: change btrfs_del_leaf to drop locks earlier btrfs_del_leaf does two things. First it removes the pointer in the parent, and then it frees the block that has the leaf. It has the parent node locked for both operations. But, it only needs the parent locked while it is deleting the pointer. After that it can safely free the block without the parent locked. Signed-off-by: Chris Mason --- fs/btrfs/ctree.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'fs/btrfs/ctree.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 3af777357ac..f6916ceb392 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -3630,15 +3630,22 @@ noinline int btrfs_del_leaf(struct btrfs_trans_handle *trans, { int ret; u64 root_gen = btrfs_header_generation(path->nodes[1]); + u64 parent_start = path->nodes[1]->start; + u64 parent_owner = btrfs_header_owner(path->nodes[1]); ret = del_ptr(trans, root, path, 1, path->slots[1]); if (ret) return ret; + /* + * btrfs_free_extent is expensive, we want to make sure we + * aren't holding any locks when we call it + */ + btrfs_unlock_up_safe(path, 0); + ret = btrfs_free_extent(trans, root, bytenr, btrfs_level_size(root, 0), - path->nodes[1]->start, - btrfs_header_owner(path->nodes[1]), + parent_start, parent_owner, root_gen, 0, 1); return ret; } -- cgit v1.2.3-70-g09d2 From 12f4daccfc3732280debba8f9ba49720372de831 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 4 Feb 2009 09:31:42 -0500 Subject: Btrfs: fix btrfs_unlock_up_safe to walk the entire path btrfs_unlock_up_safe would break out at the first NULL node entry or unlocked node it found in the path. Some of the callers have missing nodes at the lower levels of the path, so this commit fixes things to check all the nodes in the path before returning. Signed-off-by: Chris Mason --- fs/btrfs/ctree.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'fs/btrfs/ctree.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index f6916ceb392..0d1e3b91e7b 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1439,9 +1439,9 @@ noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level) for (i = level; i < BTRFS_MAX_LEVEL; i++) { if (!path->nodes[i]) - break; + continue; if (!path->locks[i]) - break; + continue; btrfs_tree_unlock(path->nodes[i]); path->locks[i] = 0; } -- cgit v1.2.3-70-g09d2 From 7b78c170dc4f538cc7ee66f47b3aac3f3974a36c Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 4 Feb 2009 09:12:46 -0500 Subject: Btrfs: Only prep for btree deletion balances when nodes are mostly empty Whenever an item deletion is done, we need to balance all the nodes in the tree to make sure we don't end up with an empty node if a pointer is deleted. This balance prep happens from the root of the tree down so we can drop our locks as we go. reada_for_balance was triggering read-ahead on neighboring nodes even when no balancing was required. This adds an extra check to avoid calling balance_level() and avoid reada_for_balance() when a balance won't be required. Signed-off-by: Chris Mason --- fs/btrfs/ctree.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'fs/btrfs/ctree.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 0d1e3b91e7b..551177c0011 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1518,18 +1518,19 @@ again: */ if (prealloc_block.objectid && prealloc_block.offset != b->len) { - btrfs_set_path_blocking(p); + btrfs_release_path(root, p); btrfs_free_reserved_extent(root, prealloc_block.objectid, prealloc_block.offset); prealloc_block.objectid = 0; + goto again; } /* * for higher level blocks, try not to allocate blocks * with the block and the parent locks held. */ - if (level > 1 && !prealloc_block.objectid && + if (level > 0 && !prealloc_block.objectid && btrfs_path_lock_waiting(p, level)) { u32 size = b->len; u64 hint = b->start; @@ -1614,7 +1615,9 @@ cow_done: } b = p->nodes[level]; slot = p->slots[level]; - } else if (ins_len < 0) { + } else if (ins_len < 0 && + btrfs_header_nritems(b) < + BTRFS_NODEPTRS_PER_BLOCK(root) / 4) { int sret; sret = reada_for_balance(root, p, level); -- cgit v1.2.3-70-g09d2 From 284b066af41579f62649048fdec5c5e7091703e6 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Mon, 9 Feb 2009 16:22:03 -0500 Subject: Btrfs: don't use spin_is_contended Btrfs was using spin_is_contended to see if it should drop locks before doing extent allocations during btrfs_search_slot. The idea was to avoid expensive searches in the tree unless the lock was actually contended. But, spin_is_contended is specific to the ticket spinlocks on x86, so this is causing compile errors everywhere else. In practice, the contention could easily appear some time after we started doing the extent allocation, and it makes more sense to always drop the lock instead. Signed-off-by: Chris Mason --- fs/btrfs/ctree.c | 3 +-- fs/btrfs/locking.c | 22 ---------------------- fs/btrfs/locking.h | 2 -- 3 files changed, 1 insertion(+), 26 deletions(-) (limited to 'fs/btrfs/ctree.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 551177c0011..35443cc4b9a 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1530,8 +1530,7 @@ again: * for higher level blocks, try not to allocate blocks * with the block and the parent locks held. */ - if (level > 0 && !prealloc_block.objectid && - btrfs_path_lock_waiting(p, level)) { + if (level > 0 && !prealloc_block.objectid) { u32 size = b->len; u64 hint = b->start; diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c index 68fd9ccf180..9ebe9385129 100644 --- a/fs/btrfs/locking.c +++ b/fs/btrfs/locking.c @@ -236,25 +236,3 @@ int btrfs_tree_locked(struct extent_buffer *eb) return test_bit(EXTENT_BUFFER_BLOCKING, &eb->bflags) || spin_is_locked(&eb->lock); } - -/* - * btrfs_search_slot uses this to decide if it should drop its locks - * before doing something expensive like allocating free blocks for cow. - */ -int btrfs_path_lock_waiting(struct btrfs_path *path, int level) -{ - int i; - struct extent_buffer *eb; - - for (i = level; i <= level + 1 && i < BTRFS_MAX_LEVEL; i++) { - eb = path->nodes[i]; - if (!eb) - break; - smp_mb(); - if (spin_is_contended(&eb->lock) || - waitqueue_active(&eb->lock_wq)) - return 1; - } - return 0; -} - diff --git a/fs/btrfs/locking.h b/fs/btrfs/locking.h index d92e707f587..6bb0afbff92 100644 --- a/fs/btrfs/locking.h +++ b/fs/btrfs/locking.h @@ -26,8 +26,6 @@ int btrfs_tree_locked(struct extent_buffer *eb); int btrfs_try_tree_lock(struct extent_buffer *eb); int btrfs_try_spin_lock(struct extent_buffer *eb); -int btrfs_path_lock_waiting(struct btrfs_path *path, int level); - void btrfs_set_lock_blocking(struct extent_buffer *eb); void btrfs_clear_lock_blocking(struct extent_buffer *eb); #endif -- cgit v1.2.3-70-g09d2