From 7a7eaa40a39bde4eefc91aadeb1ce3dc4e6a1252 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Wed, 13 Apr 2011 12:54:33 -0400 Subject: Btrfs: take away the num_items argument from btrfs_join_transaction I keep forgetting that btrfs_join_transaction() just ignores the num_items argument, which leads me to sending pointless patches and looking stupid :). So just kill the num_items argument from btrfs_join_transaction and btrfs_start_ioctl_transaction, since neither of them use it. Thanks, Signed-off-by: Josef Bacik --- fs/btrfs/relocation.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'fs/btrfs/relocation.c') diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 199a80134312..8bb256667f2d 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -2149,7 +2149,7 @@ again: err = ret; } - trans = btrfs_join_transaction(rc->extent_root, 1); + trans = btrfs_join_transaction(rc->extent_root); if (IS_ERR(trans)) { if (!err) btrfs_block_rsv_release(rc->extent_root, @@ -3233,7 +3233,7 @@ truncate: goto out; } - trans = btrfs_join_transaction(root, 0); + trans = btrfs_join_transaction(root); if (IS_ERR(trans)) { btrfs_free_path(path); ret = PTR_ERR(trans); @@ -3642,7 +3642,7 @@ int prepare_to_relocate(struct reloc_control *rc) rc->create_reloc_tree = 1; set_reloc_control(rc); - trans = btrfs_join_transaction(rc->extent_root, 1); + trans = btrfs_join_transaction(rc->extent_root); BUG_ON(IS_ERR(trans)); btrfs_commit_transaction(trans, rc->extent_root); return 0; @@ -3831,7 +3831,7 @@ restart: btrfs_block_rsv_release(rc->extent_root, rc->block_rsv, (u64)-1); /* get rid of pinned extents */ - trans = btrfs_join_transaction(rc->extent_root, 1); + trans = btrfs_join_transaction(rc->extent_root); if (IS_ERR(trans)) err = PTR_ERR(trans); else @@ -4156,7 +4156,7 @@ int btrfs_recover_relocation(struct btrfs_root *root) set_reloc_control(rc); - trans = btrfs_join_transaction(rc->extent_root, 1); + trans = btrfs_join_transaction(rc->extent_root); if (IS_ERR(trans)) { unset_reloc_control(rc); err = PTR_ERR(trans); @@ -4190,7 +4190,7 @@ int btrfs_recover_relocation(struct btrfs_root *root) unset_reloc_control(rc); - trans = btrfs_join_transaction(rc->extent_root, 1); + trans = btrfs_join_transaction(rc->extent_root); if (IS_ERR(trans)) err = PTR_ERR(trans); else -- cgit v1.2.3 From a4abeea41adfa3c143c289045f4625dfaeba2212 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Mon, 11 Apr 2011 17:25:13 -0400 Subject: Btrfs: kill trans_mutex We use trans_mutex for lots of things, here's a basic list 1) To serialize trans_handles joining the currently running transaction 2) To make sure that no new trans handles are started while we are committing 3) To protect the dead_roots list and the transaction lists Really the serializing trans_handles joining is not too hard, and can really get bogged down in acquiring a reference to the transaction. So replace the trans_mutex with a trans_lock spinlock and use it to do the following 1) Protect fs_info->running_transaction. All trans handles have to do is check this, and then take a reference of the transaction and keep on going. 2) Protect the fs_info->trans_list. This doesn't get used too much, basically it just holds the current transactions, which will usually just be the currently committing transaction and the currently running transaction at most. 3) Protect the dead roots list. This is only ever processed by splicing the list so this is relatively simple. 4) Protect the fs_info->reloc_ctl stuff. This is very lightweight and was using the trans_mutex before, so this is a pretty straightforward change. 5) Protect fs_info->no_trans_join. Because we don't hold the trans_lock over the entirety of the commit we need to have a way to block new people from creating a new transaction while we're doing our work. So we set no_trans_join and in join_transaction we test to see if that is set, and if it is we do a wait_on_commit. 6) Make the transaction use count atomic so we don't need to take locks to modify it when we're dropping references. 7) Add a commit_lock to the transaction to make sure multiple people trying to commit the same transaction don't race and commit at the same time. 8) Make open_ioctl_trans an atomic so we don't have to take any locks for ioctl trans. I have tested this with xfstests, but obviously it is a pretty hairy change so lots of testing is greatly appreciated. Thanks, Signed-off-by: Josef Bacik --- fs/btrfs/ctree.h | 6 +- fs/btrfs/disk-io.c | 30 +++--- fs/btrfs/extent-tree.c | 3 +- fs/btrfs/file.c | 4 +- fs/btrfs/ioctl.c | 12 +-- fs/btrfs/relocation.c | 16 +-- fs/btrfs/transaction.c | 271 ++++++++++++++++++++++++++----------------------- fs/btrfs/transaction.h | 4 +- 8 files changed, 177 insertions(+), 169 deletions(-) (limited to 'fs/btrfs/relocation.c') diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 8f4b81de3ae2..522a39b0033d 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -919,7 +919,6 @@ struct btrfs_fs_info { * is required instead of the faster short fsync log commits */ u64 last_trans_log_full_commit; - u64 open_ioctl_trans; unsigned long mount_opt:20; unsigned long compress_type:4; u64 max_inline; @@ -936,7 +935,6 @@ struct btrfs_fs_info { struct super_block *sb; struct inode *btree_inode; struct backing_dev_info bdi; - struct mutex trans_mutex; struct mutex tree_log_mutex; struct mutex transaction_kthread_mutex; struct mutex cleaner_mutex; @@ -957,6 +955,7 @@ struct btrfs_fs_info { struct rw_semaphore subvol_sem; struct srcu_struct subvol_srcu; + spinlock_t trans_lock; struct list_head trans_list; struct list_head hashers; struct list_head dead_roots; @@ -969,6 +968,7 @@ struct btrfs_fs_info { atomic_t async_submit_draining; atomic_t nr_async_bios; atomic_t async_delalloc_pages; + atomic_t open_ioctl_trans; /* * this is used by the balancing code to wait for all the pending @@ -1032,6 +1032,7 @@ struct btrfs_fs_info { int closing; int log_root_recovering; int enospc_unlink; + int trans_no_join; u64 total_pinned; @@ -1053,7 +1054,6 @@ struct btrfs_fs_info { struct reloc_control *reloc_ctl; spinlock_t delalloc_lock; - spinlock_t new_trans_lock; u64 delalloc_bytes; /* data_alloc_cluster is only used in ssd mode */ diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 9d6c9e332ca3..93ef254ec432 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1551,22 +1551,22 @@ static int transaction_kthread(void *arg) vfs_check_frozen(root->fs_info->sb, SB_FREEZE_WRITE); mutex_lock(&root->fs_info->transaction_kthread_mutex); - spin_lock(&root->fs_info->new_trans_lock); + spin_lock(&root->fs_info->trans_lock); cur = root->fs_info->running_transaction; if (!cur) { - spin_unlock(&root->fs_info->new_trans_lock); + spin_unlock(&root->fs_info->trans_lock); goto sleep; } now = get_seconds(); if (!cur->blocked && (now < cur->start_time || now - cur->start_time < 30)) { - spin_unlock(&root->fs_info->new_trans_lock); + spin_unlock(&root->fs_info->trans_lock); delay = HZ * 5; goto sleep; } transid = cur->transid; - spin_unlock(&root->fs_info->new_trans_lock); + spin_unlock(&root->fs_info->trans_lock); trans = btrfs_join_transaction(root); BUG_ON(IS_ERR(trans)); @@ -1658,7 +1658,7 @@ struct btrfs_root *open_ctree(struct super_block *sb, INIT_LIST_HEAD(&fs_info->ordered_operations); INIT_LIST_HEAD(&fs_info->caching_block_groups); spin_lock_init(&fs_info->delalloc_lock); - spin_lock_init(&fs_info->new_trans_lock); + spin_lock_init(&fs_info->trans_lock); spin_lock_init(&fs_info->ref_cache_lock); spin_lock_init(&fs_info->fs_roots_radix_lock); spin_lock_init(&fs_info->delayed_iput_lock); @@ -1687,6 +1687,7 @@ struct btrfs_root *open_ctree(struct super_block *sb, fs_info->sb = sb; fs_info->max_inline = 8192 * 1024; fs_info->metadata_ratio = 0; + fs_info->trans_no_join = 0; fs_info->thread_pool_size = min_t(unsigned long, num_online_cpus() + 2, 8); @@ -1735,7 +1736,6 @@ struct btrfs_root *open_ctree(struct super_block *sb, fs_info->do_barriers = 1; - mutex_init(&fs_info->trans_mutex); mutex_init(&fs_info->ordered_operations_mutex); mutex_init(&fs_info->tree_log_mutex); mutex_init(&fs_info->chunk_mutex); @@ -3006,10 +3006,13 @@ static int btrfs_cleanup_transaction(struct btrfs_root *root) WARN_ON(1); - mutex_lock(&root->fs_info->trans_mutex); mutex_lock(&root->fs_info->transaction_kthread_mutex); + spin_lock(&root->fs_info->trans_lock); list_splice_init(&root->fs_info->trans_list, &list); + root->fs_info->trans_no_join = 1; + spin_unlock(&root->fs_info->trans_lock); + while (!list_empty(&list)) { t = list_entry(list.next, struct btrfs_transaction, list); if (!t) @@ -3034,23 +3037,18 @@ static int btrfs_cleanup_transaction(struct btrfs_root *root) t->blocked = 0; if (waitqueue_active(&root->fs_info->transaction_wait)) wake_up(&root->fs_info->transaction_wait); - mutex_unlock(&root->fs_info->trans_mutex); - mutex_lock(&root->fs_info->trans_mutex); t->commit_done = 1; if (waitqueue_active(&t->commit_wait)) wake_up(&t->commit_wait); - mutex_unlock(&root->fs_info->trans_mutex); - - mutex_lock(&root->fs_info->trans_mutex); btrfs_destroy_pending_snapshots(t); btrfs_destroy_delalloc_inodes(root); - spin_lock(&root->fs_info->new_trans_lock); + spin_lock(&root->fs_info->trans_lock); root->fs_info->running_transaction = NULL; - spin_unlock(&root->fs_info->new_trans_lock); + spin_unlock(&root->fs_info->trans_lock); btrfs_destroy_marked_extents(root, &t->dirty_pages, EXTENT_DIRTY); @@ -3064,8 +3062,10 @@ static int btrfs_cleanup_transaction(struct btrfs_root *root) kmem_cache_free(btrfs_transaction_cachep, t); } + spin_lock(&root->fs_info->trans_lock); + root->fs_info->trans_no_join = 0; + spin_unlock(&root->fs_info->trans_lock); mutex_unlock(&root->fs_info->transaction_kthread_mutex); - mutex_unlock(&root->fs_info->trans_mutex); return 0; } diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 941b28e78931..ca599654ce19 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -3200,7 +3200,8 @@ alloc: /* commit the current transaction and try again */ commit_trans: - if (!committed && !root->fs_info->open_ioctl_trans) { + if (!committed && + !atomic_read(&root->fs_info->open_ioctl_trans)) { committed = 1; trans = btrfs_join_transaction(root); if (IS_ERR(trans)) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 75899a01dded..cd5e82e500cf 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1222,14 +1222,12 @@ int btrfs_sync_file(struct file *file, int datasync) * the current transaction, we can bail out now without any * syncing */ - mutex_lock(&root->fs_info->trans_mutex); + smp_mb(); if (BTRFS_I(inode)->last_trans <= root->fs_info->last_trans_committed) { BTRFS_I(inode)->last_trans = 0; - mutex_unlock(&root->fs_info->trans_mutex); goto out; } - mutex_unlock(&root->fs_info->trans_mutex); /* * ok we haven't committed the transaction yet, lets do a commit diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 908c3d4b48c6..a578620e06a8 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2177,9 +2177,7 @@ static long btrfs_ioctl_trans_start(struct file *file) if (ret) goto out; - mutex_lock(&root->fs_info->trans_mutex); - root->fs_info->open_ioctl_trans++; - mutex_unlock(&root->fs_info->trans_mutex); + atomic_inc(&root->fs_info->open_ioctl_trans); ret = -ENOMEM; trans = btrfs_start_ioctl_transaction(root); @@ -2190,9 +2188,7 @@ static long btrfs_ioctl_trans_start(struct file *file) return 0; out_drop: - mutex_lock(&root->fs_info->trans_mutex); - root->fs_info->open_ioctl_trans--; - mutex_unlock(&root->fs_info->trans_mutex); + atomic_dec(&root->fs_info->open_ioctl_trans); mnt_drop_write(file->f_path.mnt); out: return ret; @@ -2426,9 +2422,7 @@ long btrfs_ioctl_trans_end(struct file *file) btrfs_end_transaction(trans, root); - mutex_lock(&root->fs_info->trans_mutex); - root->fs_info->open_ioctl_trans--; - mutex_unlock(&root->fs_info->trans_mutex); + atomic_dec(&root->fs_info->open_ioctl_trans); mnt_drop_write(file->f_path.mnt); return 0; diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 8bb256667f2d..09c30d37d43e 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -2136,10 +2136,10 @@ int prepare_to_merge(struct reloc_control *rc, int err) u64 num_bytes = 0; int ret; - mutex_lock(&root->fs_info->trans_mutex); + spin_lock(&root->fs_info->trans_lock); rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2; rc->merging_rsv_size += rc->nodes_relocated * 2; - mutex_unlock(&root->fs_info->trans_mutex); + spin_unlock(&root->fs_info->trans_lock); again: if (!err) { num_bytes = rc->merging_rsv_size; @@ -2208,9 +2208,9 @@ int merge_reloc_roots(struct reloc_control *rc) int ret; again: root = rc->extent_root; - mutex_lock(&root->fs_info->trans_mutex); + spin_lock(&root->fs_info->trans_lock); list_splice_init(&rc->reloc_roots, &reloc_roots); - mutex_unlock(&root->fs_info->trans_mutex); + spin_unlock(&root->fs_info->trans_lock); while (!list_empty(&reloc_roots)) { found = 1; @@ -3583,17 +3583,17 @@ next: static void set_reloc_control(struct reloc_control *rc) { struct btrfs_fs_info *fs_info = rc->extent_root->fs_info; - mutex_lock(&fs_info->trans_mutex); + spin_lock(&fs_info->trans_lock); fs_info->reloc_ctl = rc; - mutex_unlock(&fs_info->trans_mutex); + spin_unlock(&fs_info->trans_lock); } static void unset_reloc_control(struct reloc_control *rc) { struct btrfs_fs_info *fs_info = rc->extent_root->fs_info; - mutex_lock(&fs_info->trans_mutex); + spin_lock(&fs_info->trans_lock); fs_info->reloc_ctl = NULL; - mutex_unlock(&fs_info->trans_mutex); + spin_unlock(&fs_info->trans_lock); } static int check_extent_flags(u64 flags) diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 46f40564c168..43816f8b23e7 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -34,6 +34,7 @@ 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)); memset(transaction, 0, sizeof(*transaction)); kmem_cache_free(btrfs_transaction_cachep, transaction); } @@ -48,47 +49,73 @@ static noinline void switch_commit_root(struct btrfs_root *root) /* * either allocate a new transaction or hop into the existing one */ -static noinline int join_transaction(struct btrfs_root *root) +static noinline int join_transaction(struct btrfs_root *root, int nofail) { struct btrfs_transaction *cur_trans; + + spin_lock(&root->fs_info->trans_lock); + if (root->fs_info->trans_no_join) { + if (!nofail) { + spin_unlock(&root->fs_info->trans_lock); + return -EBUSY; + } + } + cur_trans = root->fs_info->running_transaction; - if (!cur_trans) { - cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, - GFP_NOFS); - if (!cur_trans) - return -ENOMEM; - root->fs_info->generation++; - atomic_set(&cur_trans->num_writers, 1); - cur_trans->num_joined = 0; - cur_trans->transid = root->fs_info->generation; - init_waitqueue_head(&cur_trans->writer_wait); - init_waitqueue_head(&cur_trans->commit_wait); - cur_trans->in_commit = 0; - cur_trans->blocked = 0; - atomic_set(&cur_trans->use_count, 1); - cur_trans->commit_done = 0; - cur_trans->start_time = get_seconds(); - - cur_trans->delayed_refs.root = RB_ROOT; - cur_trans->delayed_refs.num_entries = 0; - cur_trans->delayed_refs.num_heads_ready = 0; - cur_trans->delayed_refs.num_heads = 0; - cur_trans->delayed_refs.flushing = 0; - cur_trans->delayed_refs.run_delayed_start = 0; - spin_lock_init(&cur_trans->delayed_refs.lock); - - INIT_LIST_HEAD(&cur_trans->pending_snapshots); - list_add_tail(&cur_trans->list, &root->fs_info->trans_list); - extent_io_tree_init(&cur_trans->dirty_pages, - root->fs_info->btree_inode->i_mapping, - GFP_NOFS); - spin_lock(&root->fs_info->new_trans_lock); - root->fs_info->running_transaction = cur_trans; - spin_unlock(&root->fs_info->new_trans_lock); - } else { + if (cur_trans) { + atomic_inc(&cur_trans->use_count); + atomic_inc(&cur_trans->num_writers); + cur_trans->num_joined++; + spin_unlock(&root->fs_info->trans_lock); + return 0; + } + spin_unlock(&root->fs_info->trans_lock); + + cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS); + if (!cur_trans) + return -ENOMEM; + spin_lock(&root->fs_info->trans_lock); + if (root->fs_info->running_transaction) { + kmem_cache_free(btrfs_transaction_cachep, cur_trans); + cur_trans = root->fs_info->running_transaction; + atomic_inc(&cur_trans->use_count); atomic_inc(&cur_trans->num_writers); cur_trans->num_joined++; + spin_unlock(&root->fs_info->trans_lock); + return 0; } + atomic_set(&cur_trans->num_writers, 1); + cur_trans->num_joined = 0; + init_waitqueue_head(&cur_trans->writer_wait); + init_waitqueue_head(&cur_trans->commit_wait); + cur_trans->in_commit = 0; + cur_trans->blocked = 0; + /* + * One for this trans handle, one so it will live on until we + * commit the transaction. + */ + atomic_set(&cur_trans->use_count, 2); + cur_trans->commit_done = 0; + cur_trans->start_time = get_seconds(); + + cur_trans->delayed_refs.root = RB_ROOT; + cur_trans->delayed_refs.num_entries = 0; + cur_trans->delayed_refs.num_heads_ready = 0; + cur_trans->delayed_refs.num_heads = 0; + cur_trans->delayed_refs.flushing = 0; + cur_trans->delayed_refs.run_delayed_start = 0; + spin_lock_init(&cur_trans->commit_lock); + spin_lock_init(&cur_trans->delayed_refs.lock); + + INIT_LIST_HEAD(&cur_trans->pending_snapshots); + list_add_tail(&cur_trans->list, &root->fs_info->trans_list); + extent_io_tree_init(&cur_trans->dirty_pages, + root->fs_info->btree_inode->i_mapping, + GFP_NOFS); + root->fs_info->generation++; + cur_trans->transid = root->fs_info->generation; + root->fs_info->running_transaction = cur_trans; + spin_unlock(&root->fs_info->trans_lock); return 0; } @@ -99,39 +126,28 @@ static noinline int join_transaction(struct btrfs_root *root) * to make sure the old root from before we joined the transaction is deleted * when the transaction commits */ -static noinline int record_root_in_trans(struct btrfs_trans_handle *trans, - struct btrfs_root *root) +int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans, + struct btrfs_root *root) { if (root->ref_cows && root->last_trans < trans->transid) { WARN_ON(root == root->fs_info->extent_root); WARN_ON(root->commit_root != root->node); + spin_lock(&root->fs_info->fs_roots_radix_lock); + if (root->last_trans == trans->transid) { + spin_unlock(&root->fs_info->fs_roots_radix_lock); + return 0; + } + root->last_trans = trans->transid; radix_tree_tag_set(&root->fs_info->fs_roots_radix, (unsigned long)root->root_key.objectid, BTRFS_ROOT_TRANS_TAG); - root->last_trans = trans->transid; + spin_unlock(&root->fs_info->fs_roots_radix_lock); btrfs_init_reloc_root(trans, root); } return 0; } -int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans, - struct btrfs_root *root) -{ - if (!root->ref_cows) - return 0; - - mutex_lock(&root->fs_info->trans_mutex); - if (root->last_trans == trans->transid) { - mutex_unlock(&root->fs_info->trans_mutex); - return 0; - } - - record_root_in_trans(trans, root); - mutex_unlock(&root->fs_info->trans_mutex); - return 0; -} - /* wait for commit against the current transaction to become unblocked * when this is done, it is safe to start a new transaction, but the current * transaction might not be fully on disk. @@ -140,21 +156,23 @@ static void wait_current_trans(struct btrfs_root *root) { struct btrfs_transaction *cur_trans; + spin_lock(&root->fs_info->trans_lock); cur_trans = root->fs_info->running_transaction; if (cur_trans && cur_trans->blocked) { DEFINE_WAIT(wait); atomic_inc(&cur_trans->use_count); + spin_unlock(&root->fs_info->trans_lock); while (1) { prepare_to_wait(&root->fs_info->transaction_wait, &wait, TASK_UNINTERRUPTIBLE); if (!cur_trans->blocked) break; - mutex_unlock(&root->fs_info->trans_mutex); schedule(); - mutex_lock(&root->fs_info->trans_mutex); } finish_wait(&root->fs_info->transaction_wait, &wait); put_transaction(cur_trans); + } else { + spin_unlock(&root->fs_info->trans_lock); } } @@ -167,10 +185,16 @@ enum btrfs_trans_type { static int may_wait_transaction(struct btrfs_root *root, int type) { - if (!root->fs_info->log_root_recovering && - ((type == TRANS_START && !root->fs_info->open_ioctl_trans) || - type == TRANS_USERSPACE)) + if (root->fs_info->log_root_recovering) + return 0; + + if (type == TRANS_USERSPACE) + return 1; + + if (type == TRANS_START && + !atomic_read(&root->fs_info->open_ioctl_trans)) return 1; + return 0; } @@ -198,23 +222,21 @@ again: if (!h) return ERR_PTR(-ENOMEM); - if (type != TRANS_JOIN_NOLOCK) - mutex_lock(&root->fs_info->trans_mutex); if (may_wait_transaction(root, type)) wait_current_trans(root); - ret = join_transaction(root); + do { + ret = join_transaction(root, type == TRANS_JOIN_NOLOCK); + if (ret == -EBUSY) + wait_current_trans(root); + } while (ret == -EBUSY); + if (ret < 0) { kmem_cache_free(btrfs_trans_handle_cachep, h); - if (type != TRANS_JOIN_NOLOCK) - mutex_unlock(&root->fs_info->trans_mutex); return ERR_PTR(ret); } cur_trans = root->fs_info->running_transaction; - atomic_inc(&cur_trans->use_count); - if (type != TRANS_JOIN_NOLOCK) - mutex_unlock(&root->fs_info->trans_mutex); h->transid = cur_trans->transid; h->transaction = cur_trans; @@ -253,11 +275,7 @@ again: } got_it: - if (type != TRANS_JOIN_NOLOCK) - mutex_lock(&root->fs_info->trans_mutex); - record_root_in_trans(h, root); - if (type != TRANS_JOIN_NOLOCK) - mutex_unlock(&root->fs_info->trans_mutex); + btrfs_record_root_in_trans(h, root); if (!current->journal_info && type != TRANS_USERSPACE) current->journal_info = h; @@ -289,17 +307,13 @@ static noinline int wait_for_commit(struct btrfs_root *root, struct btrfs_transaction *commit) { DEFINE_WAIT(wait); - mutex_lock(&root->fs_info->trans_mutex); while (!commit->commit_done) { prepare_to_wait(&commit->commit_wait, &wait, TASK_UNINTERRUPTIBLE); if (commit->commit_done) break; - mutex_unlock(&root->fs_info->trans_mutex); schedule(); - mutex_lock(&root->fs_info->trans_mutex); } - mutex_unlock(&root->fs_info->trans_mutex); finish_wait(&commit->commit_wait, &wait); return 0; } @@ -309,50 +323,49 @@ int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid) struct btrfs_transaction *cur_trans = NULL, *t; int ret; - mutex_lock(&root->fs_info->trans_mutex); - ret = 0; if (transid) { if (transid <= root->fs_info->last_trans_committed) - goto out_unlock; + goto out; /* find specified transaction */ + spin_lock(&root->fs_info->trans_lock); list_for_each_entry(t, &root->fs_info->trans_list, list) { if (t->transid == transid) { cur_trans = t; + atomic_inc(&cur_trans->use_count); break; } if (t->transid > transid) break; } + spin_unlock(&root->fs_info->trans_lock); ret = -EINVAL; if (!cur_trans) - goto out_unlock; /* bad transid */ + goto out; /* bad transid */ } else { /* find newest transaction that is committing | committed */ + spin_lock(&root->fs_info->trans_lock); list_for_each_entry_reverse(t, &root->fs_info->trans_list, list) { if (t->in_commit) { if (t->commit_done) - goto out_unlock; + goto out; cur_trans = t; + atomic_inc(&cur_trans->use_count); break; } } + spin_unlock(&root->fs_info->trans_lock); if (!cur_trans) - goto out_unlock; /* nothing committing|committed */ + goto out; /* nothing committing|committed */ } - atomic_inc(&cur_trans->use_count); - mutex_unlock(&root->fs_info->trans_mutex); - wait_for_commit(root, cur_trans); - mutex_lock(&root->fs_info->trans_mutex); put_transaction(cur_trans); ret = 0; -out_unlock: - mutex_unlock(&root->fs_info->trans_mutex); +out: return ret; } @@ -401,10 +414,8 @@ harder: void btrfs_throttle(struct btrfs_root *root) { - mutex_lock(&root->fs_info->trans_mutex); - if (!root->fs_info->open_ioctl_trans) + if (!atomic_read(&root->fs_info->open_ioctl_trans)) wait_current_trans(root); - mutex_unlock(&root->fs_info->trans_mutex); } static int should_end_transaction(struct btrfs_trans_handle *trans, @@ -422,6 +433,7 @@ int btrfs_should_end_transaction(struct btrfs_trans_handle *trans, struct btrfs_transaction *cur_trans = trans->transaction; int updates; + smp_mb(); if (cur_trans->blocked || cur_trans->delayed_refs.flushing) return 1; @@ -467,9 +479,11 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans, btrfs_trans_release_metadata(trans, root); - if (lock && !root->fs_info->open_ioctl_trans && - should_end_transaction(trans, root)) + if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) && + should_end_transaction(trans, root)) { trans->transaction->blocked = 1; + smp_wmb(); + } if (lock && cur_trans->blocked && !cur_trans->in_commit) { if (throttle) @@ -739,9 +753,9 @@ static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans, */ int btrfs_add_dead_root(struct btrfs_root *root) { - mutex_lock(&root->fs_info->trans_mutex); + spin_lock(&root->fs_info->trans_lock); list_add(&root->root_list, &root->fs_info->dead_roots); - mutex_unlock(&root->fs_info->trans_mutex); + spin_unlock(&root->fs_info->trans_lock); return 0; } @@ -757,6 +771,7 @@ static noinline int commit_fs_roots(struct btrfs_trans_handle *trans, int ret; int err = 0; + spin_lock(&fs_info->fs_roots_radix_lock); while (1) { ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix, (void **)gang, 0, @@ -769,6 +784,7 @@ static noinline int commit_fs_roots(struct btrfs_trans_handle *trans, radix_tree_tag_clear(&fs_info->fs_roots_radix, (unsigned long)root->root_key.objectid, BTRFS_ROOT_TRANS_TAG); + spin_unlock(&fs_info->fs_roots_radix_lock); btrfs_free_log(trans, root); btrfs_update_reloc_root(trans, root); @@ -783,10 +799,12 @@ static noinline int commit_fs_roots(struct btrfs_trans_handle *trans, err = btrfs_update_root(trans, fs_info->tree_root, &root->root_key, &root->root_item); + spin_lock(&fs_info->fs_roots_radix_lock); if (err) break; } } + spin_unlock(&fs_info->fs_roots_radix_lock); return err; } @@ -972,7 +990,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans, parent = dget_parent(dentry); parent_inode = parent->d_inode; parent_root = BTRFS_I(parent_inode)->root; - record_root_in_trans(trans, parent_root); + btrfs_record_root_in_trans(trans, parent_root); /* * insert the directory item @@ -990,7 +1008,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans, ret = btrfs_update_inode(trans, parent_root, parent_inode); BUG_ON(ret); - record_root_in_trans(trans, root); + btrfs_record_root_in_trans(trans, root); btrfs_set_root_last_snapshot(&root->root_item, trans->transid); memcpy(new_root_item, &root->root_item, sizeof(*new_root_item)); btrfs_check_and_init_root_item(new_root_item); @@ -1080,20 +1098,20 @@ static void update_super_roots(struct btrfs_root *root) int btrfs_transaction_in_commit(struct btrfs_fs_info *info) { int ret = 0; - spin_lock(&info->new_trans_lock); + spin_lock(&info->trans_lock); if (info->running_transaction) ret = info->running_transaction->in_commit; - spin_unlock(&info->new_trans_lock); + spin_unlock(&info->trans_lock); return ret; } int btrfs_transaction_blocked(struct btrfs_fs_info *info) { int ret = 0; - spin_lock(&info->new_trans_lock); + spin_lock(&info->trans_lock); if (info->running_transaction) ret = info->running_transaction->blocked; - spin_unlock(&info->new_trans_lock); + spin_unlock(&info->trans_lock); return ret; } @@ -1117,9 +1135,7 @@ static void wait_current_trans_commit_start(struct btrfs_root *root, &wait); break; } - mutex_unlock(&root->fs_info->trans_mutex); schedule(); - mutex_lock(&root->fs_info->trans_mutex); finish_wait(&root->fs_info->transaction_blocked_wait, &wait); } } @@ -1145,9 +1161,7 @@ static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root, &wait); break; } - mutex_unlock(&root->fs_info->trans_mutex); schedule(); - mutex_lock(&root->fs_info->trans_mutex); finish_wait(&root->fs_info->transaction_wait, &wait); } @@ -1193,22 +1207,18 @@ int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans, } /* take transaction reference */ - mutex_lock(&root->fs_info->trans_mutex); cur_trans = trans->transaction; atomic_inc(&cur_trans->use_count); - mutex_unlock(&root->fs_info->trans_mutex); btrfs_end_transaction(trans, root); schedule_delayed_work(&ac->work, 0); /* wait for transaction to start and unblock */ - mutex_lock(&root->fs_info->trans_mutex); if (wait_for_unblock) wait_current_trans_commit_start_and_unblock(root, cur_trans); else wait_current_trans_commit_start(root, cur_trans); put_transaction(cur_trans); - mutex_unlock(&root->fs_info->trans_mutex); return 0; } @@ -1252,38 +1262,41 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, ret = btrfs_run_delayed_refs(trans, root, 0); BUG_ON(ret); - mutex_lock(&root->fs_info->trans_mutex); + spin_lock(&cur_trans->commit_lock); if (cur_trans->in_commit) { + spin_unlock(&cur_trans->commit_lock); atomic_inc(&cur_trans->use_count); - mutex_unlock(&root->fs_info->trans_mutex); btrfs_end_transaction(trans, root); ret = wait_for_commit(root, cur_trans); BUG_ON(ret); - mutex_lock(&root->fs_info->trans_mutex); put_transaction(cur_trans); - mutex_unlock(&root->fs_info->trans_mutex); return 0; } trans->transaction->in_commit = 1; trans->transaction->blocked = 1; + spin_unlock(&cur_trans->commit_lock); wake_up(&root->fs_info->transaction_blocked_wait); + spin_lock(&root->fs_info->trans_lock); if (cur_trans->list.prev != &root->fs_info->trans_list) { prev_trans = list_entry(cur_trans->list.prev, struct btrfs_transaction, list); if (!prev_trans->commit_done) { atomic_inc(&prev_trans->use_count); - mutex_unlock(&root->fs_info->trans_mutex); + spin_unlock(&root->fs_info->trans_lock); wait_for_commit(root, prev_trans); - mutex_lock(&root->fs_info->trans_mutex); put_transaction(prev_trans); + } else { + spin_unlock(&root->fs_info->trans_lock); } + } else { + spin_unlock(&root->fs_info->trans_lock); } if (now < cur_trans->start_time || now - cur_trans->start_time < 1) @@ -1291,12 +1304,12 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, do { int snap_pending = 0; + joined = cur_trans->num_joined; if (!list_empty(&trans->transaction->pending_snapshots)) snap_pending = 1; WARN_ON(cur_trans != trans->transaction); - mutex_unlock(&root->fs_info->trans_mutex); if (flush_on_commit || snap_pending) { btrfs_start_delalloc_inodes(root, 1); @@ -1316,14 +1329,15 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, prepare_to_wait(&cur_trans->writer_wait, &wait, TASK_UNINTERRUPTIBLE); - smp_mb(); if (atomic_read(&cur_trans->num_writers) > 1) schedule_timeout(MAX_SCHEDULE_TIMEOUT); else if (should_grow) schedule_timeout(1); - mutex_lock(&root->fs_info->trans_mutex); finish_wait(&cur_trans->writer_wait, &wait); + spin_lock(&root->fs_info->trans_lock); + root->fs_info->trans_no_join = 1; + spin_unlock(&root->fs_info->trans_lock); } while (atomic_read(&cur_trans->num_writers) > 1 || (should_grow && cur_trans->num_joined != joined)); @@ -1364,9 +1378,6 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, btrfs_prepare_extent_commit(trans, root); cur_trans = root->fs_info->running_transaction; - spin_lock(&root->fs_info->new_trans_lock); - root->fs_info->running_transaction = NULL; - spin_unlock(&root->fs_info->new_trans_lock); btrfs_set_root_node(&root->fs_info->tree_root->root_item, root->fs_info->tree_root->node); @@ -1387,10 +1398,13 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, sizeof(root->fs_info->super_copy)); trans->transaction->blocked = 0; + spin_lock(&root->fs_info->trans_lock); + root->fs_info->running_transaction = NULL; + root->fs_info->trans_no_join = 0; + spin_unlock(&root->fs_info->trans_lock); wake_up(&root->fs_info->transaction_wait); - mutex_unlock(&root->fs_info->trans_mutex); ret = btrfs_write_and_wait_transaction(trans, root); BUG_ON(ret); write_ctree_super(trans, root, 0); @@ -1403,22 +1417,21 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, btrfs_finish_extent_commit(trans, root); - mutex_lock(&root->fs_info->trans_mutex); - cur_trans->commit_done = 1; root->fs_info->last_trans_committed = cur_trans->transid; wake_up(&cur_trans->commit_wait); + spin_lock(&root->fs_info->trans_lock); list_del_init(&cur_trans->list); + spin_unlock(&root->fs_info->trans_lock); + put_transaction(cur_trans); put_transaction(cur_trans); trace_btrfs_transaction_commit(root); - mutex_unlock(&root->fs_info->trans_mutex); - if (current->journal_info == trans) current->journal_info = NULL; @@ -1438,9 +1451,9 @@ int btrfs_clean_old_snapshots(struct btrfs_root *root) LIST_HEAD(list); struct btrfs_fs_info *fs_info = root->fs_info; - mutex_lock(&fs_info->trans_mutex); + spin_lock(&fs_info->trans_lock); list_splice_init(&fs_info->dead_roots, &list); - mutex_unlock(&fs_info->trans_mutex); + spin_unlock(&fs_info->trans_lock); while (!list_empty(&list)) { root = list_entry(list.next, struct btrfs_root, root_list); diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h index 154314f80f8d..11c6efcd4ed2 100644 --- a/fs/btrfs/transaction.h +++ b/fs/btrfs/transaction.h @@ -28,10 +28,12 @@ struct btrfs_transaction { * transaction can end */ atomic_t num_writers; + atomic_t use_count; unsigned long num_joined; + + spinlock_t commit_lock; int in_commit; - atomic_t use_count; int commit_done; int blocked; struct list_head list; -- cgit v1.2.3 From 026fd317828500524cdc7e5ff9e8e7923abb2868 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Fri, 13 May 2011 10:32:11 -0400 Subject: Btrfs: don't always do readahead Our readahead is sort of sloppy, and really isn't always needed. For example if ls is doing a stating ls (which is the default) it's going to stat in non-disk order, so if say you have a directory with a stupid amount of files, readahead is going to do nothing but waste time in the case of doing the stat. Taking the unconditional readahead out made my test go from 57 minutes to 36 minutes. This means that everywhere we do loop through the tree we want to make sure we do set path->reada properly, so I went through and found all of the places where we loop through the path and set reada to 1. Thanks, Signed-off-by: Josef Bacik --- fs/btrfs/ctree.c | 2 -- fs/btrfs/extent-tree.c | 3 ++- fs/btrfs/inode.c | 14 ++++++++++++-- fs/btrfs/relocation.c | 6 ++++++ 4 files changed, 20 insertions(+), 5 deletions(-) (limited to 'fs/btrfs/relocation.c') diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index f7a0a64b868f..f61c16c1481a 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -48,8 +48,6 @@ struct btrfs_path *btrfs_alloc_path(void) { struct btrfs_path *path; path = kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS); - if (path) - path->reada = 1; return path; } diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 96be62450318..1ba2cc58eab5 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -347,7 +347,7 @@ static int caching_kthread(void *data) */ path->skip_locking = 1; path->search_commit_root = 1; - path->reada = 2; + path->reada = 1; key.objectid = last; key.offset = 0; @@ -8556,6 +8556,7 @@ int btrfs_read_block_groups(struct btrfs_root *root) path = btrfs_alloc_path(); if (!path) return -ENOMEM; + path->reada = 1; cache_gen = btrfs_super_cache_generation(&root->fs_info->super_copy); if (cache_gen != 0 && diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index dd5938a7de21..6228a304b547 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -4242,7 +4242,9 @@ static int btrfs_real_readdir(struct file *filp, void *dirent, filp->f_pos = 2; } path = btrfs_alloc_path(); - path->reada = 2; + if (!path) + return -ENOMEM; + path->reada = 1; btrfs_set_key_type(&key, key_type); key.offset = filp->f_pos; @@ -5043,7 +5045,15 @@ again: if (!path) { path = btrfs_alloc_path(); - BUG_ON(!path); + if (!path) { + err = -ENOMEM; + goto out; + } + /* + * Chances are we'll be called again, so go ahead and do + * readahead + */ + path->reada = 1; } ret = btrfs_lookup_file_extent(trans, root, path, diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 09c30d37d43e..5872b41581f4 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -676,6 +676,8 @@ struct backref_node *build_backref_tree(struct reloc_control *rc, err = -ENOMEM; goto out; } + path1->reada = 1; + path2->reada = 2; node = alloc_backref_node(cache); if (!node) { @@ -1996,6 +1998,7 @@ static noinline_for_stack int merge_reloc_root(struct reloc_control *rc, path = btrfs_alloc_path(); if (!path) return -ENOMEM; + path->reada = 1; reloc_root = root->reloc_root; root_item = &reloc_root->root_item; @@ -3297,6 +3300,7 @@ static int find_data_references(struct reloc_control *rc, path = btrfs_alloc_path(); if (!path) return -ENOMEM; + path->reada = 1; root = read_fs_root(rc->extent_root->fs_info, ref_root); if (IS_ERR(root)) { @@ -3665,6 +3669,7 @@ static noinline_for_stack int relocate_block_group(struct reloc_control *rc) path = btrfs_alloc_path(); if (!path) return -ENOMEM; + path->reada = 1; ret = prepare_to_relocate(rc); if (ret) { @@ -4090,6 +4095,7 @@ int btrfs_recover_relocation(struct btrfs_root *root) path = btrfs_alloc_path(); if (!path) return -ENOMEM; + path->reada = -1; key.objectid = BTRFS_TREE_RELOC_OBJECTID; key.type = BTRFS_ROOT_ITEM_KEY; -- cgit v1.2.3 From 7585717f304f5ed005cc4ad933a69aab3efbd136 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Mon, 13 Jun 2011 20:00:16 -0400 Subject: Btrfs: fix relocation races The recent commit to get rid of our trans_mutex introduced some races with block group relocation. The problem is that relocation needs to do some record keeping about each root, and it was relying on the transaction mutex to coordinate things in subtle ways. This fix adds a mutex just for the relocation code and makes sure it doesn't have a big impact on normal operations. The race is really fixed in btrfs_record_root_in_trans, which is where we step back and wait for the relocation code to finish accounting setup. Signed-off-by: Chris Mason --- fs/btrfs/ctree.h | 14 ++++++++++ fs/btrfs/disk-io.c | 1 + fs/btrfs/relocation.c | 30 ++++++++++++++------- fs/btrfs/transaction.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++--- 4 files changed, 105 insertions(+), 13 deletions(-) (limited to 'fs/btrfs/relocation.c') diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 8490ee063709..a2c91a102b72 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -967,6 +967,12 @@ struct btrfs_fs_info { struct srcu_struct subvol_srcu; spinlock_t trans_lock; + /* + * the reloc mutex goes with the trans lock, it is taken + * during commit to protect us from the relocation code + */ + struct mutex reloc_mutex; + struct list_head trans_list; struct list_head hashers; struct list_head dead_roots; @@ -1172,6 +1178,14 @@ struct btrfs_root { u32 type; u64 highest_objectid; + + /* btrfs_record_root_in_trans is a multi-step process, + * and it can race with the balancing code. But the + * race is very small, and only the first time the root + * is added to each transaction. So in_trans_setup + * is used to tell us when more checks are required + */ + unsigned long in_trans_setup; int ref_cows; int track_dirty; int in_radix; diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 20c111b3fa0d..0b2b4b759136 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1620,6 +1620,7 @@ struct btrfs_root *open_ctree(struct super_block *sb, spin_lock_init(&fs_info->fs_roots_radix_lock); spin_lock_init(&fs_info->delayed_iput_lock); spin_lock_init(&fs_info->defrag_inodes_lock); + mutex_init(&fs_info->reloc_mutex); init_completion(&fs_info->kobj_unregister); fs_info->tree_root = tree_root; diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index f25b10a22a0a..086b1e6b8614 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -1368,7 +1368,7 @@ int btrfs_update_reloc_root(struct btrfs_trans_handle *trans, int ret; if (!root->reloc_root) - return 0; + goto out; reloc_root = root->reloc_root; root_item = &reloc_root->root_item; @@ -1390,6 +1390,8 @@ int btrfs_update_reloc_root(struct btrfs_trans_handle *trans, ret = btrfs_update_root(trans, root->fs_info->tree_root, &reloc_root->root_key, root_item); BUG_ON(ret); + +out: return 0; } @@ -2142,10 +2144,11 @@ int prepare_to_merge(struct reloc_control *rc, int err) u64 num_bytes = 0; int ret; - spin_lock(&root->fs_info->trans_lock); + mutex_lock(&root->fs_info->reloc_mutex); rc->merging_rsv_size += root->nodesize * (BTRFS_MAX_LEVEL - 1) * 2; rc->merging_rsv_size += rc->nodes_relocated * 2; - spin_unlock(&root->fs_info->trans_lock); + mutex_unlock(&root->fs_info->reloc_mutex); + again: if (!err) { num_bytes = rc->merging_rsv_size; @@ -2214,9 +2217,16 @@ int merge_reloc_roots(struct reloc_control *rc) int ret; again: root = rc->extent_root; - spin_lock(&root->fs_info->trans_lock); + + /* + * this serializes us with btrfs_record_root_in_transaction, + * we have to make sure nobody is in the middle of + * adding their roots to the list while we are + * doing this splice + */ + mutex_lock(&root->fs_info->reloc_mutex); list_splice_init(&rc->reloc_roots, &reloc_roots); - spin_unlock(&root->fs_info->trans_lock); + mutex_unlock(&root->fs_info->reloc_mutex); while (!list_empty(&reloc_roots)) { found = 1; @@ -3590,17 +3600,19 @@ next: static void set_reloc_control(struct reloc_control *rc) { struct btrfs_fs_info *fs_info = rc->extent_root->fs_info; - spin_lock(&fs_info->trans_lock); + + mutex_lock(&fs_info->reloc_mutex); fs_info->reloc_ctl = rc; - spin_unlock(&fs_info->trans_lock); + mutex_unlock(&fs_info->reloc_mutex); } static void unset_reloc_control(struct reloc_control *rc) { struct btrfs_fs_info *fs_info = rc->extent_root->fs_info; - spin_lock(&fs_info->trans_lock); + + mutex_lock(&fs_info->reloc_mutex); fs_info->reloc_ctl = NULL; - spin_unlock(&fs_info->trans_lock); + mutex_unlock(&fs_info->reloc_mutex); } static int check_extent_flags(u64 flags) diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 2b3590b9fe98..833996a0c628 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -126,28 +126,85 @@ static noinline int join_transaction(struct btrfs_root *root, int nofail) * to make sure the old root from before we joined the transaction is deleted * when the transaction commits */ -int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans, +static int record_root_in_trans(struct btrfs_trans_handle *trans, struct btrfs_root *root) { if (root->ref_cows && root->last_trans < trans->transid) { WARN_ON(root == root->fs_info->extent_root); WARN_ON(root->commit_root != root->node); + /* + * see below for in_trans_setup usage rules + * we have the reloc mutex held now, so there + * is only one writer in this function + */ + root->in_trans_setup = 1; + + /* make sure readers find in_trans_setup before + * they find our root->last_trans update + */ + smp_wmb(); + spin_lock(&root->fs_info->fs_roots_radix_lock); if (root->last_trans == trans->transid) { spin_unlock(&root->fs_info->fs_roots_radix_lock); return 0; } - root->last_trans = trans->transid; radix_tree_tag_set(&root->fs_info->fs_roots_radix, (unsigned long)root->root_key.objectid, BTRFS_ROOT_TRANS_TAG); spin_unlock(&root->fs_info->fs_roots_radix_lock); + root->last_trans = trans->transid; + + /* this is pretty tricky. We don't want to + * take the relocation lock in btrfs_record_root_in_trans + * unless we're really doing the first setup for this root in + * this transaction. + * + * Normally we'd use root->last_trans as a flag to decide + * if we want to take the expensive mutex. + * + * But, we have to set root->last_trans before we + * init the relocation root, otherwise, we trip over warnings + * in ctree.c. The solution used here is to flag ourselves + * with root->in_trans_setup. When this is 1, we're still + * fixing up the reloc trees and everyone must wait. + * + * When this is zero, they can trust root->last_trans and fly + * through btrfs_record_root_in_trans without having to take the + * lock. smp_wmb() makes sure that all the writes above are + * done before we pop in the zero below + */ btrfs_init_reloc_root(trans, root); + smp_wmb(); + root->in_trans_setup = 0; } return 0; } + +int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans, + struct btrfs_root *root) +{ + if (!root->ref_cows) + return 0; + + /* + * see record_root_in_trans for comments about in_trans_setup usage + * and barriers + */ + smp_rmb(); + if (root->last_trans == trans->transid && + !root->in_trans_setup) + return 0; + + mutex_lock(&root->fs_info->reloc_mutex); + record_root_in_trans(trans, root); + mutex_unlock(&root->fs_info->reloc_mutex); + + return 0; +} + /* wait for commit against the current transaction to become unblocked * when this is done, it is safe to start a new transaction, but the current * transaction might not be fully on disk. @@ -882,7 +939,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans, parent = dget_parent(dentry); parent_inode = parent->d_inode; parent_root = BTRFS_I(parent_inode)->root; - btrfs_record_root_in_trans(trans, parent_root); + record_root_in_trans(trans, parent_root); /* * insert the directory item @@ -900,7 +957,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans, ret = btrfs_update_inode(trans, parent_root, parent_inode); BUG_ON(ret); - btrfs_record_root_in_trans(trans, root); + record_root_in_trans(trans, root); btrfs_set_root_last_snapshot(&root->root_item, trans->transid); memcpy(new_root_item, &root->root_item, sizeof(*new_root_item)); btrfs_check_and_init_root_item(new_root_item); @@ -1247,6 +1304,13 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, } while (atomic_read(&cur_trans->num_writers) > 1 || (should_grow && cur_trans->num_joined != joined)); + /* + * the reloc mutex makes sure that we stop + * the balancing code from coming in and moving + * extents around in the middle of the commit + */ + mutex_lock(&root->fs_info->reloc_mutex); + ret = create_pending_snapshots(trans, root->fs_info); BUG_ON(ret); @@ -1312,6 +1376,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, root->fs_info->running_transaction = NULL; root->fs_info->trans_no_join = 0; spin_unlock(&root->fs_info->trans_lock); + mutex_unlock(&root->fs_info->reloc_mutex); wake_up(&root->fs_info->transaction_wait); -- cgit v1.2.3