From 964fb15acfcd672ac691f04879b71f07ccc21e0c Mon Sep 17 00:00:00 2001 From: Ilya Dryomov Date: Wed, 2 Oct 2013 19:39:50 +0300 Subject: Btrfs: eliminate races in worker stopping code The current implementation of worker threads in Btrfs has races in worker stopping code, which cause all kinds of panics and lockups when running btrfs/011 xfstest in a loop. The problem is that btrfs_stop_workers is unsynchronized with respect to check_idle_worker, check_busy_worker and __btrfs_start_workers. E.g., check_idle_worker race flow: btrfs_stop_workers(): check_idle_worker(aworker): - grabs the lock - splices the idle list into the working list - removes the first worker from the working list - releases the lock to wait for its kthread's completion - grabs the lock - if aworker is on the working list, moves aworker from the working list to the idle list - releases the lock - grabs the lock - puts the worker - removes the second worker from the working list ...... btrfs_stop_workers returns, aworker is on the idle list FS is umounted, memory is freed ...... aworker is waken up, fireworks ensue With this applied, I wasn't able to trigger the problem in 48 hours, whereas previously I could reliably reproduce at least one of these races within an hour. Reported-by: David Sterba Signed-off-by: Ilya Dryomov Signed-off-by: Josef Bacik --- fs/btrfs/async-thread.c | 25 +++++++++++++++++++------ 1 file changed, 19 insertions(+), 6 deletions(-) (limited to 'fs/btrfs/async-thread.c') diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c index 58b7d14b08ee..08cc08f037a6 100644 --- a/fs/btrfs/async-thread.c +++ b/fs/btrfs/async-thread.c @@ -107,7 +107,8 @@ static void check_idle_worker(struct btrfs_worker_thread *worker) worker->idle = 1; /* the list may be empty if the worker is just starting */ - if (!list_empty(&worker->worker_list)) { + if (!list_empty(&worker->worker_list) && + !worker->workers->stopping) { list_move(&worker->worker_list, &worker->workers->idle_list); } @@ -127,7 +128,8 @@ static void check_busy_worker(struct btrfs_worker_thread *worker) spin_lock_irqsave(&worker->workers->lock, flags); worker->idle = 0; - if (!list_empty(&worker->worker_list)) { + if (!list_empty(&worker->worker_list) && + !worker->workers->stopping) { list_move_tail(&worker->worker_list, &worker->workers->worker_list); } @@ -412,6 +414,7 @@ void btrfs_stop_workers(struct btrfs_workers *workers) int can_stop; spin_lock_irq(&workers->lock); + workers->stopping = 1; list_splice_init(&workers->idle_list, &workers->worker_list); while (!list_empty(&workers->worker_list)) { cur = workers->worker_list.next; @@ -455,6 +458,7 @@ void btrfs_init_workers(struct btrfs_workers *workers, char *name, int max, workers->ordered = 0; workers->atomic_start_pending = 0; workers->atomic_worker_start = async_helper; + workers->stopping = 0; } /* @@ -480,15 +484,19 @@ static int __btrfs_start_workers(struct btrfs_workers *workers) atomic_set(&worker->num_pending, 0); atomic_set(&worker->refs, 1); worker->workers = workers; - worker->task = kthread_run(worker_loop, worker, - "btrfs-%s-%d", workers->name, - workers->num_workers + 1); + worker->task = kthread_create(worker_loop, worker, + "btrfs-%s-%d", workers->name, + workers->num_workers + 1); if (IS_ERR(worker->task)) { ret = PTR_ERR(worker->task); - kfree(worker); goto fail; } + spin_lock_irq(&workers->lock); + if (workers->stopping) { + spin_unlock_irq(&workers->lock); + goto fail_kthread; + } list_add_tail(&worker->worker_list, &workers->idle_list); worker->idle = 1; workers->num_workers++; @@ -496,8 +504,13 @@ static int __btrfs_start_workers(struct btrfs_workers *workers) WARN_ON(workers->num_workers_starting < 0); spin_unlock_irq(&workers->lock); + wake_up_process(worker->task); return 0; + +fail_kthread: + kthread_stop(worker->task); fail: + kfree(worker); spin_lock_irq(&workers->lock); workers->num_workers_starting--; spin_unlock_irq(&workers->lock); -- cgit v1.2.3 From 678712545b62715a6c867471320ff5f60a521f3a Mon Sep 17 00:00:00 2001 From: Dulshani Gunawardhana Date: Thu, 31 Oct 2013 10:33:04 +0530 Subject: btrfs: Fix checkpatch.pl warning of spacing issues Fix spacing issues detected via checkpatch.pl in accordance with the kernel style guidelines. Signed-off-by: Dulshani Gunawardhana Signed-off-by: Josef Bacik Signed-off-by: Chris Mason --- fs/btrfs/async-thread.c | 2 +- fs/btrfs/compression.c | 2 +- fs/btrfs/ctree.c | 2 +- fs/btrfs/extent-tree.c | 6 +++--- fs/btrfs/extent_io.c | 2 +- fs/btrfs/file.c | 2 +- fs/btrfs/free-space-cache.c | 2 +- fs/btrfs/inode.c | 6 +++--- fs/btrfs/ioctl.c | 14 +++++++------- 9 files changed, 19 insertions(+), 19 deletions(-) (limited to 'fs/btrfs/async-thread.c') diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c index 08cc08f037a6..8aec751fa464 100644 --- a/fs/btrfs/async-thread.c +++ b/fs/btrfs/async-thread.c @@ -262,7 +262,7 @@ static struct btrfs_work *get_next_work(struct btrfs_worker_thread *worker, struct btrfs_work *work = NULL; struct list_head *cur = NULL; - if(!list_empty(prio_head)) + if (!list_empty(prio_head)) cur = prio_head->next; smp_mb(); diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index df019c7f58b2..1499b27b4186 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -359,7 +359,7 @@ int btrfs_submit_compressed_write(struct inode *inode, u64 start, bdev = BTRFS_I(inode)->root->fs_info->fs_devices->latest_bdev; bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS); - if(!bio) { + if (!bio) { kfree(cb); return -ENOMEM; } diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 03c606cefd50..316136bd6dd7 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -4018,7 +4018,7 @@ again: data_size > BTRFS_LEAF_DATA_SIZE(root)) { if (data_size && !tried_avoid_double) goto push_for_double; - split = 2 ; + split = 2; } } } diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 2d58461bd035..fb5c76795eda 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -5017,7 +5017,7 @@ int btrfs_delalloc_reserve_metadata(struct inode *inode, u64 num_bytes) mutex_unlock(&BTRFS_I(inode)->delalloc_mutex); if (to_reserve) - trace_btrfs_space_reservation(root->fs_info,"delalloc", + trace_btrfs_space_reservation(root->fs_info, "delalloc", btrfs_ino(inode), to_reserve, 1); block_rsv_add_bytes(block_rsv, to_reserve, 1); @@ -8022,7 +8022,7 @@ u64 btrfs_account_ro_block_groups_free_space(struct btrfs_space_info *sinfo) spin_lock(&sinfo->lock); - for(i = 0; i < BTRFS_NR_RAID_TYPES; i++) + for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) if (!list_empty(&sinfo->block_groups[i])) free_bytes += __btrfs_get_ro_block_group_free_space( &sinfo->block_groups[i]); @@ -8310,7 +8310,7 @@ int btrfs_free_block_groups(struct btrfs_fs_info *info) release_global_block_rsv(info); - while(!list_empty(&info->space_info)) { + while (!list_empty(&info->space_info)) { space_info = list_entry(info->space_info.next, struct btrfs_space_info, list); diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index fb782ed62426..856bc2b2192c 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -4034,7 +4034,7 @@ static struct extent_map *get_extent_skip_holes(struct inode *inode, if (offset >= last) return NULL; - while(1) { + while (1) { len = last - offset; if (len == 0) break; diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 3a20a12513b2..82d0342763c5 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -369,7 +369,7 @@ int btrfs_run_defrag_inodes(struct btrfs_fs_info *fs_info) u64 root_objectid = 0; atomic_inc(&fs_info->defrag_running); - while(1) { + while (1) { /* Pause the auto defragger. */ if (test_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state)) diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index d7c445c30a16..057be95b1e1e 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -2280,7 +2280,7 @@ u64 btrfs_alloc_from_cluster(struct btrfs_block_group_cache *block_group, goto out; entry = rb_entry(node, struct btrfs_free_space, offset_index); - while(1) { + while (1) { if (entry->bytes < bytes && entry->bytes > *max_extent_size) *max_extent_size = entry->bytes; diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index ddecc9c332f4..57fa19d69e90 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -6262,7 +6262,7 @@ struct extent_map *btrfs_get_extent_fiemap(struct inode *inode, struct page *pag /* adjust the range_start to make sure it doesn't * go backwards from the start they passed in */ - range_start = max(start,range_start); + range_start = max(start, range_start); found = found_end - range_start; if (found > 0) { @@ -7066,7 +7066,7 @@ static int btrfs_submit_direct_hook(int rw, struct btrfs_dio_private *dip, } } else { submit_len += bvec->bv_len; - nr_pages ++; + nr_pages++; bvec++; } } @@ -8367,7 +8367,7 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry, int err; int drop_inode = 0; u64 objectid; - u64 index = 0 ; + u64 index = 0; int name_len; int datasize; unsigned long ptr; diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 3712ef86ca82..6523108d2984 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -686,7 +686,7 @@ static inline int btrfs_check_sticky(struct inode *dir, struct inode *inode) * nfs_async_unlink(). */ -static int btrfs_may_delete(struct inode *dir,struct dentry *victim,int isdir) +static int btrfs_may_delete(struct inode *dir, struct dentry *victim, int isdir) { int error; @@ -856,7 +856,7 @@ static int find_new_extents(struct btrfs_root *root, path->keep_locks = 1; - while(1) { + while (1) { ret = btrfs_search_forward(root, &min_key, path, newer_than); if (ret != 0) goto none; @@ -1918,7 +1918,7 @@ static noinline int search_ioctl(struct inode *inode, path->keep_locks = 1; - while(1) { + while (1) { ret = btrfs_search_forward(root, &key, path, sk->min_transid); if (ret != 0) { if (ret > 0) @@ -2004,7 +2004,7 @@ static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info, key.type = BTRFS_INODE_REF_KEY; key.offset = (u64)-1; - while(1) { + while (1) { ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); if (ret < 0) goto out; @@ -2033,7 +2033,7 @@ static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info, } *(ptr + len) = '/'; - read_extent_buffer(l, ptr,(unsigned long)(iref + 1), len); + read_extent_buffer(l, ptr, (unsigned long)(iref + 1), len); if (key.offset == BTRFS_FIRST_FREE_OBJECTID) break; @@ -2044,7 +2044,7 @@ static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info, dirid = key.objectid; } memmove(name, ptr, total_len); - name[total_len]='\0'; + name[total_len] = '\0'; ret = 0; out: btrfs_free_path(path); @@ -2130,7 +2130,7 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file, inode = dentry->d_inode; dest = BTRFS_I(inode)->root; - if (!capable(CAP_SYS_ADMIN)){ + if (!capable(CAP_SYS_ADMIN)) { /* * Regular user. Only allow this with a special mount * option, when the user has write+exec access to the -- cgit v1.2.3