From ac0c7cf8be00f269f82964cf7b144ca3edc5dbc4 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Fri, 6 Jan 2017 14:12:51 +0100 Subject: btrfs: fix crash when tracepoint arguments are freed by wq callbacks Enabling btrfs tracepoints leads to instant crash, as reported. The wq callbacks could free the memory and the tracepoints started to dereference the members to get to fs_info. The proposed fix https://marc.info/?l=linux-btrfs&m=148172436722606&w=2 removed the tracepoints but we could preserve them by passing only the required data in a safe way. Fixes: bc074524e123 ("btrfs: prefix fsid to all trace events") CC: stable@vger.kernel.org # 4.8+ Reported-by: Sebastian Andrzej Siewior Reviewed-by: Qu Wenruo Signed-off-by: David Sterba --- fs/btrfs/async-thread.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) (limited to 'fs') diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c index 63d197724519..ff0b0be92d61 100644 --- a/fs/btrfs/async-thread.c +++ b/fs/btrfs/async-thread.c @@ -273,6 +273,8 @@ static void run_ordered_work(struct __btrfs_workqueue *wq) unsigned long flags; while (1) { + void *wtag; + spin_lock_irqsave(lock, flags); if (list_empty(list)) break; @@ -299,11 +301,13 @@ static void run_ordered_work(struct __btrfs_workqueue *wq) spin_unlock_irqrestore(lock, flags); /* - * we don't want to call the ordered free functions - * with the lock held though + * We don't want to call the ordered free functions with the + * lock held though. Save the work as tag for the trace event, + * because the callback could free the structure. */ + wtag = work; work->ordered_free(work); - trace_btrfs_all_work_done(work); + trace_btrfs_all_work_done(wq->fs_info, wtag); } spin_unlock_irqrestore(lock, flags); } @@ -311,6 +315,7 @@ static void run_ordered_work(struct __btrfs_workqueue *wq) static void normal_work_helper(struct btrfs_work *work) { struct __btrfs_workqueue *wq; + void *wtag; int need_order = 0; /* @@ -324,6 +329,8 @@ static void normal_work_helper(struct btrfs_work *work) if (work->ordered_func) need_order = 1; wq = work->wq; + /* Safe for tracepoints in case work gets freed by the callback */ + wtag = work; trace_btrfs_work_sched(work); thresh_exec_hook(wq); @@ -333,7 +340,7 @@ static void normal_work_helper(struct btrfs_work *work) run_ordered_work(wq); } if (!need_order) - trace_btrfs_all_work_done(work); + trace_btrfs_all_work_done(wq->fs_info, wtag); } void btrfs_init_work(struct btrfs_work *work, btrfs_work_func_t uniq_func, -- cgit v1.2.3 From 92a1bf76a89ad338f00eb9a2c7689a3907fbcaad Mon Sep 17 00:00:00 2001 From: Liu Bo Date: Thu, 17 Nov 2016 15:00:50 -0800 Subject: Btrfs: add 'inode' for extent map tracepoint 'inode' is an important field for btrfs_get_extent, lets trace it. Signed-off-by: Liu Bo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/inode.c | 2 +- include/trace/events/btrfs.h | 12 ++++++++---- 2 files changed, 9 insertions(+), 5 deletions(-) (limited to 'fs') diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index a713d9d324b0..fab189c67eff 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -7059,7 +7059,7 @@ insert: write_unlock(&em_tree->lock); out: - trace_btrfs_get_extent(root, em); + trace_btrfs_get_extent(root, inode, em); btrfs_free_path(path); if (trans) { diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h index b09225c77676..3048f5205363 100644 --- a/include/trace/events/btrfs.h +++ b/include/trace/events/btrfs.h @@ -184,14 +184,16 @@ DEFINE_EVENT(btrfs__inode, btrfs_inode_evict, TRACE_EVENT_CONDITION(btrfs_get_extent, - TP_PROTO(struct btrfs_root *root, struct extent_map *map), + TP_PROTO(struct btrfs_root *root, struct inode *inode, + struct extent_map *map), - TP_ARGS(root, map), + TP_ARGS(root, inode, map), TP_CONDITION(map), TP_STRUCT__entry_btrfs( __field( u64, root_objectid ) + __field( u64, ino ) __field( u64, start ) __field( u64, len ) __field( u64, orig_start ) @@ -204,7 +206,8 @@ TRACE_EVENT_CONDITION(btrfs_get_extent, TP_fast_assign_btrfs(root->fs_info, __entry->root_objectid = root->root_key.objectid; - __entry->start = map->start; + __entry->ino = btrfs_ino(inode); + __entry->start = map->start; __entry->len = map->len; __entry->orig_start = map->orig_start; __entry->block_start = map->block_start; @@ -214,11 +217,12 @@ TRACE_EVENT_CONDITION(btrfs_get_extent, __entry->compress_type = map->compress_type; ), - TP_printk_btrfs("root = %llu(%s), start = %llu, len = %llu, " + TP_printk_btrfs("root = %llu(%s), ino = %llu start = %llu, len = %llu, " "orig_start = %llu, block_start = %llu(%s), " "block_len = %llu, flags = %s, refs = %u, " "compress_type = %u", show_root_type(__entry->root_objectid), + (unsigned long long)__entry->ino, (unsigned long long)__entry->start, (unsigned long long)__entry->len, (unsigned long long)__entry->orig_start, -- cgit v1.2.3