From 2fefd5583f8b86171c898f90cadac7c09ccf9d73 Mon Sep 17 00:00:00 2001 From: Zhao Lei Date: Thu, 7 Jan 2016 18:38:48 +0800 Subject: btrfs: reada: limit max works count Reada creates 2 works for each level of tree recursively. In case of a tree having many levels, the number of created works is 2^level_of_tree. Actually we don't need so many works in parallel, this patch limits max works to BTRFS_MAX_MIRRORS * 2. The per-fs works_counter will be also used for btrfs_reada_wait() to check is there are background workers. Signed-off-by: Zhao Lei Signed-off-by: David Sterba --- fs/btrfs/reada.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'fs/btrfs/reada.c') diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c index 9157d789ae86..e97bc8eb01e2 100644 --- a/fs/btrfs/reada.c +++ b/fs/btrfs/reada.c @@ -748,6 +748,8 @@ static void reada_start_machine_worker(struct btrfs_work *work) set_task_ioprio(current, BTRFS_IOPRIO_READA); __reada_start_machine(fs_info); set_task_ioprio(current, old_ioprio); + + atomic_dec(&fs_info->reada_works_cnt); } static void __reada_start_machine(struct btrfs_fs_info *fs_info) @@ -779,8 +781,12 @@ static void __reada_start_machine(struct btrfs_fs_info *fs_info) * enqueue to workers to finish it. This will distribute the load to * the cores. */ - for (i = 0; i < 2; ++i) + for (i = 0; i < 2; ++i) { reada_start_machine(fs_info); + if (atomic_read(&fs_info->reada_works_cnt) > + BTRFS_MAX_MIRRORS * 2) + break; + } } static void reada_start_machine(struct btrfs_fs_info *fs_info) @@ -797,6 +803,7 @@ static void reada_start_machine(struct btrfs_fs_info *fs_info) rmw->fs_info = fs_info; btrfs_queue_work(fs_info->readahead_workers, &rmw->work); + atomic_inc(&fs_info->reada_works_cnt); } #ifdef DEBUG -- cgit v1.2.3