From 959b1c04675735aa51b9a7b3e28963c4141bf3e7 Mon Sep 17 00:00:00 2001 From: Nikolay Borisov Date: Fri, 29 Jun 2018 08:26:05 +0300 Subject: [PATCH] btrfs: close devices without offloading to a temporary list Since commit 88c14590cdd6 ("btrfs: use RCU in btrfs_show_devname for device list traversal") btrfs_show_devname no longer takes device_list_mutex. As such the deadlock that 0ccd05285e7f ("btrfs: fix a possible umount deadlock") aimed to fix no longer exists, we can free the devices immediatelly and remove the code that does the pending work. Signed-off-by: Nikolay Borisov Reviewed-by: Anand Jain [ update changelog ] Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/volumes.c | 26 ++++++-------------------- 1 file changed, 6 insertions(+), 20 deletions(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index f7191fdfb44c..3c3359d7e91d 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1001,7 +1001,7 @@ static void btrfs_close_bdev(struct btrfs_device *device) blkdev_put(device->bdev, device->mode); } -static void btrfs_prepare_close_one_device(struct btrfs_device *device) +static void btrfs_close_one_device(struct btrfs_device *device) { struct btrfs_fs_devices *fs_devices = device->fs_devices; struct btrfs_device *new_device; @@ -1019,6 +1019,8 @@ static void btrfs_prepare_close_one_device(struct btrfs_device *device) if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state)) fs_devices->missing_devices--; + btrfs_close_bdev(device); + new_device = btrfs_alloc_device(NULL, &device->devid, device->uuid); BUG_ON(IS_ERR(new_device)); /* -ENOMEM */ @@ -1032,39 +1034,23 @@ static void btrfs_prepare_close_one_device(struct btrfs_device *device) list_replace_rcu(&device->dev_list, &new_device->dev_list); new_device->fs_devices = device->fs_devices; + + call_rcu(&device->rcu, free_device_rcu); } static int close_fs_devices(struct btrfs_fs_devices *fs_devices) { struct btrfs_device *device, *tmp; - struct list_head pending_put; - - INIT_LIST_HEAD(&pending_put); if (--fs_devices->opened > 0) return 0; mutex_lock(&fs_devices->device_list_mutex); list_for_each_entry_safe(device, tmp, &fs_devices->devices, dev_list) { - btrfs_prepare_close_one_device(device); - list_add(&device->dev_list, &pending_put); + btrfs_close_one_device(device); } mutex_unlock(&fs_devices->device_list_mutex); - /* - * btrfs_show_devname() is using the device_list_mutex, - * sometimes call to blkdev_put() leads vfs calling - * into this func. So do put outside of device_list_mutex, - * as of now. - */ - while (!list_empty(&pending_put)) { - device = list_first_entry(&pending_put, - struct btrfs_device, dev_list); - list_del(&device->dev_list); - btrfs_close_bdev(device); - call_rcu(&device->rcu, free_device_rcu); - } - WARN_ON(fs_devices->open_devices); WARN_ON(fs_devices->rw_devices); fs_devices->opened = 0; -- 2.30.2