From 321f69f86a0fc40203b43659c3a39464f15c2ee9 Mon Sep 17 00:00:00 2001 From: Johannes Thumshirn Date: Wed, 4 Dec 2019 14:36:39 +0100 Subject: [PATCH] btrfs: reset device back to allocation state when removing When closing a device, btrfs_close_one_device() first allocates a new device, copies the device to close's name, replaces it in the dev_list with the copy and then finally frees it. This involves two memory allocation, which can potentially fail. As this code path is tricky to unwind, the allocation failures where handled by BUG_ON()s. But this copying isn't strictly needed, all that is needed is resetting the device in question to it's state it had after the allocation. Signed-off-by: Johannes Thumshirn Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/volumes.c | 29 ++++++++++++----------------- 1 file changed, 12 insertions(+), 17 deletions(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index ac7b483754c4..86990b7a60ed 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1066,8 +1066,6 @@ static void btrfs_close_bdev(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; - struct rcu_string *name; if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state) && device->devid != BTRFS_DEV_REPLACE_DEVID) { @@ -1079,25 +1077,22 @@ static void btrfs_close_one_device(struct btrfs_device *device) fs_devices->missing_devices--; btrfs_close_bdev(device); - if (device->bdev) + if (device->bdev) { fs_devices->open_devices--; - - new_device = btrfs_alloc_device(NULL, &device->devid, - device->uuid); - BUG_ON(IS_ERR(new_device)); /* -ENOMEM */ - - /* Safe because we are under uuid_mutex */ - if (device->name) { - name = rcu_string_strdup(device->name->str, GFP_NOFS); - BUG_ON(!name); /* -ENOMEM */ - rcu_assign_pointer(new_device->name, name); + device->bdev = NULL; } + clear_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state); - list_replace_rcu(&device->dev_list, &new_device->dev_list); - new_device->fs_devices = device->fs_devices; + device->fs_info = NULL; + atomic_set(&device->dev_stats_ccnt, 0); + extent_io_tree_release(&device->alloc_state); - synchronize_rcu(); - btrfs_free_device(device); + /* Verify the device is back in a pristine state */ + ASSERT(!test_bit(BTRFS_DEV_STATE_FLUSH_SENT, &device->dev_state)); + ASSERT(!test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state)); + ASSERT(list_empty(&device->dev_alloc_list)); + ASSERT(list_empty(&device->post_commit_list)); + ASSERT(atomic_read(&device->reada_in_flight) == 0); } static int close_fs_devices(struct btrfs_fs_devices *fs_devices) -- 2.45.2