On 05/16/2018 12:30 AM, David Sterba wrote:
On Thu, Apr 12, 2018 at 10:29:35AM +0800, Anand Jain wrote:close_fs_devices() closes devices of a given fsid, and it is limited to all the devices of a fsid, so we don't have to hold the global uuid_mutex, instead we need the device_list_mutex as the device state is being changed. Signed-off-by: Anand Jain <anand.j...@oracle.com> --- fs/btrfs/volumes.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index dfebf8f29916..4c29214e0c18 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -995,7 +995,6 @@ static void btrfs_prepare_close_one_device(struct btrfs_device *device) 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 */ @@ -1013,10 +1012,12 @@ static int close_fs_devices(struct btrfs_fs_devices *fs_devices)INIT_LIST_HEAD(&pending_put); - if (--fs_devices->opened > 0)+ mutex_lock(&fs_devices->device_list_mutex); + if (--fs_devices->opened > 0) { + mutex_unlock(&fs_devices->device_list_mutex); 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); @@ -1050,13 +1051,11 @@ int btrfs_close_devices(struct btrfs_fs_devices *fs_devices) struct btrfs_fs_devices *seed_devices = NULL; int ret;- mutex_lock(&uuid_mutex);ret = close_fs_devices(fs_devices); if (!fs_devices->opened) { seed_devices = fs_devices->seed; fs_devices->seed = NULL;This still touches ->seed, and also reads ->opened, some locking is required here or it has to be clearly explained why it's not.
The ->seed here is %fs_devices local so we don't need the global uuid_mutex. We cloned it in btrfs_prepare_sprout(). Will add comments and send v2. Thanks, Anand
} - mutex_unlock(&uuid_mutex);while (seed_devices) {fs_devices = seed_devices; -- 2.7.0 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html-- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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