| Message ID | 20180412022938.8257-13-anand.jain@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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.jain@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. > } > - 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 majordomo@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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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.jain@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 majordomo@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 majordomo@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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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; } - mutex_unlock(&uuid_mutex); while (seed_devices) { fs_devices = seed_devices;
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.jain@oracle.com> --- fs/btrfs/volumes.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)