On 02/02/2017 07:34 PM, Jan Kara wrote: > So far we just relied on block device to hold a bdi reference for us > while the filesystem is mounted. While that works perfectly fine, it is > a bit awkward that we have a pointer to a refcounted structure in the > superblock without proper reference. So make s_bdi hold a proper > reference to block device's BDI. No filesystem using mount_bdev() > actually changes s_bdi so this is safe and will make bdev filesystems > work the same way as filesystems needing to set up their private bdi. > > Signed-off-by: Jan Kara <[email protected]> > --- > fs/super.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) > > diff --git a/fs/super.c b/fs/super.c > index 31dc4c6450ef..dfb95ccd4351 100644 > --- a/fs/super.c > +++ b/fs/super.c > @@ -1047,12 +1047,9 @@ static int set_bdev_super(struct super_block *s, void > *data) > { > s->s_bdev = data; > s->s_dev = s->s_bdev->bd_dev; > + s->s_bdi = bdi_get(s->s_bdev->bd_bdi); > + s->s_iflags |= SB_I_DYNBDI; > > - /* > - * We set the bdi here to the queue backing, file systems can > - * overwrite this in ->fill_super() > - */
Question: So I have an FS that uses mount_bdev but than goes and overrides sb->s_bdev in ->fill_super() anyway. This is because of two reasons. One because I have many more devices. (like btrfs I'm moulti-dev) but I like to use mount_bdev because of the somewhat delicate handling of automatic bind-mounts. For me it is a bigger hack to get the ref-counting and bind-mounts locking correctly then to bdi_put and say the new super_setup_bdi(sb) in fill_super. Would you expect problems? Thanks for any help Boaz > - s->s_bdi = bdev_get_queue(s->s_bdev)->backing_dev_info; > return 0; > } > >
