Re: [PATCH 05/24] fs: Get proper reference for s_bdi
From: Boaz Harrosh <hidden>
Date: 2017-02-09 14:44:15
Also in:
linux-fsdevel
On 02/02/2017 07:34 PM, Jan Kara wrote:
quoted hunk ↗ jump to hunk
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 <jack@suse.cz> --- 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; }