From: Rakesh Pandit <rakesh@tuxera.com>
To: Jan Kara <jack@suse.cz>, Miklos Szeredi <miklos@szeredi.hu>
Cc: Jens Axboe <axboe@kernel.dk>, <linux-block@vger.kernel.org>,
<linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH 16/25] fuse: Convert to separately allocated bdi
Date: Mon, 15 May 2017 23:34:00 +0300 [thread overview]
Message-ID: <20170515203400.GA8068@hercules.tuxera.com> (raw)
In-Reply-To: <20170412102449.16901-17-jack@suse.cz>
Hi Jan, Miklos,
On Wed, Apr 12, 2017 at 12:24:40PM +0200, Jan Kara wrote:
> Allocate struct backing_dev_info separately instead of embedding it
> inside the superblock. This unifies handling of bdi among users.
>
> CC: Miklos Szeredi <miklos@szeredi.hu>
> CC: linux-fsdevel@vger.kernel.org
> Acked-by: Miklos Szeredi <mszeredi@redhat.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Jan Kara <jack@suse.cz>
...
> static int fuse_bdi_init(struct fuse_conn *fc, struct super_block *sb)
> {
> int err;
> + char *suffix = "";
>
> - fc->bdi.name = "fuse";
> - fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_SIZE;
> - /* fuse does it's own writeback accounting */
> - fc->bdi.capabilities = BDI_CAP_NO_ACCT_WB | BDI_CAP_STRICTLIMIT;
> -
> - err = bdi_init(&fc->bdi);
> + if (sb->s_bdev)
> + suffix = "-fuseblk";
> + err = super_setup_bdi_name(sb, "%u:%u%s", MAJOR(fc->dev),
> + MINOR(fc->dev), suffix);
> if (err)
> return err;
>
This call to super_setup_bdi_name would only work with "fuse" but not
with "fuseblk" as mounting a block device in userspace triggers
mount_bdev call which results in set_bdev_super taking a reference
from block device's BDI. But super_setup_bdi_name allocates a new bdi
and ignores the already existing reference which triggers:
WARN_ON(sb->s_bdi != &noop_backing_dev_info);
as sb->s_bdi already has a reference from set_bdev_super. This works
for "fuse" (without a blocking device) for obvious reasons. I can
reproduce this on -rc1 and also found a report on lkml:
https://lkml.org/lkml/2017/5/2/445
Only sane solution seems to be maintaining a private bdi instace just
for fuseblk and let fuse use the common new infrastructure.
Best regards,
Rakesh
next prev parent reply other threads:[~2017-05-15 20:34 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-12 10:24 [PATCH 0/25 v3] fs: Convert all embedded bdis into separate ones Jan Kara
2017-04-12 10:24 ` [PATCH 01/25] bdi: Provide bdi_register_va() and bdi_alloc() Jan Kara
2017-04-12 10:24 ` [PATCH 02/25] block: Unregister bdi on last reference drop Jan Kara
2017-04-12 10:24 ` [PATCH 03/25] bdi: Export bdi_alloc_node() and bdi_put() Jan Kara
2017-04-12 10:24 ` [PATCH 04/25] fs: Provide infrastructure for dynamic BDIs in filesystems Jan Kara
2017-04-12 10:24 ` [PATCH 05/25] fs: Get proper reference for s_bdi Jan Kara
2017-04-12 10:24 ` [PATCH 06/25] lustre: Convert to separately allocated bdi Jan Kara
2017-04-12 10:24 ` [PATCH 07/25] 9p: " Jan Kara
2017-04-12 10:24 ` [PATCH 08/25] btrfs: " Jan Kara
2017-04-12 10:24 ` [PATCH 09/25] ceph: " Jan Kara
2017-04-12 10:24 ` [PATCH 10/25] cifs: " Jan Kara
2017-04-12 10:24 ` [PATCH 11/25] ecryptfs: " Jan Kara
2017-04-12 10:24 ` [PATCH 12/25] afs: " Jan Kara
2017-04-12 10:24 ` [PATCH 13/25] mtd: Convert to dynamically allocated bdi infrastructure Jan Kara
2017-04-12 10:24 ` [PATCH 14/25] coda: Convert to separately allocated bdi Jan Kara
2017-04-12 10:24 ` [PATCH 15/25] exofs: " Jan Kara
2017-04-12 10:24 ` [PATCH 16/25] fuse: " Jan Kara
2017-05-15 20:34 ` Rakesh Pandit [this message]
2017-05-16 10:48 ` Jan Kara
2017-05-16 18:37 ` Rakesh Pandit
2017-05-16 23:24 ` Jens Axboe
2017-05-17 7:46 ` Jan Kara
2017-05-17 14:15 ` Jens Axboe
2017-04-12 10:24 ` [PATCH 17/25] fuse: Get rid of bdi_initialized Jan Kara
2017-04-12 10:24 ` [PATCH 18/25] gfs2: Convert to properly refcounting bdi Jan Kara
2017-04-12 10:24 ` [PATCH 19/25] nilfs2: " Jan Kara
2017-04-12 13:47 ` Ryusuke Konishi
2017-04-12 10:24 ` [PATCH 20/25] ncpfs: Convert to separately allocated bdi Jan Kara
2017-04-12 10:24 ` [PATCH 21/25] nfs: " Jan Kara
2017-04-20 18:06 ` Trond Myklebust
2017-04-12 10:24 ` [PATCH 22/25] ubifs: " Jan Kara
2017-04-12 10:24 ` [PATCH 23/25] fs: Remove SB_I_DYNBDI flag Jan Kara
2017-04-12 10:24 ` [PATCH 24/25] block: Remove unused functions Jan Kara
2017-04-12 10:24 ` [PATCH 25/25] bdi: Drop 'parent' argument from bdi_register[_va]() Jan Kara
2017-04-20 18:11 ` [PATCH 0/25 v3] fs: Convert all embedded bdis into separate ones Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2017-03-29 10:55 [PATCH 0/25 v2] " Jan Kara
2017-03-29 10:56 ` [PATCH 16/25] fuse: Convert to separately allocated bdi Jan Kara
2017-04-12 8:15 ` Christoph Hellwig
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