From: Miklos Szeredi <miklos@szeredi.hu>
To: Ben Hutchings <ben@decadent.org.uk>
Cc: viro@ZenIV.linux.org.uk, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, hch@infradead.org,
torvalds@linux-foundation.org, akpm@linux-foundation.org,
apw@canonical.com, nbd@openwrt.org, neilb@suse.de,
hramrach@centrum.cz, jordipujolp@gmail.com,
ezk@fsl.cs.sunysb.edu, ricwheeler@gmail.com, dhowells@redhat.com,
hpj@urpla.net, sedat.dilek@googlemail.com, penberg@kernel.org,
goran.cetusic@gmail.com, romain@orebokech.com
Subject: Re: [PATCH 05/13] overlayfs: add statfs support
Date: Thu, 30 Aug 2012 00:48:28 +0200 [thread overview]
Message-ID: <87d32971s3.fsf@tucsk.pomaz.szeredi.hu> (raw)
In-Reply-To: <20120817182051.GC29217@decadent.org.uk> (Ben Hutchings's message of "Fri, 17 Aug 2012 19:20:51 +0100")
Ben Hutchings <ben@decadent.org.uk> writes:
> On Wed, Aug 15, 2012 at 05:48:12PM +0200, Miklos Szeredi wrote:
>> From: Andy Whitcroft <apw@canonical.com>
>>
>> Add support for statfs to the overlayfs filesystem. As the upper layer
>> is the target of all write operations assume that the space in that
>> filesystem is the space in the overlayfs. There will be some inaccuracy as
>> overwriting a file will copy it up and consume space we were not expecting,
>> but it is better than nothing.
>>
>> Use the upper layer dentry and mount from the overlayfs root inode,
>> passing the statfs call to that filesystem.
> [...]
>> +/**
>> + * ovl_statfs
>> + * @sb: The overlayfs super block
>> + * @buf: The struct kstatfs to fill in with stats
>> + *
>> + * Get the filesystem statistics. As writes always target the upper layer
>> + * filesystem pass the statfs to the same filesystem.
>> + */
>> +static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
>> +{
>> + struct dentry *root_dentry = dentry->d_sb->s_root;
>> + struct path path;
>> + ovl_path_upper(root_dentry, &path);
>> +
>> + if (!path.dentry->d_sb->s_op->statfs)
>> + return -ENOSYS;
>> + return path.dentry->d_sb->s_op->statfs(path.dentry, buf);
>> +}
> [...]
>
> In case f_namelen differs between the upper and lower filesystems, you
> need to return the greater of the two.
Maybe. I've never seen any app use f_namelen for anything useful.
>
> Should f_type be overridden to indicate overlayfs? I'm not sure what
> userland is likely to do with f_type. (For presentation to the user,
> it should get the mount type name with getmntent() or libmount. And
> that will just work.)
Yeah we could do that.
Thanks,
Miklos
next prev parent reply other threads:[~2012-08-29 22:47 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-15 15:48 [PATCH 00/13] overlay filesystem: request for inclusion (v14) Miklos Szeredi
2012-08-15 15:48 ` [PATCH 01/13] vfs: add i_op->open() Miklos Szeredi
2012-08-15 17:21 ` J. Bruce Fields
2012-08-15 20:28 ` NeilBrown
2012-08-16 10:10 ` Miklos Szeredi
2012-08-15 15:48 ` [PATCH 02/13] vfs: export do_splice_direct() to modules Miklos Szeredi
2012-08-15 15:48 ` [PATCH 03/13] vfs: introduce clone_private_mount() Miklos Szeredi
2012-08-15 15:48 ` [PATCH 04/13] overlay filesystem Miklos Szeredi
2012-08-16 6:24 ` Eric W. Biederman
2012-08-16 10:25 ` Miklos Szeredi
2012-08-15 15:48 ` [PATCH 05/13] overlayfs: add statfs support Miklos Szeredi
2012-08-17 18:20 ` Ben Hutchings
2012-08-29 22:48 ` Miklos Szeredi [this message]
2012-08-30 5:54 ` Ben Hutchings
2012-08-31 12:47 ` J. R. Okajima
2012-08-15 15:48 ` [PATCH 06/13] overlayfs: implement show_options Miklos Szeredi
2012-08-15 15:48 ` [PATCH 07/13] overlay: overlay filesystem documentation Miklos Szeredi
2012-08-15 19:53 ` J. Bruce Fields
2012-08-16 10:09 ` Miklos Szeredi
2012-09-10 1:47 ` Jan Engelhardt
2012-09-10 3:18 ` NeilBrown
2012-08-15 15:48 ` [PATCH 08/13] fs: limit filesystem stacking depth Miklos Szeredi
2012-08-16 8:02 ` Sedat Dilek
2012-08-16 8:30 ` Sedat Dilek
2012-08-16 10:42 ` Miklos Szeredi
2012-08-16 13:24 ` Sedat Dilek
2012-09-03 15:05 ` Miklos Szeredi
2012-08-15 15:48 ` [PATCH 09/13] overlayfs: fix possible leak in ovl_new_inode Miklos Szeredi
2012-08-15 15:48 ` [PATCH 10/13] overlayfs: create new inode in ovl_link Miklos Szeredi
2012-08-15 15:48 ` [PATCH 11/13] vfs: export __inode_permission() to modules Miklos Szeredi
2012-08-15 17:17 ` Sedat Dilek
2012-08-15 15:48 ` [PATCH 12/13] ovl: switch to __inode_permission() Miklos Szeredi
2012-08-15 16:59 ` Casey Schaufler
2012-08-15 17:07 ` Andy Whitcroft
2012-08-15 17:34 ` Casey Schaufler
2012-08-15 15:48 ` [PATCH 13/13] overlayfs: copy up i_uid/i_gid from the underlying inode Miklos Szeredi
2012-08-15 17:14 ` [PATCH 00/13] overlay filesystem: request for inclusion (v14) Sedat Dilek
2012-09-20 18:55 [PATCH 00/13] overlay filesystem: request for inclusion (v15) Miklos Szeredi
2012-09-20 18:55 ` [PATCH 05/13] overlayfs: add statfs support Miklos Szeredi
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