From: "J. R. Okajima" <hooanon05g@gmail.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: Amir Goldstein <amir73il@gmail.com>,
"linux-unionfs@vger.kernel.org" <linux-unionfs@vger.kernel.org>
Subject: Re: [PATCH 0/6] ovl: consistent_fd feature
Date: Sat, 08 Apr 2017 12:03:24 +0900 [thread overview]
Message-ID: <19134.1491620604@jrobl> (raw)
In-Reply-To: <CAJfpegsidjjP_DPpAGAjUtOZEw70nu5jnoTO5E+yzPkONG4X9A@mail.gmail.com>
Miklos Szeredi:
> The other idea is to store the database separately from the upper tree
> (this is what aufs does, apparently). This works for reverse mapping
> as well. Makes all operations (except rename) more complicated.
> Keeping whole mapping in kernel memory is prone to resource hogging
> and DoS. Could have a bitmap created by hashing the ino's that are
:::
I am afraid you are misunderstanding a little.
Aufs XINO (external inode number translation table) is a simple regular
file.
- created and unlinked in mounting aufs, kept in-use.
- the default path is "<first writable layer>/.aufs.xino".
- users can change the path by a mount option "xino=..."
- users can change the path on the fly by remounting anytime.
- users can stop using XINO by a mount/remount option "noxino"
It should not be a kernel memory pressure (unless users put XINO on
tmpfs or something).
XINO is not a so complicated operation. Receiving the inum on the layer
fs, returns the aufs inum. Its maintenance simply follows the lifetime of
aufs inode.
- in creating aufs inode, the mapping of the layer fs inum and the aufs
inum is added.
- in destroying aufs inode, if the link count of the layer fs inode is
zero, then the mapping is removed.
- in copy-up, the mapping is added obviously.
J. R. Okajima
prev parent reply other threads:[~2017-04-08 3:03 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-29 14:36 [PATCH 0/6] ovl: consistent_fd feature Amir Goldstein
2017-03-29 14:36 ` [PATCH 1/6] ovl: store path type in dentry Amir Goldstein
2017-03-29 14:36 ` [PATCH 2/6] ovl: cram opaque boolean into type flags Amir Goldstein
2017-03-29 14:36 ` [PATCH 3/6] ovl: check if all layers are on the same fs Amir Goldstein
2017-03-29 14:36 ` [PATCH 4/6] ovl: check if clone from lower to upper is supported Amir Goldstein
2017-03-29 14:36 ` [PATCH 5/6] ovl: copy on read with consistent_fd feature Amir Goldstein
2017-03-30 11:28 ` Amir Goldstein
2017-03-31 17:58 ` Vivek Goyal
2017-04-01 9:27 ` Amir Goldstein
2017-04-05 13:20 ` Amir Goldstein
2017-03-29 14:36 ` [PATCH 6/6] ovl: link upper tempfile on open for write Amir Goldstein
2017-03-30 11:26 ` [PATCH 7/7] ovl: prevent copy on read if no upper/work dir Amir Goldstein
2017-03-30 11:34 ` [PATCH 0/6] ovl: consistent_fd feature Amir Goldstein
2017-04-06 15:20 ` Miklos Szeredi
2017-04-06 15:37 ` Miklos Szeredi
2017-04-06 16:25 ` Amir Goldstein
2017-04-07 9:32 ` Miklos Szeredi
2017-04-07 9:56 ` Miklos Szeredi
2017-04-07 10:47 ` Amir Goldstein
2017-04-07 13:03 ` Miklos Szeredi
2017-04-07 15:07 ` Amir Goldstein
2017-04-06 16:46 ` Amir Goldstein
2017-04-07 9:43 ` Miklos Szeredi
2017-04-07 11:04 ` Amir Goldstein
2017-04-08 3:03 ` J. R. Okajima [this message]
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