Max binds

Hi

I'm building chrooted environment for users and I'm using mount --bind <what> <where> -scheme to mount some important directories for the user. This works fine for couple users but what is the limit for binding directories to show up on a different place? I tried googling but couldn't find any direct answers.

Thanks,
Jarmo

See
http://groups.google.com/groups?dq=&hl=en&lr=&ie=UTF-8&threadm=linux.kernel.3AE307AD.821AB47C%40linuxjedi.org&rnum=1&prev=/groups%3Fq%3Dg:thl1557665770d%26dq%3D%26hl%3Den%26lr%3D%26ie%3DUTF-8%26selm%3Dlinux.kernel.3AE307AD.821AB47C%2540linuxjedi.org

-- v --

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Hmm, I read the thread and it contained mostly stats on memory usage on different scenarios. Also, bit outdated discussion (kernel v 2.4.4). No direct answer though.

Jarmo

I'm no expert on the mount --bind stuff, but as far as I understand it, this is simple (I guess Al Viro would agree *g*) VFS magic, so what happens seems to be the following:

- a new vfsmount entry is created by either copying the old tree or cloning the original mount (if it is a mountpoint)
- the required dentries are added to the dcache

so the number of --bind mounts from another mount point will be roughly limited by the number of vfsmount structures possible, and the space available to cache/store dentries ...

I guess there will be some tradeoff when the number of --bind mounts becomes very high, but I guess it is neglectible for normal use ...

I might be totaly wrong, so do not rely on it 8-)

HTH,
Herbert