rsync - Jan 2011 - [PATCH] One more -x to not traverse cyclic bind-mounts

This patch allows one to repeat the '-x' option a third time to stop 
rsync from traversing potentially cyclic bind mounts that are on the 
same filesystem.

For example, the following scenario would cyclically traverse the bind 
mounts until the OS (Linux in this case) hits a maximum traversal count, 
thank goodness.  Other OSes may traverse the bind mount indefinitely...

su
cd
mkdir ~/cycle
touch ~/cycle/file.txt
mkdir ~/cycle/cycle
mount -o bind ~/cycle ~/cycle/cycle
rsync -avxx ~/cycle ~/cycle2

Please let me if there is any feedback on this patch and when/if this 
patch can be merged.  Thanks!

-Jeff

-- 
//Jeff Hansen
////Card Access, Inc.//
//11778 So. Election Rd., Ste. 260//
//Salt Lake City, UT 84020//
//JHansen at CardAccess-inc.com// <mailto:JHansen at CardAccess-inc.com>
//www.CardAccess-inc.com <http://www.cardaccess-inc.com/>//
//801-748-4900 ext 26 (Office)//
//801-748-4901 (fax)//

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On Thu, 2011-01-13 at 11:24 -0700, Jeff Hansen wrote:
> This patch allows one to repeat the '-x' option a third time to
stop
> rsync from traversing potentially cyclic bind mounts that are on the
> same filesystem.
Your patch does not do anything about bind mounts, it simply excludes
subdirectories of the source arguments.  Try it and see.

-- 
Matt

On Thu, Jan 13, 2011 at 10:24 AM, Jeff Hansen <jhansen at
cardaccess-inc.com>wrote:
>  This patch allows one to repeat the '-x' option a third time to
stop rsync
> from traversing potentially cyclic bind mounts that are on the same
> filesystem.
>
See the support/mnt-excl script for one way exclude all mounts (including
bind mounts) from an rsync.  The script also recommends an awk command piped
into an absolute-anchored exclude, but does get some of the details wrong.
 Here's a better explanation:

awk '{print $2}' /proc/mounts | rsync -avf 'merge,/- -' /dir
host:/dest/

The above will get a list of all mount points on the system and use it as an
exclude list to prevent any mounts from being traversed.  However, what it
will not do is to protect the related mount points on the receiving side
from deletion unless you happen to be copying into an exactly-the-same path
on the destination.  If you want the excluded directories to be protected on
the receiving side, you're better off using the mnt-excl script (which
tweaks the excludes to be relative to the transfer).

..wayne..
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