[RFC] fs, proc: Introduce the /proc/<pid>/map_files/ directory v2

Pavel Emelyanov xemul at parallels.com
Wed Aug 24 08:19:47 PDT 2011

On 08/24/2011 07:05 PM, Zan Lynx wrote:
> On 8/24/2011 2:53 AM, Cyrill Gorcunov wrote:
>> From: Pavel Emelyanov <xemul at parallels.com>
>> This one behaves similarly to the /proc/<pid>/fd/ one - it contains symlinks
>> one for each mapping with file, the name of a symlink is vma->vm_start, the
>> target is the file. Opening a symlink results in a file that point exactly
>> to the same inode as them vma's one.
>> This thing is aimed to help checkpointing processes.
>> For example the ls -l of some arbitrary /proc/<pid>/map_files/
>>  | lr-x------ 1 cyrill cyrill 64 Aug  9 15:25 0x3d73a00000 -> /lib64/ld-2.5.so
> [snip]
> Just curious: How do these symlinks work when the process reading a
> /proc file is in a chroot or a different namespace?
> For example, a chroot environment might have independent copies of
> /lib64/ld-2.5.so and a bind mount of /proc. Does the symlink then point
> to the wrong file?

No and this is the trick - when you readlink it - it give you trash, but
when you open one - you get exactly the same file as the map points to.

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