[Box Backup] Question about mount-point parsing

Joe Krahn boxbackup@fluffy.co.uk
Mon, 13 Dec 2004 17:34:03 -0500

Ben Summers wrote:
> On 13 Dec 2004, at 21:04, Joe Krahn wrote:
>> Ben Summers wrote:
>>> On 13 Dec 2004, at 17:18, Joe Krahn wrote:
>>>> Is the mount-point lookup in BackupDaemon.cpp related to avoiding 
>>>> 'one filesystem' problems?
>>> No.
>>>> The comment says:
>>>> // Linux can't tell you where a directory is mounted. So we have to
>>>> // read the mount entries from /etc/mtab! Bizarre that the OS itself
>>>> // can't tell you, but there you go.
>>>> This is sort of what the stat.st_dev field is for, but not exactly. 
>>>> Depends what you're trying to do.
>>> For this purpose, the integer device ID isn't good enough and the 
>>> actual name is required.
>> OK, but what is the purpose of determining the mount point?
> To know which of file and directory tracking database to use. The inode 
> numbers are used to track files so that if they're renamed, it can issue 
> a rename command instead of uploading the data again.
> Ben
I see... you need is a unique FileSystem identifier. And, I also see noe 
that Linux statfs does not support the statfs.f_fsid field! Very strange