Hi Martin,
thank you very much for your explanation. +1
Il Ven 17 Lug 2020, 12:14 J Martin Rushton via CentOS <centos@xxxxxxxxxx>
ha scritto:
> On 17/07/2020 10:30, Alessandro Baggi wrote:
> >
> > Il 17/07/20 10:54, Karl Vogel ha scritto:
> >> It depends on the size of the variables in the structure used by the
> >> stat() call. In ext4, the "links" variable is an unsigned 16-bit
> >> integer,
> >> so you have your limit of 64k or so. I've worked with systems where
> >> the limit was a signed 16-bit integer, so it maxed out at 32k.
> >>
> >> XFS may be a full 32-bit integer, so your test script could be running
> >> for quite some time. Or it may just allocate space as it needs. It
> >> sounds
> >> like you have plenty of room for links, so I wouldn't worry.
> >>
> >> --
> >> Karl Vogel / vogelke@xxxxxxxxx / I don't speak for the USAF or my
> company
> >>
> >> Don't accept your dog's admiration as
> >> conclusive evidence that you are wonderful. --Ann Landers
> >
> > Hi Karl,
> >
> > thank you for your clarification. I will try to rearch this limit (by
> > curiosity)
> >
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>
> Have a look at
>
> https://mirrors.edge.kernel.org/pub/linux/utils/fs/xfs/docs/xfs_filesystem_structure.pdf
>
> On page 105 the inode structure is given:
>
> __uint16_t di_onlink;
> ...
> __uint32_t di_nlink
>
> Page 107 gives more detail:
>
> di_onlink:
> In v1 inodes, this specifies the number of links to the inode from
> directories. When the number exceeds 65535,the inode is converted to v2
> and the link count is stored in di_nlink.
>
> di_nlink:
> Specifies the number of links to the inode from directories. This is
> maintained for both inode versions for current versions of XFS. Prior to
> v2 inodes, this field was part of di_pad.
>
> So, the effect is that whatever version you start with, adding more than
> 65535 links will force it to version 2 and give you up to 4,294,967,295
> links!
>
> --
> J Martin Rushton MBCS
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>
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