filesystem time stamp resolution

From: Ulrich Drepper
Date: Thu Feb 26 2009 - 18:18:26 EST


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How can code at userlevel (e.g., glibc) determine the resolution of the
a filesystem timestamp?

Boundary condition:

- - I cannot create or modify a file since the information must also
be available for filesystems where the caller has no write permission

- - it has to work going forward (i.e., hardcoding information is no good
idea)

One acceptable solution (for me) would be to have directories for the
filesystem types under /proc/fs (or /sys/fs) which show this
information. E.g.:

/proc/fs/ext4/timestamp-resolution

Measured in nano-seconds or so.

As a bonus have symlinks like

/proc/fs/ef53 -> /proc/fs/ext4

(i.e., map the superblock magic number to a name. But I can live with
this missing.)

As a second bonus any help for network filesystems would be good but.

Do I miss anything that is there already?

- --
â Ulrich Drepper â Red Hat, Inc. â 444 Castro St â Mountain View, CA â
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