Paul Eggert <egg...@cs.ucla.edu> wrote:
> On 01/29/2013 06:44 PM, Eric Wong wrote:
> > eglibc on Debian is only configured to only use features available in
> > Linux 2.6.26 at build time. This means statvfs() uses stat() internally
> > regardless of the run-time kernel version[1].
>
> That sounds like a bug in eglibc. Perhaps you can fix this problem on the
> eglibc side. That is, eglibc can use only 2.6.26 features, but make an
> exception for this feature, since it's obviously needed.
Actually, reading the eglibc and kernel source more closely, my initial
analysis seems wrong, and I'm even more at a loss as to why stat()
gets called when I call statvfs().
The stat() I see after statfs() is /not/ happening from a check of
where the 2.6.36+ kernel sets ST_VALID:
At first, I thought the following code was entering __statvfs_getflags()
in sysdeps/unix/sysv/linux/internal_statvfs.c:
#ifndef __ASSUME_STATFS_F_FLAGS
if ((fsbuf->f_flags & ST_VALID) == 0)
/* Determining the flags is tricky. We have to read /proc/mounts or
the /etc/mtab file and search for the entry which matches the given
file. The way we can test for matching filesystem is using the
device number. */
buf->f_flag = __statvfs_getflags (name, fsbuf->f_type, st);
else
#endif
buf->f_flag = fsbuf->f_flags ^ ST_VALID;
-----------------------------------------------------------------
But now I see it's not, since __statvfs_getflags() would also
open /proc/mounts (which I don't see happening).
Anyways I've filed a bug report with Debian:
http://bugs.debian.org/699321
Thanks for looking at this, hopefully somebody from Debian can help.
