Messages in this thread | | | Date | Mon, 6 Apr 2020 11:17:01 +0200 | From | Karel Zak <> | Subject | Re: Upcoming: Notifications, FS notifications and fsinfo() |
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On Fri, Apr 03, 2020 at 04:30:24PM -0400, J. Bruce Fields wrote: > On Fri, Apr 03, 2020 at 05:12:23PM +0200, Lennart Poettering wrote: > > BTW, while we are at it: one more thing I'd love to see exposed by > > statx() is a simple flag whether the inode is a mount point. There's > > plenty code that implements a test like this all over the place, and > > it usually isn't very safe. There's one implementation in util-linux > > for example (in the /usr/bin/mountpoint binary), and another one in > > systemd. Would be awesome to just have a statx() return flag for that, > > that would make things *so* much easier and more robust. because in > > fact most code isn't very good that implements this, as much of it > > just compares st_dev of the specified file and its parent. Better code > > compares the mount ID, but as mentioned that's not as pretty as it > > could be so far... > > nfs-utils/support/misc/mountpoint.c:check_is_mountpoint() stats the file > and ".." and returns true if they have different st_dev or the same > st_ino. Comparing mount ids sounds better.
BTW, this traditional st_dev+st_ino way is not reliable for bind mounts. For mountpoint(1) we search the directory in /proc/self/mountinfo.
> So anyway, yes, everybody reinvents the wheel here, and this would be > useful.
+1
Karel
-- Karel Zak <kzak@redhat.com> http://karelzak.blogspot.com
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