[Bug 845245] New: chmod and chgrp make unnecessary disc writes
https://bugzilla.novell.com/show_bug.cgi?id=845245 https://bugzilla.novell.com/show_bug.cgi?id=845245#c0 Summary: chmod and chgrp make unnecessary disc writes Classification: openSUSE Product: openSUSE 12.3 Version: Final Platform: x86-64 OS/Version: openSUSE 12.3 Status: NEW Severity: Normal Priority: P5 - None Component: Basesystem AssignedTo: bnc-team-screening@forge.provo.novell.com ReportedBy: R.Vickers@cs.rhul.ac.uk QAContact: qa-bugs@suse.de Found By: --- Blocker: --- User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Firefox/24.0 Using chmod or chgrp alters the last-change time of a file even if no changes are actually made. This may seem like a very minor matter, but if you are dealing with a large number of files (for example with the -R option) then there are a number of bad consequences: (1) system performance is impacted while the command is running (2) incremental backups take longer and consume more space (3) restores after a disc failure take much longer because many large incremental backups have to be processed We use cron jobs to set correct permissions on shared directories, because it is not fair on users to expect them to manage this themselves. On one file system we find a third of the files are backed up every night because of this, and it extended the recovery time after a disc failure by many hours. Reproducible: Always Steps to Reproduce: $ touch test $ chmod 700 test $ stat test $ chmod 700 test $ stat test Actual Results: The Change time is updated after every chmod. Expected Results: The Change time should only be updated if the mode was changed. -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.
https://bugzilla.novell.com/show_bug.cgi?id=845245 https://bugzilla.novell.com/show_bug.cgi?id=845245#c Christian Boltz <suse-beta@cboltz.de> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |suse-beta@cboltz.de AssignedTo|bnc-team-screening@forge.pr |mail@bernhard-voelker.de |ovo.novell.com | -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.
https://bugzilla.novell.com/show_bug.cgi?id=845245 https://bugzilla.novell.com/show_bug.cgi?id=845245#c1 Bernhard Voelker <mail@bernhard-voelker.de> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |ASSIGNED --- Comment #1 from Bernhard Voelker <mail@bernhard-voelker.de> 2013-10-13 13:22:39 UTC --- Changing ctime seems to violate POSIX at first glance, but opposite source change has been made years back. Started upstream discussion: http://lists.gnu.org/archive/html/coreutils/2013-10/msg00028.html -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.
http://bugzilla.novell.com/show_bug.cgi?id=845245 http://bugzilla.novell.com/show_bug.cgi?id=845245#c4 Bernhard Voelker <mail@bernhard-voelker.de> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|CONFIRMED |RESOLVED Resolution|--- |WONTFIX --- Comment #4 from Bernhard Voelker <mail@bernhard-voelker.de> --- As per discussions like [1] and [2], it is problematic to skip the chmod(3) syscall because e.g. the ACLs on an NFS file system may change even if the UNIX file permission bits do not. Thus said, the only instance knowing if the ctime has to be changed is the kernel. Trying to workaround that in chmod(1) seems to be quirky. [1] http://lists.gnu.org/archive/html/bug-coreutils/2010-01/msg00303.html [2] https://lists.gnu.org/archive/html/coreutils/2013-10/msg00030.html -- You are receiving this mail because: You are on the CC list for the bug.
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