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Our 'fs flush' and related commands (flushall, flushvolume) clear the
relevant entries in the OpenAFS stat cache and data cache, which can
fix problems if the cache ever becomes incorrect for any reason. (This
can happen after bugs, repairing corrupted volumes, disaster recovery
scenarios, and similar edge cases.)
However, on Linux, these commands don't affect the VFS dentry cache.
If someone needs to use an 'fs flush' command to fix a problem, this
will fix the OpenAFS cache, but the Linux dcache can still be wrong.
The only way to manually flush dcache entries is to use the global
'drop_caches' mechanism, which is a very heavweight operation, only
accessible to root.
For example:
$ ls -l
ls: cannot access foo.1: No such file or directory
total 2
drwxrwxr-x. 2 bin adeason 2048 Apr 6 14:20 dir
-?????????? ? ? ? ? ? foo.1
$ fs flush .
$ ls -l
ls: cannot access foo.1: No such file or directory
total 2
drwxrwxr-x. 2 bin adeason 2048 Apr 6 14:20 dir
-?????????? ? ? ? ? ? foo.1
$ sudo sysctl -q -w vm.drop_caches=3
$ ls -l
total 3
drwxrwxr-x. 2 bin adeason 2048 Apr 6 14:20 dir
-rw-rw-r--. 1 bin adeason 29 Sep 22 2022 foo.1
To make the 'fs flush' commands be effective in more situations,
change afs_ResetVCache() to also invalidate the dcache entries
associated with each vcache we reset. To make things simpler and
reduce locking complexity, do this by setting d_time to 0, and don't
directly run dcache-managing functions like d_invalidate or d_drop,
etc.
The above example now becomes:
$ ls -l
ls: cannot access foo.1: No such file or directory
total 2
drwxrwxr-x. 2 bin adeason 2048 Apr 6 14:20 dir
-?????????? ? ? ? ? ? foo.1
$ fs flush .
$ ls -l
total 3
drwxrwxr-x. 2 bin adeason 2048 Apr 6 14:20 dir
-rw-rw-r--. 1 bin adeason 29 Sep 22 2022 foo.1
Reviewed-on: https://gerrit.openafs.org/15391
Reviewed-by: Cheyenne Wills <cwills@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
(cherry picked from commit d460b616ebad763f7e480e194b2bffc28df99721)
Change-Id: I184046469c396b0421752d91c47477ebe8eaed13
Reviewed-on: https://gerrit.openafs.org/15515
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Tested-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>
AFS is a distributed file system that enables users to share and access all of the files stored in a network of computers as easily as they access the files stored on their local machines. The file system is called distributed for this exact reason: files can reside on many different machines, but are available to users on every machine. OpenAFS 1.0 was originally released by IBM under the terms of the IBM Public License 1.0 (IPL10). For details on IPL10 see the LICENSE file in this directory. The current OpenAFS distribution is licensed under a combination of the IPL10 and many other licenses as granted by the relevant copyright holders. The LICENSE file in this directory contains more details, thought it is not a comprehensive statement. See INSTALL for information about building and installing OpenAFS on various platforms. See CODING for developer information and guidelines. See NEWS for recent changes to OpenAFS.