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vos: fix name availability check in vos rename

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The UV_RenameVolume() function first updates the volume name in the
VLDB, then read-write volume header and backup volume header, and
finally all of the read-only volume headers. If this function is
interrupted or a remote site is not reachable, the names in some of the
volume headers will be out of sync with name in the VLDB entry.

The implementation of UV_RenameVolume() is idempotent, so can be safely
called with the same name as in the volume's VLDB entry. This could be
used to bring all the names in the volume headers in sync with the name
in the VLDB.

Unfortunately, due to the check of the -newname parameter, vos
rename will not invoke UV_RenameVolume() when the name in the VLDB has
already been changed.  The vos rename command attempts to verify the
desired name (-newname) is available before invoking UV_RenameVolume()
by simply checking if a VLDB entry exists with that name, and
incorrectly assumes when a VLDB entry exists with that name it is an
entry for a different volume.

Change the -newname check to allow vos rename to proceed when name has
already been set in the VLDB entry of the volume being renamed. This
allows admins to run vos rename command to complete a previously
incomplete rename operation and bring the names in the volume headers in
sync with the name in the VLDB entry.

Note: Before this commit, administrators could workaround this vos
rename limitation by renaming the volume twice, first to an unused
volume name, then to the actual desired volume name.

Remove the useless checks of the code1 return code after exit in
the RenameVolume() function. These checks for code1 are never performed
since the function exits early when the first VLDB_GetEntryByName()
fails for any reason.

Update the vos rename man page to show vos rename can be used to fix
previously interrupted/failed rename. Also document the -oldname
parameter accepts a numeric volume id to specify the volume to be
renamed.

Change-Id: Ibb5dbe3148e9b8295347925a59cd7bdbccbe8fe0
Reviewed-on: https://gerrit.openafs.org/13720
Reviewed-by: Cheyenne Wills <cwills@sinenomine.net>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
This commit is contained in:
Michael Meffie 2019-07-22 15:20:24 -04:00 committed by Benjamin Kaduk
parent 6c54bc9e12
commit 9238b1eb9e
2 changed files with 31 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
doc/man-pages/pod1/vos_rename.pod.in
View File

@ -40,14 +40,17 @@ command.
=over 4
=item B<-oldname> <I<old volume name>>
=item B<-oldname> <I<old volume name or id>>
Is the current name of the read/write volume.
Is the current name or numeric id of the read/write volume to be renamed.
=item B<-newname> <I<new volume name>>
Is the desired new name for the volume.
The new name may be the same as the current volume name in the VLDB
in order to complete a previously interrupted volume rename.
=include fragments/vos-common.pod
=back

38
src/volser/vos.c
View File

@ -4153,25 +4153,39 @@ VolserStatus(struct cmd_syndesc *as, void *arock)
static int
RenameVolume(struct cmd_syndesc *as, void *arock)
{
afs_int32 code1, code2, code;
afs_int32 code;
struct nvldbentry entry;
struct nvldbentry entry2;
code1 = VLDB_GetEntryByName(as->parms[0].items->data, &entry);
if (code1) {
/* Get the entry of the volume to be renamed (-oldname), by name or id. */
code = VLDB_GetEntryByName(as->parms[0].items->data, &entry);
if (code) {
fprintf(STDERR, "vos: Could not find entry for volume %s\n",
as->parms[0].items->data);
exit(1);
}
code2 = VLDB_GetEntryByName(as->parms[1].items->data, &entry);
if ((!code1) && (!code2)) { /*the newname already exists */
fprintf(STDERR, "vos: volume %s already exists\n",
as->parms[1].items->data);
PrintError("", code);
exit(1);
}
if (code1 && code2) {
fprintf(STDERR, "vos: Could not find entry for volume %s or %s\n",
as->parms[0].items->data, as->parms[1].items->data);
/*
* Verify the new name is available before attempting to rename.
* Allow renaming of the same volume in order to complete a
* previously interrupted rename.
*/
code = VLDB_GetEntryByName(as->parms[1].items->data, &entry2);
if (code != 0 && code != VL_NOENT) {
fprintf(STDERR, "vos: Could not check entry for volume %s\n",
as->parms[1].items->data);
PrintError("", code);
exit(1);
}
if (code == 0 && entry.volumeId[RWVOL] != entry2.volumeId[RWVOL]) {
fprintf(STDERR, "vos: Cannot rename volume %s (%lu) to %s;"
" volume %s (%lu) already exists\n",
as->parms[0].items->data,
(unsigned long)entry.volumeId[RWVOL],
as->parms[1].items->data,
as->parms[1].items->data,
(unsigned long)entry2.volumeId[RWVOL]);
exit(1);
}
if (!VolNameOK(as->parms[0].items->data)) {