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afs: Add comments on abort handling 

Add some comments on AFS abort code handling in the rotation algorithm and
adjust the errors produced to match.

Reported-by: Jeffrey E Altman <jaltman@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeffrey Altman <jaltman@auristor.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
This commit is contained in:
David Howells 2023-10-18 08:42:18 +01:00
parent bad1a11c0f
commit fe245c8fcd
1 changed files with 90 additions and 11 deletions
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99
fs/afs/rotate.c
View File

@ -13,6 +13,7 @@
#include <linux/sched/signal.h>
#include "internal.h"
#include "afs_fs.h"
#include "protocol_uae.h"
/*
* Begin iteration through a server list, starting with the vnode's last used
@ -143,6 +144,11 @@ bool afs_select_fileserver(struct afs_operation *op)
case -ECONNABORTED:
/* The far side rejected the operation on some grounds. This
* might involve the server being busy or the volume having been moved.
*
* Note that various V* errors should not be sent to a cache manager
* by a fileserver as they should be translated to more modern UAE*
* errors instead. IBM AFS and OpenAFS fileservers, however, do leak
* these abort codes.
*/
switch (op->ac.abort_code) {
case VNOVOL:
@ -150,6 +156,11 @@ bool afs_select_fileserver(struct afs_operation *op)
* - May indicate that the VL is wrong - retry once and compare
* the results.
* - May indicate that the fileserver couldn't attach to the vol.
* - The volume might have been temporarily removed so that it can
* be replaced by a volume restore. "vos" might have ended one
* transaction and has yet to create the next.
* - The volume might not be blessed or might not be in-service
* (administrative action).
*/
if (op->flags & AFS_OPERATION_VNOVOL) {
op->error = -EREMOTEIO;
@ -183,16 +194,56 @@ bool afs_select_fileserver(struct afs_operation *op)
_leave(" = t [vnovol]");
return true;
case VSALVAGE: /* TODO: Should this return an error or iterate? */
case VVOLEXISTS:
case VNOSERVICE:
case VONLINE:
case VDISKFULL:
case VOVERQUOTA:
op->error = afs_abort_to_error(op->ac.abort_code);
/* These should not be returned from the fileserver. */
pr_warn("Fileserver returned unexpected abort %d\n",
op->ac.abort_code);
op->error = -EREMOTEIO;
goto next_server;
case VNOSERVICE:
/* Prior to AFS 3.2 VNOSERVICE was returned from the fileserver
* if the volume was neither in-service nor administratively
* blessed. All usage was replaced by VNOVOL because AFS 3.1 and
* earlier cache managers did not handle VNOSERVICE and assumed
* it was the client OSes errno 105.
*
* Starting with OpenAFS 1.4.8 VNOSERVICE was repurposed as the
* fileserver idle dead time error which was sent in place of
* RX_CALL_TIMEOUT (-3). The error was intended to be sent if the
* fileserver took too long to send a reply to the client.
* RX_CALL_TIMEOUT would have caused the cache manager to mark the
* server down whereas VNOSERVICE since AFS 3.2 would cause cache
* manager to temporarily (up to 15 minutes) mark the volume
* instance as unusable.
*
* The idle dead logic resulted in cache inconsistency since a
* state changing call that the cache manager assumed was dead
* could still be processed to completion by the fileserver. This
* logic was removed in OpenAFS 1.8.0 and VNOSERVICE is no longer
* returned. However, many 1.4.8 through 1.6.24 fileservers are
* still in existence.
*
* AuriStorFS fileservers have never returned VNOSERVICE.
*
* VNOSERVICE should be treated as an alias for RX_CALL_TIMEOUT.
*/
case RX_CALL_TIMEOUT:
op->error = -ETIMEDOUT;
goto next_server;
case VSALVAGING: /* This error should not be leaked to cache managers
* but is from OpenAFS demand attach fileservers.
* It should be treated as an alias for VOFFLINE.
*/
case VSALVAGE: /* VSALVAGE should be treated as a synonym of VOFFLINE */
case VOFFLINE:
/* The volume is in use by the volserver or another volume utility
* for an operation that might alter the contents. The volume is
* expected to come back but it might take a long time (could be
* days).
*/
if (!test_and_set_bit(AFS_VOLUME_OFFLINE, &op->volume->flags)) {
afs_busy(op->volume, op->ac.abort_code);
clear_bit(AFS_VOLUME_BUSY, &op->volume->flags);
@ -207,11 +258,20 @@ bool afs_select_fileserver(struct afs_operation *op)
}
goto busy;
case VSALVAGING:
case VRESTARTING:
case VRESTARTING: /* The fileserver is either shutting down or starting up. */
case VBUSY:
/* Retry after going round all the servers unless we
* have a file lock we need to maintain.
/* The volume is in use by the volserver or another volume
* utility for an operation that is not expected to alter the
* contents of the volume. VBUSY does not need to be returned
* for a ROVOL or BACKVOL bound to an ITBusy volserver
* transaction. The fileserver is permitted to continue serving
* content from ROVOLs and BACKVOLs during an ITBusy transaction
* because the content will not change. However, many fileserver
* releases do return VBUSY for ROVOL and BACKVOL instances under
* many circumstances.
*
* Retry after going round all the servers unless we have a file
* lock we need to maintain.
*/
if (op->flags & AFS_OPERATION_NO_VSLEEP) {
op->error = -EBUSY;
@ -270,10 +330,29 @@ bool afs_select_fileserver(struct afs_operation *op)
goto restart_from_beginning;
case VDISKFULL:
case UAENOSPC:
/* The partition is full. Only applies to RWVOLs.
* Translate locally and return ENOSPC.
* No replicas to failover to.
*/
op->error = -ENOSPC;
goto failed_but_online;
case VOVERQUOTA:
case UAEDQUOT:
/* Volume is full. Only applies to RWVOLs.
* Translate locally and return EDQUOT.
* No replicas to failover to.
*/
op->error = -EDQUOT;
goto failed_but_online;
default:
op->error = afs_abort_to_error(op->ac.abort_code);
failed_but_online:
clear_bit(AFS_VOLUME_OFFLINE, &op->volume->flags);
clear_bit(AFS_VOLUME_BUSY, &op->volume->flags);
op->error = afs_abort_to_error(op->ac.abort_code);
goto failed;
}