AuxXxilium/linux_dsm_epyc7002
1
0
Fork 0
mirror of https://github.com/AuxXxilium/linux_dsm_epyc7002.git synced 2024-12-04 02:16:45 +07:00
Code Issues Actions Packages Projects Releases Wiki Activity

FS-Cache: Permit fscache_cancel_op() to cancel in-progress operations too

Browse Source 
Currently, fscache_cancel_op() only cancels pending operations - attempts to
cancel in-progress operations are ignored.  This leads to a problem in
fscache_wait_for_operation_activation() whereby the wait is terminated, but
the object has been killed.

The check at the end of the function now triggers because it's no longer
contingent on the cache having produced an I/O error since the commit that
fixed the logic error in fscache_object_is_dead().

The result of the check is that it tries to cancel the operation - but since
the object may not be pending by this point, the cancellation request may be
ignored - with the result that the the object is just put by the caller and
fscache_put_operation has an assertion failure because the operation isn't in
either the COMPLETE or the CANCELLED states.

To fix this, we permit in-progress ops to be cancelled under some
circumstances.

The bug results in an oops that looks something like this:

	FS-Cache: fscache_wait_for_operation_activation() = -ENOBUFS [obj dead 3]
	FS-Cache:
	FS-Cache: Assertion failed
	FS-Cache: 3 == 5 is false
	------------[ cut here ]------------
	kernel BUG at ../fs/fscache/operation.c:432!
	...
	RIP: 0010:[<ffffffffa0088574>] fscache_put_operation+0xf2/0x2cd
	Call Trace:
	 [<ffffffffa008b92a>] __fscache_read_or_alloc_pages+0x2ec/0x3b3
	 [<ffffffffa00b761f>] __nfs_readpages_from_fscache+0x59/0xbf [nfs]
	 [<ffffffffa00b06c5>] nfs_readpages+0x10c/0x185 [nfs]
	 [<ffffffff81124925>] ? alloc_pages_current+0x119/0x13e
	 [<ffffffff810ee5fd>] ? __page_cache_alloc+0xfb/0x10a
	 [<ffffffff810f87f8>] __do_page_cache_readahead+0x188/0x22c
	 [<ffffffff810f8b3a>] ondemand_readahead+0x29e/0x2af
	 [<ffffffff810f8c92>] page_cache_sync_readahead+0x38/0x3a
	 [<ffffffff810ef337>] generic_file_read_iter+0x1a2/0x55a
	 [<ffffffffa00a9dff>] ? nfs_revalidate_mapping+0xd6/0x288 [nfs]
	 [<ffffffffa00a6a23>] nfs_file_read+0x49/0x70 [nfs]
	 [<ffffffff811363be>] new_sync_read+0x78/0x9c
	 [<ffffffff81137164>] __vfs_read+0x13/0x38
	 [<ffffffff8113721e>] vfs_read+0x95/0x121
	 [<ffffffff811372f6>] SyS_read+0x4c/0x8a
	 [<ffffffff81557a52>] system_call_fastpath+0x12/0x17

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Steve Dickson <steved@redhat.com>
Acked-by: Jeff Layton <jeff.layton@primarydata.com>
This commit is contained in:
David Howells 2015-02-24 10:05:28 +00:00
parent 8702152630
commit 418b7eb9e1
3 changed files with 21 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
fs/fscache/internal.h
View File

@ -125,7 +125,8 @@ extern int fscache_submit_exclusive_op(struct fscache_object *,
extern int fscache_submit_op(struct fscache_object *,
struct fscache_operation *);
extern int fscache_cancel_op(struct fscache_operation *,
void (*)(struct fscache_operation *));
void (*)(struct fscache_operation *),
bool);
extern void fscache_cancel_all_ops(struct fscache_object *);
extern void fscache_abort_object(struct fscache_object *);
extern void fscache_start_operations(struct fscache_object *);

20
fs/fscache/operation.c
View File

@ -312,9 +312,11 @@ void fscache_start_operations(struct fscache_object *object)
* cancel an operation that's pending on an object
*/
int fscache_cancel_op(struct fscache_operation *op,
void (*do_cancel)(struct fscache_operation *))
void (*do_cancel)(struct fscache_operation *),
bool cancel_in_progress_op)
{
struct fscache_object *object = op->object;
bool put = false;
int ret;
_enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id);
@ -328,8 +330,19 @@ int fscache_cancel_op(struct fscache_operation *op,
ret = -EBUSY;
if (op->state == FSCACHE_OP_ST_PENDING) {
ASSERT(!list_empty(&op->pend_link));
fscache_stat(&fscache_n_op_cancelled);
list_del_init(&op->pend_link);
put = true;
fscache_stat(&fscache_n_op_cancelled);
if (do_cancel)
do_cancel(op);
op->state = FSCACHE_OP_ST_CANCELLED;
if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
object->n_exclusive--;
if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
ret = 0;
} else if (op->state == FSCACHE_OP_ST_IN_PROGRESS && cancel_in_progress_op) {
fscache_stat(&fscache_n_op_cancelled);
if (do_cancel)
do_cancel(op);
op->state = FSCACHE_OP_ST_CANCELLED;
@ -337,10 +350,11 @@ int fscache_cancel_op(struct fscache_operation *op,
object->n_exclusive--;
if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
fscache_put_operation(op);
ret = 0;
}
if (put)
fscache_put_operation(op);
spin_unlock(&object->lock);
_leave(" = %d", ret);
return ret;

4
fs/fscache/page.c
View File

@ -359,7 +359,7 @@ int fscache_wait_for_operation_activation(struct fscache_object *object,
fscache_stat(stat_op_waits);
if (wait_on_bit(&op->flags, FSCACHE_OP_WAITING,
TASK_INTERRUPTIBLE) != 0) {
ret = fscache_cancel_op(op, do_cancel);
ret = fscache_cancel_op(op, do_cancel, false);
if (ret == 0)
return -ERESTARTSYS;
@ -380,7 +380,7 @@ int fscache_wait_for_operation_activation(struct fscache_object *object,
if (unlikely(fscache_object_is_dying(object) ||
fscache_cache_is_broken(object))) {
enum fscache_operation_state state = op->state;
fscache_cancel_op(op, do_cancel);
fscache_cancel_op(op, do_cancel, true);
if (stat_object_dead)
fscache_stat(stat_object_dead);
_leave(" = -ENOBUFS [obj dead %d]", state);