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alistair23-linux/fs/fscache/operation.c
David Howells 402cb8dda9 fscache: Attach the index key and aux data to the cookie 
Attach copies of the index key and auxiliary data to the fscache cookie so
that:

 (1) The callbacks to the netfs for this stuff can be eliminated.  This
     can simplify things in the cache as the information is still
     available, even after the cache has relinquished the cookie.

 (2) Simplifies the locking requirements of accessing the information as we
     don't have to worry about the netfs object going away on us.

 (3) The cache can do lazy updating of the coherency information on disk.
     As long as the cache is flushed before reboot/poweroff, there's no
     need to update the coherency info on disk every time it changes.

 (4) Cookies can be hashed or put in a tree as the index key is easily
     available.  This allows:

     (a) Checks for duplicate cookies can be made at the top fscache layer
     	 rather than down in the bowels of the cache backend.

     (b) Caching can be added to a netfs object that has a cookie if the
     	 cache is brought online after the netfs object is allocated.

A certain amount of space is made in the cookie for inline copies of the
data, but if it won't fit there, extra memory will be allocated for it.

The downside of this is that live cache operation requires more memory.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Anna Schumaker <anna.schumaker@netapp.com>
Tested-by: Steve Dickson <steved@redhat.com>
2018-04-04 13:41:28 +01:00

636 lines
17 KiB
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/* FS-Cache worker operation management routines
*
* Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* See Documentation/filesystems/caching/operations.txt
*/
#define FSCACHE_DEBUG_LEVEL OPERATION
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include "internal.h"
atomic_t fscache_op_debug_id;
EXPORT_SYMBOL(fscache_op_debug_id);
static void fscache_operation_dummy_cancel(struct fscache_operation *op)
{
}
/**
* fscache_operation_init - Do basic initialisation of an operation
* @op: The operation to initialise
* @release: The release function to assign
*
* Do basic initialisation of an operation. The caller must still set flags,
* object and processor if needed.
*/
void fscache_operation_init(struct fscache_cookie *cookie,
struct fscache_operation *op,
fscache_operation_processor_t processor,
fscache_operation_cancel_t cancel,
fscache_operation_release_t release)
{
INIT_WORK(&op->work, fscache_op_work_func);
atomic_set(&op->usage, 1);
op->state = FSCACHE_OP_ST_INITIALISED;
op->debug_id = atomic_inc_return(&fscache_op_debug_id);
op->processor = processor;
op->cancel = cancel ?: fscache_operation_dummy_cancel;
op->release = release;
INIT_LIST_HEAD(&op->pend_link);
fscache_stat(&fscache_n_op_initialised);
trace_fscache_op(cookie, op, fscache_op_init);
}
EXPORT_SYMBOL(fscache_operation_init);
/**
* fscache_enqueue_operation - Enqueue an operation for processing
* @op: The operation to enqueue
*
* Enqueue an operation for processing by the FS-Cache thread pool.
*
* This will get its own ref on the object.
*/
void fscache_enqueue_operation(struct fscache_operation *op)
{
struct fscache_cookie *cookie = op->object->cookie;
_enter("{OBJ%x OP%x,%u}",
op->object->debug_id, op->debug_id, atomic_read(&op->usage));
ASSERT(list_empty(&op->pend_link));
ASSERT(op->processor != NULL);
ASSERT(fscache_object_is_available(op->object));
ASSERTCMP(atomic_read(&op->usage), >, 0);
ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS);
fscache_stat(&fscache_n_op_enqueue);
switch (op->flags & FSCACHE_OP_TYPE) {
case FSCACHE_OP_ASYNC:
trace_fscache_op(cookie, op, fscache_op_enqueue_async);
_debug("queue async");
atomic_inc(&op->usage);
if (!queue_work(fscache_op_wq, &op->work))
fscache_put_operation(op);
break;
case FSCACHE_OP_MYTHREAD:
trace_fscache_op(cookie, op, fscache_op_enqueue_mythread);
_debug("queue for caller's attention");
break;
default:
pr_err("Unexpected op type %lx", op->flags);
BUG();
break;
}
}
EXPORT_SYMBOL(fscache_enqueue_operation);
/*
* start an op running
*/
static void fscache_run_op(struct fscache_object *object,
struct fscache_operation *op)
{
ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
op->state = FSCACHE_OP_ST_IN_PROGRESS;
object->n_in_progress++;
if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
if (op->processor)
fscache_enqueue_operation(op);
else
trace_fscache_op(object->cookie, op, fscache_op_run);
fscache_stat(&fscache_n_op_run);
}
/*
* report an unexpected submission
*/
static void fscache_report_unexpected_submission(struct fscache_object *object,
struct fscache_operation *op,
const struct fscache_state *ostate)
{
static bool once_only;
struct fscache_operation *p;
unsigned n;
if (once_only)
return;
once_only = true;
kdebug("unexpected submission OP%x [OBJ%x %s]",
op->debug_id, object->debug_id, object->state->name);
kdebug("objstate=%s [%s]", object->state->name, ostate->name);
kdebug("objflags=%lx", object->flags);
kdebug("objevent=%lx [%lx]", object->events, object->event_mask);
kdebug("ops=%u inp=%u exc=%u",
object->n_ops, object->n_in_progress, object->n_exclusive);
if (!list_empty(&object->pending_ops)) {
n = 0;
list_for_each_entry(p, &object->pending_ops, pend_link) {
ASSERTCMP(p->object, ==, object);
kdebug("%p %p", op->processor, op->release);
n++;
}
kdebug("n=%u", n);
}
dump_stack();
}
/*
* submit an exclusive operation for an object
* - other ops are excluded from running simultaneously with this one
* - this gets any extra refs it needs on an op
*/
int fscache_submit_exclusive_op(struct fscache_object *object,
struct fscache_operation *op)
{
const struct fscache_state *ostate;
unsigned long flags;
int ret;
_enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);
trace_fscache_op(object->cookie, op, fscache_op_submit_ex);
ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
ASSERTCMP(atomic_read(&op->usage), >, 0);
spin_lock(&object->lock);
ASSERTCMP(object->n_ops, >=, object->n_in_progress);
ASSERTCMP(object->n_ops, >=, object->n_exclusive);
ASSERT(list_empty(&op->pend_link));
ostate = object->state;
smp_rmb();
op->state = FSCACHE_OP_ST_PENDING;
flags = READ_ONCE(object->flags);
if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
fscache_stat(&fscache_n_op_rejected);
op->cancel(op);
op->state = FSCACHE_OP_ST_CANCELLED;
ret = -ENOBUFS;
} else if (unlikely(fscache_cache_is_broken(object))) {
op->cancel(op);
op->state = FSCACHE_OP_ST_CANCELLED;
ret = -EIO;
} else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
op->object = object;
object->n_ops++;
object->n_exclusive++; /* reads and writes must wait */
if (object->n_in_progress > 0) {
atomic_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
} else if (!list_empty(&object->pending_ops)) {
atomic_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
fscache_start_operations(object);
} else {
ASSERTCMP(object->n_in_progress, ==, 0);
fscache_run_op(object, op);
}
/* need to issue a new write op after this */
clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
ret = 0;
} else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
op->object = object;
object->n_ops++;
object->n_exclusive++; /* reads and writes must wait */
atomic_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
ret = 0;
} else if (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
op->cancel(op);
op->state = FSCACHE_OP_ST_CANCELLED;
ret = -ENOBUFS;
} else {
fscache_report_unexpected_submission(object, op, ostate);
op->cancel(op);
op->state = FSCACHE_OP_ST_CANCELLED;
ret = -ENOBUFS;
}
spin_unlock(&object->lock);
return ret;
}
/*
* submit an operation for an object
* - objects may be submitted only in the following states:
* - during object creation (write ops may be submitted)
* - whilst the object is active
* - after an I/O error incurred in one of the two above states (op rejected)
* - this gets any extra refs it needs on an op
*/
int fscache_submit_op(struct fscache_object *object,
struct fscache_operation *op)
{
const struct fscache_state *ostate;
unsigned long flags;
int ret;
_enter("{OBJ%x OP%x},{%u}",
object->debug_id, op->debug_id, atomic_read(&op->usage));
trace_fscache_op(object->cookie, op, fscache_op_submit);
ASSERTCMP(op->state, ==, FSCACHE_OP_ST_INITIALISED);
ASSERTCMP(atomic_read(&op->usage), >, 0);
spin_lock(&object->lock);
ASSERTCMP(object->n_ops, >=, object->n_in_progress);
ASSERTCMP(object->n_ops, >=, object->n_exclusive);
ASSERT(list_empty(&op->pend_link));
ostate = object->state;
smp_rmb();
op->state = FSCACHE_OP_ST_PENDING;
flags = READ_ONCE(object->flags);
if (unlikely(!(flags & BIT(FSCACHE_OBJECT_IS_LIVE)))) {
fscache_stat(&fscache_n_op_rejected);
op->cancel(op);
op->state = FSCACHE_OP_ST_CANCELLED;
ret = -ENOBUFS;
} else if (unlikely(fscache_cache_is_broken(object))) {
op->cancel(op);
op->state = FSCACHE_OP_ST_CANCELLED;
ret = -EIO;
} else if (flags & BIT(FSCACHE_OBJECT_IS_AVAILABLE)) {
op->object = object;
object->n_ops++;
if (object->n_exclusive > 0) {
atomic_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
} else if (!list_empty(&object->pending_ops)) {
atomic_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
fscache_start_operations(object);
} else {
ASSERTCMP(object->n_exclusive, ==, 0);
fscache_run_op(object, op);
}
ret = 0;
} else if (flags & BIT(FSCACHE_OBJECT_IS_LOOKED_UP)) {
op->object = object;
object->n_ops++;
atomic_inc(&op->usage);
list_add_tail(&op->pend_link, &object->pending_ops);
fscache_stat(&fscache_n_op_pend);
ret = 0;
} else if (flags & BIT(FSCACHE_OBJECT_KILLED_BY_CACHE)) {
op->cancel(op);
op->state = FSCACHE_OP_ST_CANCELLED;
ret = -ENOBUFS;
} else {
fscache_report_unexpected_submission(object, op, ostate);
ASSERT(!fscache_object_is_active(object));
op->cancel(op);
op->state = FSCACHE_OP_ST_CANCELLED;
ret = -ENOBUFS;
}
spin_unlock(&object->lock);
return ret;
}
/*
* queue an object for withdrawal on error, aborting all following asynchronous
* operations
*/
void fscache_abort_object(struct fscache_object *object)
{
_enter("{OBJ%x}", object->debug_id);
fscache_raise_event(object, FSCACHE_OBJECT_EV_ERROR);
}
/*
* Jump start the operation processing on an object. The caller must hold
* object->lock.
*/
void fscache_start_operations(struct fscache_object *object)
{
struct fscache_operation *op;
bool stop = false;
while (!list_empty(&object->pending_ops) && !stop) {
op = list_entry(object->pending_ops.next,
struct fscache_operation, pend_link);
if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags)) {
if (object->n_in_progress > 0)
break;
stop = true;
}
list_del_init(&op->pend_link);
fscache_run_op(object, op);
/* the pending queue was holding a ref on the object */
fscache_put_operation(op);
}
ASSERTCMP(object->n_in_progress, <=, object->n_ops);
_debug("woke %d ops on OBJ%x",
object->n_in_progress, object->debug_id);
}
/*
* cancel an operation that's pending on an object
*/
int fscache_cancel_op(struct fscache_operation *op,
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);
trace_fscache_op(object->cookie, op, fscache_op_cancel);
ASSERTCMP(op->state, >=, FSCACHE_OP_ST_PENDING);
ASSERTCMP(op->state, !=, FSCACHE_OP_ST_CANCELLED);
ASSERTCMP(atomic_read(&op->usage), >, 0);
spin_lock(&object->lock);
ret = -EBUSY;
if (op->state == FSCACHE_OP_ST_PENDING) {
ASSERT(!list_empty(&op->pend_link));
list_del_init(&op->pend_link);
put = true;
fscache_stat(&fscache_n_op_cancelled);
op->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) {
ASSERTCMP(object->n_in_progress, >, 0);
if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
object->n_exclusive--;
object->n_in_progress--;
if (object->n_in_progress == 0)
fscache_start_operations(object);
fscache_stat(&fscache_n_op_cancelled);
op->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;
}
if (put)
fscache_put_operation(op);
spin_unlock(&object->lock);
_leave(" = %d", ret);
return ret;
}
/*
* Cancel all pending operations on an object
*/
void fscache_cancel_all_ops(struct fscache_object *object)
{
struct fscache_operation *op;
_enter("OBJ%x", object->debug_id);
spin_lock(&object->lock);
while (!list_empty(&object->pending_ops)) {
op = list_entry(object->pending_ops.next,
struct fscache_operation, pend_link);
fscache_stat(&fscache_n_op_cancelled);
list_del_init(&op->pend_link);
trace_fscache_op(object->cookie, op, fscache_op_cancel_all);
ASSERTCMP(op->state, ==, FSCACHE_OP_ST_PENDING);
op->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);
fscache_put_operation(op);
cond_resched_lock(&object->lock);
}
spin_unlock(&object->lock);
_leave("");
}
/*
* Record the completion or cancellation of an in-progress operation.
*/
void fscache_op_complete(struct fscache_operation *op, bool cancelled)
{
struct fscache_object *object = op->object;
_enter("OBJ%x", object->debug_id);
ASSERTCMP(op->state, ==, FSCACHE_OP_ST_IN_PROGRESS);
ASSERTCMP(object->n_in_progress, >, 0);
ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags),
object->n_exclusive, >, 0);
ASSERTIFCMP(test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags),
object->n_in_progress, ==, 1);
spin_lock(&object->lock);
if (!cancelled) {
trace_fscache_op(object->cookie, op, fscache_op_completed);
op->state = FSCACHE_OP_ST_COMPLETE;
} else {
op->cancel(op);
trace_fscache_op(object->cookie, op, fscache_op_cancelled);
op->state = FSCACHE_OP_ST_CANCELLED;
}
if (test_bit(FSCACHE_OP_EXCLUSIVE, &op->flags))
object->n_exclusive--;
object->n_in_progress--;
if (object->n_in_progress == 0)
fscache_start_operations(object);
spin_unlock(&object->lock);
_leave("");
}
EXPORT_SYMBOL(fscache_op_complete);
/*
* release an operation
* - queues pending ops if this is the last in-progress op
*/
void fscache_put_operation(struct fscache_operation *op)
{
struct fscache_object *object;
struct fscache_cache *cache;
_enter("{OBJ%x OP%x,%d}",
op->object->debug_id, op->debug_id, atomic_read(&op->usage));
ASSERTCMP(atomic_read(&op->usage), >, 0);
if (!atomic_dec_and_test(&op->usage))
return;
trace_fscache_op(op->object ? op->object->cookie : NULL, op, fscache_op_put);
_debug("PUT OP");
ASSERTIFCMP(op->state != FSCACHE_OP_ST_INITIALISED &&
op->state != FSCACHE_OP_ST_COMPLETE,
op->state, ==, FSCACHE_OP_ST_CANCELLED);
fscache_stat(&fscache_n_op_release);
if (op->release) {
op->release(op);
op->release = NULL;
}
op->state = FSCACHE_OP_ST_DEAD;
object = op->object;
if (likely(object)) {
if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags))
atomic_dec(&object->n_reads);
if (test_bit(FSCACHE_OP_UNUSE_COOKIE, &op->flags))
fscache_unuse_cookie(object);
/* now... we may get called with the object spinlock held, so we
* complete the cleanup here only if we can immediately acquire the
* lock, and defer it otherwise */
if (!spin_trylock(&object->lock)) {
_debug("defer put");
fscache_stat(&fscache_n_op_deferred_release);
cache = object->cache;
spin_lock(&cache->op_gc_list_lock);
list_add_tail(&op->pend_link, &cache->op_gc_list);
spin_unlock(&cache->op_gc_list_lock);
schedule_work(&cache->op_gc);
_leave(" [defer]");
return;
}
ASSERTCMP(object->n_ops, >, 0);
object->n_ops--;
if (object->n_ops == 0)
fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
spin_unlock(&object->lock);
}
kfree(op);
_leave(" [done]");
}
EXPORT_SYMBOL(fscache_put_operation);
/*
* garbage collect operations that have had their release deferred
*/
void fscache_operation_gc(struct work_struct *work)
{
struct fscache_operation *op;
struct fscache_object *object;
struct fscache_cache *cache =
container_of(work, struct fscache_cache, op_gc);
int count = 0;
_enter("");
do {
spin_lock(&cache->op_gc_list_lock);
if (list_empty(&cache->op_gc_list)) {
spin_unlock(&cache->op_gc_list_lock);
break;
}
op = list_entry(cache->op_gc_list.next,
struct fscache_operation, pend_link);
list_del(&op->pend_link);
spin_unlock(&cache->op_gc_list_lock);
object = op->object;
trace_fscache_op(object->cookie, op, fscache_op_gc);
spin_lock(&object->lock);
_debug("GC DEFERRED REL OBJ%x OP%x",
object->debug_id, op->debug_id);
fscache_stat(&fscache_n_op_gc);
ASSERTCMP(atomic_read(&op->usage), ==, 0);
ASSERTCMP(op->state, ==, FSCACHE_OP_ST_DEAD);
ASSERTCMP(object->n_ops, >, 0);
object->n_ops--;
if (object->n_ops == 0)
fscache_raise_event(object, FSCACHE_OBJECT_EV_CLEARED);
spin_unlock(&object->lock);
kfree(op);
} while (count++ < 20);
if (!list_empty(&cache->op_gc_list))
schedule_work(&cache->op_gc);
_leave("");
}
/*
* execute an operation using fs_op_wq to provide processing context -
* the caller holds a ref to this object, so we don't need to hold one
*/
void fscache_op_work_func(struct work_struct *work)
{
struct fscache_operation *op =
container_of(work, struct fscache_operation, work);
unsigned long start;
_enter("{OBJ%x OP%x,%d}",
op->object->debug_id, op->debug_id, atomic_read(&op->usage));
trace_fscache_op(op->object->cookie, op, fscache_op_work);
ASSERT(op->processor != NULL);
start = jiffies;
op->processor(op);
fscache_hist(fscache_ops_histogram, start);
fscache_put_operation(op);
_leave("");
}
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