diff options
| -rw-r--r-- | Documentation/filesystems/caching/backend-api.txt | 9 | ||||
| -rw-r--r-- | Documentation/filesystems/caching/netfs-api.txt | 17 | ||||
| -rw-r--r-- | fs/fscache/cookie.c | 71 | ||||
| -rw-r--r-- | fs/fscache/internal.h | 6 | ||||
| -rw-r--r-- | fs/fscache/page.c | 55 | ||||
| -rw-r--r-- | include/linux/fscache-cache.h | 4 | ||||
| -rw-r--r-- | include/linux/fscache.h | 20 |
7 files changed, 154 insertions, 28 deletions
diff --git a/Documentation/filesystems/caching/backend-api.txt b/Documentation/filesystems/caching/backend-api.txt index d78bab9..277d1e8 100644 --- a/Documentation/filesystems/caching/backend-api.txt +++ b/Documentation/filesystems/caching/backend-api.txt @@ -299,6 +299,15 @@ performed on the denizens of the cache. These are held in a structure of type: enough space in the cache to permit this. + (*) Check coherency state of an object [mandatory]: + + int (*check_consistency)(struct fscache_object *object) + + This method is called to have the cache check the saved auxiliary data of + the object against the netfs's idea of the state. 0 should be returned + if they're consistent and -ESTALE otherwise. -ENOMEM and -ERESTARTSYS + may also be returned. + (*) Update object [mandatory]: int (*update_object)(struct fscache_object *object) diff --git a/Documentation/filesystems/caching/netfs-api.txt b/Documentation/filesystems/caching/netfs-api.txt index 97e6c0e..12b3442 100644 --- a/Documentation/filesystems/caching/netfs-api.txt +++ b/Documentation/filesystems/caching/netfs-api.txt @@ -32,7 +32,7 @@ This document contains the following sections: (9) Setting the data file size (10) Page alloc/read/write (11) Page uncaching - (12) Index and data file update + (12) Index and data file consistency (13) Miscellaneous cookie operations (14) Cookie unregistration (15) Index invalidation @@ -690,9 +690,18 @@ written to the cache and for the cache to finish with the page generally. No error is returned. -========================== -INDEX AND DATA FILE UPDATE -========================== +=============================== +INDEX AND DATA FILE CONSISTENCY +=============================== + +To find out whether auxiliary data for an object is up to data within the +cache, the following function can be called: + + int fscache_check_consistency(struct fscache_cookie *cookie) + +This will call back to the netfs to check whether the auxiliary data associated +with a cookie is correct. It returns 0 if it is and -ESTALE if it isn't; it +may also return -ENOMEM and -ERESTARTSYS. To request an update of the index data for an index or other object, the following function should be called: diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c index 0e91a3c..318e843 100644 --- a/fs/fscache/cookie.c +++ b/fs/fscache/cookie.c @@ -558,3 +558,74 @@ void __fscache_cookie_put(struct fscache_cookie *cookie) _leave(""); } + +/* + * check the consistency between the netfs inode and the backing cache + * + * NOTE: it only serves no-index type + */ +int __fscache_check_consistency(struct fscache_cookie *cookie) +{ + struct fscache_operation *op; + struct fscache_object *object; + int ret; + + _enter("%p,", cookie); + + ASSERTCMP(cookie->def->type, ==, FSCACHE_COOKIE_TYPE_DATAFILE); + + if (fscache_wait_for_deferred_lookup(cookie) < 0) + return -ERESTARTSYS; + + if (hlist_empty(&cookie->backing_objects)) + return 0; + + op = kzalloc(sizeof(*op), GFP_NOIO | __GFP_NOMEMALLOC | __GFP_NORETRY); + if (!op) + return -ENOMEM; + + fscache_operation_init(op, NULL, NULL); + op->flags = FSCACHE_OP_MYTHREAD | + (1 << FSCACHE_OP_WAITING); + + spin_lock(&cookie->lock); + + if (hlist_empty(&cookie->backing_objects)) + goto inconsistent; + object = hlist_entry(cookie->backing_objects.first, + struct fscache_object, cookie_link); + if (test_bit(FSCACHE_IOERROR, &object->cache->flags)) + goto inconsistent; + + op->debug_id = atomic_inc_return(&fscache_op_debug_id); + + atomic_inc(&cookie->n_active); + if (fscache_submit_op(object, op) < 0) + goto submit_failed; + + /* the work queue now carries its own ref on the object */ + spin_unlock(&cookie->lock); + + ret = fscache_wait_for_operation_activation(object, op, + NULL, NULL, NULL); + if (ret == 0) { + /* ask the cache to honour the operation */ + ret = object->cache->ops->check_consistency(op); + fscache_op_complete(op, false); + } else if (ret == -ENOBUFS) { + ret = 0; + } + + fscache_put_operation(op); + _leave(" = %d", ret); + return ret; + +submit_failed: + atomic_dec(&cookie->n_active); +inconsistent: + spin_unlock(&cookie->lock); + kfree(op); + _leave(" = -ESTALE"); + return -ESTALE; +} +EXPORT_SYMBOL(__fscache_check_consistency); diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h index 12d505b..4226f66 100644 --- a/fs/fscache/internal.h +++ b/fs/fscache/internal.h @@ -130,6 +130,12 @@ extern void fscache_operation_gc(struct work_struct *); /* * page.c */ +extern int fscache_wait_for_deferred_lookup(struct fscache_cookie *); +extern int fscache_wait_for_operation_activation(struct fscache_object *, + struct fscache_operation *, + atomic_t *, + atomic_t *, + void (*)(struct fscache_operation *)); extern void fscache_invalidate_writes(struct fscache_cookie *); /* diff --git a/fs/fscache/page.c b/fs/fscache/page.c index d479ab3..793e3d5 100644 --- a/fs/fscache/page.c +++ b/fs/fscache/page.c @@ -278,7 +278,7 @@ static struct fscache_retrieval *fscache_alloc_retrieval( /* * wait for a deferred lookup to complete */ -static int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie) +int fscache_wait_for_deferred_lookup(struct fscache_cookie *cookie) { unsigned long jif; @@ -322,42 +322,46 @@ static void fscache_do_cancel_retrieval(struct fscache_operation *_op) /* * wait for an object to become active (or dead) */ -static int fscache_wait_for_retrieval_activation(struct fscache_object *object, - struct fscache_retrieval *op, - atomic_t *stat_op_waits, - atomic_t *stat_object_dead) +int fscache_wait_for_operation_activation(struct fscache_object *object, + struct fscache_operation *op, + atomic_t *stat_op_waits, + atomic_t *stat_object_dead, + void (*do_cancel)(struct fscache_operation *)) { int ret; - if (!test_bit(FSCACHE_OP_WAITING, &op->op.flags)) + if (!test_bit(FSCACHE_OP_WAITING, &op->flags)) goto check_if_dead; _debug(">>> WT"); - fscache_stat(stat_op_waits); - if (wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, + if (stat_op_waits) + fscache_stat(stat_op_waits); + if (wait_on_bit(&op->flags, FSCACHE_OP_WAITING, fscache_wait_bit_interruptible, TASK_INTERRUPTIBLE) != 0) { - ret = fscache_cancel_op(&op->op, fscache_do_cancel_retrieval); + ret = fscache_cancel_op(op, do_cancel); if (ret == 0) return -ERESTARTSYS; /* it's been removed from the pending queue by another party, * so we should get to run shortly */ - wait_on_bit(&op->op.flags, FSCACHE_OP_WAITING, + wait_on_bit(&op->flags, FSCACHE_OP_WAITING, fscache_wait_bit, TASK_UNINTERRUPTIBLE); } _debug("<<< GO"); check_if_dead: - if (op->op.state == FSCACHE_OP_ST_CANCELLED) { - fscache_stat(stat_object_dead); + if (op->state == FSCACHE_OP_ST_CANCELLED) { + if (stat_object_dead) + fscache_stat(stat_object_dead); _leave(" = -ENOBUFS [cancelled]"); return -ENOBUFS; } if (unlikely(fscache_object_is_dead(object))) { - pr_err("%s() = -ENOBUFS [obj dead %d]\n", __func__, op->op.state); - fscache_cancel_op(&op->op, fscache_do_cancel_retrieval); - fscache_stat(stat_object_dead); + pr_err("%s() = -ENOBUFS [obj dead %d]\n", __func__, op->state); + fscache_cancel_op(op, do_cancel); + if (stat_object_dead) + fscache_stat(stat_object_dead); return -ENOBUFS; } return 0; @@ -432,10 +436,11 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie, /* we wait for the operation to become active, and then process it * *here*, in this thread, and not in the thread pool */ - ret = fscache_wait_for_retrieval_activation( - object, op, + ret = fscache_wait_for_operation_activation( + object, &op->op, __fscache_stat(&fscache_n_retrieval_op_waits), - __fscache_stat(&fscache_n_retrievals_object_dead)); + __fscache_stat(&fscache_n_retrievals_object_dead), + fscache_do_cancel_retrieval); if (ret < 0) goto error; @@ -557,10 +562,11 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie, /* we wait for the operation to become active, and then process it * *here*, in this thread, and not in the thread pool */ - ret = fscache_wait_for_retrieval_activation( - object, op, + ret = fscache_wait_for_operation_activation( + object, &op->op, __fscache_stat(&fscache_n_retrieval_op_waits), - __fscache_stat(&fscache_n_retrievals_object_dead)); + __fscache_stat(&fscache_n_retrievals_object_dead), + fscache_do_cancel_retrieval); if (ret < 0) goto error; @@ -658,10 +664,11 @@ int __fscache_alloc_page(struct fscache_cookie *cookie, fscache_stat(&fscache_n_alloc_ops); - ret = fscache_wait_for_retrieval_activation( - object, op, + ret = fscache_wait_for_operation_activation( + object, &op->op, __fscache_stat(&fscache_n_alloc_op_waits), - __fscache_stat(&fscache_n_allocs_object_dead)); + __fscache_stat(&fscache_n_allocs_object_dead), + fscache_do_cancel_retrieval); if (ret < 0) goto error; diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h index a9ff9a3..7823e9e 100644 --- a/include/linux/fscache-cache.h +++ b/include/linux/fscache-cache.h @@ -251,6 +251,10 @@ struct fscache_cache_ops { /* unpin an object in the cache */ void (*unpin_object)(struct fscache_object *object); + /* check the consistency between the backing cache and the FS-Cache + * cookie */ + bool (*check_consistency)(struct fscache_operation *op); + /* store the updated auxiliary data on an object */ void (*update_object)(struct fscache_object *object); diff --git a/include/linux/fscache.h b/include/linux/fscache.h index 7a08623..d984aff 100644 --- a/include/linux/fscache.h +++ b/include/linux/fscache.h @@ -183,6 +183,7 @@ extern struct fscache_cookie *__fscache_acquire_cookie( const struct fscache_cookie_def *, void *); extern void __fscache_relinquish_cookie(struct fscache_cookie *, int); +extern int __fscache_check_consistency(struct fscache_cookie *); extern void __fscache_update_cookie(struct fscache_cookie *); extern int __fscache_attr_changed(struct fscache_cookie *); extern void __fscache_invalidate(struct fscache_cookie *); @@ -326,6 +327,25 @@ void fscache_relinquish_cookie(struct fscache_cookie *cookie, int retire) } /** + * fscache_check_consistency - Request that if the cache is updated + * @cookie: The cookie representing the cache object + * + * Request an consistency check from fscache, which passes the request + * to the backing cache. + * + * Returns 0 if consistent and -ESTALE if inconsistent. May also + * return -ENOMEM and -ERESTARTSYS. + */ +static inline +int fscache_check_consistency(struct fscache_cookie *cookie) +{ + if (fscache_cookie_valid(cookie)) + return __fscache_check_consistency(cookie); + else + return 0; +} + +/** * fscache_update_cookie - Request that a cache object be updated * @cookie: The cookie representing the cache object * |
