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authorLinus Torvalds <torvalds@linux-foundation.org>2013-07-02 09:52:47 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-02 09:52:47 -0700
commitbcd7351e83728859833e3c5b8aae9a2816914e4b (patch)
tree940487a8b04f6ec79212836954d9c1389a9d80ed /include
parent6072a93b98e660211c4b46a8381833425bdcf7b7 (diff)
parentdcfae32f892f03dee9896b19d1960c1ecd3f0583 (diff)
Merge tag 'fscache-20130702' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs
Pull FS-Cache updates from David Howells: "This contains a number of fixes for various FS-Cache issues plus some cleanups. The commits are, in order: 1) Provide a system wait_on_atomic_t() and wake_up_atomic_t() sharing the bit-wait table (enhancement for #8). 2) Don't put spin_lock() in a while-condition as spin_lock() may have a do {} while(0) wrapper (cleanup). 3) Symbolically name i_mutex lock classes rather than using numbers in CacheFiles (cleanup). 4) Don't sleep in page release if __GFP_FS is not set (deadlock vs ext4). 5) Uninline fscache_object_init() (cleanup for #7). 6) Wrap checks on object state (cleanup for #7). 7) Simplify the object state machine by separating work states from wait states. 8) Simplify cookie retention by objects (NULL pointer deref fix). 9) Remove unused list_to_page() macro (cleanup). 10) Make the remaining-pages counter in the retrieval op atomic (assertion failure fix). 11) Don't use spin_is_locked() in assertions (assertion failure fix)" * tag 'fscache-20130702' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs: FS-Cache: Don't use spin_is_locked() in assertions FS-Cache: The retrieval remaining-pages counter needs to be atomic_t cachefiles: remove unused macro list_to_page() FS-Cache: Simplify cookie retention for fscache_objects, fixing oops FS-Cache: Fix object state machine to have separate work and wait states FS-Cache: Wrap checks on object state FS-Cache: Uninline fscache_object_init() FS-Cache: Don't sleep in page release if __GFP_FS is not set CacheFiles: name i_mutex lock class explicitly fs/fscache: remove spin_lock() from the condition in while() Add wait_on_atomic_t() and wake_up_atomic_t()
Diffstat (limited to 'include')
-rw-r--r--include/linux/fscache-cache.h175
-rw-r--r--include/linux/wait.h24
2 files changed, 113 insertions, 86 deletions
diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index 5dfa0aa216b6..a9ff9a36b86d 100644
--- a/include/linux/fscache-cache.h
+++ b/include/linux/fscache-cache.h
@@ -97,7 +97,8 @@ struct fscache_operation {
#define FSCACHE_OP_WAITING 4 /* cleared when op is woken */
#define FSCACHE_OP_EXCLUSIVE 5 /* exclusive op, other ops must wait */
#define FSCACHE_OP_DEC_READ_CNT 6 /* decrement object->n_reads on destruction */
-#define FSCACHE_OP_KEEP_FLAGS 0x0070 /* flags to keep when repurposing an op */
+#define FSCACHE_OP_UNUSE_COOKIE 7 /* call fscache_unuse_cookie() on completion */
+#define FSCACHE_OP_KEEP_FLAGS 0x00f0 /* flags to keep when repurposing an op */
enum fscache_operation_state state;
atomic_t usage;
@@ -150,7 +151,7 @@ struct fscache_retrieval {
void *context; /* netfs read context (pinned) */
struct list_head to_do; /* list of things to be done by the backend */
unsigned long start_time; /* time at which retrieval started */
- unsigned n_pages; /* number of pages to be retrieved */
+ atomic_t n_pages; /* number of pages to be retrieved */
};
typedef int (*fscache_page_retrieval_func_t)(struct fscache_retrieval *op,
@@ -194,15 +195,14 @@ static inline void fscache_enqueue_retrieval(struct fscache_retrieval *op)
static inline void fscache_retrieval_complete(struct fscache_retrieval *op,
int n_pages)
{
- op->n_pages -= n_pages;
- if (op->n_pages <= 0)
+ atomic_sub(n_pages, &op->n_pages);
+ if (atomic_read(&op->n_pages) <= 0)
fscache_op_complete(&op->op, true);
}
/**
* fscache_put_retrieval - Drop a reference to a retrieval operation
* @op: The retrieval operation affected
- * @n_pages: The number of pages to account for
*
* Drop a reference to a retrieval operation.
*/
@@ -314,6 +314,7 @@ struct fscache_cache_ops {
struct fscache_cookie {
atomic_t usage; /* number of users of this cookie */
atomic_t n_children; /* number of children of this cookie */
+ atomic_t n_active; /* number of active users of netfs ptrs */
spinlock_t lock;
spinlock_t stores_lock; /* lock on page store tree */
struct hlist_head backing_objects; /* object(s) backing this file/index */
@@ -326,13 +327,11 @@ struct fscache_cookie {
unsigned long flags;
#define FSCACHE_COOKIE_LOOKING_UP 0 /* T if non-index cookie being looked up still */
-#define FSCACHE_COOKIE_CREATING 1 /* T if non-index object being created still */
-#define FSCACHE_COOKIE_NO_DATA_YET 2 /* T if new object with no cached data yet */
-#define FSCACHE_COOKIE_PENDING_FILL 3 /* T if pending initial fill on object */
-#define FSCACHE_COOKIE_FILLING 4 /* T if filling object incrementally */
-#define FSCACHE_COOKIE_UNAVAILABLE 5 /* T if cookie is unavailable (error, etc) */
-#define FSCACHE_COOKIE_WAITING_ON_READS 6 /* T if cookie is waiting on reads */
-#define FSCACHE_COOKIE_INVALIDATING 7 /* T if cookie is being invalidated */
+#define FSCACHE_COOKIE_NO_DATA_YET 1 /* T if new object with no cached data yet */
+#define FSCACHE_COOKIE_UNAVAILABLE 2 /* T if cookie is unavailable (error, etc) */
+#define FSCACHE_COOKIE_INVALIDATING 3 /* T if cookie is being invalidated */
+#define FSCACHE_COOKIE_RELINQUISHED 4 /* T if cookie has been relinquished */
+#define FSCACHE_COOKIE_RETIRED 5 /* T if cookie was retired */
};
extern struct fscache_cookie fscache_fsdef_index;
@@ -341,45 +340,40 @@ extern struct fscache_cookie fscache_fsdef_index;
* Event list for fscache_object::{event_mask,events}
*/
enum {
- FSCACHE_OBJECT_EV_REQUEUE, /* T if object should be requeued */
+ FSCACHE_OBJECT_EV_NEW_CHILD, /* T if object has a new child */
+ FSCACHE_OBJECT_EV_PARENT_READY, /* T if object's parent is ready */
FSCACHE_OBJECT_EV_UPDATE, /* T if object should be updated */
FSCACHE_OBJECT_EV_INVALIDATE, /* T if cache requested object invalidation */
FSCACHE_OBJECT_EV_CLEARED, /* T if accessors all gone */
FSCACHE_OBJECT_EV_ERROR, /* T if fatal error occurred during processing */
- FSCACHE_OBJECT_EV_RELEASE, /* T if netfs requested object release */
- FSCACHE_OBJECT_EV_RETIRE, /* T if netfs requested object retirement */
- FSCACHE_OBJECT_EV_WITHDRAW, /* T if cache requested object withdrawal */
+ FSCACHE_OBJECT_EV_KILL, /* T if netfs relinquished or cache withdrew object */
NR_FSCACHE_OBJECT_EVENTS
};
#define FSCACHE_OBJECT_EVENTS_MASK ((1UL << NR_FSCACHE_OBJECT_EVENTS) - 1)
/*
+ * States for object state machine.
+ */
+struct fscache_transition {
+ unsigned long events;
+ const struct fscache_state *transit_to;
+};
+
+struct fscache_state {
+ char name[24];
+ char short_name[8];
+ const struct fscache_state *(*work)(struct fscache_object *object,
+ int event);
+ const struct fscache_transition transitions[];
+};
+
+/*
* on-disk cache file or index handle
*/
struct fscache_object {
- enum fscache_object_state {
- FSCACHE_OBJECT_INIT, /* object in initial unbound state */
- FSCACHE_OBJECT_LOOKING_UP, /* looking up object */
- FSCACHE_OBJECT_CREATING, /* creating object */
-
- /* active states */
- FSCACHE_OBJECT_AVAILABLE, /* cleaning up object after creation */
- FSCACHE_OBJECT_ACTIVE, /* object is usable */
- FSCACHE_OBJECT_INVALIDATING, /* object is invalidating */
- FSCACHE_OBJECT_UPDATING, /* object is updating */
-
- /* terminal states */
- FSCACHE_OBJECT_DYING, /* object waiting for accessors to finish */
- FSCACHE_OBJECT_LC_DYING, /* object cleaning up after lookup/create */
- FSCACHE_OBJECT_ABORT_INIT, /* abort the init state */
- FSCACHE_OBJECT_RELEASING, /* releasing object */
- FSCACHE_OBJECT_RECYCLING, /* retiring object */
- FSCACHE_OBJECT_WITHDRAWING, /* withdrawing object */
- FSCACHE_OBJECT_DEAD, /* object is now dead */
- FSCACHE_OBJECT__NSTATES
- } state;
-
+ const struct fscache_state *state; /* Object state machine state */
+ const struct fscache_transition *oob_table; /* OOB state transition table */
int debug_id; /* debugging ID */
int n_children; /* number of child objects */
int n_ops; /* number of extant ops on object */
@@ -390,6 +384,7 @@ struct fscache_object {
spinlock_t lock; /* state and operations lock */
unsigned long lookup_jif; /* time at which lookup started */
+ unsigned long oob_event_mask; /* OOB events this object is interested in */
unsigned long event_mask; /* events this object is interested in */
unsigned long events; /* events to be processed by this object
* (order is important - using fls) */
@@ -398,6 +393,9 @@ struct fscache_object {
#define FSCACHE_OBJECT_LOCK 0 /* T if object is busy being processed */
#define FSCACHE_OBJECT_PENDING_WRITE 1 /* T if object has pending write */
#define FSCACHE_OBJECT_WAITING 2 /* T if object is waiting on its parent */
+#define FSCACHE_OBJECT_IS_LIVE 3 /* T if object is not withdrawn or relinquished */
+#define FSCACHE_OBJECT_IS_LOOKED_UP 4 /* T if object has been looked up */
+#define FSCACHE_OBJECT_IS_AVAILABLE 5 /* T if object has become active */
struct list_head cache_link; /* link in cache->object_list */
struct hlist_node cookie_link; /* link in cookie->backing_objects */
@@ -415,62 +413,40 @@ struct fscache_object {
loff_t store_limit_l; /* current storage limit */
};
-extern const char *fscache_object_states[];
+extern void fscache_object_init(struct fscache_object *, struct fscache_cookie *,
+ struct fscache_cache *);
+extern void fscache_object_destroy(struct fscache_object *);
-#define fscache_object_is_active(obj) \
- (!test_bit(FSCACHE_IOERROR, &(obj)->cache->flags) && \
- (obj)->state >= FSCACHE_OBJECT_AVAILABLE && \
- (obj)->state < FSCACHE_OBJECT_DYING)
+extern void fscache_object_lookup_negative(struct fscache_object *object);
+extern void fscache_obtained_object(struct fscache_object *object);
-#define fscache_object_is_dead(obj) \
- (test_bit(FSCACHE_IOERROR, &(obj)->cache->flags) && \
- (obj)->state >= FSCACHE_OBJECT_DYING)
+static inline bool fscache_object_is_live(struct fscache_object *object)
+{
+ return test_bit(FSCACHE_OBJECT_IS_LIVE, &object->flags);
+}
-extern void fscache_object_work_func(struct work_struct *work);
+static inline bool fscache_object_is_dying(struct fscache_object *object)
+{
+ return !fscache_object_is_live(object);
+}
-/**
- * fscache_object_init - Initialise a cache object description
- * @object: Object description
- *
- * Initialise a cache object description to its basic values.
- *
- * See Documentation/filesystems/caching/backend-api.txt for a complete
- * description.
- */
-static inline
-void fscache_object_init(struct fscache_object *object,
- struct fscache_cookie *cookie,
- struct fscache_cache *cache)
+static inline bool fscache_object_is_available(struct fscache_object *object)
{
- atomic_inc(&cache->object_count);
-
- object->state = FSCACHE_OBJECT_INIT;
- spin_lock_init(&object->lock);
- INIT_LIST_HEAD(&object->cache_link);
- INIT_HLIST_NODE(&object->cookie_link);
- INIT_WORK(&object->work, fscache_object_work_func);
- INIT_LIST_HEAD(&object->dependents);
- INIT_LIST_HEAD(&object->dep_link);
- INIT_LIST_HEAD(&object->pending_ops);
- object->n_children = 0;
- object->n_ops = object->n_in_progress = object->n_exclusive = 0;
- object->events = object->event_mask = 0;
- object->flags = 0;
- object->store_limit = 0;
- object->store_limit_l = 0;
- object->cache = cache;
- object->cookie = cookie;
- object->parent = NULL;
+ return test_bit(FSCACHE_OBJECT_IS_AVAILABLE, &object->flags);
}
-extern void fscache_object_lookup_negative(struct fscache_object *object);
-extern void fscache_obtained_object(struct fscache_object *object);
+static inline bool fscache_object_is_active(struct fscache_object *object)
+{
+ return fscache_object_is_available(object) &&
+ fscache_object_is_live(object) &&
+ !test_bit(FSCACHE_IOERROR, &object->cache->flags);
+}
-#ifdef CONFIG_FSCACHE_OBJECT_LIST
-extern void fscache_object_destroy(struct fscache_object *object);
-#else
-#define fscache_object_destroy(object) do {} while(0)
-#endif
+static inline bool fscache_object_is_dead(struct fscache_object *object)
+{
+ return fscache_object_is_dying(object) &&
+ test_bit(FSCACHE_IOERROR, &object->cache->flags);
+}
/**
* fscache_object_destroyed - Note destruction of an object in a cache
@@ -531,6 +507,33 @@ static inline void fscache_end_io(struct fscache_retrieval *op,
op->end_io_func(page, op->context, error);
}
+/**
+ * fscache_use_cookie - Request usage of cookie attached to an object
+ * @object: Object description
+ *
+ * Request usage of the cookie attached to an object. NULL is returned if the
+ * relinquishment had reduced the cookie usage count to 0.
+ */
+static inline bool fscache_use_cookie(struct fscache_object *object)
+{
+ struct fscache_cookie *cookie = object->cookie;
+ return atomic_inc_not_zero(&cookie->n_active) != 0;
+}
+
+/**
+ * fscache_unuse_cookie - Cease usage of cookie attached to an object
+ * @object: Object description
+ *
+ * Cease usage of the cookie attached to an object. When the users count
+ * reaches zero then the cookie relinquishment will be permitted to proceed.
+ */
+static inline void fscache_unuse_cookie(struct fscache_object *object)
+{
+ struct fscache_cookie *cookie = object->cookie;
+ if (atomic_dec_and_test(&cookie->n_active))
+ wake_up_atomic_t(&cookie->n_active);
+}
+
/*
* out-of-line cache backend functions
*/
diff --git a/include/linux/wait.h b/include/linux/wait.h
index 1133695eb067..f487a4750b7f 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -23,6 +23,7 @@ struct __wait_queue {
struct wait_bit_key {
void *flags;
int bit_nr;
+#define WAIT_ATOMIC_T_BIT_NR -1
};
struct wait_bit_queue {
@@ -60,6 +61,9 @@ struct task_struct;
#define __WAIT_BIT_KEY_INITIALIZER(word, bit) \
{ .flags = word, .bit_nr = bit, }
+#define __WAIT_ATOMIC_T_KEY_INITIALIZER(p) \
+ { .flags = p, .bit_nr = WAIT_ATOMIC_T_BIT_NR, }
+
extern void __init_waitqueue_head(wait_queue_head_t *q, const char *name, struct lock_class_key *);
#define init_waitqueue_head(q) \
@@ -146,8 +150,10 @@ void __wake_up_bit(wait_queue_head_t *, void *, int);
int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, int (*)(void *), unsigned);
void wake_up_bit(void *, int);
+void wake_up_atomic_t(atomic_t *);
int out_of_line_wait_on_bit(void *, int, int (*)(void *), unsigned);
int out_of_line_wait_on_bit_lock(void *, int, int (*)(void *), unsigned);
+int out_of_line_wait_on_atomic_t(atomic_t *, int (*)(atomic_t *), unsigned);
wait_queue_head_t *bit_waitqueue(void *, int);
#define wake_up(x) __wake_up(x, TASK_NORMAL, 1, NULL)
@@ -902,5 +908,23 @@ static inline int wait_on_bit_lock(void *word, int bit,
return 0;
return out_of_line_wait_on_bit_lock(word, bit, action, mode);
}
+
+/**
+ * wait_on_atomic_t - Wait for an atomic_t to become 0
+ * @val: The atomic value being waited on, a kernel virtual address
+ * @action: the function used to sleep, which may take special actions
+ * @mode: the task state to sleep in
+ *
+ * Wait for an atomic_t to become 0. We abuse the bit-wait waitqueue table for
+ * the purpose of getting a waitqueue, but we set the key to a bit number
+ * outside of the target 'word'.
+ */
+static inline
+int wait_on_atomic_t(atomic_t *val, int (*action)(atomic_t *), unsigned mode)
+{
+ if (atomic_read(val) == 0)
+ return 0;
+ return out_of_line_wait_on_atomic_t(val, action, mode);
+}
#endif