3 files changed, 135 insertions, 4 deletions

diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index 84d3532dd3ea..7be0c6fbe880 100644
--- a/include/linux/fscache-cache.h
+++ b/include/linux/fscache-cache.h
@@ -91,6 +91,8 @@ 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_DEAD         6       /* op is now dead */
+#define FSCACHE_OP_DEC_READ_CNT 7       /* decrement object->n_reads on destruction */
+#define FSCACHE_OP_KEEP_FLAGS   0xc0    /* flags to keep when repurposing an op */
 
         atomic_t                usage;
         unsigned                debug_id;       /* debugging ID */
@@ -102,6 +104,16 @@ struct fscache_operation {
 
         /* operation releaser */
         fscache_operation_release_t release;
+
+#ifdef CONFIG_SLOW_WORK_PROC
+        const char *name;               /* operation name */
+        const char *state;              /* operation state */
+#define fscache_set_op_name(OP, N)      do { (OP)->name  = (N); } while(0)
+#define fscache_set_op_state(OP, S)     do { (OP)->state = (S); } while(0)
+#else
+#define fscache_set_op_name(OP, N)      do { } while(0)
+#define fscache_set_op_state(OP, S)     do { } while(0)
+#endif
 };
 
 extern atomic_t fscache_op_debug_id;
@@ -125,6 +137,7 @@ static inline void fscache_operation_init(struct fscache_operation *op,
         op->debug_id = atomic_inc_return(&fscache_op_debug_id);
         op->release = release;
         INIT_LIST_HEAD(&op->pend_link);
+        fscache_set_op_state(op, "Init");
 }
 
 /**
@@ -221,8 +234,10 @@ struct fscache_cache_ops {
         struct fscache_object *(*alloc_object)(struct fscache_cache *cache,
                                                struct fscache_cookie *cookie);
 
-        /* look up the object for a cookie */
-        void (*lookup_object)(struct fscache_object *object);
+        /* look up the object for a cookie
+         * - return -ETIMEDOUT to be requeued
+         */
+        int (*lookup_object)(struct fscache_object *object);
 
         /* finished looking up */
         void (*lookup_complete)(struct fscache_object *object);
@@ -297,12 +312,14 @@ struct fscache_cookie {
         atomic_t                        usage;          /* number of users of this cookie */
         atomic_t                        n_children;     /* number of children of this cookie */
         spinlock_t                      lock;
+        spinlock_t                      stores_lock;    /* lock on page store tree */
         struct hlist_head               backing_objects; /* object(s) backing this file/index */
         const struct fscache_cookie_def *def;           /* definition */
         struct fscache_cookie           *parent;        /* parent of this entry */
         void                            *netfs_data;    /* back pointer to netfs */
         struct radix_tree_root          stores;         /* pages to be stored on this cookie */
 #define FSCACHE_COOKIE_PENDING_TAG      0               /* pages tag: pending write to cache */
+#define FSCACHE_COOKIE_STORING_TAG      1               /* pages tag: writing to cache */
 
         unsigned long                   flags;
 #define FSCACHE_COOKIE_LOOKING_UP       0       /* T if non-index cookie being looked up still */
@@ -337,6 +354,7 @@ struct fscache_object {
                 FSCACHE_OBJECT_RECYCLING,       /* retiring object */
                 FSCACHE_OBJECT_WITHDRAWING,     /* withdrawing object */
                 FSCACHE_OBJECT_DEAD,            /* object is now dead */
+                FSCACHE_OBJECT__NSTATES
         } state;
 
         int                     debug_id;       /* debugging ID */
@@ -345,6 +363,7 @@ struct fscache_object {
         int                     n_obj_ops;      /* number of object ops outstanding on object */
         int                     n_in_progress;  /* number of ops in progress */
         int                     n_exclusive;    /* number of exclusive ops queued */
+        atomic_t                n_reads;        /* number of read ops in progress */
         spinlock_t              lock;           /* state and operations lock */
 
         unsigned long           lookup_jif;     /* time at which lookup started */
@@ -358,6 +377,7 @@ struct fscache_object {
 #define FSCACHE_OBJECT_EV_RELEASE       4       /* T if netfs requested object release */
 #define FSCACHE_OBJECT_EV_RETIRE        5       /* T if netfs requested object retirement */
 #define FSCACHE_OBJECT_EV_WITHDRAW      6       /* T if cache requested object withdrawal */
+#define FSCACHE_OBJECT_EVENTS_MASK      0x7f    /* mask of all events*/
 
         unsigned long           flags;
 #define FSCACHE_OBJECT_LOCK             0       /* T if object is busy being processed */
@@ -373,7 +393,11 @@ struct fscache_object {
         struct list_head        dependents;     /* FIFO of dependent objects */
         struct list_head        dep_link;       /* link in parent's dependents list */
         struct list_head        pending_ops;    /* unstarted operations on this object */
+#ifdef CONFIG_FSCACHE_OBJECT_LIST
+        struct rb_node          objlist_link;   /* link in global object list */
+#endif
         pgoff_t                 store_limit;    /* current storage limit */
+        loff_t                  store_limit_l;  /* current storage limit */
 };
 
 extern const char *fscache_object_states[];
@@ -383,6 +407,10 @@ extern const char *fscache_object_states[];
          (obj)->state >= FSCACHE_OBJECT_AVAILABLE &&          \
          (obj)->state < FSCACHE_OBJECT_DYING)
 
+#define fscache_object_is_dead(obj)                             \
+        (test_bit(FSCACHE_IOERROR, &(obj)->cache->flags) &&     \
+         (obj)->state >= FSCACHE_OBJECT_DYING)
+
 extern const struct slow_work_ops fscache_object_slow_work_ops;
 
 /**
@@ -414,6 +442,7 @@ void fscache_object_init(struct fscache_object *object,
         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;
@@ -422,6 +451,12 @@ void fscache_object_init(struct fscache_object *object,
 extern void fscache_object_lookup_negative(struct fscache_object *object);
 extern void fscache_obtained_object(struct fscache_object *object);
 
+#ifdef CONFIG_FSCACHE_OBJECT_LIST
+extern void fscache_object_destroy(struct fscache_object *object);
+#else
+#define fscache_object_destroy(object) do {} while(0)
+#endif
+
 /**
  * fscache_object_destroyed - Note destruction of an object in a cache
  * @cache: The cache from which the object came
@@ -460,6 +495,7 @@ static inline void fscache_object_lookup_error(struct fscache_object *object)
 static inline
 void fscache_set_store_limit(struct fscache_object *object, loff_t i_size)
 {
+        object->store_limit_l = i_size;
         object->store_limit = i_size >> PAGE_SHIFT;
         if (i_size & ~PAGE_MASK)
                 object->store_limit++;
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index 6d8ee466e0a0..595ce49288b7 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -202,6 +202,8 @@ extern int __fscache_write_page(struct fscache_cookie *, struct page *, gfp_t);
 extern void __fscache_uncache_page(struct fscache_cookie *, struct page *);
 extern bool __fscache_check_page_write(struct fscache_cookie *, struct page *);
 extern void __fscache_wait_on_page_write(struct fscache_cookie *, struct page *);
+extern bool __fscache_maybe_release_page(struct fscache_cookie *, struct page *,
+                                         gfp_t);
 
 /**
  * fscache_register_netfs - Register a filesystem as desiring caching services
@@ -615,4 +617,29 @@ void fscache_wait_on_page_write(struct fscache_cookie *cookie,
                 __fscache_wait_on_page_write(cookie, page);
 }
 
+/**
+ * fscache_maybe_release_page - Consider releasing a page, cancelling a store
+ * @cookie: The cookie representing the cache object
+ * @page: The netfs page that is being cached.
+ * @gfp: The gfp flags passed to releasepage()
+ *
+ * Consider releasing a page for the vmscan algorithm, on behalf of the netfs's
+ * releasepage() call.  A storage request on the page may cancelled if it is
+ * not currently being processed.
+ *
+ * The function returns true if the page no longer has a storage request on it,
+ * and false if a storage request is left in place.  If true is returned, the
+ * page will have been passed to fscache_uncache_page().  If false is returned
+ * the page cannot be freed yet.
+ */
+static inline
+bool fscache_maybe_release_page(struct fscache_cookie *cookie,
+                                struct page *page,
+                                gfp_t gfp)
+{
+        if (fscache_cookie_valid(cookie) && PageFsCache(page))
+                return __fscache_maybe_release_page(cookie, page, gfp);
+        return false;
+}
+
 #endif /* _LINUX_FSCACHE_H */
diff --git a/include/linux/slow-work.h b/include/linux/slow-work.h
index b65c8881f07a..5035a2691739 100644
--- a/include/linux/slow-work.h
+++ b/include/linux/slow-work.h
@@ -17,13 +17,20 @@
 #ifdef CONFIG_SLOW_WORK
 
 #include <linux/sysctl.h>
+#include <linux/timer.h>
 
 struct slow_work;
+#ifdef CONFIG_SLOW_WORK_PROC
+struct seq_file;
+#endif
 
 /*
  * The operations used to support slow work items
  */
 struct slow_work_ops {
+        /* owner */
+        struct module *owner;
+
         /* get a ref on a work item
          * - return 0 if successful, -ve if not
          */
@@ -34,6 +41,11 @@ struct slow_work_ops {
 
         /* execute a work item */
         void (*execute)(struct slow_work *work);
+
+#ifdef CONFIG_SLOW_WORK_PROC
+        /* describe a work item for /proc */
+        void (*desc)(struct slow_work *work, struct seq_file *m);
+#endif
 };
 
 /*
@@ -42,13 +54,24 @@ struct slow_work_ops {
  *   queued
  */
 struct slow_work {
+        struct module           *owner; /* the owning module */
         unsigned long           flags;
 #define SLOW_WORK_PENDING       0       /* item pending (further) execution */
 #define SLOW_WORK_EXECUTING     1       /* item currently executing */
 #define SLOW_WORK_ENQ_DEFERRED  2       /* item enqueue deferred */
 #define SLOW_WORK_VERY_SLOW     3       /* item is very slow */
+#define SLOW_WORK_CANCELLING    4       /* item is being cancelled, don't enqueue */
+#define SLOW_WORK_DELAYED       5       /* item is struct delayed_slow_work with active timer */
         const struct slow_work_ops *ops; /* operations table for this item */
         struct list_head        link;   /* link in queue */
+#ifdef CONFIG_SLOW_WORK_PROC
+        struct timespec         mark;   /* jiffies at which queued or exec begun */
+#endif
+};
+
+struct delayed_slow_work {
+        struct slow_work        work;
+        struct timer_list       timer;
 };
 
 /**
@@ -67,6 +90,20 @@ static inline void slow_work_init(struct slow_work *work,
 }
 
 /**
+ * slow_work_init - Initialise a delayed slow work item
+ * @work: The work item to initialise
+ * @ops: The operations to use to handle the slow work item
+ *
+ * Initialise a delayed slow work item.
+ */
+static inline void delayed_slow_work_init(struct delayed_slow_work *dwork,
+                                          const struct slow_work_ops *ops)
+{
+        init_timer(&dwork->timer);
+        slow_work_init(&dwork->work, ops);
+}
+
+/**
  * vslow_work_init - Initialise a very slow work item
  * @work: The work item to initialise
  * @ops: The operations to use to handle the slow work item
@@ -83,9 +120,40 @@ static inline void vslow_work_init(struct slow_work *work,
         INIT_LIST_HEAD(&work->link);
 }
 
+/**
+ * slow_work_is_queued - Determine if a slow work item is on the work queue
+ * work: The work item to test
+ *
+ * Determine if the specified slow-work item is on the work queue.  This
+ * returns true if it is actually on the queue.
+ *
+ * If the item is executing and has been marked for requeue when execution
+ * finishes, then false will be returned.
+ *
+ * Anyone wishing to wait for completion of execution can wait on the
+ * SLOW_WORK_EXECUTING bit.
+ */
+static inline bool slow_work_is_queued(struct slow_work *work)
+{
+        unsigned long flags = work->flags;
+        return flags & SLOW_WORK_PENDING && !(flags & SLOW_WORK_EXECUTING);
+}
+
 extern int slow_work_enqueue(struct slow_work *work);
-extern int slow_work_register_user(void);
-extern void slow_work_unregister_user(void);
+extern void slow_work_cancel(struct slow_work *work);
+extern int slow_work_register_user(struct module *owner);
+extern void slow_work_unregister_user(struct module *owner);
+
+extern int delayed_slow_work_enqueue(struct delayed_slow_work *dwork,
+                                     unsigned long delay);
+
+static inline void delayed_slow_work_cancel(struct delayed_slow_work *dwork)
+{
+        slow_work_cancel(&dwork->work);
+}
+
+extern bool slow_work_sleep_till_thread_needed(struct slow_work *work,
+                                               signed long *_timeout);
 
 #ifdef CONFIG_SYSCTL
 extern ctl_table slow_work_sysctls[];