1 files changed, 92 insertions, 28 deletions

diff --git a/fs/fscache/operation.c b/fs/fscache/operation.c
index e7f8d53b8b6b..313e79a14266 100644
--- a/fs/fscache/operation.c
+++ b/fs/fscache/operation.c
@@ -13,6 +13,7 @@
 
 #define FSCACHE_DEBUG_LEVEL OPERATION
 #include <linux/module.h>
+#include <linux/seq_file.h>
 #include "internal.h"
 
 atomic_t fscache_op_debug_id;
@@ -31,32 +32,33 @@ void fscache_enqueue_operation(struct fscache_operation *op)
         _enter("{OBJ%x OP%x,%u}",
                op->object->debug_id, op->debug_id, atomic_read(&op->usage));
 
+        fscache_set_op_state(op, "EnQ");
+
+        ASSERT(list_empty(&op->pend_link));
         ASSERT(op->processor != NULL);
         ASSERTCMP(op->object->state, >=, FSCACHE_OBJECT_AVAILABLE);
         ASSERTCMP(atomic_read(&op->usage), >, 0);
 
-        if (list_empty(&op->pend_link)) {
-                switch (op->flags & FSCACHE_OP_TYPE) {
-                case FSCACHE_OP_FAST:
-                        _debug("queue fast");
-                        atomic_inc(&op->usage);
-                        if (!schedule_work(&op->fast_work))
-                                fscache_put_operation(op);
-                        break;
-                case FSCACHE_OP_SLOW:
-                        _debug("queue slow");
-                        slow_work_enqueue(&op->slow_work);
-                        break;
-                case FSCACHE_OP_MYTHREAD:
-                        _debug("queue for caller's attention");
-                        break;
-                default:
-                        printk(KERN_ERR "FS-Cache: Unexpected op type %lx",
-                               op->flags);
-                        BUG();
-                        break;
-                }
-                fscache_stat(&fscache_n_op_enqueue);
+        fscache_stat(&fscache_n_op_enqueue);
+        switch (op->flags & FSCACHE_OP_TYPE) {
+        case FSCACHE_OP_FAST:
+                _debug("queue fast");
+                atomic_inc(&op->usage);
+                if (!schedule_work(&op->fast_work))
+                        fscache_put_operation(op);
+                break;
+        case FSCACHE_OP_SLOW:
+                _debug("queue slow");
+                slow_work_enqueue(&op->slow_work);
+                break;
+        case FSCACHE_OP_MYTHREAD:
+                _debug("queue for caller's attention");
+                break;
+        default:
+                printk(KERN_ERR "FS-Cache: Unexpected op type %lx",
+                       op->flags);
+                BUG();
+                break;
         }
 }
 EXPORT_SYMBOL(fscache_enqueue_operation);
@@ -67,6 +69,8 @@ EXPORT_SYMBOL(fscache_enqueue_operation);
 static void fscache_run_op(struct fscache_object *object,
                            struct fscache_operation *op)
 {
+        fscache_set_op_state(op, "Run");
+
         object->n_in_progress++;
         if (test_and_clear_bit(FSCACHE_OP_WAITING, &op->flags))
                 wake_up_bit(&op->flags, FSCACHE_OP_WAITING);
@@ -87,9 +91,12 @@ int fscache_submit_exclusive_op(struct fscache_object *object,
 
         _enter("{OBJ%x OP%x},", object->debug_id, op->debug_id);
 
+        fscache_set_op_state(op, "SubmitX");
+
         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));
 
         ret = -ENOBUFS;
         if (fscache_object_is_active(object)) {
@@ -190,9 +197,12 @@ int fscache_submit_op(struct fscache_object *object,
 
         ASSERTCMP(atomic_read(&op->usage), >, 0);
 
+        fscache_set_op_state(op, "Submit");
+
         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();
@@ -222,6 +232,11 @@ int fscache_submit_op(struct fscache_object *object,
                 list_add_tail(&op->pend_link, &object->pending_ops);
                 fscache_stat(&fscache_n_op_pend);
                 ret = 0;
+        } else if (object->state == FSCACHE_OBJECT_DYING ||
+                   object->state == FSCACHE_OBJECT_LC_DYING ||
+                   object->state == FSCACHE_OBJECT_WITHDRAWING) {
+                fscache_stat(&fscache_n_op_rejected);
+                ret = -ENOBUFS;
         } else if (!test_bit(FSCACHE_IOERROR, &object->cache->flags)) {
                 fscache_report_unexpected_submission(object, op, ostate);
                 ASSERT(!fscache_object_is_active(object));
@@ -264,12 +279,7 @@ void fscache_start_operations(struct fscache_object *object)
                         stop = true;
                 }
                 list_del_init(&op->pend_link);
-                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);
+                fscache_run_op(object, op);
 
                 /* the pending queue was holding a ref on the object */
                 fscache_put_operation(op);
@@ -282,6 +292,36 @@ 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)
+{
+        struct fscache_object *object = op->object;
+        int ret;
+
+        _enter("OBJ%x OP%x}", op->object->debug_id, op->debug_id);
+
+        spin_lock(&object->lock);
+
+        ret = -EBUSY;
+        if (!list_empty(&op->pend_link)) {
+                fscache_stat(&fscache_n_op_cancelled);
+                list_del_init(&op->pend_link);
+                object->n_ops--;
+                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);
+                ret = 0;
+        }
+
+        spin_unlock(&object->lock);
+        _leave(" = %d", ret);
+        return ret;
+}
+
+/*
  * release an operation
  * - queues pending ops if this is the last in-progress op
  */
@@ -298,6 +338,8 @@ void fscache_put_operation(struct fscache_operation *op)
         if (!atomic_dec_and_test(&op->usage))
                 return;
 
+        fscache_set_op_state(op, "Put");
+
         _debug("PUT OP");
         if (test_and_set_bit(FSCACHE_OP_DEAD, &op->flags))
                 BUG();
@@ -311,6 +353,9 @@ void fscache_put_operation(struct fscache_operation *op)
 
         object = op->object;
 
+        if (test_bit(FSCACHE_OP_DEC_READ_CNT, &op->flags))
+                atomic_dec(&object->n_reads);
+
         /* 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 */
@@ -452,8 +497,27 @@ static void fscache_op_execute(struct slow_work *work)
         _leave("");
 }
 
+/*
+ * describe an operation for slow-work debugging
+ */
+#ifdef CONFIG_SLOW_WORK_PROC
+static void fscache_op_desc(struct slow_work *work, struct seq_file *m)
+{
+        struct fscache_operation *op =
+                container_of(work, struct fscache_operation, slow_work);
+
+        seq_printf(m, "FSC: OBJ%x OP%x: %s/%s fl=%lx",
+                   op->object->debug_id, op->debug_id,
+                   op->name, op->state, op->flags);
+}
+#endif
+
 const struct slow_work_ops fscache_op_slow_work_ops = {
+        .owner          = THIS_MODULE,
         .get_ref        = fscache_op_get_ref,
         .put_ref        = fscache_op_put_ref,
         .execute        = fscache_op_execute,
+#ifdef CONFIG_SLOW_WORK_PROC
+        .desc           = fscache_op_desc,
+#endif
 };