FS-Cache: Annotate slow-work runqueue proc lines for FS-Cache work items

Annotate slow-work runqueue proc lines for FS-Cache work items.  Objects
include the object ID and the state.  Operations include the object ID, the
operation ID and the operation type and state.

Signed-off-by: David Howells <dhowells@redhat.com>

4 files changed, 103 insertions, 6 deletions

diff --git a/fs/fscache/object.c b/fs/fscache/object.c
index d236eb1d6f37..615b63dd9ecc 100644
--- a/fs/fscache/object.c
+++ b/fs/fscache/object.c
@@ -14,9 +14,10 @@
 
 #define FSCACHE_DEBUG_LEVEL COOKIE
 #include <linux/module.h>
+#include <linux/seq_file.h>
 #include "internal.h"
 
-const char *fscache_object_states[] = {
+const char *fscache_object_states[FSCACHE_OBJECT__NSTATES] = {
         [FSCACHE_OBJECT_INIT]           = "OBJECT_INIT",
         [FSCACHE_OBJECT_LOOKING_UP]     = "OBJECT_LOOKING_UP",
         [FSCACHE_OBJECT_CREATING]       = "OBJECT_CREATING",
@@ -33,9 +34,28 @@ const char *fscache_object_states[] = {
 };
 EXPORT_SYMBOL(fscache_object_states);
 
+static const char fscache_object_states_short[FSCACHE_OBJECT__NSTATES][5] = {
+        [FSCACHE_OBJECT_INIT]           = "INIT",
+        [FSCACHE_OBJECT_LOOKING_UP]     = "LOOK",
+        [FSCACHE_OBJECT_CREATING]       = "CRTN",
+        [FSCACHE_OBJECT_AVAILABLE]      = "AVBL",
+        [FSCACHE_OBJECT_ACTIVE]         = "ACTV",
+        [FSCACHE_OBJECT_UPDATING]       = "UPDT",
+        [FSCACHE_OBJECT_DYING]          = "DYNG",
+        [FSCACHE_OBJECT_LC_DYING]       = "LCDY",
+        [FSCACHE_OBJECT_ABORT_INIT]     = "ABTI",
+        [FSCACHE_OBJECT_RELEASING]      = "RELS",
+        [FSCACHE_OBJECT_RECYCLING]      = "RCYC",
+        [FSCACHE_OBJECT_WITHDRAWING]    = "WTHD",
+        [FSCACHE_OBJECT_DEAD]           = "DEAD",
+};
+
 static void fscache_object_slow_work_put_ref(struct slow_work *);
 static int  fscache_object_slow_work_get_ref(struct slow_work *);
 static void fscache_object_slow_work_execute(struct slow_work *);
+#ifdef CONFIG_SLOW_WORK_PROC
+static void fscache_object_slow_work_desc(struct slow_work *, struct seq_file *);
+#endif
 static void fscache_initialise_object(struct fscache_object *);
 static void fscache_lookup_object(struct fscache_object *);
 static void fscache_object_available(struct fscache_object *);
@@ -49,6 +69,9 @@ const struct slow_work_ops fscache_object_slow_work_ops = {
         .get_ref        = fscache_object_slow_work_get_ref,
         .put_ref        = fscache_object_slow_work_put_ref,
         .execute        = fscache_object_slow_work_execute,
+#ifdef CONFIG_SLOW_WORK_PROC
+        .desc           = fscache_object_slow_work_desc,
+#endif
 };
 EXPORT_SYMBOL(fscache_object_slow_work_ops);
 
@@ -327,6 +350,22 @@ static void fscache_object_slow_work_execute(struct slow_work *work)
 }
 
 /*
+ * describe an object for slow-work debugging
+ */
+#ifdef CONFIG_SLOW_WORK_PROC
+static void fscache_object_slow_work_desc(struct slow_work *work,
+                                          struct seq_file *m)
+{
+        struct fscache_object *object =
+                container_of(work, struct fscache_object, work);
+
+        seq_printf(m, "FSC: OBJ%x: %s",
+                   object->debug_id,
+                   fscache_object_states_short[object->state]);
+}
+#endif
+
+/*
  * initialise an object
  * - check the specified object's parent to see if we can make use of it
  *   immediately to do a creation
diff --git a/fs/fscache/operation.c b/fs/fscache/operation.c
index f1a2857b2ff5..91bbe6f0377c 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;
@@ -31,6 +32,8 @@ 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(op->processor != NULL);
         ASSERTCMP(op->object->state, >=, FSCACHE_OBJECT_AVAILABLE);
         ASSERTCMP(atomic_read(&op->usage), >, 0);
@@ -67,6 +70,8 @@ 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);
@@ -87,6 +92,8 @@ 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);
@@ -190,6 +197,8 @@ 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);
@@ -298,6 +307,8 @@ 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();
@@ -452,9 +463,27 @@ 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
 };
diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index 2568e0eb644f..e8bbc395cef6 100644
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -63,14 +63,19 @@ static void fscache_end_page_write(struct fscache_cookie *cookie, struct page *p
 static void fscache_attr_changed_op(struct fscache_operation *op)
 {
         struct fscache_object *object = op->object;
+        int ret;
 
         _enter("{OBJ%x OP%x}", object->debug_id, op->debug_id);
 
         fscache_stat(&fscache_n_attr_changed_calls);
 
-        if (fscache_object_is_active(object) &&
-            object->cache->ops->attr_changed(object) < 0)
-                fscache_abort_object(object);
+        if (fscache_object_is_active(object)) {
+                fscache_set_op_state(op, "CallFS");
+                ret = object->cache->ops->attr_changed(object);
+                fscache_set_op_state(op, "Done");
+                if (ret < 0)
+                        fscache_abort_object(object);
+        }
 
         _leave("");
 }
@@ -99,6 +104,7 @@ int __fscache_attr_changed(struct fscache_cookie *cookie)
         fscache_operation_init(op, NULL);
         fscache_operation_init_slow(op, fscache_attr_changed_op);
         op->flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_EXCLUSIVE);
+        fscache_set_op_name(op, "Attr");
 
         spin_lock(&cookie->lock);
 
@@ -184,6 +190,7 @@ static struct fscache_retrieval *fscache_alloc_retrieval(
         op->start_time  = jiffies;
         INIT_WORK(&op->op.fast_work, fscache_retrieval_work);
         INIT_LIST_HEAD(&op->to_do);
+        fscache_set_op_name(&op->op, "Retr");
         return op;
 }
 
@@ -257,6 +264,7 @@ int __fscache_read_or_alloc_page(struct fscache_cookie *cookie,
                 _leave(" = -ENOMEM");
                 return -ENOMEM;
         }
+        fscache_set_op_name(&op->op, "RetrRA1");
 
         spin_lock(&cookie->lock);
 
@@ -369,6 +377,7 @@ int __fscache_read_or_alloc_pages(struct fscache_cookie *cookie,
         op = fscache_alloc_retrieval(mapping, end_io_func, context);
         if (!op)
                 return -ENOMEM;
+        fscache_set_op_name(&op->op, "RetrRAN");
 
         spin_lock(&cookie->lock);
 
@@ -461,6 +470,7 @@ int __fscache_alloc_page(struct fscache_cookie *cookie,
         op = fscache_alloc_retrieval(page->mapping, NULL, NULL);
         if (!op)
                 return -ENOMEM;
+        fscache_set_op_name(&op->op, "RetrAL1");
 
         spin_lock(&cookie->lock);
 
@@ -529,6 +539,8 @@ static void fscache_write_op(struct fscache_operation *_op)
 
         _enter("{OP%x,%d}", op->op.debug_id, atomic_read(&op->op.usage));
 
+        fscache_set_op_state(&op->op, "GetPage");
+
         spin_lock(&cookie->lock);
         spin_lock(&object->lock);
 
@@ -559,13 +571,17 @@ static void fscache_write_op(struct fscache_operation *_op)
         spin_unlock(&cookie->lock);
 
         if (page) {
+                fscache_set_op_state(&op->op, "Store");
                 ret = object->cache->ops->write_page(op, page);
+                fscache_set_op_state(&op->op, "EndWrite");
                 fscache_end_page_write(cookie, page);
                 page_cache_release(page);
-                if (ret < 0)
+                if (ret < 0) {
+                        fscache_set_op_state(&op->op, "Abort");
                         fscache_abort_object(object);
-                else
+                } else {
                         fscache_enqueue_operation(&op->op);
+                }
         }
 
         _leave("");
@@ -634,6 +650,7 @@ int __fscache_write_page(struct fscache_cookie *cookie,
         fscache_operation_init(&op->op, fscache_release_write_op);
         fscache_operation_init_slow(&op->op, fscache_write_op);
         op->op.flags = FSCACHE_OP_SLOW | (1 << FSCACHE_OP_WAITING);
+        fscache_set_op_name(&op->op, "Write1");
 
         ret = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
         if (ret < 0)
diff --git a/include/linux/fscache-cache.h b/include/linux/fscache-cache.h
index 84d3532dd3ea..7a9847ccd192 100644
--- a/include/linux/fscache-cache.h
+++ b/include/linux/fscache-cache.h
@@ -102,6 +102,16 @@ 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 +135,7 @@ 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");
 }
 
 /**
@@ -337,6 +348,7 @@ 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 */