[PATCH 43/64] cachefiles: Implement object lifecycle funcs

From: David Howells
Date: Mon Nov 29 2021 - 09:35:39 EST

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Implement allocate, get, see and put functions for the cachefiles_object
struct. The members of the struct we're going to need are also added.

Additionally, implement a lifecycle tracepoint.

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: linux-cachefs@xxxxxxxxxx
---

fs/cachefiles/interface.c | 86 +++++++++++++++++++++++++++++++++++++
fs/cachefiles/internal.h | 35 ++++++++++++++-
fs/cachefiles/main.c | 16 +++++++
include/trace/events/cachefiles.h | 58 +++++++++++++++++++++++++
include/trace/events/fscache.h | 4 ++
5 files changed, 197 insertions(+), 2 deletions(-)

diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c
index 1793e46bd3e7..68bb7b6c4945 100644
--- a/fs/cachefiles/interface.c
+++ b/fs/cachefiles/interface.c
@@ -13,6 +13,92 @@
#include <trace/events/fscache.h>
#include "internal.h"

+static atomic_t cachefiles_object_debug_id;
+
+/*
+ * Allocate a cache object record.
+ */
+static
+struct cachefiles_object *cachefiles_alloc_object(struct fscache_cookie *cookie)
+{
+ struct fscache_volume *vcookie = cookie->volume;
+ struct cachefiles_volume *volume = vcookie->cache_priv;
+ struct cachefiles_object *object;
+
+ _enter("{%s},%x,", vcookie->key, cookie->debug_id);
+
+ object = kmem_cache_zalloc(cachefiles_object_jar, GFP_KERNEL);
+ if (!object)
+ return NULL;
+
+ refcount_set(&object->ref, 1);
+
+ spin_lock_init(&object->lock);
+ INIT_LIST_HEAD(&object->cache_link);
+ object->volume = volume;
+ object->debug_id = atomic_inc_return(&cachefiles_object_debug_id);
+ object->cookie = fscache_get_cookie(cookie, fscache_cookie_get_attach_object);
+
+ fscache_count_object(vcookie->cache);
+ trace_cachefiles_ref(object->debug_id, cookie->debug_id, 1,
+ cachefiles_obj_new);
+ return object;
+}
+
+/*
+ * Note that an object has been seen.
+ */
+void cachefiles_see_object(struct cachefiles_object *object,
+ enum cachefiles_obj_ref_trace why)
+{
+ trace_cachefiles_ref(object->debug_id, object->cookie->debug_id,
+ refcount_read(&object->ref), why);
+}
+
+/*
+ * Increment the usage count on an object;
+ */
+struct cachefiles_object *cachefiles_grab_object(struct cachefiles_object *object,
+ enum cachefiles_obj_ref_trace why)
+{
+ int r;
+
+ __refcount_inc(&object->ref, &r);
+ trace_cachefiles_ref(object->debug_id, object->cookie->debug_id, r, why);
+ return object;
+}
+
+/*
+ * dispose of a reference to an object
+ */
+void cachefiles_put_object(struct cachefiles_object *object,
+ enum cachefiles_obj_ref_trace why)
+{
+ unsigned int object_debug_id = object->debug_id;
+ unsigned int cookie_debug_id = object->cookie->debug_id;
+ struct fscache_cache *cache;
+ bool done;
+ int r;
+
+ done = __refcount_dec_and_test(&object->ref, &r);
+ trace_cachefiles_ref(object_debug_id, cookie_debug_id, r, why);
+ if (done) {
+ _debug("- kill object OBJ%x", object_debug_id);
+
+ ASSERTCMP(object->file, ==, NULL);
+
+ kfree(object->d_name);
+
+ cache = object->volume->cache->cache;
+ fscache_put_cookie(object->cookie, fscache_cookie_put_object);
+ object->cookie = NULL;
+ kmem_cache_free(cachefiles_object_jar, object);
+ fscache_uncount_object(cache);
+ }
+
+ _leave("");
+}
+
const struct fscache_cache_ops cachefiles_cache_ops = {
.name = "cachefiles",
.acquire_volume = cachefiles_acquire_volume,
diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h
index 3b1a6d67cf96..ff378171c71d 100644
--- a/fs/cachefiles/internal.h
+++ b/fs/cachefiles/internal.h
@@ -19,6 +19,16 @@
struct cachefiles_cache;
struct cachefiles_object;

+enum cachefiles_content {
+ /* These values are saved on disk */
+ CACHEFILES_CONTENT_NO_DATA = 0, /* No content stored */
+ CACHEFILES_CONTENT_SINGLE = 1, /* Content is monolithic, all is present */
+ CACHEFILES_CONTENT_ALL = 2, /* Content is all present, no map */
+ CACHEFILES_CONTENT_BACKFS_MAP = 3, /* Content is piecemeal, mapped through backing fs */
+ CACHEFILES_CONTENT_DIRTY = 4, /* Content is dirty (only seen on disk) */
+ nr__cachefiles_content
+};
+
/*
* Cached volume representation.
*/
@@ -31,10 +41,20 @@ struct cachefiles_volume {
};

/*
- * Data file records.
+ * Backing file state.
*/
struct cachefiles_object {
- int debug_id; /* debugging ID */
+ struct fscache_cookie *cookie; /* Netfs data storage object cookie */
+ struct cachefiles_volume *volume; /* Cache volume that holds this object */
+ struct list_head cache_link; /* Link in cache->*_list */
+ struct file *file; /* The file representing this object */
+ char *d_name; /* Backing file name */
+ int debug_id;
+ spinlock_t lock;
+ refcount_t ref;
+ u8 d_name_len; /* Length of filename */
+ enum cachefiles_content content_info:8; /* Info about content presence */
+ unsigned long flags;
};

/*
@@ -146,6 +166,17 @@ static inline int cachefiles_inject_remove_error(void)
* interface.c
*/
extern const struct fscache_cache_ops cachefiles_cache_ops;
+extern void cachefiles_see_object(struct cachefiles_object *object,
+ enum cachefiles_obj_ref_trace why);
+extern struct cachefiles_object *cachefiles_grab_object(struct cachefiles_object *object,
+ enum cachefiles_obj_ref_trace why);
+extern void cachefiles_put_object(struct cachefiles_object *object,
+ enum cachefiles_obj_ref_trace why);
+
+/*
+ * main.c
+ */
+extern struct kmem_cache *cachefiles_object_jar;

/*
* namei.c
diff --git a/fs/cachefiles/main.c b/fs/cachefiles/main.c
index 533e3067d80f..3f369c6f816d 100644
--- a/fs/cachefiles/main.c
+++ b/fs/cachefiles/main.c
@@ -31,6 +31,8 @@ MODULE_DESCRIPTION("Mounted-filesystem based cache");
MODULE_AUTHOR("Red Hat, Inc.");
MODULE_LICENSE("GPL");

+struct kmem_cache *cachefiles_object_jar;
+
static struct miscdevice cachefiles_dev = {
.minor = MISC_DYNAMIC_MINOR,
.name = "cachefiles",
@@ -51,9 +53,22 @@ static int __init cachefiles_init(void)
if (ret < 0)
goto error_dev;

+ /* create an object jar */
+ ret = -ENOMEM;
+ cachefiles_object_jar =
+ kmem_cache_create("cachefiles_object_jar",
+ sizeof(struct cachefiles_object),
+ 0, SLAB_HWCACHE_ALIGN, NULL);
+ if (!cachefiles_object_jar) {
+ pr_notice("Failed to allocate an object jar\n");
+ goto error_object_jar;
+ }
+
pr_info("Loaded\n");
return 0;

+error_object_jar:
+ misc_deregister(&cachefiles_dev);
error_dev:
cachefiles_unregister_error_injection();
error_einj:
@@ -70,6 +85,7 @@ static void __exit cachefiles_exit(void)
{
pr_info("Unloading\n");

+ kmem_cache_destroy(cachefiles_object_jar);
misc_deregister(&cachefiles_dev);
cachefiles_unregister_error_injection();
}
diff --git a/include/trace/events/cachefiles.h b/include/trace/events/cachefiles.h
index b548dbaf85bb..493afa7fbfec 100644
--- a/include/trace/events/cachefiles.h
+++ b/include/trace/events/cachefiles.h
@@ -18,6 +18,21 @@
#ifndef __CACHEFILES_DECLARE_TRACE_ENUMS_ONCE_ONLY
#define __CACHEFILES_DECLARE_TRACE_ENUMS_ONCE_ONLY

+enum cachefiles_obj_ref_trace {
+ cachefiles_obj_get_ioreq,
+ cachefiles_obj_new,
+ cachefiles_obj_put_alloc_fail,
+ cachefiles_obj_put_detach,
+ cachefiles_obj_put_ioreq,
+ cachefiles_obj_see_clean_commit,
+ cachefiles_obj_see_clean_delete,
+ cachefiles_obj_see_clean_drop_tmp,
+ cachefiles_obj_see_lookup_cookie,
+ cachefiles_obj_see_lookup_failed,
+ cachefiles_obj_see_withdraw_cookie,
+ cachefiles_obj_see_withdrawal,
+};
+
enum fscache_why_object_killed {
FSCACHE_OBJECT_IS_STALE,
FSCACHE_OBJECT_IS_WEIRD,
@@ -66,6 +81,20 @@ enum cachefiles_error_trace {
EM(FSCACHE_OBJECT_WAS_RETIRED, "was_retired") \
E_(FSCACHE_OBJECT_WAS_CULLED, "was_culled")

+#define cachefiles_obj_ref_traces \
+ EM(cachefiles_obj_get_ioreq, "GET ioreq") \
+ EM(cachefiles_obj_new, "NEW obj") \
+ EM(cachefiles_obj_put_alloc_fail, "PUT alloc_fail") \
+ EM(cachefiles_obj_put_detach, "PUT detach") \
+ EM(cachefiles_obj_put_ioreq, "PUT ioreq") \
+ EM(cachefiles_obj_see_clean_commit, "SEE clean_commit") \
+ EM(cachefiles_obj_see_clean_delete, "SEE clean_delete") \
+ EM(cachefiles_obj_see_clean_drop_tmp, "SEE clean_drop_tmp") \
+ EM(cachefiles_obj_see_lookup_cookie, "SEE lookup_cookie") \
+ EM(cachefiles_obj_see_lookup_failed, "SEE lookup_failed") \
+ EM(cachefiles_obj_see_withdraw_cookie, "SEE withdraw_cookie") \
+ E_(cachefiles_obj_see_withdrawal, "SEE withdrawal")
+
#define cachefiles_trunc_traces \
EM(cachefiles_trunc_dio_adjust, "DIOADJ") \
EM(cachefiles_trunc_expand_tmpfile, "EXPTMP") \
@@ -100,6 +129,7 @@ enum cachefiles_error_trace {
#define E_(a, b) TRACE_DEFINE_ENUM(a);

cachefiles_obj_kill_traces;
+cachefiles_obj_ref_traces;
cachefiles_trunc_traces;
cachefiles_error_traces;

@@ -113,6 +143,34 @@ cachefiles_error_traces;
#define E_(a, b) { a, b }

+TRACE_EVENT(cachefiles_ref,
+ TP_PROTO(unsigned int object_debug_id,
+ unsigned int cookie_debug_id,
+ int usage,
+ enum cachefiles_obj_ref_trace why),
+
+ TP_ARGS(object_debug_id, cookie_debug_id, usage, why),
+
+ /* Note that obj may be NULL */
+ TP_STRUCT__entry(
+ __field(unsigned int, obj )
+ __field(unsigned int, cookie )
+ __field(enum cachefiles_obj_ref_trace, why )
+ __field(int, usage )
+ ),
+
+ TP_fast_assign(
+ __entry->obj = object_debug_id;
+ __entry->cookie = cookie_debug_id;
+ __entry->usage = usage;
+ __entry->why = why;
+ ),
+
+ TP_printk("c=%08x o=%08x u=%d %s",
+ __entry->cookie, __entry->obj, __entry->usage,
+ __print_symbolic(__entry->why, cachefiles_obj_ref_traces))
+ );
+
TRACE_EVENT(cachefiles_lookup,
TP_PROTO(struct cachefiles_object *obj,
struct dentry *de),
diff --git a/include/trace/events/fscache.h b/include/trace/events/fscache.h
index 6bdff5bcbf6c..7d26388ef9d8 100644
--- a/include/trace/events/fscache.h
+++ b/include/trace/events/fscache.h
@@ -49,6 +49,7 @@ enum fscache_volume_trace {
enum fscache_cookie_trace {
fscache_cookie_collision,
fscache_cookie_discard,
+ fscache_cookie_get_attach_object,
fscache_cookie_get_end_access,
fscache_cookie_get_hash_collision,
fscache_cookie_get_inval_work,
@@ -57,6 +58,7 @@ enum fscache_cookie_trace {
fscache_cookie_new_acquire,
fscache_cookie_put_hash_collision,
fscache_cookie_put_lru,
+ fscache_cookie_put_object,
fscache_cookie_put_over_queued,
fscache_cookie_put_relinquish,
fscache_cookie_put_withdrawn,
@@ -122,6 +124,7 @@ enum fscache_access_trace {
#define fscache_cookie_traces \
EM(fscache_cookie_collision, "*COLLIDE*") \
EM(fscache_cookie_discard, "DISCARD ") \
+ EM(fscache_cookie_get_attach_object, "GET attch") \
EM(fscache_cookie_get_hash_collision, "GET hcoll") \
EM(fscache_cookie_get_end_access, "GQ endac") \
EM(fscache_cookie_get_inval_work, "GQ inval") \
@@ -130,6 +133,7 @@ enum fscache_access_trace {
EM(fscache_cookie_new_acquire, "NEW acq ") \
EM(fscache_cookie_put_hash_collision, "PUT hcoll") \
EM(fscache_cookie_put_lru, "PUT lru ") \
+ EM(fscache_cookie_put_object, "PUT obj ") \
EM(fscache_cookie_put_over_queued, "PQ overq") \
EM(fscache_cookie_put_relinquish, "PUT relnq") \
EM(fscache_cookie_put_withdrawn, "PUT wthdn") \

Next message: David Howells: "[PATCH 44/64] cachefiles: Implement key to filename encoding"
Previous message: David Howells: "[PATCH 42/64] cachefiles: Add tracepoints for calls to the VFS"
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