[PATCH 05/12] fscache: Procfile to display cookies
From: David Howells
Date: Mon Jun 21 2021 - 17:46:01 EST
Add /proc/fs/fscache/cookies to display active cookies.
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---
fs/fscache/cookie.c | 103 +++++++++++++++++++++++++++++++++++++++++++++++
fs/fscache/internal.h | 1
fs/fscache/proc.c | 7 +++
include/linux/fscache.h | 1
4 files changed, 112 insertions(+)
diff --git a/fs/fscache/cookie.c b/fs/fscache/cookie.c
index f2be98d2c64d..c7047544972b 100644
--- a/fs/fscache/cookie.c
+++ b/fs/fscache/cookie.c
@@ -19,6 +19,8 @@ static atomic_t fscache_object_debug_id = ATOMIC_INIT(0);
#define fscache_cookie_hash_shift 15
static struct hlist_bl_head fscache_cookie_hash[1 << fscache_cookie_hash_shift];
+static LIST_HEAD(fscache_cookies);
+static DEFINE_RWLOCK(fscache_cookies_lock);
static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie,
loff_t object_size);
@@ -65,6 +67,9 @@ void fscache_free_cookie(struct fscache_cookie *cookie)
{
if (cookie) {
BUG_ON(!hlist_empty(&cookie->backing_objects));
+ write_lock(&fscache_cookies_lock);
+ list_del(&cookie->proc_link);
+ write_unlock(&fscache_cookies_lock);
if (cookie->aux_len > sizeof(cookie->inline_aux))
kfree(cookie->aux);
if (cookie->key_len > sizeof(cookie->inline_key))
@@ -192,6 +197,10 @@ struct fscache_cookie *fscache_alloc_cookie(
/* radix tree insertion won't use the preallocation pool unless it's
* told it may not wait */
INIT_RADIX_TREE(&cookie->stores, GFP_NOFS & ~__GFP_DIRECT_RECLAIM);
+
+ write_lock(&fscache_cookies_lock);
+ list_add_tail(&cookie->proc_link, &fscache_cookies);
+ write_unlock(&fscache_cookies_lock);
return cookie;
nomem:
@@ -969,3 +978,97 @@ int __fscache_check_consistency(struct fscache_cookie *cookie,
return -ESTALE;
}
EXPORT_SYMBOL(__fscache_check_consistency);
+
+/*
+ * Generate a list of extant cookies in /proc/fs/fscache/cookies
+ */
+static int fscache_cookies_seq_show(struct seq_file *m, void *v)
+{
+ struct fscache_cookie *cookie;
+ unsigned int keylen = 0, auxlen = 0;
+ char _type[3], *type;
+ u8 *p;
+
+ if (v == &fscache_cookies) {
+ seq_puts(m,
+ "COOKIE PARENT USAGE CHILD ACT TY FL DEF NETFS_DATA\n"
+ "======== ======== ===== ===== === == === ================ ==========\n"
+ );
+ return 0;
+ }
+
+ cookie = list_entry(v, struct fscache_cookie, proc_link);
+
+ switch (cookie->type) {
+ case 0:
+ type = "IX";
+ break;
+ case 1:
+ type = "DT";
+ break;
+ default:
+ snprintf(_type, sizeof(_type), "%02u",
+ cookie->type);
+ type = _type;
+ break;
+ }
+
+ seq_printf(m,
+ "%08x %08x %5u %5u %3u %s %03lx %-16s %px",
+ cookie->debug_id,
+ cookie->parent ? cookie->parent->debug_id : 0,
+ atomic_read(&cookie->usage),
+ atomic_read(&cookie->n_children),
+ atomic_read(&cookie->n_active),
+ type,
+ cookie->flags,
+ cookie->def->name,
+ cookie->netfs_data);
+
+ keylen = cookie->key_len;
+ auxlen = cookie->aux_len;
+
+ if (keylen > 0 || auxlen > 0) {
+ seq_puts(m, " ");
+ p = keylen <= sizeof(cookie->inline_key) ?
+ cookie->inline_key : cookie->key;
+ for (; keylen > 0; keylen--)
+ seq_printf(m, "%02x", *p++);
+ if (auxlen > 0) {
+ seq_puts(m, ", ");
+ p = auxlen <= sizeof(cookie->inline_aux) ?
+ cookie->inline_aux : cookie->aux;
+ for (; auxlen > 0; auxlen--)
+ seq_printf(m, "%02x", *p++);
+ }
+ }
+
+ seq_puts(m, "\n");
+ return 0;
+}
+
+static void *fscache_cookies_seq_start(struct seq_file *m, loff_t *_pos)
+ __acquires(fscache_cookies_lock)
+{
+ read_lock(&fscache_cookies_lock);
+ return seq_list_start_head(&fscache_cookies, *_pos);
+}
+
+static void *fscache_cookies_seq_next(struct seq_file *m, void *v, loff_t *_pos)
+{
+ return seq_list_next(v, &fscache_cookies, _pos);
+}
+
+static void fscache_cookies_seq_stop(struct seq_file *m, void *v)
+ __releases(rcu)
+{
+ read_unlock(&fscache_cookies_lock);
+}
+
+
+const struct seq_operations fscache_cookies_seq_ops = {
+ .start = fscache_cookies_seq_start,
+ .next = fscache_cookies_seq_next,
+ .stop = fscache_cookies_seq_stop,
+ .show = fscache_cookies_seq_show,
+};
diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h
index c483863b740a..207a6bc81ca9 100644
--- a/fs/fscache/internal.h
+++ b/fs/fscache/internal.h
@@ -45,6 +45,7 @@ extern struct fscache_cache *fscache_select_cache_for_object(
* cookie.c
*/
extern struct kmem_cache *fscache_cookie_jar;
+extern const struct seq_operations fscache_cookies_seq_ops;
extern void fscache_free_cookie(struct fscache_cookie *);
extern struct fscache_cookie *fscache_alloc_cookie(struct fscache_cookie *,
diff --git a/fs/fscache/proc.c b/fs/fscache/proc.c
index 90a7bc22f7e1..da51fdfc8641 100644
--- a/fs/fscache/proc.c
+++ b/fs/fscache/proc.c
@@ -21,6 +21,10 @@ int __init fscache_proc_init(void)
if (!proc_mkdir("fs/fscache", NULL))
goto error_dir;
+ if (!proc_create_seq("fs/fscache/cookies", S_IFREG | 0444, NULL,
+ &fscache_cookies_seq_ops))
+ goto error_cookies;
+
#ifdef CONFIG_FSCACHE_STATS
if (!proc_create_single("fs/fscache/stats", S_IFREG | 0444, NULL,
fscache_stats_show))
@@ -53,6 +57,8 @@ int __init fscache_proc_init(void)
remove_proc_entry("fs/fscache/stats", NULL);
error_stats:
#endif
+ remove_proc_entry("fs/fscache/cookies", NULL);
+error_cookies:
remove_proc_entry("fs/fscache", NULL);
error_dir:
_leave(" = -ENOMEM");
@@ -73,5 +79,6 @@ void fscache_proc_cleanup(void)
#ifdef CONFIG_FSCACHE_STATS
remove_proc_entry("fs/fscache/stats", NULL);
#endif
+ remove_proc_entry("fs/fscache/cookies", NULL);
remove_proc_entry("fs/fscache", NULL);
}
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index ba58c427cf9a..ea61e54a6bc5 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -133,6 +133,7 @@ struct fscache_cookie {
const struct fscache_cookie_def *def; /* definition */
struct fscache_cookie *parent; /* parent of this entry */
struct hlist_bl_node hash_link; /* Link in hash table */
+ struct list_head proc_link; /* Link in proc list */
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 */