From patchwork Fri Oct 22 19:02:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 12578617 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E935FC433EF for ; Fri, 22 Oct 2021 19:02:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CD21A61038 for ; Fri, 22 Oct 2021 19:02:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233568AbhJVTEo (ORCPT ); Fri, 22 Oct 2021 15:04:44 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:24008 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234030AbhJVTEk (ORCPT ); Fri, 22 Oct 2021 15:04:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634929342; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=pTKUPqqhLn13oYPq3rhi9ijm3zwM7t7uFhQagyxsqOg=; b=E6PxVDQPRzDb2eXNUFvDICTJ9fT2aAInReMDbEZvP2V7k34cwT2OBTfdxKRApDDziUX1Ka xbiSUETMounIet2RUzi3jvBAE9au22sZ30JG3tot8QhBEjEaHY4JjP++6d+84EQZKpgMlb 6BUjMMcZ24xfkGsgF3Vbrlf/6RovBP8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-246-pHBC_Mw6NYuUtO8ZZgTlOw-1; Fri, 22 Oct 2021 15:02:19 -0400 X-MC-Unique: pHBC_Mw6NYuUtO8ZZgTlOw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id E4E2318D6A25; Fri, 22 Oct 2021 19:02:16 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id D30CC5C1A3; Fri, 22 Oct 2021 19:02:03 +0000 (UTC) Organization: Red Hat UK Ltd. 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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH v2 12/53] fscache: Implement cache-level access helpers From: David Howells To: linux-cachefs@redhat.com Cc: dhowells@redhat.com, Trond Myklebust , Anna Schumaker , Steve French , Dominique Martinet , Jeff Layton , Matthew Wilcox , Alexander Viro , Omar Sandoval , Linus Torvalds , linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Fri, 22 Oct 2021 20:02:03 +0100 Message-ID: <163492932300.1038219.13528401231144480258.stgit@warthog.procyon.org.uk> In-Reply-To: <163492911924.1038219.13107463173777870713.stgit@warthog.procyon.org.uk> References: <163492911924.1038219.13107463173777870713.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org Add a pair of helper functions to pin/unpin a cache that we're wanting to do a high-level access to (such as creating or removing a volume). Signed-off-by: David Howells cc: linux-cachefs@redhat.com --- fs/fscache/cache.c | 37 ++++++++++++++++++++++++++++++++++++ fs/fscache/internal.h | 2 ++ fs/fscache/main.c | 2 ++ include/trace/events/fscache.h | 41 ++++++++++++++++++++++++++++++++++++++++ 4 files changed, 82 insertions(+) diff --git a/fs/fscache/cache.c b/fs/fscache/cache.c index da08e29ee5b9..3cde698c5015 100644 --- a/fs/fscache/cache.c +++ b/fs/fscache/cache.c @@ -171,6 +171,43 @@ void fscache_put_cache(struct fscache_cache *cache, } EXPORT_SYMBOL(fscache_put_cache); +/* + * Get an increment on a cache's access counter if the cache is live to prevent + * it from going away whilst we're accessing it. + */ +bool fscache_begin_cache_access(struct fscache_cache *cache, enum fscache_access_trace why) +{ + int n_accesses; + + if (!fscache_cache_is_live(cache)) + return false; + + n_accesses = atomic_inc_return(&cache->n_accesses); + smp_mb__after_atomic(); /* Reread live flag after n_accesses */ + trace_fscache_access_cache(cache->debug_id, refcount_read(&cache->ref), + n_accesses, why); + if (!fscache_cache_is_live(cache)) { + fscache_end_cache_access(cache, fscache_access_unlive); + return false; + } + return true; +} + +/* + * Drop an increment on a cache's access counter. + */ +void fscache_end_cache_access(struct fscache_cache *cache, enum fscache_access_trace why) +{ + int n_accesses; + + smp_mb__before_atomic(); + n_accesses = atomic_dec_return(&cache->n_accesses); + trace_fscache_access_cache(cache->debug_id, refcount_read(&cache->ref), + n_accesses, why); + if (n_accesses == 0) + wake_up_var(&cache->n_accesses); +} + #ifdef CONFIG_PROC_FS static const char fscache_cache_states[NR__FSCACHE_CACHE_STATE] = "-PAEW"; diff --git a/fs/fscache/internal.h b/fs/fscache/internal.h index 9daacd7de9ea..5546c24d18d8 100644 --- a/fs/fscache/internal.h +++ b/fs/fscache/internal.h @@ -23,6 +23,8 @@ #ifdef CONFIG_PROC_FS extern const struct seq_operations fscache_caches_seq_ops; #endif +bool fscache_begin_cache_access(struct fscache_cache *cache, enum fscache_access_trace why); +void fscache_end_cache_access(struct fscache_cache *cache, enum fscache_access_trace why); struct fscache_cache *fscache_lookup_cache(const char *name, bool is_cache); /* diff --git a/fs/fscache/main.c b/fs/fscache/main.c index fad9c1933987..e1f14b29cff4 100644 --- a/fs/fscache/main.c +++ b/fs/fscache/main.c @@ -21,6 +21,8 @@ module_param_named(debug, fscache_debug, uint, MODULE_PARM_DESC(fscache_debug, "FS-Cache debugging mask"); +EXPORT_TRACEPOINT_SYMBOL(fscache_access_cache); + struct workqueue_struct *fscache_wq; EXPORT_SYMBOL(fscache_wq); diff --git a/include/trace/events/fscache.h b/include/trace/events/fscache.h index cfa4c153c72b..d09d7e3ac86c 100644 --- a/include/trace/events/fscache.h +++ b/include/trace/events/fscache.h @@ -59,6 +59,12 @@ enum fscache_cookie_trace { fscache_cookie_see_work, }; +enum fscache_access_trace { + fscache_access_cache_pin, + fscache_access_cache_unpin, + fscache_access_unlive, +}; + #endif /* @@ -101,6 +107,11 @@ enum fscache_cookie_trace { EM(fscache_cookie_see_withdraw, "- x-wth") \ E_(fscache_cookie_see_work, "- work ") +#define fscache_access_traces \ + EM(fscache_access_cache_pin, "PIN cache ") \ + EM(fscache_access_cache_unpin, "UNPIN cache ") \ + E_(fscache_access_unlive, "END unlive ") + /* * Export enum symbols via userspace. */ @@ -112,6 +123,7 @@ enum fscache_cookie_trace { fscache_cache_traces; fscache_volume_traces; fscache_cookie_traces; +fscache_access_traces; /* * Now redefine the EM() and E_() macros to map the enums to the strings that @@ -198,6 +210,35 @@ TRACE_EVENT(fscache_cookie, __entry->ref) ); +TRACE_EVENT(fscache_access_cache, + TP_PROTO(unsigned int cache_debug_id, + int ref, + int n_accesses, + enum fscache_access_trace why), + + TP_ARGS(cache_debug_id, ref, n_accesses, why), + + TP_STRUCT__entry( + __field(unsigned int, cache ) + __field(int, ref ) + __field(int, n_accesses ) + __field(enum fscache_access_trace, why ) + ), + + TP_fast_assign( + __entry->cache = cache_debug_id; + __entry->ref = ref; + __entry->n_accesses = n_accesses; + __entry->why = why; + ), + + TP_printk("C=%08x %s r=%d a=%d", + __entry->cache, + __print_symbolic(__entry->why, fscache_access_traces), + __entry->ref, + __entry->n_accesses) + ); + TRACE_EVENT(fscache_acquire, TP_PROTO(struct fscache_cookie *cookie),