From patchwork Wed Dec 13 15:23:33 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 13491193 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BkIBQMfx" Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5B1D8D5B for ; Wed, 13 Dec 2023 07:25:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1702481139; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=/P39zA4P9i416f7rYVx3fltLx7nFHwqFVafrmIB+g6A=; b=BkIBQMfx5m4tgQ4KfNLcxmR1Y6MlZ7u5SpUtuu2AaxASvhUuExBxvhSx35WNXbslvEwcMC 7FvxIQIp7ci3orF9Umk+x48BFbB5PovKLlXmh96QW02EZl0Gr5WW10ELjBYOE7nYL6I2Qz pmDAGLZ/EmyOpBImQKY+Vz0BFS8wB8Y= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-16-M56nMa6TPRejKwmGXDGC8A-1; Wed, 13 Dec 2023 10:25:36 -0500 X-MC-Unique: M56nMa6TPRejKwmGXDGC8A-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 6F1BE8828D5; Wed, 13 Dec 2023 15:25:33 +0000 (UTC) Received: from warthog.procyon.org.com (unknown [10.42.28.2]) by smtp.corp.redhat.com (Postfix) with ESMTP id 36718492BE6; Wed, 13 Dec 2023 15:25:30 +0000 (UTC) From: David Howells To: Jeff Layton , Steve French Cc: David Howells , Matthew Wilcox , Marc Dionne , Paulo Alcantara , Shyam Prasad N , Tom Talpey , Dominique Martinet , Eric Van Hensbergen , Ilya Dryomov , Christian Brauner , linux-cachefs@redhat.com, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 23/39] netfs: Prep to use folio->private for write grouping and streaming write Date: Wed, 13 Dec 2023 15:23:33 +0000 Message-ID: <20231213152350.431591-24-dhowells@redhat.com> In-Reply-To: <20231213152350.431591-1-dhowells@redhat.com> References: <20231213152350.431591-1-dhowells@redhat.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.10 Prepare to use folio->private to hold information write grouping and streaming write. These are implemented in the same commit as they both make use of folio->private and will be both checked at the same time in several places. "Write grouping" involves ordering the writeback of groups of writes, such as is needed for ceph snaps. A group is represented by a filesystem-supplied object which must contain a netfs_group struct. This contains just a refcount and a pointer to a destructor. "Streaming write" is the storage of data in folios that are marked dirty, but not uptodate, to avoid unnecessary reads of data. This is represented by a netfs_folio struct. This contains the offset and length of the modified region plus the otherwise displaced write grouping pointer. The way folio->private is multiplexed is: (1) If private is NULL then neither is in operation on a dirty folio. (2) If private is set, with bit 0 clear, then this points to a group. (3) If private is set, with bit 0 set, then this points to a netfs_folio struct (with bit 0 AND'ed out). Signed-off-by: David Howells cc: Jeff Layton cc: linux-cachefs@redhat.com cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org --- fs/netfs/internal.h | 28 ++++++++++++++++++++++++++ fs/netfs/misc.c | 46 +++++++++++++++++++++++++++++++++++++++++++ include/linux/netfs.h | 41 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 115 insertions(+) diff --git a/fs/netfs/internal.h b/fs/netfs/internal.h index 8d1bfc9c3e2f..1b83c534593a 100644 --- a/fs/netfs/internal.h +++ b/fs/netfs/internal.h @@ -149,6 +149,34 @@ static inline bool netfs_is_cache_enabled(struct netfs_inode *ctx) #endif } +/* + * Get a ref on a netfs group attached to a dirty page (e.g. a ceph snap). + */ +static inline struct netfs_group *netfs_get_group(struct netfs_group *netfs_group) +{ + if (netfs_group) + refcount_inc(&netfs_group->ref); + return netfs_group; +} + +/* + * Dispose of a netfs group attached to a dirty page (e.g. a ceph snap). + */ +static inline void netfs_put_group(struct netfs_group *netfs_group) +{ + if (netfs_group && refcount_dec_and_test(&netfs_group->ref)) + netfs_group->free(netfs_group); +} + +/* + * Dispose of a netfs group attached to a dirty page (e.g. a ceph snap). + */ +static inline void netfs_put_group_many(struct netfs_group *netfs_group, int nr) +{ + if (netfs_group && refcount_sub_and_test(nr, &netfs_group->ref)) + netfs_group->free(netfs_group); +} + /* * fscache-cache.c */ diff --git a/fs/netfs/misc.c b/fs/netfs/misc.c index 96014c3d1683..40421ced4cd3 100644 --- a/fs/netfs/misc.c +++ b/fs/netfs/misc.c @@ -177,9 +177,55 @@ EXPORT_SYMBOL(netfs_clear_inode_writeback); */ void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length) { + struct netfs_folio *finfo = NULL; + size_t flen = folio_size(folio); + _enter("{%lx},%zx,%zx", folio_index(folio), offset, length); folio_wait_fscache(folio); + + if (!folio_test_private(folio)) + return; + + finfo = netfs_folio_info(folio); + + if (offset == 0 && length >= flen) + goto erase_completely; + + if (finfo) { + /* We have a partially uptodate page from a streaming write. */ + unsigned int fstart = finfo->dirty_offset; + unsigned int fend = fstart + finfo->dirty_len; + unsigned int end = offset + length; + + if (offset >= fend) + return; + if (end <= fstart) + return; + if (offset <= fstart && end >= fend) + goto erase_completely; + if (offset <= fstart && end > fstart) + goto reduce_len; + if (offset > fstart && end >= fend) + goto move_start; + /* A partial write was split. The caller has already zeroed + * it, so just absorb the hole. + */ + } + return; + +erase_completely: + netfs_put_group(netfs_folio_group(folio)); + folio_detach_private(folio); + folio_clear_uptodate(folio); + kfree(finfo); + return; +reduce_len: + finfo->dirty_len = offset + length - finfo->dirty_offset; + return; +move_start: + finfo->dirty_len -= offset - finfo->dirty_offset; + finfo->dirty_offset = offset; } EXPORT_SYMBOL(netfs_invalidate_folio); diff --git a/include/linux/netfs.h b/include/linux/netfs.h index a14af93efccf..2406e11b41bd 100644 --- a/include/linux/netfs.h +++ b/include/linux/netfs.h @@ -140,6 +140,47 @@ struct netfs_inode { #define NETFS_ICTX_ODIRECT 0 /* The file has DIO in progress */ }; +/* + * A netfs group - for instance a ceph snap. This is marked on dirty pages and + * pages marked with a group must be flushed before they can be written under + * the domain of another group. + */ +struct netfs_group { + refcount_t ref; + void (*free)(struct netfs_group *netfs_group); +}; + +/* + * Information about a dirty page (attached only if necessary). + * folio->private + */ +struct netfs_folio { + struct netfs_group *netfs_group; /* Filesystem's grouping marker (or NULL). */ + unsigned int dirty_offset; /* Write-streaming dirty data offset */ + unsigned int dirty_len; /* Write-streaming dirty data length */ +}; +#define NETFS_FOLIO_INFO 0x1UL /* OR'd with folio->private. */ + +static inline struct netfs_folio *netfs_folio_info(struct folio *folio) +{ + void *priv = folio_get_private(folio); + + if ((unsigned long)priv & NETFS_FOLIO_INFO) + return (struct netfs_folio *)((unsigned long)priv & ~NETFS_FOLIO_INFO); + return NULL; +} + +static inline struct netfs_group *netfs_folio_group(struct folio *folio) +{ + struct netfs_folio *finfo; + void *priv = folio_get_private(folio); + + finfo = netfs_folio_info(folio); + if (finfo) + return finfo->netfs_group; + return priv; +} + /* * Resources required to do operations on a cache. */