From mboxrd@z Thu Jan 1 00:00:00 1970 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 63D6DC433FE for ; Thu, 30 Sep 2021 11:49:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4DD46619E1 for ; Thu, 30 Sep 2021 11:49:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350608AbhI3Lu6 (ORCPT ); Thu, 30 Sep 2021 07:50:58 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:54754 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350606AbhI3Lu6 (ORCPT ); Thu, 30 Sep 2021 07:50:58 -0400 Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 1577420018 for ; Thu, 30 Sep 2021 11:49:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1633002555; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=8RS4Br1m7XPMpVOrnwiC3H0hwuvS9thyPfvBHm+fNOI=; b=DdnuiDGc9RzZfai7WGYghRaFKe5xWYZZZHHGIZlgRcn2Wumx/ul2wRaAvXSwaSxe5mqeOk ojARPRrYS6vgOFJRr3sb5WDoZBj0XEQ1o8NBJbDC5i11CGscmHt75xXpJ7JFo56W1KArbs LJJEgLSOiSslYyeTNb0jEBQYKxN6iNM= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 696C113B05 for ; Thu, 30 Sep 2021 11:49:14 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 8HzqDDqkVWELJQAAMHmgww (envelope-from ) for ; Thu, 30 Sep 2021 11:49:14 +0000 From: Qu Wenruo To: linux-btrfs@vger.kernel.org Subject: [PATCH v2 1/2] btrfs-progs: receive: fallback to buffered copy if clone failed Date: Thu, 30 Sep 2021 19:48:54 +0800 Message-Id: <20210930114855.39225-2-wqu@suse.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210930114855.39225-1-wqu@suse.com> References: <20210930114855.39225-1-wqu@suse.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org [BUG] There are two very basic send streams: (a/m/ctime and uuid omitted) Stream 1: (Parent subvolume) subvol ./parent_subv transid=8 chown ./parent_subv/ gid=0 uid=0 chmod ./parent_subv/ mode=755 utimes ./parent_subv/ mkfile ./parent_subv/o257-7-0 rename ./parent_subv/o257-7-0 dest=./parent_subv/source utimes ./parent_subv/ write ./parent_subv/source offset=0 len=16384 chown ./parent_subv/source gid=0 uid=0 chmod ./parent_subv/source mode=600 utimes ./parent_subv/source Stream 2: (snapshot and clone) snapshot ./dest_subv transid=14 parent_transid=10 utimes ./dest_subv/ mkfile ./dest_subv/o258-14-0 rename ./dest_subv/o258-14-0 dest=./dest_subv/reflink utimes ./dest_subv/ clone ./dest_subv/reflink offset=0 len=16384 from=./dest_subv/source clone_offset=0 chown ./dest_subv/reflink gid=0 uid=0 chmod ./dest_subv/reflink mode=600 utimes ./dest_subv/reflink But if we receive the first stream with default mount, then remount to nodatasum, and try to receive the second stream, it will fail: # mount /mnt/btrfs # btrfs receive -f ~/parent_stream /mnt/btrfs/ At subvol parent_subv # mount -o remount,nodatasum /mnt/btrfs # btrfs receive -f ~/clone_stream /mnt/btrfs/ At snapshot dest_subv ERROR: failed to clone extents to reflink: Invalid argument # echo $? 1 [CAUSE] Btrfs doesn't allow clone source and destination files have different NODATASUM flags. This is to prevent a data extent to be owned by both NODATASUM inode and regular DATASUM inode. For above receive operations, the clone destination is inheriting the NODATASUM flag from mount option, while the clone source has no NODATASUM flag, thus preventing us from doing the clone. [FIX] Btrfs send/receive doesn't require the underlying inode has the same flags (thus we can send from compressed extent and receive on a non-compressed filesystem). So here we add a new command line option, '--clone-fallback', to allow btrfs-receive to fall back to buffered write to copy data from the source file. Since such behavior can result much less clone operations, which may not be what the end users really want, and can hide bugs in send stream. Thus this behavior must be explicitly specified by the new option. And we will output a warning message each time such fallback is triggered if the user wants extra debug output. Signed-off-by: Qu Wenruo --- Documentation/btrfs-receive.asciidoc | 12 ++++++ cmds/receive.c | 62 ++++++++++++++++++++++++++-- 2 files changed, 71 insertions(+), 3 deletions(-) diff --git a/Documentation/btrfs-receive.asciidoc b/Documentation/btrfs-receive.asciidoc index e4c4d2c0bf3d..9c934a399a9c 100644 --- a/Documentation/btrfs-receive.asciidoc +++ b/Documentation/btrfs-receive.asciidoc @@ -65,6 +65,18 @@ dump the stream metadata, one line per operation + Does not require the 'path' parameter. The filesystem remains unchanged. +--clone-fallback:: +when clone opeartions fail, attempt to directly copy the data instead. ++ +When the source and destination filesystems have different sector sizes, or +when source and destination files have differnt 'nodatacow' and/or 'nodatasum' +flags (can be set per-file or through mount options), clone operations can fail. ++ +This option makes the receive process attempt to manually copy data from the +source to the destination file when a clone operation fails (caused by above +reasons). When this happens, extents will end up not being shared +between the files, thus will take up more space. + -q|--quiet:: (deprecated) alias for global '-q' option diff --git a/cmds/receive.c b/cmds/receive.c index 48c774cea587..31746d571016 100644 --- a/cmds/receive.c +++ b/cmds/receive.c @@ -76,6 +76,8 @@ struct btrfs_receive struct subvol_uuid_search sus; int honor_end_cmd; + + bool clone_fallback; }; static int finish_subvol(struct btrfs_receive *rctx) @@ -705,6 +707,44 @@ out: return ret; } +static int buffered_copy(int src_fd, int dst_fd, u64 src_offset, u64 len, + u64 dest_offset) +{ + unsigned char buf[SZ_32K]; + u64 copied = 0; + int ret = 0; + + while (copied < len) { + u32 copy_len = min_t(u32, ARRAY_SIZE(buf), len - copied); + u32 written = 0; + ssize_t read_size; + + read_size = pread(src_fd, buf, copy_len, src_offset + copied); + if (read < 0) { + ret = -errno; + error("failed to read source file: %m"); + return ret; + } + + /* Write the buffer to dest file */ + while (written < read_size) { + ssize_t write_size; + + write_size = pwrite(dst_fd, buf + written, + read_size - written, + dest_offset + copied + written); + if (write_size < 0) { + ret = -errno; + error("failed to write source file: %m"); + return ret; + } + written += write_size; + } + copied += read_size; + } + return ret; +} + static int process_clone(const char *path, u64 offset, u64 len, const u8 *clone_uuid, u64 clone_ctransid, const char *clone_path, u64 clone_offset, @@ -788,8 +828,17 @@ static int process_clone(const char *path, u64 offset, u64 len, ret = ioctl(rctx->write_fd, BTRFS_IOC_CLONE_RANGE, &clone_args); if (ret < 0) { ret = -errno; - error("failed to clone extents to %s: %m", path); - goto out; + if (ret != -EINVAL || !rctx->clone_fallback) { + error("failed to clone extents to %s: %m", path); + goto out; + } + + if (bconf.verbose >= 2) + warning( + "failed to clone extents to %s, fallback to buffered write", + path); + ret = buffered_copy(clone_fd, rctx->write_fd, clone_offset, + len, offset); } out: @@ -1197,6 +1246,8 @@ static const char * const cmd_receive_usage[] = { " this file system is mounted.", "--dump dump stream metadata, one line per operation,", " does not require the MOUNT parameter", + "--clone-fallback when clone operations fail, attempt to directly copy" + " the data instead" "-v deprecated, alias for global -v option", HELPINFO_INSERT_GLOBALS, HELPINFO_INSERT_VERBOSE, @@ -1238,11 +1289,13 @@ static int cmd_receive(const struct cmd_struct *cmd, int argc, char **argv) optind = 0; while (1) { int c; - enum { GETOPT_VAL_DUMP = 257 }; + enum { GETOPT_VAL_DUMP = 257, GETOPT_VAL_CLONE_FALLBACK }; static const struct option long_opts[] = { { "max-errors", required_argument, NULL, 'E' }, { "chroot", no_argument, NULL, 'C' }, { "dump", no_argument, NULL, GETOPT_VAL_DUMP }, + { "clone-fallback", no_argument, NULL, + GETOPT_VAL_CLONE_FALLBACK}, { "quiet", no_argument, NULL, 'q' }, { NULL, 0, NULL, 0 } }; @@ -1286,6 +1339,9 @@ static int cmd_receive(const struct cmd_struct *cmd, int argc, char **argv) case GETOPT_VAL_DUMP: dump = 1; break; + case GETOPT_VAL_CLONE_FALLBACK: + rctx.clone_fallback = true; + break; default: usage_unknown_option(cmd, argv); } -- 2.33.0