From patchwork Mon Aug 9 03:55:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 12425369 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B01D3C4320E for ; Mon, 9 Aug 2021 03:58:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 970B76101C for ; Mon, 9 Aug 2021 03:58:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232979AbhHID6z (ORCPT ); Sun, 8 Aug 2021 23:58:55 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:58014 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232975AbhHID6y (ORCPT ); Sun, 8 Aug 2021 23:58:54 -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 EF38E1FD81; Mon, 9 Aug 2021 03:58:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1628481513; h=from:from:reply-to: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=G0ibLBgniy8dCGHqoQUyeVYBRb/qOQupZTOIJDvgt2g=; b=wk060BaOhIZOXaR0QlITcFG7NDUq3rpdEZmceRtUc2s0dQyTHZsNc/2/knOfoV02wFTHxq 810lLyD7rnBbSoTrs7UnIJTXy/1W3DmHweCz0r8/v8mHHYUjmkjtKlQbije9IFgQ9X6Fc1 mSGOI1ul62Vo/e/HyywTWmgrM7nBQjc= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1628481513; h=from:from:reply-to: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=G0ibLBgniy8dCGHqoQUyeVYBRb/qOQupZTOIJDvgt2g=; b=YzxzSz0ZacRppfs06O0PP5e2MS9+UCD9f4binoggxaCxVjU7n5Uiq+U0aMnOTCHM8mSRnO b8OGCnPzWnPEaBBg== 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 320BE13A9F; Mon, 9 Aug 2021 03:58:30 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id wB06OOanEGHZBgAAMHmgww (envelope-from ); Mon, 09 Aug 2021 03:58:30 +0000 Subject: [PATCH 3/4] VFS/btrfs: add STATX_TREE_ID From: NeilBrown To: Josef Bacik , Chris Mason , David Sterba Cc: linux-fsdevel@vger.kernel.org, Linux NFS list , Btrfs BTRFS Date: Mon, 09 Aug 2021 13:55:27 +1000 Message-ID: <162848132775.25823.2813836616908535300.stgit@noble.brown> In-Reply-To: <162848123483.25823.15844774651164477866.stgit@noble.brown> References: <162848123483.25823.15844774651164477866.stgit@noble.brown> User-Agent: StGit/0.23 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org A new 64bit field is added to the data that can be returned by statx() - the "tree id". The tree id serves two needs. 1/ it extends the available inode number space. While a filesystem SHOULD ensure the inode number is unique across the filesystem, this is sometimes impractical. In such situations, 'tree id' may be used to guarantee uniqueness. It can identify a separate allocation domain. A particular case when separate allocation domains is useful is when a directory tree can be effectively "reflink"ed. Updating all inode numbers in such a tree is prohibitively expensive. 2/ it can identify a collection of objects that provide a coherent "tree" in some locally-defined sense. This patch uses STATX_TREE_ID to export the subvol id for btrfs. samples/vfs/test_statx.c is extended to report the treeid. Also: a new superblock field is added: s_tree_id_bits. This can store the number of significant bits in the reported treeid. It is currently unused, but could be used by overlayfs to determine how to add a filesystem number to the treeid to differentiate files in different underlying filesystems. Signed-off-by: NeilBrown --- fs/btrfs/inode.c | 4 ++++ fs/btrfs/super.c | 1 + fs/stat.c | 1 + include/linux/fs.h | 2 +- include/linux/stat.h | 13 +++++++++++++ include/uapi/linux/stat.h | 3 ++- samples/vfs/test-statx.c | 4 +++- 7 files changed, 25 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 30fa64cbe6dc..c878726d090c 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -9215,6 +9215,10 @@ static int btrfs_getattr(struct user_namespace *mnt_userns, case BTRFS_MANY_DEVS: stat->dev = BTRFS_I(inode)->root->anon_dev; } + if (request_mask & STATX_TREE_ID) { + stat->tree_id = BTRFS_I(inode)->root->root_key.objectid; + stat->result_mask |= STATX_TREE_ID; + } spin_lock(&BTRFS_I(inode)->lock); delalloc_bytes = BTRFS_I(inode)->new_delalloc_bytes; diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index b1aecb834234..e6d166150660 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -1410,6 +1410,7 @@ static int btrfs_fill_super(struct super_block *sb, #endif sb->s_flags |= SB_I_VERSION; sb->s_iflags |= SB_I_CGROUPWB; + sb->s_tree_id_bits = 48; err = super_setup_bdi(sb); if (err) { diff --git a/fs/stat.c b/fs/stat.c index 1fa38bdec1a6..2dd5d3d67793 100644 --- a/fs/stat.c +++ b/fs/stat.c @@ -580,6 +580,7 @@ cp_statx(const struct kstat *stat, struct statx __user *buffer) tmp.stx_dev_major = MAJOR(stat->dev); tmp.stx_dev_minor = MINOR(stat->dev); tmp.stx_mnt_id = stat->mnt_id; + tmp.stx_tree_id = stat->tree_id; return copy_to_user(buffer, &tmp, sizeof(tmp)) ? -EFAULT : 0; } diff --git a/include/linux/fs.h b/include/linux/fs.h index 640574294216..a777c1b1706a 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1482,7 +1482,7 @@ struct super_block { unsigned int s_max_links; fmode_t s_mode; - + short s_tree_id_bits; /* * The next field is for VFS *only*. No filesystems have any business * even looking at it. You had been warned. diff --git a/include/linux/stat.h b/include/linux/stat.h index fff27e603814..08ee409786b3 100644 --- a/include/linux/stat.h +++ b/include/linux/stat.h @@ -46,6 +46,19 @@ struct kstat { struct timespec64 btime; /* File creation time */ u64 blocks; u64 mnt_id; + /* Treeid can be used to extend the inode number space. Two inodes + * with different 'tree_id' are different, even if 'ino' is the same + * (though fs should make ino different as often as possible). + * When tree_id is requested and STATX_TREE_ID is set in result_mask, + * 'ino' MUST be unique across the filesystem. Specifically, two + * open files that report the same dev, ino, and tree_id MUST be + * the same. + * If a directory and an object in that directory have the same dev + * and tree_id, they can be assumed to be in a meaningful tree, though + * the meaning is subject to local interpretation. The set of inodes + * with a common tree_id is not required to be contiguous. + */ + u64 tree_id; }; #endif diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h index 1500a0f58041..725cf3f8e873 100644 --- a/include/uapi/linux/stat.h +++ b/include/uapi/linux/stat.h @@ -124,7 +124,7 @@ struct statx { __u32 stx_dev_minor; /* 0x90 */ __u64 stx_mnt_id; - __u64 __spare2; + __u64 stx_tree_id; /* 0xa0 */ __u64 __spare3[12]; /* Spare space for future expansion */ /* 0x100 */ @@ -152,6 +152,7 @@ struct statx { #define STATX_BASIC_STATS 0x000007ffU /* The stuff in the normal stat struct */ #define STATX_BTIME 0x00000800U /* Want/got stx_btime */ #define STATX_MNT_ID 0x00001000U /* Got stx_mnt_id */ +#define STATX_TREE_ID 0x00002000U /* Want/got stx_treeid and clean stX_ino */ #define STATX__RESERVED 0x80000000U /* Reserved for future struct statx expansion */ diff --git a/samples/vfs/test-statx.c b/samples/vfs/test-statx.c index 49c7a46cee07..c1141764fa2e 100644 --- a/samples/vfs/test-statx.c +++ b/samples/vfs/test-statx.c @@ -118,6 +118,8 @@ static void dump_statx(struct statx *stx) break; } } + if (stx->stx_mask & STATX_TREE_ID) + printf(" Tree: %-12llu", (unsigned long long) stx->stx_tree_id); printf("\n"); if (stx->stx_mask & STATX_MODE) @@ -218,7 +220,7 @@ int main(int argc, char **argv) struct statx stx; int ret, raw = 0, atflag = AT_SYMLINK_NOFOLLOW; - unsigned int mask = STATX_BASIC_STATS | STATX_BTIME; + unsigned int mask = STATX_BASIC_STATS | STATX_BTIME | STATX_TREE_ID; for (argv++; *argv; argv++) { if (strcmp(*argv, "-F") == 0) {