- added experimental bcachefs support

LIBVERSION

@@ -1 +1 @@
-7.4.0
+7.4.1

configure.ac

@@ -77,6 +77,14 @@ if test "x$with_btrfs" = "xyes"; then
 	AC_DEFINE(ENABLE_BTRFS, 1, [Enable Btrfs internal snapshots support])
 fi
 
+AC_ARG_ENABLE([bcachefs], AS_HELP_STRING([--disable-bcachefs], [Disable Bcachefs internal snapshots support]),
+		[with_bcachefs=$enableval], [with_bcachefs=yes])
+AM_CONDITIONAL(ENABLE_BCACHEFS, [test "x$with_bcachefs" = "xyes"])
+
+if test "x$with_bcachefs" = "xyes"; then
+	AC_DEFINE(ENABLE_BCACHEFS, 1, [Enable Bcachefs internal snapshots support])
+fi
+
 AC_ARG_ENABLE([ext4], AS_HELP_STRING([--disable-ext4], [Disable ext4 snapshots support]),
 		[with_ext4=$enableval], [with_ext4=yes])
 AM_CONDITIONAL(ENABLE_EXT4, [test "x$with_ext4" = "xyes"])

dists/debian/rules

@@ -16,8 +16,8 @@ endif
 
 override_dh_auto_configure:
 	dh_auto_configure -- --docdir=/usr/share/doc/packages/snapper --disable-silent-rules	\
-	  --disable-ext4 --enable-xattrs --disable-rollback --disable-btrfs-quota		\
-	  --with-pam-security=/lib/security
+	  --disable-bcachefs --disable-ext4 --enable-xattrs --disable-rollback			\
+	  --disable-btrfs-quota --with-pam-security=/lib/security
 
 override_dh_auto_install:
 	dh_auto_install

doc/bcachefs.txt

@@ -0,0 +1,14 @@
+
+bcachefs support is experimental
+
+TODOs (at least):
+
+- ioctl for snapshot creation takes path instead of fd
+
+- read-only snapshots not supported by bcachefs
+  - background comparison started anyway
+
+- check if a directory is a snapshot
+
+- get ioctl defines from a header file or use a library
+

package/snapper.changes

@@ -1,3 +1,8 @@
+-------------------------------------------------------------------
+Wed Feb 14 09:14:32 CET 2024 - [email protected]
+
+- added experimental bcachefs support (gh#openSUSE/snapper#858)
+
 -------------------------------------------------------------------
 Wed Feb 07 11:16:40 CET 2024 - [email protected]
 

server/Client.cc

@@ -1081,7 +1081,11 @@ Client::create_post_snapshot(DBus::Connection& conn, DBus::Message& msg)
     bool background_comparison = true;
     it->getConfigInfo().get_value("BACKGROUND_COMPARISON", background_comparison);
     if (background_comparison)
-	clients.backgrounds().add_task(it, snap1, snap2);
+    {
+	// TODO isReadOnly is wrong if read-only is not supported by file system
+	if (snap1->isReadOnly() && snap2->isReadOnly())
+	    clients.backgrounds().add_task(it, snap1, snap2);
+    }
 
     DBus::MessageMethodReturn reply(msg);
 

snapper.spec.in

@@ -143,7 +143,7 @@ autoreconf -fvi
 	--disable-btrfs-quota							\
 %endif
 	%{?with_selinux:--enable-selinux}					\
-	--disable-silent-rules --disable-ext4
+	--disable-silent-rules --disable-bcachefs --disable-ext4
 make %{?_smp_mflags}
 
 %install

snapper/Bcachefs.cc

@@ -0,0 +1,323 @@
+/*
+ * Copyright (c) 2024 SUSE LLC
+ *
+ * All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2 of the GNU General Public License as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, contact Novell, Inc.
+ *
+ * To contact Novell about this file by physical or electronic mail, you may
+ * find current contact information at www.novell.com.
+ */
+
+
+#include "config.h"
+
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include "snapper/Log.h"
+#include "snapper/Bcachefs.h"
+#include "snapper/BcachefsUtils.h"
+#include "snapper/File.h"
+#include "snapper/Snapper.h"
+#include "snapper/SnapperTmpl.h"
+
+#include "snapper/Acls.h"
+#include "snapper/Exception.h"
+#ifdef ENABLE_SELINUX
+#include "snapper/Selinux.h"
+#endif
+
+
+namespace snapper
+{
+    using namespace std;
+
+    using namespace BcachefsUtils;
+
+
+    Filesystem*
+    Bcachefs::create(const string& fstype, const string& subvolume, const string& root_prefix)
+    {
+	if (fstype == "bcachefs")
+	    return new Bcachefs(subvolume, root_prefix);
+
+	return nullptr;
+    }
+
+
+    Bcachefs::Bcachefs(const string& subvolume, const string& root_prefix)
+	: Filesystem(subvolume, root_prefix)
+    {
+    }
+
+
+    void
+    Bcachefs::createConfig() const
+    {
+	SDir subvolume_dir = openSubvolumeDir();
+
+	try
+	{
+	    create_subvolume(subvolume_dir.fd(), ".snapshots");
+	}
+	catch (const runtime_error_with_errno& e)
+	{
+	    y2err("create subvolume failed, " << e.what());
+
+	    switch (e.error_number)
+	    {
+		case EEXIST:
+		    SN_THROW(CreateConfigFailedException("creating bcachefs subvolume .snapshots failed "
+							 "since it already exists"));
+		    break;
+
+		default:
+		    SN_THROW(CreateConfigFailedException("creating bcachefs subvolume .snapshots failed"));
+	    }
+	}
+
+	SFile x(subvolume_dir, ".snapshots");
+
+#ifdef ENABLE_SELINUX
+	try
+	{
+	    SnapperContexts scontexts;
+
+	    x.fsetfilecon(scontexts.subvolume_context());
+	}
+	catch (const SelinuxException& e)
+	{
+	    SN_CAUGHT(e);
+	    // fall through intentional
+	}
+#endif
+
+	struct stat stat;
+	if (x.stat(&stat, 0) == 0)
+	    x.chmod(stat.st_mode & ~0027, 0);
+    }
+
+
+    void
+    Bcachefs::deleteConfig() const
+    {
+	SDir subvolume_dir = openSubvolumeDir();
+
+	try
+	{
+	    delete_subvolume(subvolume_dir.fd(), ".snapshots");
+	}
+	catch (const runtime_error& e)
+	{
+	    y2err("delete subvolume failed, " << e.what());
+	    SN_THROW(DeleteConfigFailedException("deleting bcachefs snapshot failed"));
+	}
+    }
+
+
+    string
+    Bcachefs::snapshotDir(unsigned int num) const
+    {
+	return (subvolume == "/" ? "" : subvolume) + "/.snapshots/" + decString(num) +
+	    "/snapshot";
+    }
+
+
+    SDir
+    Bcachefs::openSubvolumeDir() const
+    {
+	SDir subvolume_dir = Filesystem::openSubvolumeDir();
+
+	struct stat stat;
+	if (subvolume_dir.stat(&stat) != 0)
+	{
+	    SN_THROW(IOErrorException("stat on subvolume directory failed"));
+	}
+
+	if (!is_subvolume(stat))
+	{
+	    SN_THROW(IOErrorException("subvolume is not a bcachefs subvolume"));
+	}
+
+	return subvolume_dir;
+    }
+
+
+    SDir
+    Bcachefs::openInfosDir() const
+    {
+	SDir subvolume_dir = openSubvolumeDir();
+	SDir infos_dir(subvolume_dir, ".snapshots");
+
+	struct stat stat;
+	if (infos_dir.stat(&stat) != 0)
+	{
+	    SN_THROW(IOErrorException("stat on info directory failed"));
+	}
+
+	if (!is_subvolume(stat))
+	{
+	    SN_THROW(IOErrorException(".snapshots is not a bcachefs subvolume"));
+	}
+
+	if (stat.st_uid != 0)
+	{
+	    y2err(".snapshots must have owner root");
+	    SN_THROW(IOErrorException(".snapshots must have owner root"));
+	}
+
+	if (stat.st_gid != 0 && stat.st_mode & S_IWGRP)
+	{
+	    y2err(".snapshots must have group root or must not be group-writable");
+	    SN_THROW(IOErrorException(".snapshots must have group root or must not be group-writable"));
+	}
+
+	if (stat.st_mode & S_IWOTH)
+	{
+	    y2err(".snapshots must not be world-writable");
+	    SN_THROW(IOErrorException(".snapshots must not be world-writable"));
+	}
+
+	return infos_dir;
+    }
+
+
+    SDir
+    Bcachefs::openSnapshotDir(unsigned int num) const
+    {
+	SDir info_dir = openInfoDir(num);
+	SDir snapshot_dir(info_dir, "snapshot");
+
+	return snapshot_dir;
+    }
+
+
+    void
+    Bcachefs::createSnapshot(unsigned int num, unsigned int num_parent, bool read_only, bool quota,
+			     bool empty) const
+    {
+	if (num_parent == 0)
+	{
+	    SDir subvolume_dir = openSubvolumeDir();
+	    SDir info_dir = openInfoDir(num);
+
+	    try
+	    {
+		if (empty)
+		    create_subvolume(info_dir.fd(), "snapshot");
+		else
+		    create_snapshot(subvolume_dir.fd(), subvolume, info_dir.fd(), "snapshot", read_only);
+	    }
+	    catch (const runtime_error& e)
+	    {
+		y2err("create snapshot failed, " << e.what());
+		SN_THROW(CreateSnapshotFailedException());
+	    }
+	}
+	else
+	{
+	    SDir snapshot_dir = openSnapshotDir(num_parent);
+	    SDir info_dir = openInfoDir(num);
+
+	    try
+	    {
+		create_snapshot(snapshot_dir.fd(), subvolume, info_dir.fd(), "snapshot", read_only);
+	    }
+	    catch (const runtime_error& e)
+	    {
+		y2err("create snapshot failed, " << e.what());
+		SN_THROW(CreateSnapshotFailedException());
+	    }
+	}
+    }
+
+
+    void
+    Bcachefs::deleteSnapshot(unsigned int num) const
+    {
+	SDir info_dir = openInfoDir(num);
+
+	try
+	{
+	    delete_subvolume(info_dir.fd(), "snapshot");
+	}
+	catch (const runtime_error& e)
+	{
+	    y2err("delete snapshot failed, " << e.what());
+	    SN_THROW(DeleteSnapshotFailedException());
+	}
+    }
+
+
+    bool
+    Bcachefs::isSnapshotMounted(unsigned int num) const
+    {
+	return true;
+    }
+
+
+    void
+    Bcachefs::mountSnapshot(unsigned int num) const
+    {
+    }
+
+
+    void
+    Bcachefs::umountSnapshot(unsigned int num) const
+    {
+    }
+
+
+    bool
+    Bcachefs::isSnapshotReadOnly(unsigned int num) const
+    {
+	SDir snapshot_dir = openSnapshotDir(num);
+	return is_subvolume_read_only(snapshot_dir.fd());
+    }
+
+
+    void
+    Bcachefs::setSnapshotReadOnly(unsigned int num, bool read_only) const
+    {
+	SDir snapshot_dir = openSnapshotDir(num);
+	set_subvolume_read_only(snapshot_dir.fd(), read_only);
+    }
+
+
+    bool
+    Bcachefs::checkSnapshot(unsigned int num) const
+    {
+	try
+	{
+	    SDir info_dir = openInfoDir(num);
+
+	    struct stat stat;
+	    int r = info_dir.stat("snapshot", &stat, AT_SYMLINK_NOFOLLOW);
+	    return r == 0 && is_subvolume(stat);
+	}
+	catch (const IOErrorException& e)
+	{
+	    SN_CAUGHT(e);
+
+	    // TODO the openInfoDir above logs an error although when this
+	    // function is used from nextNumber the failure is ok
+
+	    return false;
+	}
+    }
+
+}