[PATCH 0/3] strace: Add support for Btrfs ioctls

[PATCH 0/3] strace: Add support for Btrfs ioctls

[Filipe Brandenburger]

Hi,

This is a patch to strace!!! Not btrfs-next or btrfs-progs. I just wanted to
circulate it on this list before submitting it to the strace maintainers.

It also depends on "[PATCH] Btrfs: move fs/btrfs/ioctl.h to
include/uapi/linux/btrfs.h" being committed as that's what will export
linux/btrfs.h to userspace and this patch to strace depends on that file.

I added a patch decoding a specific ioctl to have an idea of whether the output
format is good or should be tweaked differently. I opted to be a bit more
verbose but increase readability. I also ended up deciding to truncate the
output to show at most 10 results, not sure if that's OK or should be
configurable somewhere (maybe I can tap into strace's "-s" parameter to
estimate the size of output allowable?)

Without the patch:

    $ strace -e ioctl btrfs fi df .
    ioctl(3, 0xc0109414, 0x195b040)         = 0
    ioctl(3, 0xc0109414, 0x195b040)         = 0
    Data: total=1.01GB, used=4.87MB
    System, DUP: total=8.00MB, used=4.00KB
    System: total=4.00MB, used=0.00
    Metadata, DUP: total=1.75GB, used=1.38GB
    Metadata: total=8.00MB, used=0.00
    +++ exited with 0 +++


With the patch:

    $ strace -e ioctl btrfs fi df .
    ioctl(3, BTRFS_IOC_SPACE_INFO, {space_slots=0, total_spaces=5}) = 0
    ioctl(3, BTRFS_IOC_SPACE_INFO, {space_slots=5, total_spaces=5, spaces={[0]={flags=0x1 /* BTRFS_BLOCK_GROUP_DATA */, total_bytes=1081999360, used_bytes=5107712}, [1]={flags=0x22 /* BTRFS_BLOCK_GROUP_SYSTEM|BTRFS_BLOCK_GROUP_DUP */, total_bytes=8388608, used_bytes=4096}, [2]={flags=0x2 /* BTRFS_BLOCK_GROUP_SYSTEM */, total_bytes=4194304, used_bytes=0}, [3]={flags=0x24 /* BTRFS_BLOCK_GROUP_METADATA|BTRFS_BLOCK_GROUP_DUP */, total_bytes=1878982656, used_bytes=1485590528}, [4]={flags=0x4 /* BTRFS_BLOCK_GROUP_METADATA */, total_bytes=8388608, used_bytes=0}}}) = 0
    Data: total=1.01GB, used=4.87MB
    System, DUP: total=8.00MB, used=4.00KB
    System: total=4.00MB, used=0.00
    Metadata, DUP: total=1.75GB, used=1.38GB
    Metadata: total=8.00MB, used=0.00
    +++ exited with 0 +++


Any comments? Or do you think this is good enough? Before submitting to the
strace project I'd like to review the constants and structs that need to be in
linux/btrfs.h and move them there (which should be further commits to
btrfs-next) so that I don't need to duplicate them there, but before I do that
I'd like to have some feedback if you think this is the right approach.

Thanks!
Filipe


Filipe Brandenburger (3):
  Add support for Btrfs ioctls: decode them by name
  Add support for Btrfs ioctls: infrastructure to decode ioctl structs
  Add support for Btrfs ioctls: BTRFS_IOC_SPACE_INFO (filesystem df)

 Makefile.am         |   2 +-
 btrfs.c             | 159 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 configure.ac        |   1 +
 defs.h              |   1 +
 ioctl.c             |   2 +
 linux/ioctlent.h.in |  44 +++++++++++++++
 6 files changed, 208 insertions(+), 1 deletion(-)
 create mode 100644 btrfs.c

-- 
1.7.11.7

[PATCH 1/3] Add support for Btrfs ioctls: decode them by name

[Filipe Brandenburger]

This patch will include Btrfs-specific ioctls from linux/btrfs.h into
ioctlent.h.in so that they get translated by strace. That's useful for using
strace to debug the tools in btrfs-progs.

Signed-off-by: Filipe Brandenburger <filbranden@google.com>
---
 linux/ioctlent.h.in | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/linux/ioctlent.h.in b/linux/ioctlent.h.in
index 8843b47..06a5300 100644
--- a/linux/ioctlent.h.in
+++ b/linux/ioctlent.h.in
@@ -1825,6 +1825,50 @@
 	{"linux/auto_fs4.h",	"AUTOFS_IOC_EXPIRE_MULTI",	0x9366},
 	{"linux/auto_fs4.h",	"AUTOFS_IOC_PROTOSUBVER",	0x9367},
 	{"linux/auto_fs4.h",	"AUTOFS_IOC_ASKUMOUNT",	0x9370},
+	{"linux/btrfs.h",	"BTRFS_IOC_SNAP_CREATE",	0x9401},
+	{"linux/btrfs.h",	"BTRFS_IOC_DEFRAG",	0x9402},
+	{"linux/btrfs.h",	"BTRFS_IOC_RESIZE",	0x9403},
+	{"linux/btrfs.h",	"BTRFS_IOC_SCAN_DEV",	0x9404},
+	{"linux/btrfs.h",	"BTRFS_IOC_TRANS_START",	0x9406},
+	{"linux/btrfs.h",	"BTRFS_IOC_TRANS_END",	0x9407},
+	{"linux/btrfs.h",	"BTRFS_IOC_SYNC",	0x9408},
+	{"linux/btrfs.h",	"BTRFS_IOC_CLONE",	0x9409},
+	{"linux/btrfs.h",	"BTRFS_IOC_ADD_DEV",	0x940a},
+	{"linux/btrfs.h",	"BTRFS_IOC_RM_DEV",	0x940b},
+	{"linux/btrfs.h",	"BTRFS_IOC_BALANCE",	0x940c},
+	{"linux/btrfs.h",	"BTRFS_IOC_CLONE_RANGE",	0x940d},
+	{"linux/btrfs.h",	"BTRFS_IOC_SUBVOL_CREATE",	0x940e},
+	{"linux/btrfs.h",	"BTRFS_IOC_SNAP_DESTROY",	0x940f},
+	{"linux/btrfs.h",	"BTRFS_IOC_DEFRAG_RANGE",	0x9410},
+	{"linux/btrfs.h",	"BTRFS_IOC_TREE_SEARCH",	0x9411},
+	{"linux/btrfs.h",	"BTRFS_IOC_INO_LOOKUP",	0x9412},
+	{"linux/btrfs.h",	"BTRFS_IOC_DEFAULT_SUBVOL",	0x9413},
+	{"linux/btrfs.h",	"BTRFS_IOC_SPACE_INFO",	0x9414},
+	{"linux/btrfs.h",	"BTRFS_IOC_WAIT_SYNC",	0x9416},
+	{"linux/btrfs.h",	"BTRFS_IOC_SNAP_CREATE_V2",	0x9417},
+	{"linux/btrfs.h",	"BTRFS_IOC_START_SYNC",	0x9418},
+	{"linux/btrfs.h",	"BTRFS_IOC_SUBVOL_CREATE_V2",	0x9418},
+	{"linux/btrfs.h",	"BTRFS_IOC_SUBVOL_GETFLAGS",	0x9419},
+	{"linux/btrfs.h",	"BTRFS_IOC_SUBVOL_SETFLAGS",	0x941a},
+	{"linux/btrfs.h",	"BTRFS_IOC_SCRUB",	0x941b},
+	{"linux/btrfs.h",	"BTRFS_IOC_SCRUB_CANCEL",	0x941c},
+	{"linux/btrfs.h",	"BTRFS_IOC_SCRUB_PROGRESS",	0x941d},
+	{"linux/btrfs.h",	"BTRFS_IOC_DEV_INFO",	0x941e},
+	{"linux/btrfs.h",	"BTRFS_IOC_FS_INFO",	0x941f},
+	{"linux/btrfs.h",	"BTRFS_IOC_BALANCE_V2",	0x9420},
+	{"linux/btrfs.h",	"BTRFS_IOC_BALANCE_CTL",	0x9421},
+	{"linux/btrfs.h",	"BTRFS_IOC_BALANCE_PROGRESS",	0x9422},
+	{"linux/btrfs.h",	"BTRFS_IOC_INO_PATHS",	0x9423},
+	{"linux/btrfs.h",	"BTRFS_IOC_LOGICAL_INO",	0x9424},
+	{"linux/btrfs.h",	"BTRFS_IOC_SET_RECEIVED_SUBVOL",	0x9425},
+	{"linux/btrfs.h",	"BTRFS_IOC_SEND",	0x9426},
+	{"linux/btrfs.h",	"BTRFS_IOC_DEVICES_READY",	0x9427},
+	{"linux/btrfs.h",	"BTRFS_IOC_QUOTA_CTL",	0x9428},
+	{"linux/btrfs.h",	"BTRFS_IOC_QGROUP_ASSIGN",	0x9429},
+	{"linux/btrfs.h",	"BTRFS_IOC_QGROUP_CREATE",	0x942a},
+	{"linux/btrfs.h",	"BTRFS_IOC_QGROUP_LIMIT",	0x942b},
+	{"linux/btrfs.h",	"BTRFS_IOC_GET_DEV_STATS",	0x9434},
+	{"linux/btrfs.h",	"BTRFS_IOC_DEV_REPLACE",	0x9435},
 	{"linux/nbd.h",	"NBD_SET_SOCK",	0xab00},
 	{"linux/nbd.h",	"NBD_SET_BLKSIZE",	0xab01},
 	{"linux/nbd.h",	"NBD_SET_SIZE",	0xab02},
-- 
1.7.11.7

[PATCH 2/3] Add support for Btrfs ioctls: infrastructure to decode ioctl structs

[Filipe Brandenburger]

This adds a new btrfs_ioctl() function that can be used to decode Btrfs structs
from Btrfs-specific ioctls. It adds a new case to ioctl_decode() to handle
Btrfs ioctls.

This adds autoconf detection of header file linux/btrfs.h so that the code can
be disabled when the header is not present.

Signed-off-by: Filipe Brandenburger <filbranden@google.com>
---
 Makefile.am  |  2 +-
 btrfs.c      | 39 +++++++++++++++++++++++++++++++++++++++
 configure.ac |  1 +
 defs.h       |  1 +
 ioctl.c      |  2 ++
 5 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 btrfs.c

diff --git a/Makefile.am b/Makefile.am
index aa1a5f4..fe809b8 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -18,7 +18,7 @@ strace_SOURCES = strace.c syscall.c count.c util.c desc.c file.c ipc.c \
 		 io.c ioctl.c mem.c net.c process.c bjm.c quota.c \
 		 resource.c signal.c sock.c system.c term.c time.c \
 		 scsi.c stream.c block.c pathtrace.c mtd.c vsprintf.c \
-		 loop.c
+		 loop.c btrfs.c
 noinst_HEADERS = defs.h
 
 EXTRA_DIST = $(man_MANS) errnoent.sh signalent.sh syscallent.sh ioctlsort.c \
diff --git a/btrfs.c b/btrfs.c
new file mode 100644
index 0000000..a4895e4
--- /dev/null
+++ b/btrfs.c
@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2013 Filipe Brandenburger <filbranden@google.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "defs.h"
+#include <sys/ioctl.h>
+
+#ifdef HAVE_LINUX_BTRFS_H
+#include <linux/btrfs.h>
+#endif /* HAVE_LINUX_BTRFS_H */
+
+int
+btrfs_ioctl(struct tcb *tcp, long code, long arg)
+{
+	return 0;
+}
diff --git a/configure.ac b/configure.ac
index f44eaf1..9021fe1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -222,6 +222,7 @@ AC_CHECK_HEADERS([asm/sigcontext.h], [], [], [#include <signal.h>])
 AC_CHECK_TYPES([struct sigcontext_struct,
 		struct sigcontext],,, [#include <signal.h>])
 AC_CHECK_HEADERS([netinet/tcp.h netinet/udp.h],,, [#include <netinet/in.h>])
+AC_CHECK_HEADERS([linux/btrfs.h])
 
 AC_CHECK_MEMBERS([struct msghdr.msg_control],,, [#include <sys/socket.h>])
 
diff --git a/defs.h b/defs.h
index 0e05c6e..9270786 100644
--- a/defs.h
+++ b/defs.h
@@ -631,6 +631,7 @@ extern int scsi_ioctl(struct tcb *, long, long);
 extern int block_ioctl(struct tcb *, long, long);
 extern int mtd_ioctl(struct tcb *, long, long);
 extern int loop_ioctl(struct tcb *, long, long);
+extern int btrfs_ioctl(struct tcb *, long, long);
 
 extern int tv_nz(struct timeval *);
 extern int tv_cmp(struct timeval *, struct timeval *);
diff --git a/ioctl.c b/ioctl.c
index 323946d..6c39fc0 100644
--- a/ioctl.c
+++ b/ioctl.c
@@ -92,6 +92,8 @@ ioctl_decode(struct tcb *tcp, long code, long arg)
 		return loop_ioctl(tcp, code, arg);
 	case 'M':
 		return mtd_ioctl(tcp, code, arg);
+	case 0x94:
+		return btrfs_ioctl(tcp, code, arg);
 	default:
 		break;
 	}
-- 
1.7.11.7

[PATCH 3/3] Add support for Btrfs ioctls: BTRFS_IOC_SPACE_INFO (filesystem df)

[Filipe Brandenburger]

This adds support for the BTRFS_IOC_SPACE_INFO (used by `btrfs filesystem df')
by parsing the struct passed by userspace to the kernel and interpreting the
output fields filled in by kernel code.

TODO: Some constants are defined in the C file because they're not currently
present in linux/btrfs.h, but they should be moved to that file in Btrfs source
code so that they can be used by userspace programs that need those constants.

Signed-off-by: Filipe Brandenburger <filbranden@google.com>
---
 btrfs.c | 120 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 120 insertions(+)

diff --git a/btrfs.c b/btrfs.c
index a4895e4..799ae46 100644
--- a/btrfs.c
+++ b/btrfs.c
@@ -30,10 +30,130 @@
 
 #ifdef HAVE_LINUX_BTRFS_H
 #include <linux/btrfs.h>
+
+/* TODO: in btrfs source code, these are currently in ctree.h, must be moved to btrfs.h */
+#ifndef BTRFS_BLOCK_GROUP_DATA
+#define BTRFS_BLOCK_GROUP_DATA          (1ULL << 0)
+#define BTRFS_BLOCK_GROUP_SYSTEM        (1ULL << 1)
+#define BTRFS_BLOCK_GROUP_METADATA      (1ULL << 2)
+#define BTRFS_BLOCK_GROUP_RAID0         (1ULL << 3)
+#define BTRFS_BLOCK_GROUP_RAID1         (1ULL << 4)
+#define BTRFS_BLOCK_GROUP_DUP           (1ULL << 5)
+#define BTRFS_BLOCK_GROUP_RAID10        (1ULL << 6)
+#endif /* BTRFS_BLOCK_GROUP_DATA */
+
+static const struct xlat btrfs_space_info_flags[] = {
+	{BTRFS_BLOCK_GROUP_DATA,        "BTRFS_BLOCK_GROUP_DATA"},
+	{BTRFS_BLOCK_GROUP_SYSTEM,      "BTRFS_BLOCK_GROUP_SYSTEM"},
+	{BTRFS_BLOCK_GROUP_METADATA,    "BTRFS_BLOCK_GROUP_METADATA"},
+	{BTRFS_BLOCK_GROUP_RAID0,       "BTRFS_BLOCK_GROUP_RAID0"},
+	{BTRFS_BLOCK_GROUP_RAID1,       "BTRFS_BLOCK_GROUP_RAID1"},
+	{BTRFS_BLOCK_GROUP_DUP,         "BTRFS_BLOCK_GROUP_DUP"},
+	{BTRFS_BLOCK_GROUP_RAID10,      "BTRFS_BLOCK_GROUP_RAID10"},
+	{0, NULL}
+};
+
+static void
+print_space_info(struct btrfs_ioctl_space_info *si)
+{
+	__u64 flags;
+	int first;
+	const struct xlat *xl;
+
+	flags = si->flags;
+	tprintf("{flags=%#llx", flags);
+	first = 1;
+	for (xl = btrfs_space_info_flags; flags && xl->val; xl++) {
+		if (flags & xl->val) {
+			if (first)
+				tprints(" /* ");
+			else
+				tprints("|");
+			first = 0;
+			tprints(xl->str);
+			flags &= ~xl->val;
+		}
+	}
+	if (!first) {
+		/* flags were expanded at least once */
+		if (flags)
+			tprintf("|%#llx */", flags);
+		else
+			tprints(" */");
+	}
+	tprintf(", total_bytes=%llu, used_bytes=%llu}", si->total_bytes, si->used_bytes);
+}
+
+static void
+print_space_args_out(struct tcb *tcp, long arg)
+{
+	struct btrfs_ioctl_space_args sa, *sa_ptr;
+	__u64 i, total;
+	int truncated;
+	long sa_size;
+
+	if (syserror(tcp) || umove(tcp, arg, &sa) < 0)
+		return;
+
+	total = sa.total_spaces;
+	tprintf(", total_spaces=%llu", total);
+	if (total > sa.space_slots)
+		total = sa.space_slots;
+	if (total <= 0)
+		return;
+	/* if total > 10 then truncate it */
+	truncated = 0;
+	if (total > 10) {
+		total = 10;
+		truncated = 1;
+	}
+
+	sa_size = sizeof(struct btrfs_ioctl_space_args) + total * sizeof(struct btrfs_ioctl_space_info);
+	sa_ptr = malloc(sa_size);
+	if (!sa_ptr)
+		return;
+
+	if (umoven(tcp, arg, sa_size, (char *) sa_ptr) < 0)
+		goto out;
+
+	tprints(", spaces={");
+	for (i = 0L; i < total; i++) {
+		if (i)
+			tprints(", ");
+		tprintf("[%llu]=", i);
+		print_space_info(&sa_ptr->spaces[i]);
+	}
+	if (truncated)
+		tprints(", ...");
+	tprints("}");
+
+out:
+	free(sa_ptr);
+}
+
 #endif /* HAVE_LINUX_BTRFS_H */
 
 int
 btrfs_ioctl(struct tcb *tcp, long code, long arg)
 {
+#ifdef HAVE_LINUX_BTRFS_H
+	switch (code) {
+	case BTRFS_IOC_SPACE_INFO:
+		if (entering(tcp)) {
+			struct btrfs_ioctl_space_args sa;
+			if (umove(tcp, arg, &sa) < 0)
+				tprintf(", %#lx", arg);
+			else {
+				tprintf(", {space_slots=%llu", sa.space_slots);
+			}
+		}
+		if (exiting(tcp)) {
+			print_space_args_out(tcp, arg);
+			tprints("}");
+		}
+		return 1;
+	}
+#endif /* HAVE_LINUX_BTRFS_H */
+
 	return 0;
 }
-- 
1.7.11.7