[PATCH 07/17] fsinfo: Add fsinfo() syscall to query filesystem information [ver #17]

David Howells
2020-02-21T18:02:58Z

Add a system call to allow filesystem information to be queried. A request
value can be given to indicate the desired attribute. Support is provided
for enumerating multi-value attributes.

===============
NEW SYSTEM CALL
===============

The new system call looks like:

int ret = fsinfo(int dfd,
const char *filename,
const struct fsinfo_params *params,
void *buffer,
size_t buf_size);

The params parameter optionally points to a block of parameters:

struct fsinfo_params {
__u32 at_flags;
__u32 flags;
__u32 request;
__u32 Nth;
__u32 Mth;
__u64 __reserved[3];
};

If params is NULL, it is assumed params->request should be
FSINFO_ATTR_STATFS, params->Nth should be 0, params->Mth should be 0,
params->at_flags should be 0 and params->flags should be 0.

If params is given, all of params->__reserved[] must be 0.

dfd, filename and params->at_flags indicate the file to query. There is no
equivalent of lstat() as that can be emulated with fsinfo() by setting
AT_SYMLINK_NOFOLLOW in params->at_flags. There is also no equivalent of
fstat() as that can be emulated by passing a NULL filename to fsinfo() with
the fd of interest in dfd. AT_NO_AUTOMOUNT can also be used to an allow
automount point to be queried without triggering it.

params->request indicates the attribute/attributes to be queried. This can
be one of:

FSINFO_ATTR_STATFS - statfs-style info
FSINFO_ATTR_IDS - Filesystem IDs
FSINFO_ATTR_LIMITS - Filesystem limits
FSINFO_ATTR_SUPPORTS - What's supported in statx(), IOC flags
FSINFO_ATTR_TIMESTAMP_INFO - Inode timestamp info
FSINFO_ATTR_VOLUME_ID - Volume ID (string)
FSINFO_ATTR_VOLUME_UUID - Volume UUID
FSINFO_ATTR_VOLUME_NAME - Volume name (string)
FSINFO_ATTR_FSINFO_ATTRIBUTE_INFO - Information about attr Nth
FSINFO_ATTR_FSINFO_ATTRIBUTES - List of supported attrs

Some attributes (such as the servers backing a network filesystem) can have
multiple values. These can be enumerated by setting params->Nth and
params->Mth to 0, 1, ... until ENODATA is returned.

buffer and buf_size point to the reply buffer. The buffer is filled up to
the specified size, even if this means truncating the reply. The full size
of the reply is returned. In future versions, this will allow extra fields
to be tacked on to the end of the reply, but anyone not expecting them will
only get the subset they're expecting. If either buffer of buf_size are 0,
no copy will take place and the data size will be returned.

At the moment, this will only work on x86_64 and i386 as it requires the
system call to be wired up.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-api@vger.kernel.org
---

arch/alpha/kernel/syscalls/syscall.tbl | 1
arch/arm/tools/syscall.tbl | 1
arch/arm64/include/asm/unistd.h | 2
arch/ia64/kernel/syscalls/syscall.tbl | 1
arch/m68k/kernel/syscalls/syscall.tbl | 1
arch/microblaze/kernel/syscalls/syscall.tbl | 1
arch/mips/kernel/syscalls/syscall_n32.tbl | 1
arch/mips/kernel/syscalls/syscall_n64.tbl | 1
arch/mips/kernel/syscalls/syscall_o32.tbl | 1
arch/parisc/kernel/syscalls/syscall.tbl | 1
arch/powerpc/kernel/syscalls/syscall.tbl | 1
arch/s390/kernel/syscalls/syscall.tbl | 1
arch/sh/kernel/syscalls/syscall.tbl | 1
arch/sparc/kernel/syscalls/syscall.tbl | 1
arch/x86/entry/syscalls/syscall_32.tbl | 1
arch/x86/entry/syscalls/syscall_64.tbl | 1
arch/xtensa/kernel/syscalls/syscall.tbl | 1
fs/Kconfig | 7
fs/Makefile | 1
fs/fsinfo.c | 566 +++++++++++++++++++++++++
include/linux/fs.h | 4
include/linux/fsinfo.h | 72 +++
include/linux/syscalls.h | 4
include/uapi/asm-generic/unistd.h | 4
include/uapi/linux/fsinfo.h | 187 ++++++++
kernel/sys_ni.c | 1
samples/vfs/Makefile | 5
samples/vfs/test-fsinfo.c | 607 +++++++++++++++++++++++++++
28 files changed, 1474 insertions(+), 2 deletions(-)
create mode 100644 fs/fsinfo.c
create mode 100644 include/linux/fsinfo.h
create mode 100644 include/uapi/linux/fsinfo.h
create mode 100644 samples/vfs/test-fsinfo.c

diff --git a/arch/alpha/kernel/syscalls/syscall.tbl b/arch/alpha/kernel/syscalls/syscall.tbl
index 7c0115af9010..4d0b07dde12d 100644
--- a/arch/alpha/kernel/syscalls/syscall.tbl
+++ b/arch/alpha/kernel/syscalls/syscall.tbl
@@ -479,3 +479,4 @@
548 common pidfd_getfd sys_pidfd_getfd
549 common watch_mount sys_watch_mount
550 common watch_sb sys_watch_sb
+551 common fsinfo sys_fsinfo
diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl
index f256f009a89f..fdda8382b420 100644
--- a/arch/arm/tools/syscall.tbl
+++ b/arch/arm/tools/syscall.tbl
@@ -453,3 +453,4 @@
438 common pidfd_getfd sys_pidfd_getfd
439 common watch_mount sys_watch_mount
440 common watch_sb sys_watch_sb
+441 common fsinfo sys_fsinfo
diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h
index bc0f923e0e04..388eeb71cff0 100644
--- a/arch/arm64/include/asm/unistd.h
+++ b/arch/arm64/include/asm/unistd.h
@@ -38,7 +38,7 @@
#define __ARM_NR_compat_set_tls (__ARM_NR_COMPAT_BASE + 5)
#define __ARM_NR_COMPAT_END (__ARM_NR_COMPAT_BASE + 0x800)

-#define __NR_compat_syscalls 441
+#define __NR_compat_syscalls 442
#endif

#define __ARCH_WANT_SYS_CLONE
diff --git a/arch/ia64/kernel/syscalls/syscall.tbl b/arch/ia64/kernel/syscalls/syscall.tbl
index a4dafc659647..2316e60e031a 100644
--- a/arch/ia64/kernel/syscalls/syscall.tbl
+++ b/arch/ia64/kernel/syscalls/syscall.tbl
@@ -360,3 +360,4 @@
438 common pidfd_getfd sys_pidfd_getfd
439 common watch_mount sys_watch_mount
440 common watch_sb sys_watch_sb
+441 common fsinfo sys_fsinfo
diff --git a/arch/m68k/kernel/syscalls/syscall.tbl b/arch/m68k/kernel/syscalls/syscall.tbl
index 893fb4151547..efc2723ca91f 100644
--- a/arch/m68k/kernel/syscalls/syscall.tbl
+++ b/arch/m68k/kernel/syscalls/syscall.tbl
@@ -439,3 +439,4 @@
438 common pidfd_getfd sys_pidfd_getfd
439 common watch_mount sys_watch_mount
440 common watch_sb sys_watch_sb
+441 common fsinfo sys_fsinfo
diff --git a/arch/microblaze/kernel/syscalls/syscall.tbl b/arch/microblaze/kernel/syscalls/syscall.tbl
index 54aaf0d40c64..745c0f462fce 100644
--- a/arch/microblaze/kernel/syscalls/syscall.tbl
+++ b/arch/microblaze/kernel/syscalls/syscall.tbl
@@ -445,3 +445,4 @@
438 common pidfd_getfd sys_pidfd_getfd
439 common watch_mount sys_watch_mount
440 common watch_sb sys_watch_sb
+441 common fsinfo sys_fsinfo
diff --git a/arch/mips/kernel/syscalls/syscall_n32.tbl b/arch/mips/kernel/syscalls/syscall_n32.tbl
index fd34dd0efed0..499f83562a8c 100644
--- a/arch/mips/kernel/syscalls/syscall_n32.tbl
+++ b/arch/mips/kernel/syscalls/syscall_n32.tbl
@@ -378,3 +378,4 @@
438 n32 pidfd_getfd sys_pidfd_getfd
439 n32 watch_mount sys_watch_mount
440 n32 watch_sb sys_watch_sb
+441 n32 fsinfo sys_fsinfo
diff --git a/arch/mips/kernel/syscalls/syscall_n64.tbl b/arch/mips/kernel/syscalls/syscall_n64.tbl
index db0f4c0a0a0b..b3188bc3ab3c 100644
--- a/arch/mips/kernel/syscalls/syscall_n64.tbl
+++ b/arch/mips/kernel/syscalls/syscall_n64.tbl
@@ -354,3 +354,4 @@
438 n64 pidfd_getfd sys_pidfd_getfd
439 n64 watch_mount sys_watch_mount
440 n64 watch_sb sys_watch_sb
+441 n64 fsinfo sys_fsinfo
diff --git a/arch/mips/kernel/syscalls/syscall_o32.tbl b/arch/mips/kernel/syscalls/syscall_o32.tbl
index ce2e1326de8f..1a3e8ed5e538 100644
--- a/arch/mips/kernel/syscalls/syscall_o32.tbl
+++ b/arch/mips/kernel/syscalls/syscall_o32.tbl
@@ -427,3 +427,4 @@
438 o32 pidfd_getfd sys_pidfd_getfd
439 o32 watch_mount sys_watch_mount
440 o32 watch_sb sys_watch_sb
+441 o32 fsinfo sys_fsinfo
diff --git a/arch/parisc/kernel/syscalls/syscall.tbl b/arch/parisc/kernel/syscalls/syscall.tbl
index 6e4a7c08b64b..2572c215d861 100644
--- a/arch/parisc/kernel/syscalls/syscall.tbl
+++ b/arch/parisc/kernel/syscalls/syscall.tbl
@@ -437,3 +437,4 @@
438 common pidfd_getfd sys_pidfd_getfd
439 common watch_mount sys_watch_mount
440 common watch_sb sys_watch_sb
+441 common fsinfo sys_fsinfo
diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl
index 08943f3b8206..39d7ac7e918c 100644
--- a/arch/powerpc/kernel/syscalls/syscall.tbl
+++ b/arch/powerpc/kernel/syscalls/syscall.tbl
@@ -521,3 +521,4 @@
438 common pidfd_getfd sys_pidfd_getfd
439 common watch_mount sys_watch_mount
440 common watch_sb sys_watch_sb
+441 common fsinfo sys_fsinfo
diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl
index b3b8529d2b74..ae4cefd3dd1b 100644
--- a/arch/s390/kernel/syscalls/syscall.tbl
+++ b/arch/s390/kernel/syscalls/syscall.tbl
@@ -442,3 +442,4 @@
438 common pidfd_getfd sys_pidfd_getfd sys_pidfd_getfd
439 common watch_mount sys_watch_mount sys_watch_mount
440 common watch_sb sys_watch_sb sys_watch_sb
+441 common fsinfo sys_fsinfo sys_fsinfo
diff --git a/arch/sh/kernel/syscalls/syscall.tbl b/arch/sh/kernel/syscalls/syscall.tbl
index 89307a20657c..05945b9aee4b 100644
--- a/arch/sh/kernel/syscalls/syscall.tbl
+++ b/arch/sh/kernel/syscalls/syscall.tbl
@@ -442,3 +442,4 @@
438 common pidfd_getfd sys_pidfd_getfd
439 common watch_mount sys_watch_mount
440 common watch_sb sys_watch_sb
+441 common fsinfo sys_fsinfo
diff --git a/arch/sparc/kernel/syscalls/syscall.tbl b/arch/sparc/kernel/syscalls/syscall.tbl
index 4ff841a00450..b71b34d4b45c 100644
--- a/arch/sparc/kernel/syscalls/syscall.tbl
+++ b/arch/sparc/kernel/syscalls/syscall.tbl
@@ -485,3 +485,4 @@
438 common pidfd_getfd sys_pidfd_getfd
439 common watch_mount sys_watch_mount
440 common watch_sb sys_watch_sb
+441 common fsinfo sys_fsinfo
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index e2731d295f88..e118ba9aca4c 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -444,3 +444,4 @@
438 i386 pidfd_getfd sys_pidfd_getfd __ia32_sys_pidfd_getfd
439 i386 watch_mount sys_watch_mount __ia32_sys_watch_mount
440 i386 watch_sb sys_watch_sb __ia32_sys_watch_sb
+441 i386 fsinfo sys_fsinfo __ia32_sys_fsinfo
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index f4391176102c..067f247471d0 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -361,6 +361,7 @@
438 common pidfd_getfd __x64_sys_pidfd_getfd
439 common watch_mount __x64_sys_watch_mount
440 common watch_sb __x64_sys_watch_sb
+441 common fsinfo __x64_sys_fsinfo

#
# x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/arch/xtensa/kernel/syscalls/syscall.tbl b/arch/xtensa/kernel/syscalls/syscall.tbl
index 8e7d731ed6cf..e1ec25099d10 100644
--- a/arch/xtensa/kernel/syscalls/syscall.tbl
+++ b/arch/xtensa/kernel/syscalls/syscall.tbl
@@ -410,3 +410,4 @@
438 common pidfd_getfd sys_pidfd_getfd
439 common watch_mount sys_watch_mount
440 common watch_sb sys_watch_sb
+441 common fsinfo sys_fsinfo
diff --git a/fs/Kconfig b/fs/Kconfig
index fef1365c23a5..01d0d436b3cd 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -15,6 +15,13 @@ config VALIDATE_FS_PARSER
Enable this to perform validation of the parameter description for a
filesystem when it is registered.

+config FSINFO
+ bool "Enable the fsinfo() system call"
+ help
+ Enable the file system information querying system call to allow
+ comprehensive information to be retrieved about a filesystem,
+ superblock or mount object.
+
if BLOCK

config FS_IOMAP
diff --git a/fs/Makefile b/fs/Makefile
index 4477757780d0..b6bf2424c7f7 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -55,6 +55,7 @@ obj-$(CONFIG_COREDUMP) += coredump.o
obj-$(CONFIG_SYSCTL) += drop_caches.o

obj-$(CONFIG_FHANDLE) += fhandle.o
+obj-$(CONFIG_FSINFO) += fsinfo.o
obj-y += iomap/

obj-y += quota/
diff --git a/fs/fsinfo.c b/fs/fsinfo.c
new file mode 100644
index 000000000000..5d3ba3c3a7ad
--- /dev/null
+++ b/fs/fsinfo.c
@@ -0,0 +1,566 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Filesystem information query.
+ *
+ * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+#include <linux/syscalls.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/statfs.h>
+#include <linux/security.h>
+#include <linux/uaccess.h>
+#include <linux/fsinfo.h>
+#include <uapi/linux/mount.h>
+#include "internal.h"
+
+/**
+ * fsinfo_string - Store a NUL-terminated string as an fsinfo attribute value.
+ * @s: The string to store (may be NULL)
+ * @ctx: The parameter context
+ */
+int fsinfo_string(const char *s, struct fsinfo_context *ctx)
+{
+ unsigned int len;
+ char *p = ctx->buffer;
+ int ret = 0;
+
+ if (s) {
+ len = min_t(size_t, strlen(s), ctx->buf_size - 1);
+ if (!ctx->want_size_only) {
+ memcpy(p, s, len);
+ p[len] = 0;
+ }
+ ret = len;
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL(fsinfo_string);
+
+/*
+ * Get basic filesystem stats from statfs.
+ */
+static int fsinfo_generic_statfs(struct path *path, struct fsinfo_context *ctx)
+{
+ struct fsinfo_statfs *p = ctx->buffer;
+ struct kstatfs buf;
+ int ret;
+
+ ret = vfs_statfs(path, &buf);
+ if (ret < 0)
+ return ret;
+
+ p->f_blocks.lo = buf.f_blocks;
+ p->f_bfree.lo = buf.f_bfree;
+ p->f_bavail.lo = buf.f_bavail;
+ p->f_files.lo = buf.f_files;
+ p->f_ffree.lo = buf.f_ffree;
+ p->f_favail.lo = buf.f_ffree;
+ p->f_bsize = buf.f_bsize;
+ p->f_frsize = buf.f_frsize;
+ return sizeof(*p);
+}
+
+static int fsinfo_generic_ids(struct path *path, struct fsinfo_context *ctx)
+{
+ struct fsinfo_ids *p = ctx->buffer;
+ struct super_block *sb;
+ struct kstatfs buf;
+ int ret;
+
+ ret = vfs_statfs(path, &buf);
+ if (ret < 0 && ret != -ENOSYS)
+ return ret;
+ if (ret == 0)
+ memcpy(&p->f_fsid, &buf.f_fsid, sizeof(p->f_fsid));
+
+ sb = path->dentry->d_sb;
+ p->f_fstype = sb->s_magic;
+ p->f_dev_major = MAJOR(sb->s_dev);
+ p->f_dev_minor = MINOR(sb->s_dev);
+ p->f_sb_id = sb->s_unique_id;
+ strlcpy(p->f_fs_name, sb->s_type->name, sizeof(p->f_fs_name));
+ return sizeof(*p);
+}
+
+int fsinfo_generic_limits(struct path *path, struct fsinfo_context *ctx)
+{
+ struct fsinfo_limits *p = ctx->buffer;
+ struct super_block *sb = path->dentry->d_sb;
+
+ p->max_file_size.hi = 0;
+ p->max_file_size.lo = sb->s_maxbytes;
+ p->max_ino.hi = 0;
+ p->max_ino.lo = UINT_MAX;
+ p->max_hard_links = sb->s_max_links;
+ p->max_uid = UINT_MAX;
+ p->max_gid = UINT_MAX;
+ p->max_projid = UINT_MAX;
+ p->max_filename_len = NAME_MAX;
+ p->max_symlink_len = PATH_MAX;
+ p->max_xattr_name_len = XATTR_NAME_MAX;
+ p->max_xattr_body_len = XATTR_SIZE_MAX;
+ p->max_dev_major = 0xffffff;
+ p->max_dev_minor = 0xff;
+ return sizeof(*p);
+}
+EXPORT_SYMBOL(fsinfo_generic_limits);
+
+int fsinfo_generic_supports(struct path *path, struct fsinfo_context *ctx)
+{
+ struct fsinfo_supports *p = ctx->buffer;
+ struct super_block *sb = path->dentry->d_sb;
+
+ p->stx_mask = STATX_BASIC_STATS;
+ if (sb->s_d_op && sb->s_d_op->d_automount)
+ p->stx_attributes |= STATX_ATTR_AUTOMOUNT;
+ return sizeof(*p);
+}
+EXPORT_SYMBOL(fsinfo_generic_supports);
+
+static const struct fsinfo_timestamp_info fsinfo_default_timestamp_info = {
+ .atime = {
+ .minimum = S64_MIN,
+ .maximum = S64_MAX,
+ .gran_mantissa = 1,
+ .gran_exponent = 0,
+ },
+ .mtime = {
+ .minimum = S64_MIN,
+ .maximum = S64_MAX,
+ .gran_mantissa = 1,
+ .gran_exponent = 0,
+ },
+ .ctime = {
+ .minimum = S64_MIN,
+ .maximum = S64_MAX,
+ .gran_mantissa = 1,
+ .gran_exponent = 0,
+ },
+ .btime = {
+ .minimum = S64_MIN,
+ .maximum = S64_MAX,
+ .gran_mantissa = 1,
+ .gran_exponent = 0,
+ },
+};
+
+int fsinfo_generic_timestamp_info(struct path *path, struct fsinfo_context *ctx)
+{
+ struct fsinfo_timestamp_info *p = ctx->buffer;
+ struct super_block *sb = path->dentry->d_sb;
+ s8 exponent;
+
+ *p = fsinfo_default_timestamp_info;
+
+ if (sb->s_time_gran < 1000000000) {
+ if (sb->s_time_gran < 1000)
+ exponent = -9;
+ else if (sb->s_time_gran < 1000000)
+ exponent = -6;
+ else
+ exponent = -3;
+
+ p->atime.gran_exponent = exponent;
+ p->mtime.gran_exponent = exponent;
+ p->ctime.gran_exponent = exponent;
+ p->btime.gran_exponent = exponent;
+ }
+
+ return sizeof(*p);
+}
+EXPORT_SYMBOL(fsinfo_generic_timestamp_info);
+
+static int fsinfo_generic_volume_uuid(struct path *path, struct fsinfo_context *ctx)
+{
+ struct fsinfo_volume_uuid *p = ctx->buffer;
+ struct super_block *sb = path->dentry->d_sb;
+
+ memcpy(p, &sb->s_uuid, sizeof(*p));
+ return sizeof(*p);
+}
+
+static int fsinfo_generic_volume_id(struct path *path, struct fsinfo_context *ctx)
+{
+ return fsinfo_string(path->dentry->d_sb->s_id, ctx);
+}
+
+static const struct fsinfo_attribute fsinfo_common_attributes[] = {
+ FSINFO_VSTRUCT (FSINFO_ATTR_STATFS, fsinfo_generic_statfs),
+ FSINFO_VSTRUCT (FSINFO_ATTR_IDS, fsinfo_generic_ids),
+ FSINFO_VSTRUCT (FSINFO_ATTR_LIMITS, fsinfo_generic_limits),
+ FSINFO_VSTRUCT (FSINFO_ATTR_SUPPORTS, fsinfo_generic_supports),
+ FSINFO_VSTRUCT (FSINFO_ATTR_TIMESTAMP_INFO, fsinfo_generic_timestamp_info),
+ FSINFO_STRING (FSINFO_ATTR_VOLUME_ID, fsinfo_generic_volume_id),
+ FSINFO_VSTRUCT (FSINFO_ATTR_VOLUME_UUID, fsinfo_generic_volume_uuid),
+
+ FSINFO_LIST (FSINFO_ATTR_FSINFO_ATTRIBUTES, (void *)123UL),
+ FSINFO_VSTRUCT_N(FSINFO_ATTR_FSINFO_ATTRIBUTE_INFO, (void *)123UL),
+ {}
+};
+
+/*
+ * Determine an attribute's minimum buffer size and, if the buffer is large
+ * enough, get the attribute value.
+ */
+static int fsinfo_get_this_attribute(struct path *path,
+ struct fsinfo_context *ctx,
+ const struct fsinfo_attribute *attr)
+{
+ int buf_size;
+
+ if (ctx->Nth != 0 && !(attr->flags & (FSINFO_FLAGS_N | FSINFO_FLAGS_NM)))
+ return -ENODATA;
+ if (ctx->Mth != 0 && !(attr->flags & FSINFO_FLAGS_NM))
+ return -ENODATA;
+
+ switch (attr->type) {
+ case FSINFO_TYPE_VSTRUCT:
+ ctx->clear_tail = true;
+ buf_size = attr->size;
+ break;
+ case FSINFO_TYPE_STRING:
+ case FSINFO_TYPE_OPAQUE:
+ case FSINFO_TYPE_LIST:
+ buf_size = 4096;
+ break;
+ default:
+ return -ENOPKG;
+ }
+
+ if (ctx->buf_size < buf_size)
+ return buf_size;
+
+ return attr->get(path, ctx);
+}
+
+static void fsinfo_attributes_insert(struct fsinfo_context *ctx,
+ const struct fsinfo_attribute *attr)
+{
+ __u32 *p = ctx->buffer;
+ unsigned int i;
+
+ if (ctx->usage >= ctx->buf_size ||
+ ctx->buf_size - ctx->usage < sizeof(__u32)) {
+ ctx->usage += sizeof(__u32);
+ return;
+ }
+
+ for (i = 0; i < ctx->usage / sizeof(__u32); i++)
+ if (p[i] == attr->attr_id)
+ return;
+
+ p[i] = attr->attr_id;
+ ctx->usage += sizeof(__u32);
+}
+
+static int fsinfo_list_attributes(struct path *path,
+ struct fsinfo_context *ctx,
+ const struct fsinfo_attribute *attributes)
+{
+ const struct fsinfo_attribute *a;
+
+ for (a = attributes; a->get; a++)
+ fsinfo_attributes_insert(ctx, a);
+ return -EOPNOTSUPP; /* We want to go through all the lists */
+}
+
+static int fsinfo_get_attribute_info(struct path *path,
+ struct fsinfo_context *ctx,
+ const struct fsinfo_attribute *attributes)
+{
+ const struct fsinfo_attribute *a;
+ struct fsinfo_attribute_info *p = ctx->buffer;
+
+ if (!ctx->buf_size)
+ return sizeof(*p);
+
+ for (a = attributes; a->get; a++) {
+ if (a->attr_id == ctx->Nth) {
+ p->attr_id = a->attr_id;
+ p->type = a->type;
+ p->flags = a->flags;
+ p->size = a->size;
+ p->size = a->size;
+ return sizeof(*p);
+ }
+ }
+ return -EOPNOTSUPP; /* We want to go through all the lists */
+}
+
+/**
+ * fsinfo_get_attribute - Look up and handle an attribute
+ * @path: The object to query
+ * @params: Parameters to define a request and place to store result
+ * @attributes: List of attributes to search.
+ *
+ * Look through a list of attributes for one that matches the requested
+ * attribute then call the handler for it.
+ */
+int fsinfo_get_attribute(struct path *path, struct fsinfo_context *ctx,
+ const struct fsinfo_attribute *attributes)
+{
+ const struct fsinfo_attribute *a;
+
+ switch (ctx->requested_attr) {
+ case FSINFO_ATTR_FSINFO_ATTRIBUTE_INFO:
+ return fsinfo_get_attribute_info(path, ctx, attributes);
+ case FSINFO_ATTR_FSINFO_ATTRIBUTES:
+ return fsinfo_list_attributes(path, ctx, attributes);
+ default:
+ for (a = attributes; a->get; a++)
+ if (a->attr_id == ctx->requested_attr)
+ return fsinfo_get_this_attribute(path, ctx, a);
+ return -EOPNOTSUPP;
+ }
+}
+EXPORT_SYMBOL(fsinfo_get_attribute);
+
+/**
+ * generic_fsinfo - Handle an fsinfo attribute generically
+ * @path: The object to query
+ * @params: Parameters to define a request and place to store result
+ */
+static int fsinfo_call(struct path *path, struct fsinfo_context *ctx)
+{
+ int ret;
+
+ if (path->dentry->d_sb->s_op->fsinfo) {
+ ret = path->dentry->d_sb->s_op->fsinfo(path, ctx);
+ if (ret != -EOPNOTSUPP)
+ return ret;
+ }
+ ret = fsinfo_get_attribute(path, ctx, fsinfo_common_attributes);
+ if (ret != -EOPNOTSUPP)
+ return ret;
+
+ switch (ctx->requested_attr) {
+ case FSINFO_ATTR_FSINFO_ATTRIBUTE_INFO:
+ return -ENODATA;
+ case FSINFO_ATTR_FSINFO_ATTRIBUTES:
+ return ctx->usage;
+ default:
+ return -EOPNOTSUPP;
+ }
+}
+
+/**
+ * vfs_fsinfo - Retrieve filesystem information
+ * @path: The object to query
+ * @params: Parameters to define a request and place to store result
+ *
+ * Get an attribute on a filesystem or an object within a filesystem. The
+ * filesystem attribute to be queried is indicated by @ctx->requested_attr, and
+ * if it's a multi-valued attribute, the particular value is selected by
+ * @ctx->Nth and then @ctx->Mth.
+ *
+ * For common attributes, a value may be fabricated if it is not supported by
+ * the filesystem.
+ *
+ * On success, the size of the attribute's value is returned (0 is a valid
+ * size). A buffer will have been allocated and will be pointed to by
+ * @ctx->buffer. The caller must free this with kvfree().
+ *
+ * Errors can also be returned: -ENOMEM if a buffer cannot be allocated, -EPERM
+ * or -EACCES if permission is denied by the LSM, -EOPNOTSUPP if an attribute
+ * doesn't exist for the specified object or -ENODATA if the attribute exists,
+ * but the Nth,Mth value does not exist. -EMSGSIZE indicates that the value is
+ * unmanageable internally and -ENOPKG indicates other internal failure.
+ *
+ * Errors such as -EIO may also come from attempts to access media or servers
+ * to obtain the requested information if it's not immediately to hand.
+ *
+ * [*] Note that the caller may set @ctx->want_size_only if it only wants the
+ * size of the value and not the data. If this is set, a buffer may not be
+ * allocated under some circumstances. This is intended for size query by
+ * userspace.
+ *
+ * [*] Note that @ctx->clear_tail will be returned set if the data should be
+ * padded out with zeros when writing it to userspace.
+ */
+static int vfs_fsinfo(struct path *path, struct fsinfo_context *ctx)
+{
+ struct dentry *dentry = path->dentry;
+ int ret;
+
+ ret = security_sb_statfs(dentry);
+ if (ret)
+ return ret;
+
+ /* Call the handler to find out the buffer size required. */
+ ctx->buf_size = 0;
+ ret = fsinfo_call(path, ctx);
+ if (ret < 0 || ctx->want_size_only)
+ return ret;
+ ctx->buf_size = ret;
+
+ do {
+ /* Allocate a buffer of the requested size. */
+ if (ctx->buf_size > INT_MAX)
+ return -EMSGSIZE;
+ ctx->buffer = kvzalloc(ctx->buf_size, GFP_KERNEL);
+ if (!ctx->buffer)
+ return -ENOMEM;
+
+ ctx->usage = 0;
+ ret = fsinfo_call(path, ctx);
+ if (IS_ERR_VALUE((long)ret))
+ return ret;
+ if ((unsigned int)ret <= ctx->buf_size)
+ return ret; /* It fitted */
+
+ /* We need to resize the buffer */
+ ctx->buf_size = roundup(ret, PAGE_SIZE);
+ kvfree(ctx->buffer);
+ ctx->buffer = NULL;
+ } while (!signal_pending(current));
+
+ return -ERESTARTSYS;
+}
+
+static int vfs_fsinfo_path(int dfd, const char __user *pathname,
+ unsigned int at_flags, struct fsinfo_context *ctx)
+{
+ struct path path;
+ unsigned lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT;
+ int ret = -EINVAL;
+
+ if ((at_flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
+ AT_EMPTY_PATH)) != 0)
+ return -EINVAL;
+
+ if (at_flags & AT_SYMLINK_NOFOLLOW)
+ lookup_flags &= ~LOOKUP_FOLLOW;
+ if (at_flags & AT_NO_AUTOMOUNT)
+ lookup_flags &= ~LOOKUP_AUTOMOUNT;
+ if (at_flags & AT_EMPTY_PATH)
+ lookup_flags |= LOOKUP_EMPTY;
+
+retry:
+ ret = user_path_at(dfd, pathname, lookup_flags, &path);
+ if (ret)
+ goto out;
+
+ ret = vfs_fsinfo(&path, ctx);
+ path_put(&path);
+ if (retry_estale(ret, lookup_flags)) {
+ lookup_flags |= LOOKUP_REVAL;
+ goto retry;
+ }
+out:
+ return ret;
+}
+
+static int vfs_fsinfo_fd(unsigned int fd, struct fsinfo_context *ctx)
+{
+ struct fd f = fdget_raw(fd);
+ int ret = -EBADF;
+
+ if (f.file) {
+ ret = vfs_fsinfo(&f.file->f_path, ctx);
+ fdput(f);
+ }
+ return ret;
+}
+
+/**
+ * sys_fsinfo - System call to get filesystem information
+ * @dfd: Base directory to pathwalk from or fd referring to filesystem.
+ * @pathname: Filesystem to query or NULL.
+ * @_params: Parameters to define request (or NULL for enhanced statfs).
+ * @user_buffer: Result buffer.
+ * @user_buf_size: Size of result buffer.
+ *
+ * Get information on a filesystem. The filesystem attribute to be queried is
+ * indicated by @_params->request, and some of the attributes can have multiple
+ * values, indexed by @_params->Nth and @_params->Mth. If @_params is NULL,
+ * then the 0th fsinfo_attr_statfs attribute is queried. If an attribute does
+ * not exist, EOPNOTSUPP is returned; if the Nth,Mth value does not exist,
+ * ENODATA is returned.
+ *
+ * On success, the size of the attribute's value is returned. If
+ * @user_buf_size is 0 or @user_buffer is NULL, only the size is returned. If
+ * the size of the value is larger than @user_buf_size, it will be truncated by
+ * the copy. If the size of the value is smaller than @user_buf_size then the
+ * excess buffer space will be cleared. The full size of the value will be
+ * returned, irrespective of how much data is actually placed in the buffer.
+ */
+SYSCALL_DEFINE5(fsinfo,
+ int, dfd, const char __user *, pathname,
+ struct fsinfo_params __user *, params,
+ void __user *, user_buffer, size_t, user_buf_size)
+{
+ struct fsinfo_context ctx;
+ struct fsinfo_params user_params;
+ unsigned int at_flags = 0, result_size;
+ int ret;
+
+ if (!user_buffer && user_buf_size)
+ return -EINVAL;
+ if (user_buffer && !user_buf_size)
+ return -EINVAL;
+ if (user_buf_size > UINT_MAX)
+ return -EOVERFLOW;
+
+ memset(&ctx, 0, sizeof(ctx));
+ ctx.requested_attr = FSINFO_ATTR_STATFS;
+ if (user_buf_size == 0)
+ ctx.want_size_only = true;
+
+ if (params) {
+ if (copy_from_user(&user_params, params, sizeof(user_params)))
+ return -EFAULT;
+ if (user_params.__reserved32[0] ||
+ user_params.__reserved[0] ||
+ user_params.__reserved[1] ||
+ user_params.__reserved[2] ||
+ user_params.flags & ~FSINFO_FLAGS_QUERY_MASK)
+ return -EINVAL;
+ at_flags = user_params.at_flags;
+ ctx.flags = user_params.flags;
+ ctx.requested_attr = user_params.request;
+ ctx.Nth = user_params.Nth;
+ ctx.Mth = user_params.Mth;
+ }
+
+ switch (ctx.flags & FSINFO_FLAGS_QUERY_MASK) {
+ case FSINFO_FLAGS_QUERY_PATH:
+ ret = vfs_fsinfo_path(dfd, pathname, at_flags, &ctx);
+ break;
+ case FSINFO_FLAGS_QUERY_FD:
+ if (pathname)
+ return -EINVAL;
+ ret = vfs_fsinfo_fd(dfd, &ctx);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (ret < 0)
+ goto error;
+
+ result_size = min_t(size_t, ret, user_buf_size);
+ if (result_size > 0 &&
+ copy_to_user(user_buffer, ctx.buffer, result_size) != 0) {
+ ret = -EFAULT;
+ goto error;
+ }
+
+ /* Clear any part of the buffer that we won't fill if we're putting a
+ * struct in there. Strings, opaque objects and arrays are expected to
+ * be variable length.
+ */
+ if (ctx.clear_tail &&
+ user_buf_size > result_size &&
+ clear_user(user_buffer + result_size, user_buf_size - result_size) != 0) {
+ ret = -EFAULT;
+ goto error;
+ }
+
+error:
+ kvfree(ctx.buffer);
+ return ret;
+}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index d5128d112384..d2476c0fc978 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -69,6 +69,7 @@ struct fsverity_info;
struct fsverity_operations;
struct fs_context;
struct fs_parameter_spec;
+struct fsinfo_context;

extern void __init inode_init(void);
extern void __init inode_init_early(void);
@@ -1963,6 +1964,9 @@ struct super_operations {
int (*thaw_super) (struct super_block *);
int (*unfreeze_fs) (struct super_block *);
int (*statfs) (struct dentry *, struct kstatfs *);
+#ifdef CONFIG_FSINFO
+ int (*fsinfo)(struct path *, struct fsinfo_context *);
+#endif
int (*remount_fs) (struct super_block *, int *, char *);
void (*umount_begin) (struct super_block *);

diff --git a/include/linux/fsinfo.h b/include/linux/fsinfo.h
new file mode 100644
index 000000000000..943fbd6640f9
--- /dev/null
+++ b/include/linux/fsinfo.h
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Filesystem information query
+ *
+ * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#ifndef _LINUX_FSINFO_H
+#define _LINUX_FSINFO_H
+
+#ifdef CONFIG_FSINFO
+
+#include <uapi/linux/fsinfo.h>
+
+struct path;
+
+#define FSINFO_NORMAL_ATTR_MAX_SIZE 4096
+
+struct fsinfo_context {
+ __u32 flags; /* [in] FSINFO_FLAGS_* */
+ __u32 requested_attr; /* [in] What is being asking for */
+ __u32 Nth; /* [in] Instance of it (some may have multiple) */
+ __u32 Mth; /* [in] Subinstance */
+ bool want_size_only; /* [in] Just want to know the size, not the data */
+ bool clear_tail; /* [out] T if tail of buffer should be cleared */
+ unsigned int usage; /* [tmp] Amount of buffer used (if large) */
+ unsigned int buf_size; /* [tmp] Size of ->buffer[] */
+ void *buffer; /* [out] The reply buffer */
+};
+
+/*
+ * A filesystem information attribute definition.
+ */
+struct fsinfo_attribute {
+ unsigned int attr_id; /* The ID of the attribute */
+ enum fsinfo_value_type type:8; /* The type of the attribute's value(s) */
+ unsigned int flags:8;
+ unsigned int size:16; /* - Value size (FSINFO_STRUCT/LIST) */
+ int (*get)(struct path *path, struct fsinfo_context *params);
+};
+
+#define __FSINFO(A, T, S, G, F) \
+ { .attr_id = A, .type = T, .flags = F, .size = S, .get = G }
+
+#define _FSINFO(A, T, S, G) __FSINFO(A, T, S, G, 0)
+#define _FSINFO_N(A, T, S, G) __FSINFO(A, T, S, G, FSINFO_FLAGS_N)
+#define _FSINFO_NM(A, T, S, G) __FSINFO(A, T, S, G, FSINFO_FLAGS_NM)
+
+#define _FSINFO_VSTRUCT(A,S,G) _FSINFO (A, FSINFO_TYPE_VSTRUCT, sizeof(S), G)
+#define _FSINFO_VSTRUCT_N(A,S,G) _FSINFO_N (A, FSINFO_TYPE_VSTRUCT, sizeof(S), G)
+#define _FSINFO_VSTRUCT_NM(A,S,G) _FSINFO_NM(A, FSINFO_TYPE_VSTRUCT, sizeof(S), G)
+
+#define FSINFO_VSTRUCT(A,G) _FSINFO_VSTRUCT (A, A##__STRUCT, G)
+#define FSINFO_VSTRUCT_N(A,G) _FSINFO_VSTRUCT_N (A, A##__STRUCT, G)
+#define FSINFO_VSTRUCT_NM(A,G) _FSINFO_VSTRUCT_NM(A, A##__STRUCT, G)
+#define FSINFO_STRING(A,G) _FSINFO (A, FSINFO_TYPE_STRING, 0, G)
+#define FSINFO_STRING_N(A,G) _FSINFO_N (A, FSINFO_TYPE_STRING, 0, G)
+#define FSINFO_STRING_NM(A,G) _FSINFO_NM(A, FSINFO_TYPE_STRING, 0, G)
+#define FSINFO_OPAQUE(A,G) _FSINFO (A, FSINFO_TYPE_OPAQUE, 0, G)
+#define FSINFO_LIST(A,G) _FSINFO (A, FSINFO_TYPE_LIST, sizeof(A##__STRUCT), G)
+#define FSINFO_LIST_N(A,G) _FSINFO_N (A, FSINFO_TYPE_LIST, sizeof(A##__STRUCT), G)
+
+extern int fsinfo_string(const char *, struct fsinfo_context *);
+extern int fsinfo_generic_timestamp_info(struct path *, struct fsinfo_context *);
+extern int fsinfo_generic_supports(struct path *, struct fsinfo_context *);
+extern int fsinfo_generic_limits(struct path *, struct fsinfo_context *);
+extern int fsinfo_get_attribute(struct path *, struct fsinfo_context *,
+ const struct fsinfo_attribute *);
+
+#endif /* CONFIG_FSINFO */
+
+#endif /* _LINUX_FSINFO_H */
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index c84440d57f52..936e2eb76c8f 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -47,6 +47,7 @@ struct stat64;
struct statfs;
struct statfs64;
struct statx;
+struct fsinfo_params;
struct __sysctl_args;
struct sysinfo;
struct timespec;
@@ -1007,6 +1008,9 @@ asmlinkage long sys_watch_mount(int dfd, const char __user *path,
unsigned int at_flags, int watch_fd, int watch_id);
asmlinkage long sys_watch_sb(int dfd, const char __user *path,
unsigned int at_flags, int watch_fd, int watch_id);
+asmlinkage long sys_fsinfo(int dfd, const char __user *pathname,
+ struct fsinfo_params __user *params,
+ void __user *buffer, size_t buf_size);

/*
* Architecture-specific system calls
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index 5bff318b7ffa..7d764f86d3f5 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -859,9 +859,11 @@ __SYSCALL(__NR_pidfd_getfd, sys_pidfd_getfd)
__SYSCALL(__NR_watch_mount, sys_watch_mount)
#define __NR_watch_sb 440
__SYSCALL(__NR_watch_sb, sys_watch_sb)
+#define __NR_fsinfo 441
+__SYSCALL(__NR_fsinfo, sys_fsinfo)

#undef __NR_syscalls
-#define __NR_syscalls 441
+#define __NR_syscalls 442

/*
* 32 bit systems traditionally used different
diff --git a/include/uapi/linux/fsinfo.h b/include/uapi/linux/fsinfo.h
new file mode 100644
index 000000000000..6eb02de8a631
--- /dev/null
+++ b/include/uapi/linux/fsinfo.h
@@ -0,0 +1,187 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/* fsinfo() definitions.
+ *
+ * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+#ifndef _UAPI_LINUX_FSINFO_H
+#define _UAPI_LINUX_FSINFO_H
+
+#include <linux/types.h>
+#include <linux/socket.h>
+
+/*
+ * The filesystem attributes that can be requested. Note that some attributes
+ * may have multiple instances which can be switched in the parameter block.
+ */
+#define FSINFO_ATTR_STATFS 0x00 /* statfs()-style state */
+#define FSINFO_ATTR_IDS 0x01 /* Filesystem IDs */
+#define FSINFO_ATTR_LIMITS 0x02 /* Filesystem limits */
+#define FSINFO_ATTR_SUPPORTS 0x03 /* What's supported in statx, iocflags, ... */
+#define FSINFO_ATTR_TIMESTAMP_INFO 0x04 /* Inode timestamp info */
+#define FSINFO_ATTR_VOLUME_ID 0x05 /* Volume ID (string) */
+#define FSINFO_ATTR_VOLUME_UUID 0x06 /* Volume UUID (LE uuid) */
+#define FSINFO_ATTR_VOLUME_NAME 0x07 /* Volume name (string) */
+
+#define FSINFO_ATTR_FSINFO_ATTRIBUTE_INFO 0x100 /* Information about attr N (for path) */
+#define FSINFO_ATTR_FSINFO_ATTRIBUTES 0x101 /* List of supported attrs (for path) */
+
+/*
+ * Optional fsinfo() parameter structure.
+ *
+ * If this is not given, it is assumed that fsinfo_attr_statfs instance 0,0 is
+ * desired.
+ */
+struct fsinfo_params {
+ __u32 at_flags; /* AT_SYMLINK_NOFOLLOW and similar flags */
+ __u32 flags; /* Flags controlling fsinfo() specifically */
+#define FSINFO_FLAGS_QUERY_MASK 0x0007 /* What object should fsinfo() query? */
+#define FSINFO_FLAGS_QUERY_PATH 0x0000 /* - path, specified by dirfd,pathname,AT_EMPTY_PATH */
+#define FSINFO_FLAGS_QUERY_FD 0x0001 /* - fd specified by dirfd */
+ __u32 request; /* ID of requested attribute */
+ __u32 Nth; /* Instance of it (some may have multiple) */
+ __u32 Mth; /* Subinstance of Nth instance */
+ __u32 __reserved32[1]; /* Reserved params; all must be 0 */
+ __u64 __reserved[3];
+};
+
+enum fsinfo_value_type {
+ FSINFO_TYPE_VSTRUCT = 0, /* Version-lengthed struct (up to 4096 bytes) */
+ FSINFO_TYPE_STRING = 1, /* NUL-term var-length string (up to 4095 chars) */
+ FSINFO_TYPE_OPAQUE = 2, /* Opaque blob (unlimited size) */
+ FSINFO_TYPE_LIST = 3, /* List of ints/structs (unlimited size) */
+};
+
+/*
+ * Information struct for fsinfo(FSINFO_ATTR_FSINFO_ATTRIBUTE_INFO).
+ *
+ * This gives information about the attributes supported by fsinfo for the
+ * given path.
+ */
+struct fsinfo_attribute_info {
+ unsigned int attr_id; /* The ID of the attribute */
+ enum fsinfo_value_type type; /* The type of the attribute's value(s) */
+ unsigned int flags;
+#define FSINFO_FLAGS_N 0x01 /* - Attr has a set of values */
+#define FSINFO_FLAGS_NM 0x02 /* - Attr has a set of sets of values */
+ unsigned int size; /* - Value size (FSINFO_STRUCT/FSINFO_LIST) */
+};
+
+#define FSINFO_ATTR_FSINFO_ATTRIBUTE_INFO__STRUCT struct fsinfo_attribute_info
+#define FSINFO_ATTR_FSINFO_ATTRIBUTES__STRUCT __u32
+
+struct fsinfo_u128 {
+#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : defined(__BIG_ENDIAN)
+ __u64 hi;
+ __u64 lo;
+#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : defined(__LITTLE_ENDIAN)
+ __u64 lo;
+ __u64 hi;
+#endif
+};
+
+/*
+ * Information struct for fsinfo(FSINFO_ATTR_STATFS).
+ * - This gives extended filesystem information.
+ */
+struct fsinfo_statfs {
+ struct fsinfo_u128 f_blocks; /* Total number of blocks in fs */
+ struct fsinfo_u128 f_bfree; /* Total number of free blocks */
+ struct fsinfo_u128 f_bavail; /* Number of free blocks available to ordinary user */
+ struct fsinfo_u128 f_files; /* Total number of file nodes in fs */
+ struct fsinfo_u128 f_ffree; /* Number of free file nodes */
+ struct fsinfo_u128 f_favail; /* Number of file nodes available to ordinary user */
+ __u64 f_bsize; /* Optimal block size */
+ __u64 f_frsize; /* Fragment size */
+};
+
+#define FSINFO_ATTR_STATFS__STRUCT struct fsinfo_statfs
+
+/*
+ * Information struct for fsinfo(FSINFO_ATTR_IDS).
+ *
+ * List of basic identifiers as is normally found in statfs().
+ */
+struct fsinfo_ids {
+ char f_fs_name[15 + 1]; /* Filesystem name */
+ __u64 f_fsid; /* Short 64-bit Filesystem ID (as statfs) */
+ __u64 f_sb_id; /* Internal superblock ID for sbnotify()/mntnotify() */
+ __u32 f_fstype; /* Filesystem type from linux/magic.h [uncond] */
+ __u32 f_dev_major; /* As st_dev_* from struct statx [uncond] */
+ __u32 f_dev_minor;
+ __u32 __padding[1];
+};
+
+#define FSINFO_ATTR_IDS__STRUCT struct fsinfo_ids
+
+/*
+ * Information struct for fsinfo(FSINFO_ATTR_LIMITS).
+ *
+ * List of supported filesystem limits.
+ */
+struct fsinfo_limits {
+ struct fsinfo_u128 max_file_size; /* Maximum file size */
+ struct fsinfo_u128 max_ino; /* Maximum inode number */
+ __u64 max_uid; /* Maximum UID supported */
+ __u64 max_gid; /* Maximum GID supported */
+ __u64 max_projid; /* Maximum project ID supported */
+ __u64 max_hard_links; /* Maximum number of hard links on a file */
+ __u64 max_xattr_body_len; /* Maximum xattr content length */
+ __u32 max_xattr_name_len; /* Maximum xattr name length */
+ __u32 max_filename_len; /* Maximum filename length */
+ __u32 max_symlink_len; /* Maximum symlink content length */
+ __u32 max_dev_major; /* Maximum device major representable */
+ __u32 max_dev_minor; /* Maximum device minor representable */
+ __u32 __padding[1];
+};
+
+#define FSINFO_ATTR_LIMITS__STRUCT struct fsinfo_limits
+
+/*
+ * Information struct for fsinfo(FSINFO_ATTR_SUPPORTS).
+ *
+ * What's supported in various masks, such as statx() attribute and mask bits
+ * and IOC flags.
+ */
+struct fsinfo_supports {
+ __u64 stx_attributes; /* What statx::stx_attributes are supported */
+ __u32 stx_mask; /* What statx::stx_mask bits are supported */
+ __u32 fs_ioc_getflags; /* What FS_IOC_GETFLAGS may return */
+ __u32 fs_ioc_setflags_set; /* What FS_IOC_SETFLAGS may set */
+ __u32 fs_ioc_setflags_clear; /* What FS_IOC_SETFLAGS may clear */
+ __u32 win_file_attrs; /* What DOS/Windows FILE_* attributes are supported */
+ __u32 __padding[1];
+};
+
+#define FSINFO_ATTR_SUPPORTS__STRUCT struct fsinfo_supports
+
+struct fsinfo_timestamp_one {
+ __s64 minimum; /* Minimum timestamp value in seconds */
+ __s64 maximum; /* Maximum timestamp value in seconds */
+ __u16 gran_mantissa; /* Granularity(secs) = mant * 10^exp */
+ __s8 gran_exponent;
+ __u8 __padding[5];
+};
+
+/*
+ * Information struct for fsinfo(FSINFO_ATTR_TIMESTAMP_INFO).
+ */
+struct fsinfo_timestamp_info {
+ struct fsinfo_timestamp_one atime; /* Access time */
+ struct fsinfo_timestamp_one mtime; /* Modification time */
+ struct fsinfo_timestamp_one ctime; /* Change time */
+ struct fsinfo_timestamp_one btime; /* Birth/creation time */
+};
+
+#define FSINFO_ATTR_TIMESTAMP_INFO__STRUCT struct fsinfo_timestamp_info
+
+/*
+ * Information struct for fsinfo(FSINFO_ATTR_VOLUME_UUID).
+ */
+struct fsinfo_volume_uuid {
+ __u8 uuid[16];
+};
+
+#define FSINFO_ATTR_VOLUME_UUID__STRUCT struct fsinfo_volume_uuid
+
+#endif /* _UAPI_LINUX_FSINFO_H */
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 0ce01f86e5db..519317f3904c 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -51,6 +51,7 @@ COND_SYSCALL_COMPAT(io_pgetevents);
COND_SYSCALL(io_uring_setup);
COND_SYSCALL(io_uring_enter);
COND_SYSCALL(io_uring_register);
+COND_SYSCALL(fsinfo);

/* fs/xattr.c */

diff --git a/samples/vfs/Makefile b/samples/vfs/Makefile
index 65acdde5c117..9159ad1d7fc5 100644
--- a/samples/vfs/Makefile
+++ b/samples/vfs/Makefile
@@ -1,10 +1,15 @@
# SPDX-License-Identifier: GPL-2.0-only
# List of programs to build
+
hostprogs := \
+ test-fsinfo \
test-fsmount \
test-statx

always-y := $(hostprogs)

+HOSTCFLAGS_test-fsinfo.o += -I$(objtree)/usr/include
+HOSTLDLIBS_test-fsinfo += -static -lm
+
HOSTCFLAGS_test-fsmount.o += -I$(objtree)/usr/include
HOSTCFLAGS_test-statx.o += -I$(objtree)/usr/include
diff --git a/samples/vfs/test-fsinfo.c b/samples/vfs/test-fsinfo.c
new file mode 100644
index 000000000000..22fe3c47ff42
--- /dev/null
+++ b/samples/vfs/test-fsinfo.c
@@ -0,0 +1,607 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Test the fsinfo() system call
+ *
+ * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#define _GNU_SOURCE
+#define _ATFILE_SOURCE
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <errno.h>
+#include <time.h>
+#include <math.h>
+#include <fcntl.h>
+#include <sys/syscall.h>
+#include <linux/fsinfo.h>
+#include <linux/socket.h>
+#include <sys/stat.h>
+#include <arpa/inet.h>
+
+#ifndef __NR_fsinfo
+#define __NR_fsinfo -1
+#endif
+
+static bool debug = 0;
+
+static __attribute__((unused))
+ssize_t fsinfo(int dfd, const char *filename, struct fsinfo_params *params,
+ void *buffer, size_t buf_size)
+{
+ return syscall(__NR_fsinfo, dfd, filename, params, buffer, buf_size);
+}
+
+struct fsinfo_attribute {
+ unsigned int attr_id;
+ enum fsinfo_value_type type;
+ unsigned int size;
+ const char *name;
+ void (*dump)(void *reply, unsigned int size);
+};
+
+static const struct fsinfo_attribute fsinfo_attributes[];
+
+static void dump_hex(unsigned int *data, int from, int to)
+{
+ unsigned offset, print_offset = 1, col = 0;
+
+ from /= 4;
+ to = (to + 3) / 4;
+
+ for (offset = from; offset < to; offset++) {
+ if (print_offset) {
+ printf("%04x: ", offset * 8);
+ print_offset = 0;
+ }
+ printf("%08x", data[offset]);
+ col++;
+ if ((col & 3) == 0) {
+ printf("\n");
+ print_offset = 1;
+ } else {
+ printf(" ");
+ }
+ }
+
+ if (!print_offset)
+ printf("\n");
+}
+
+static void dump_attribute_info(void *reply, unsigned int size)
+{
+ struct fsinfo_attribute_info *attr_info = reply;
+ const struct fsinfo_attribute *attr;
+ char type[32], val_size[32];
+
+ switch (attr_info->type) {
+ case FSINFO_TYPE_VSTRUCT: strcpy(type, "V-STRUCT"); break;
+ case FSINFO_TYPE_STRING: strcpy(type, "STRING"); break;
+ case FSINFO_TYPE_OPAQUE: strcpy(type, "OPAQUE"); break;
+ case FSINFO_TYPE_LIST: strcpy(type, "LIST"); break;
+ default:
+ sprintf(type, "type-%x", attr_info->type);
+ break;
+ }
+
+ if (attr_info->flags & FSINFO_FLAGS_N)
+ strcat(type, " x N");
+ else if (attr_info->flags & FSINFO_FLAGS_NM)
+ strcat(type, " x NM");
+
+ for (attr = fsinfo_attributes; attr->name; attr++)
+ if (attr->attr_id == attr_info->attr_id)
+ break;
+
+ if (attr_info->size)
+ sprintf(val_size, "%u", attr_info->size);
+ else
+ strcpy(val_size, "-");
+
+ printf("%8x %-12s %08x %5s %s\n",
+ attr_info->attr_id,
+ type,
+ attr_info->flags,
+ val_size,
+ attr->name ? attr->name : "");
+}
+
+static void dump_fsinfo_generic_statfs(void *reply, unsigned int size)
+{
+ struct fsinfo_statfs *f = reply;
+
+ printf("\n");
+ printf("\tblocks : n=%llu fr=%llu av=%llu\n",
+ (unsigned long long)f->f_blocks.lo,
+ (unsigned long long)f->f_bfree.lo,
+ (unsigned long long)f->f_bavail.lo);
+
+ printf("\tfiles : n=%llu fr=%llu av=%llu\n",
+ (unsigned long long)f->f_files.lo,
+ (unsigned long long)f->f_ffree.lo,
+ (unsigned long long)f->f_favail.lo);
+ printf("\tbsize : %llu\n", f->f_bsize);
+ printf("\tfrsize : %llu\n", f->f_frsize);
+}
+
+static void dump_fsinfo_generic_ids(void *reply, unsigned int size)
+{
+ struct fsinfo_ids *f = reply;
+
+ printf("\n");
+ printf("\tdev : %02x:%02x\n", f->f_dev_major, f->f_dev_minor);
+ printf("\tfs : type=%x name=%s\n", f->f_fstype, f->f_fs_name);
+ printf("\tfsid : %llx\n", (unsigned long long)f->f_fsid);
+ printf("\tsbid : %llx\n", (unsigned long long)f->f_sb_id);
+}
+
+static void dump_fsinfo_generic_limits(void *reply, unsigned int size)
+{
+ struct fsinfo_limits *f = reply;
+
+ printf("\n");
+ printf("\tmax file size: %llx%016llx\n",
+ (unsigned long long)f->max_file_size.hi,
+ (unsigned long long)f->max_file_size.lo);
+ printf("\tmax ino : %llx%016llx\n",
+ (unsigned long long)f->max_ino.hi,
+ (unsigned long long)f->max_ino.lo);
+ printf("\tmax ids : u=%llx g=%llx p=%llx\n",
+ (unsigned long long)f->max_uid,
+ (unsigned long long)f->max_gid,
+ (unsigned long long)f->max_projid);
+ printf("\tmax dev : maj=%x min=%x\n",
+ f->max_dev_major, f->max_dev_minor);
+ printf("\tmax links : %llx\n",
+ (unsigned long long)f->max_hard_links);
+ printf("\tmax xattr : n=%x b=%llx\n",
+ f->max_xattr_name_len,
+ (unsigned long long)f->max_xattr_body_len);
+ printf("\tmax len : file=%x sym=%x\n",
+ f->max_filename_len, f->max_symlink_len);
+}
+
+static void dump_fsinfo_generic_supports(void *reply, unsigned int size)
+{
+ struct fsinfo_supports *f = reply;
+
+ printf("\n");
+ printf("\tstx_attr : %llx\n", (unsigned long long)f->stx_attributes);
+ printf("\tstx_mask : %x\n", f->stx_mask);
+ printf("\tfs_ioc_*flags: get=%x set=%x clr=%x\n",
+ f->fs_ioc_getflags, f->fs_ioc_setflags_set, f->fs_ioc_setflags_clear);
+ printf("\twin_fattrs : %x\n", f->win_file_attrs);
+}
+
+static void print_time(struct fsinfo_timestamp_one *t, char stamp)
+{
+ printf("\t%ctime : gran=%gs range=%llx-%llx\n",
+ stamp,
+ t->gran_mantissa * pow(10., t->gran_exponent),
+ (long long)t->minimum,
+ (long long)t->maximum);
+}
+
+static void dump_fsinfo_generic_timestamp_info(void *reply, unsigned int size)
+{
+ struct fsinfo_timestamp_info *f = reply;
+
+ printf("\n");
+ print_time(&f->atime, 'a');
+ print_time(&f->mtime, 'm');
+ print_time(&f->ctime, 'c');
+ print_time(&f->btime, 'b');
+}
+
+static void dump_fsinfo_generic_volume_uuid(void *reply, unsigned int size)
+{
+ struct fsinfo_volume_uuid *f = reply;
+
+ printf("%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x"
+ "-%02x%02x%02x%02x%02x%02x\n",
+ f->uuid[ 0], f->uuid[ 1],
+ f->uuid[ 2], f->uuid[ 3],
+ f->uuid[ 4], f->uuid[ 5],
+ f->uuid[ 6], f->uuid[ 7],
+ f->uuid[ 8], f->uuid[ 9],
+ f->uuid[10], f->uuid[11],
+ f->uuid[12], f->uuid[13],
+ f->uuid[14], f->uuid[15]);
+}
+
+static void dump_string(void *reply, unsigned int size)
+{
+ char *s = reply, *p;
+
+ p = s;
+ if (size >= 4096) {
+ size = 4096;
+ p[4092] = '.';
+ p[4093] = '.';
+ p[4094] = '.';
+ p[4095] = 0;
+ } else {
+ p[size] = 0;
+ }
+
+ for (p = s; *p; p++) {
+ if (!isprint(*p)) {
+ printf("<non-printable>\n");
+ continue;
+ }
+ }
+
+ printf("%s\n", s);
+}
+
+#define dump_fsinfo_generic_volume_id dump_string
+#define dump_fsinfo_generic_volume_name dump_string
+
+/*
+ *
+ */
+#define __FSINFO(A, T, S, U, G, F) \
+ { .attr_id = A, .type = T, .size = S, .name = #G, .dump = dump_##G }
+
+#define _FSINFO(A, T, S, U, G) __FSINFO(A, T, S, U, G, 0)
+#define _FSINFO_N(A, T, S, U, G) __FSINFO(A, T, S, U, G, FSINFO_FLAGS_N)
+#define _FSINFO_NM(A, T, S, U, G) __FSINFO(A, T, S, U, G, FSINFO_FLAGS_NM)
+
+#define _FSINFO_VSTRUCT(A,S,G) _FSINFO (A, FSINFO_TYPE_VSTRUCT, sizeof(S), 0, G)
+#define _FSINFO_VSTRUCT_N(A,S,G) _FSINFO_N (A, FSINFO_TYPE_VSTRUCT, sizeof(S), 0, G)
+#define _FSINFO_VSTRUCT_NM(A,S,G) _FSINFO_NM(A, FSINFO_TYPE_VSTRUCT, sizeof(S), 0, G)
+
+#define FSINFO_VSTRUCT(A,G) _FSINFO_VSTRUCT (A, A##__STRUCT, G)
+#define FSINFO_VSTRUCT_N(A,G) _FSINFO_VSTRUCT_N (A, A##__STRUCT, G)
+#define FSINFO_VSTRUCT_NM(A,G) _FSINFO_VSTRUCT_NM(A, A##__STRUCT, G)
+#define FSINFO_STRING(A,G) _FSINFO (A, FSINFO_TYPE_STRING, 0, 0, G)
+#define FSINFO_STRING_N(A,G) _FSINFO_N (A, FSINFO_TYPE_STRING, 0, 0, G)
+#define FSINFO_STRING_NM(A,G) _FSINFO_NM(A, FSINFO_TYPE_STRING, 0, 0, G)
+#define FSINFO_OPAQUE(A,G) _FSINFO (A, FSINFO_TYPE_OPAQUE, 0, 0, G)
+#define FSINFO_LIST(A,G) _FSINFO (A, FSINFO_TYPE_LIST, 0, sizeof(A##__STRUCT), G)
+#define FSINFO_LIST_N(A,G) _FSINFO_N (A, FSINFO_TYPE_LIST, 0, sizeof(A##__STRUCT), G)
+
+static const struct fsinfo_attribute fsinfo_attributes[] = {
+ FSINFO_VSTRUCT (FSINFO_ATTR_STATFS, fsinfo_generic_statfs),
+ FSINFO_VSTRUCT (FSINFO_ATTR_IDS, fsinfo_generic_ids),
+ FSINFO_VSTRUCT (FSINFO_ATTR_LIMITS, fsinfo_generic_limits),
+ FSINFO_VSTRUCT (FSINFO_ATTR_SUPPORTS, fsinfo_generic_supports),
+ FSINFO_VSTRUCT (FSINFO_ATTR_TIMESTAMP_INFO, fsinfo_generic_timestamp_info),
+ FSINFO_STRING (FSINFO_ATTR_VOLUME_ID, fsinfo_generic_volume_id),
+ FSINFO_VSTRUCT (FSINFO_ATTR_VOLUME_UUID, fsinfo_generic_volume_uuid),
+ FSINFO_STRING (FSINFO_ATTR_VOLUME_NAME, fsinfo_generic_volume_name),
+ {}
+};
+
+static void dump_value(unsigned int attr_id,
+ const struct fsinfo_attribute *attr,
+ const struct fsinfo_attribute_info *attr_info,
+ void *reply, unsigned int size)
+{
+ if (!attr || !attr->dump) {
+ printf("<no dumper>\n");
+ return;
+ }
+
+ if (attr->type == FSINFO_TYPE_VSTRUCT && size < attr->size) {
+ printf("<short data %u/%u>\n", size, attr->size);
+ return;
+ }
+
+ attr->dump(reply, size);
+}
+
+static void dump_list(unsigned int attr_id,
+ const struct fsinfo_attribute *attr,
+ const struct fsinfo_attribute_info *attr_info,
+ void *reply, unsigned int size)
+{
+ size_t elem_size = attr_info->size;
+ unsigned int ix = 0;
+
+ printf("\n");
+ if (!attr || !attr->dump) {
+ printf("<no dumper>\n");
+ return;
+ }
+
+ if (attr->type == FSINFO_TYPE_VSTRUCT && size < attr->size) {
+ printf("<short data %u/%u>\n", size, attr->size);
+ return;
+ }
+
+ while (size >= elem_size) {
+ printf("\t[%02x] ", ix);
+ attr->dump(reply, size);
+ reply += elem_size;
+ size -= elem_size;
+ ix++;
+ }
+}
+
+/*
+ * Call fsinfo, expanding the buffer as necessary.
+ */
+static ssize_t get_fsinfo(const char *file, const char *name,
+ struct fsinfo_params *params, void **_r)
+{
+ ssize_t ret;
+ size_t buf_size = 4096;
+ void *r;
+
+ for (;;) {
+ r = malloc(buf_size);
+ if (!r) {
+ perror("malloc");
+ exit(1);
+ }
+ memset(r, 0xbd, buf_size);
+
+ errno = 0;
+ ret = fsinfo(AT_FDCWD, file, params, r, buf_size);
+ if (ret == -1) {
+ free(r);
+ *_r = NULL;
+ return ret;
+ }
+
+ if (ret <= buf_size)
+ break;
+ buf_size = (ret + 4096 - 1) & ~(4096 - 1);
+ }
+
+ if (debug) {
+ if (ret == -1)
+ printf("fsinfo(%s,%s,%u,%u) = %m\n",
+ file, name, params->Nth, params->Mth);
+ else
+ printf("fsinfo(%s,%s,%u,%u) = %zd\n",
+ file, name, params->Nth, params->Mth, ret);
+ }
+
+ *_r = r;
+ return ret;
+}
+
+/*
+ * Try one subinstance of an attribute.
+ */
+static int try_one(const char *file, struct fsinfo_params *params,
+ const struct fsinfo_attribute_info *attr_info, bool raw)
+{
+ const struct fsinfo_attribute *attr;
+ const char *name;
+ size_t size = 4096;
+ char namebuf[32];
+ void *r;
+
+ for (attr = fsinfo_attributes; attr->name; attr++) {
+ if (attr->attr_id == params->request) {
+ name = attr->name;
+ if (strncmp(name, "fsinfo_generic_", 15) == 0)
+ name += 15;
+ goto found;
+ }
+ }
+
+ sprintf(namebuf, "<unknown-%x>", params->request);
+ name = namebuf;
+ attr = NULL;
+
+found:
+ size = get_fsinfo(file, name, params, &r);
+
+ if (size == -1) {
+ if (errno == ENODATA) {
+ if (!(attr_info->flags & (FSINFO_FLAGS_N | FSINFO_FLAGS_NM)) &&
+ params->Nth == 0 && params->Mth == 0) {
+ fprintf(stderr,
+ "Unexpected ENODATA (0x%x{%u}{%u})\n",
+ params->request, params->Nth, params->Mth);
+ exit(1);
+ }
+ free(r);
+ return (params->Mth == 0) ? 2 : 1;
+ }
+ if (errno == EOPNOTSUPP) {
+ if (params->Nth > 0 || params->Mth > 0) {
+ fprintf(stderr,
+ "Should return -ENODATA (0x%x{%u}{%u})\n",
+ params->request, params->Nth, params->Mth);
+ exit(1);
+ }
+ //printf("\e[33m%s\e[m: <not supported>\n",
+ // fsinfo_attr_names[attr]);
+ free(r);
+ return 2;
+ }
+ perror(file);
+ exit(1);
+ }
+
+ if (raw) {
+ if (size > 4096)
+ size = 4096;
+ dump_hex(r, 0, size);
+ free(r);
+ return 0;
+ }
+
+ switch (attr_info->flags & (FSINFO_FLAGS_N | FSINFO_FLAGS_NM)) {
+ case 0:
+ printf("\e[33m%s\e[m: ", name);
+ break;
+ case FSINFO_FLAGS_N:
+ printf("\e[33m%s{%u}\e[m: ", name, params->Nth);
+ break;
+ case FSINFO_FLAGS_NM:
+ printf("\e[33m%s{%u,%u}\e[m: ", name, params->Nth, params->Mth);
+ break;
+ }
+
+ switch (attr_info->type) {
+ case FSINFO_TYPE_VSTRUCT:
+ case FSINFO_TYPE_STRING:
+ dump_value(params->request, attr, attr_info, r, size);
+ free(r);
+ return 0;
+
+ case FSINFO_TYPE_LIST:
+ dump_list(params->request, attr, attr_info, r, size);
+ free(r);
+ return 0;
+
+ case FSINFO_TYPE_OPAQUE:
+ free(r);
+ return 0;
+
+ default:
+ fprintf(stderr, "Fishy about %u 0x%x,%x,%x\n",
+ params->request, attr_info->type, attr_info->flags, attr_info->size);
+ exit(1);
+ }
+}
+
+static int cmp_u32(const void *a, const void *b)
+{
+ return *(const int *)a - *(const int *)b;
+}
+
+/*
+ *
+ */
+int main(int argc, char **argv)
+{
+ struct fsinfo_attribute_info attr_info;
+ struct fsinfo_params params = {
+ .at_flags = AT_SYMLINK_NOFOLLOW,
+ .flags = FSINFO_FLAGS_QUERY_PATH,
+ };
+ unsigned int *attrs, ret, nr, i;
+ bool meta = false;
+ int raw = 0, opt, Nth, Mth;
+
+ while ((opt = getopt(argc, argv, "adlmr"))) {
+ switch (opt) {
+ case 'a':
+ params.at_flags |= AT_NO_AUTOMOUNT;
+ continue;
+ case 'd':
+ debug = true;
+ continue;
+ case 'l':
+ params.at_flags &= ~AT_SYMLINK_NOFOLLOW;
+ continue;
+ case 'm':
+ meta = true;
+ continue;
+ case 'r':
+ raw = 1;
+ continue;
+ }
+ break;
+ }
+
+ argc -= optind;
+ argv += optind;
+
+ if (argc != 1) {
+ printf("Format: test-fsinfo [-alr] <file>\n");
+ exit(2);
+ }
+
+ /* Retrieve a list of supported attribute IDs */
+ params.request = FSINFO_ATTR_FSINFO_ATTRIBUTES;
+ params.Nth = 0;
+ params.Mth = 0;
+ ret = get_fsinfo(argv[0], "attributes", &params, (void **)&attrs);
+ if (ret == -1) {
+ fprintf(stderr, "Unable to get attribute list: %m\n");
+ exit(1);
+ }
+
+ if (ret % sizeof(attrs[0])) {
+ fprintf(stderr, "Bad length of attribute list (0x%x)\n", ret);
+ exit(2);
+ }
+
+ nr = ret / sizeof(attrs[0]);
+ qsort(attrs, nr, sizeof(attrs[0]), cmp_u32);
+
+ if (meta) {
+ printf("ATTR ID TYPE FLAGS SIZE NAME\n");
+ printf("======== ============ ======== ===== =========\n");
+ for (i = 0; i < nr; i++) {
+ params.request = FSINFO_ATTR_FSINFO_ATTRIBUTE_INFO;
+ params.Nth = attrs[i];
+ params.Mth = 0;
+ ret = fsinfo(AT_FDCWD, argv[0], &params, &attr_info, sizeof(attr_info));
+ if (ret == -1) {
+ fprintf(stderr, "Can't get info for attribute %x: %m\n", attrs[i]);
+ exit(1);
+ }
+
+ dump_attribute_info(&attr_info, ret);
+ }
+ exit(0);
+ }
+
+ for (i = 0; i < nr; i++) {
+ params.request = FSINFO_ATTR_FSINFO_ATTRIBUTE_INFO;
+ params.Nth = attrs[i];
+ params.Mth = 0;
+ ret = fsinfo(AT_FDCWD, argv[0], &params, &attr_info, sizeof(attr_info));
+ if (ret == -1) {
+ fprintf(stderr, "Can't get info for attribute %x: %m\n", attrs[i]);
+ exit(1);
+ }
+
+ if (attrs[i] == FSINFO_ATTR_FSINFO_ATTRIBUTE_INFO ||
+ attrs[i] == FSINFO_ATTR_FSINFO_ATTRIBUTES)
+ continue;
+
+ if (attrs[i] != attr_info.attr_id) {
+ fprintf(stderr, "ID for %03x returned %03x\n",
+ attrs[i], attr_info.attr_id);
+ break;
+ }
+ Nth = 0;
+ do {
+ Mth = 0;
+ do {
+ params.request = attrs[i];
+ params.Nth = Nth;
+ params.Mth = Mth;
+
+ switch (try_one(argv[0], &params, &attr_info, raw)) {
+ case 0:
+ continue;
+ case 1:
+ goto done_M;
+ case 2:
+ goto done_N;
+ }
+ } while (++Mth < 100);
+
+ done_M:
+ if (Mth >= 100) {
+ fprintf(stderr, "Fishy: Mth %x[%u][%u]\n", attrs[i], Nth, Mth);
+ break;
+ }
+
+ } while (++Nth < 100);
+
+ done_N:
+ if (Nth >= 100) {
+ fprintf(stderr, "Fishy: Nth %x[%u]\n", attrs[i], Nth);
+ break;
+ }
+ }
+
+ return 0;
+}