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Message-ID: <20200219163128.GB9496@magnolia>
Date: Wed, 19 Feb 2020 08:31:28 -0800
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: David Howells <dhowells@...hat.com>
Cc: viro@...iv.linux.org.uk, raven@...maw.net, mszeredi@...hat.com,
christian@...uner.io, linux-api@...r.kernel.org,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/19] vfs: syscall: Add fsinfo() to query filesystem
information [ver #16]
On Tue, Feb 18, 2020 at 05:05:02PM +0000, David Howells wrote:
> 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 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 and
> params->at_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@...hat.com>
> cc: linux-api@...r.kernel.org
> ---
>
> arch/x86/entry/syscalls/syscall_32.tbl | 1
> arch/x86/entry/syscalls/syscall_64.tbl | 1
> fs/Kconfig | 7
> fs/Makefile | 1
> fs/fsinfo.c | 525 ++++++++++++++++++++++++++++
> include/linux/fs.h | 5
> include/linux/fsinfo.h | 70 ++++
> include/linux/syscalls.h | 4
> include/uapi/asm-generic/unistd.h | 4
> include/uapi/linux/fsinfo.h | 186 ++++++++++
> kernel/sys_ni.c | 1
> samples/vfs/Makefile | 5
> samples/vfs/test-fsinfo.c | 599 ++++++++++++++++++++++++++++++++
> 13 files changed, 1408 insertions(+), 1 deletion(-)
> 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/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
> index c17cb77eb150..b7817acb154b 100644
> --- a/arch/x86/entry/syscalls/syscall_32.tbl
> +++ b/arch/x86/entry/syscalls/syscall_32.tbl
> @@ -442,3 +442,4 @@
> 435 i386 clone3 sys_clone3 __ia32_sys_clone3
> 437 i386 openat2 sys_openat2 __ia32_sys_openat2
> 438 i386 pidfd_getfd sys_pidfd_getfd __ia32_sys_pidfd_getfd
> +439 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 44d510bc9b78..3a45ed6d28cb 100644
> --- a/arch/x86/entry/syscalls/syscall_64.tbl
> +++ b/arch/x86/entry/syscalls/syscall_64.tbl
> @@ -359,6 +359,7 @@
> 435 common clone3 __x64_sys_clone3/ptregs
> 437 common openat2 __x64_sys_openat2
> 438 common pidfd_getfd __x64_sys_pidfd_getfd
> +439 common fsinfo __x64_sys_fsinfo
>
> #
> # x32-specific system call numbers start at 512 to avoid cache impact
> diff --git a/fs/Kconfig b/fs/Kconfig
> index 708ba336e689..1d1b48059ec9 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 505e51166973..b5cc9bcd17a4 100644
> --- a/fs/Makefile
> +++ b/fs/Makefile
> @@ -54,6 +54,7 @@ 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..3bc35b91f20b
> --- /dev/null
> +++ b/fs/fsinfo.c
> @@ -0,0 +1,525 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Filesystem information query.
> + *
> + * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved.
> + * Written by David Howells (dhowells@...hat.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"
> +
> +static const struct fsinfo_attribute fsinfo_common_attributes[];
> +
> +/**
> + * fsinfo_string - Store a 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)
> +{
> + int ret = 0;
> +
> + if (s) {
> + ret = strlen(s);
> + memcpy(ctx->buffer, s, ret);
> + }
> +
> + 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.hi = 0;
> + p->f_blocks.lo = buf.f_blocks;
Er... are there filesystems (besides that (xfs++)++ one) that require
u128 counters? I suspect that the Very Large Fields are for future
expandability, but I also wonder about the whether it's worth the
complexity of doing this, since the structures can always be
version-revved later.
(I'm not opposed to u128, I'm just curious about it. :))
> + p->f_bfree.hi = 0;
> + p->f_bfree.lo = buf.f_bfree;
> + p->f_bavail.hi = 0;
> + p->f_bavail.lo = buf.f_bavail;
> + p->f_files.hi = 0;
> + p->f_files.lo = buf.f_files;
> + p->f_ffree.hi = 0;
> + p->f_ffree.lo = buf.f_ffree;
> + p->f_favail.hi = 0;
> + 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;
> +
> + 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);
> +
> + memcpy(&p->f_fsid, &buf.f_fsid, sizeof(p->f_fsid));
> + strlcpy(p->f_fs_name, path->dentry->d_sb->s_type->name,
> + sizeof(p->f_fs_name));
> + return sizeof(*p);
> +}
> +
> +static int fsinfo_generic_limits(struct path *path, struct fsinfo_context *ctx)
> +{
> + struct fsinfo_limits *lim = ctx->buffer;
> + struct super_block *sb = path->dentry->d_sb;
> +
> + lim->max_file_size.hi = 0;
> + lim->max_file_size.lo = sb->s_maxbytes;
> + lim->max_ino.hi = 0;
> + lim->max_ino.lo = UINT_MAX;
XFS inodes are u64 values...
> + lim->max_hard_links = sb->s_max_links;
> + lim->max_uid = UINT_MAX;
> + lim->max_gid = UINT_MAX;
> + lim->max_projid = UINT_MAX;
> + lim->max_filename_len = NAME_MAX;
> + lim->max_symlink_len = PAGE_SIZE;
...and the max symlink target length is 1k, not PAGE_SIZE...
> + lim->max_xattr_name_len = XATTR_NAME_MAX;
> + lim->max_xattr_body_len = XATTR_SIZE_MAX;
...so is the usage model here that XFS should call fsinfo_generic_limits
to fill out the fsinfo_limits structure, modify the values in
ctx->buffer as appropriate for XFS, and then return the structure size?
> + lim->max_dev_major = 0xffffff;
> + lim->max_dev_minor = 0xff;
> + return sizeof(*lim);
> +}
> +
> +static int fsinfo_generic_supports(struct path *path, struct fsinfo_context *ctx)
> +{
> + struct fsinfo_supports *c = ctx->buffer;
> + struct super_block *sb = path->dentry->d_sb;
> +
> + c->stx_mask = STATX_BASIC_STATS;
> + if (sb->s_d_op && sb->s_d_op->d_automount)
> + c->stx_attributes |= STATX_ATTR_AUTOMOUNT;
> + return sizeof(*c);
> +}
> +
> +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,
> + },
> +};
> +
> +static int fsinfo_generic_timestamp_info(struct path *path, struct fsinfo_context *ctx)
> +{
> + struct fsinfo_timestamp_info *ts = ctx->buffer;
> + struct super_block *sb = path->dentry->d_sb;
> + s8 exponent;
> +
> + *ts = 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;
> +
> + ts->atime.gran_exponent = exponent;
> + ts->mtime.gran_exponent = exponent;
> + ts->ctime.gran_exponent = exponent;
> + ts->btime.gran_exponent = exponent;
> + }
> +
> + return sizeof(*ts);
> +}
> +
> +static int fsinfo_generic_volume_uuid(struct path *path, struct fsinfo_context *ctx)
> +{
> + struct fsinfo_volume_uuid *vu = ctx->buffer;
> + struct super_block *sb = path->dentry->d_sb;
> +
> + memcpy(vu, &sb->s_uuid, sizeof(*vu));
> + return sizeof(*vu);
> +}
> +
> +static int fsinfo_generic_volume_id(struct path *path, struct fsinfo_context *ctx)
> +{
> + return fsinfo_string(path->dentry->d_sb->s_id, ctx);
> +}
> +
> +static int fsinfo_attribute_info(struct path *path, struct fsinfo_context *ctx)
> +{
> + const struct fsinfo_attribute *attr;
> + struct fsinfo_attribute_info *info = ctx->buffer;
> + struct dentry *dentry = path->dentry;
> +
> + if (dentry->d_sb->s_op->fsinfo_attributes)
> + for (attr = dentry->d_sb->s_op->fsinfo_attributes; attr->get; attr++)
> + if (attr->attr_id == ctx->Nth)
> + goto found;
> + for (attr = fsinfo_common_attributes; attr->get; attr++)
> + if (attr->attr_id == ctx->Nth)
> + goto found;
> + return -ENODATA;
> +
> +found:
> + info->attr_id = attr->attr_id;
> + info->type = attr->type;
> + info->flags = attr->flags;
> + info->size = attr->size;
> + info->element_size = attr->element_size;
> + return sizeof(*attr);
> +}
> +
> +static void fsinfo_attributes_insert(struct fsinfo_context *ctx,
> + const struct fsinfo_attribute *attr)
> +{
> + __u32 *buffer = 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 (buffer[i] == attr->attr_id)
> + return;
> +
> + buffer[i] = attr->attr_id;
> + ctx->usage += sizeof(__u32);
> +}
> +
> +static int fsinfo_attributes(struct path *path, struct fsinfo_context *ctx)
> +{
> + const struct fsinfo_attribute *attr;
> + struct super_block *sb = path->dentry->d_sb;
> +
> + if (sb->s_op->fsinfo_attributes)
> + for (attr = sb->s_op->fsinfo_attributes; attr->get; attr++)
> + fsinfo_attributes_insert(ctx, attr);
> + for (attr = fsinfo_common_attributes; attr->get; attr++)
> + fsinfo_attributes_insert(ctx, attr);
> + return ctx->usage;
> +}
> +
> +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),
There's a space ^ before the tab here.
> + FSINFO_VSTRUCT (FSINFO_ATTR_VOLUME_UUID, fsinfo_generic_volume_uuid),
> + FSINFO_VSTRUCT_N(FSINFO_ATTR_FSINFO_ATTRIBUTE_INFO, fsinfo_attribute_info),
> + FSINFO_LIST (FSINFO_ATTR_FSINFO_ATTRIBUTES, fsinfo_attributes),
> + {}
> +};
> +
> +/*
> + * Retrieve large filesystem information, such as an opaque blob or array of
> + * struct elements where the value isn't limited to the size of a page.
> + */
> +static int vfs_fsinfo_large(struct path *path, struct fsinfo_context *ctx,
> + const struct fsinfo_attribute *attr)
> +{
> + int ret;
> +
> + while (!signal_pending(current)) {
> + ctx->usage = 0;
> + ret = attr->get(path, ctx);
> + if (IS_ERR_VALUE((long)ret))
> + return ret; /* Error */
> + if ((unsigned int)ret <= ctx->buf_size)
> + return ret; /* It fitted */
> +
> + /* We need to resize the buffer */
> + kvfree(ctx->buffer);
> + ctx->buffer = NULL;
> + ctx->buf_size = roundup(ret, PAGE_SIZE);
> + if (ctx->buf_size > INT_MAX)
> + return -EMSGSIZE;
> + ctx->buffer = kvmalloc(ctx->buf_size, GFP_KERNEL);
> + if (!ctx->buffer)
> + return -ENOMEM;
> + }
> +
> + return -ERESTARTSYS;
> +}
> +
> +static int vfs_do_fsinfo(struct path *path, struct fsinfo_context *ctx,
> + const struct fsinfo_attribute *attr)
> +{
> + 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;
> +
> + ctx->buf_size = attr->size;
> + if (ctx->want_size_only && attr->type == FSINFO_TYPE_VSTRUCT)
> + return attr->size;
> +
> + ctx->buffer = kvzalloc(ctx->buf_size, GFP_KERNEL);
> + if (!ctx->buffer)
> + return -ENOMEM;
> +
> + switch (attr->type) {
> + case FSINFO_TYPE_VSTRUCT:
> + ctx->clear_tail = true;
> + /* Fall through */
> + case FSINFO_TYPE_STRING:
> + return attr->get(path, ctx);
> +
> + case FSINFO_TYPE_OPAQUE:
> + case FSINFO_TYPE_LIST:
> + return vfs_fsinfo_large(path, ctx, attr);
> +
> + default:
> + return -ENOPKG;
> + }
> +}
> +
> +/**
> + * 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)
> +{
> + const struct fsinfo_attribute *attr;
> + struct dentry *dentry = path->dentry;
> + int ret;
> +
> + if (dentry->d_sb->s_op->fsinfo_attributes)
> + for (attr = dentry->d_sb->s_op->fsinfo_attributes; attr->get; attr++)
> + if (attr->attr_id == ctx->requested_attr)
> + goto found;
> + for (attr = fsinfo_common_attributes; attr->get; attr++)
> + if (attr->attr_id == ctx->requested_attr)
> + goto found;
> + return -EOPNOTSUPP;
> +
> +found:
> + ret = security_sb_statfs(dentry);
> + if (ret)
> + return ret;
> +
> + return vfs_do_fsinfo(path, ctx, attr);
> +}
> +
> +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_TYPE)
> + 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_TYPE) {
> + 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 = ret;
> + if (result_size > user_buf_size)
> + result_size = 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 3cd4fe6b845e..f74a4ee36eb3 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -68,6 +68,8 @@ struct fsverity_info;
> struct fsverity_operations;
> struct fs_context;
> struct fs_parameter_spec;
> +struct fsinfo_kparams;
> +struct fsinfo_attribute;
>
> extern void __init inode_init(void);
> extern void __init inode_init_early(void);
> @@ -1954,6 +1956,9 @@ struct super_operations {
> int (*thaw_super) (struct super_block *);
> int (*unfreeze_fs) (struct super_block *);
> int (*statfs) (struct dentry *, struct kstatfs *);
> +#ifdef CONFIG_FSINFO
> + const struct fsinfo_attribute *fsinfo_attributes;
> +#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..dcd55dbb02fa
> --- /dev/null
> +++ b/include/linux/fsinfo.h
> @@ -0,0 +1,70 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Filesystem information query
> + *
> + * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved.
> + * Written by David Howells (dhowells@...hat.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) */
> + unsigned int element_size:16; /* - Element size (FSINFO_LIST) */
> + int (*get)(struct path *path, struct fsinfo_context *params);
> +};
> +
> +#define __FSINFO(A, T, S, E, G, F) \
> + { .attr_id = A, .type = T, .flags = F, .size = S, .element_size = E, .get = G }
> +
> +#define _FSINFO(A, T, S, E, G) __FSINFO(A, T, S, E, G, 0)
> +#define _FSINFO_N(A, T, S, E, G) __FSINFO(A, T, S, E, G, FSINFO_FLAGS_N)
> +#define _FSINFO_NM(A, T, S, E, G) __FSINFO(A, T, S, E, 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, FSINFO_NORMAL_ATTR_MAX_SIZE, 0, G)
> +#define FSINFO_STRING_N(A,G) _FSINFO_N (A, FSINFO_TYPE_STRING, FSINFO_NORMAL_ATTR_MAX_SIZE, 0, G)
> +#define FSINFO_STRING_NM(A,G) _FSINFO_NM(A, FSINFO_TYPE_STRING, FSINFO_NORMAL_ATTR_MAX_SIZE, 0, G)
> +#define FSINFO_OPAQUE(A,G) _FSINFO (A, FSINFO_TYPE_OPAQUE, FSINFO_NORMAL_ATTR_MAX_SIZE, 0, G)
> +#define FSINFO_LIST(A,G) _FSINFO (A, FSINFO_TYPE_LIST, FSINFO_NORMAL_ATTR_MAX_SIZE, \
> + sizeof(A##__STRUCT), G)
> +#define FSINFO_LIST_N(A,G) _FSINFO_N (A, FSINFO_TYPE_LIST, FSINFO_NORMAL_ATTR_MAX_SIZE, \
> + sizeof(A##__STRUCT), G)
> +
> +extern int fsinfo_string(const char *, struct fsinfo_context *);
> +
> +#endif /* CONFIG_FSINFO */
> +
> +#endif /* _LINUX_FSINFO_H */
> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> index 1815065d52f3..6c3157e46e7c 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;
> @@ -1003,6 +1004,9 @@ asmlinkage long sys_pidfd_send_signal(int pidfd, int sig,
> siginfo_t __user *info,
> unsigned int flags);
> asmlinkage long sys_pidfd_getfd(int pidfd, int fd, unsigned int flags);
> +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 3a3201e4618e..9d00098a3f1b 100644
> --- a/include/uapi/asm-generic/unistd.h
> +++ b/include/uapi/asm-generic/unistd.h
> @@ -855,9 +855,11 @@ __SYSCALL(__NR_clone3, sys_clone3)
> __SYSCALL(__NR_openat2, sys_openat2)
> #define __NR_pidfd_getfd 438
> __SYSCALL(__NR_pidfd_getfd, sys_pidfd_getfd)
> +#define __NR_fsinfo 439
> +__SYSCALL(__NR_fsinfo, sys_fsinfo)
>
> #undef __NR_syscalls
> -#define __NR_syscalls 439
> +#define __NR_syscalls 440
>
> /*
> * 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..365d54fe9290
> --- /dev/null
> +++ b/include/uapi/linux/fsinfo.h
> @@ -0,0 +1,186 @@
> +/* 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@...hat.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) */
I think I've muttered about the distinction between volume id and
volume name before, but I'm still wondering how confusing that will be
for users? Let me check my assumptions, though:
Volume ID is whatever's in super_block.s_id, which (at least for xfs and
ext4) is the device name (e.g. "sda1"). I guess that's useful for
correlating a thing you can call fsinfo() on against strings that were
logged in dmesg.
Volume name I think is the fs label (e.g. "home"), which I think will
have to be implemented separately by each filesystem, and that's why
there's no generic vfs implementation.
Do I have that correct?
> +
> +#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_TYPE 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 */
The 7 -> 0 -> 1 sequence here confused me until I figured out that
QUERY_TYPE is the mask for QUERY_{PATH,FD}.
> + __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) */
> + unsigned int element_size; /* - Element size (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 __reserved[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 __reserved[1];
I wonder if these structures ought to reserve more space than a single u32...
> +};
> +
> +#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 ioc_flags; /* What FS_IOC_* flags are supported */
"IOC"? That just means 'ioctl'. Is this field supposed to return the
supported FS_IOC_GETFLAGS flags, or the supported FS_IOC_FSGETXATTR
flags?
I suspect it would also be a big help to be able to tell userspace which
of the flags can be set, and which can be cleared.
> + __u32 win_file_attrs; /* What DOS/Windows FILE_* attributes are supported */
> + __u32 __reserved[1];
> +};
> +
> +#define FSINFO_ATTR_SUPPORTS__STRUCT struct fsinfo_supports
> +
> +struct fsinfo_timestamp_one {
> + __s64 minimum; /* Minimum timestamp value in seconds */
> + __u64 maximum; /* Maximum timestamp value in seconds */
Given that time64_t is s64, why is the maximum here u64?
> + __u16 gran_mantissa; /* Granularity(secs) = mant * 10^exp */
> + __s8 gran_exponent;
> + __u8 reserved[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 3b69a560a7ac..58246e6b5603 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..9a4d49db2996
> --- /dev/null
> +++ b/samples/vfs/test-fsinfo.c
> @@ -0,0 +1,599 @@
> +// 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@...hat.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];
> +
> + 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;
> +
> + printf("%8x %-12s %08x %5u %5u %s\n",
> + attr_info->attr_id,
> + type,
> + attr_info->flags,
> + attr_info->size,
> + attr_info->element_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);
> +}
> +
> +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("\tioc_flags : %x\n", f->ioc_flags);
> + 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 dump_fsinfo_generic_name_encoding 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->element_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;
> +
> + //printf("try %03x[%u][%u]\n", params->request, params->Nth, params->Mth);
Stray debugging statement?
--D
> +
> + 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", ¶ms, (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 ESIZE 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], ¶ms, &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], ¶ms, &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;
> +
> + Nth = 0;
> + do {
> + Mth = 0;
> + do {
> + params.request = attrs[i];
> + params.Nth = Nth;
> + params.Mth = Mth;
> +
> + switch (try_one(argv[0], ¶ms, &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;
> +}
>
>
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