On Thu, Apr 19, 2012 at 03:06:12PM +0100, David Howells wrote:
> Add a pair of system calls to make extended file stats available, including
> file creation time, inode version and data version where available through the
> underlying filesystem.
>
> The idea was initially proposed as a set of xattrs that could be retrieved
> with
> getxattr(), but the general preferance proved to be for new syscalls with an
> extended stat structure.
>
> This has a number of uses:
>
> (1) Creation time: The SMB protocol carries the creation time, which could be
> exported by Samba, which will in turn help CIFS make use of FS-Cache as
> that can be used for coherency data.
>
> This is also specified in NFSv4 as a recommended attribute and could be
> exported by NFSD [Steve French].
>
> (2) Lightweight stat: Ask for just those details of interest, and allow a
> netfs (such as NFS) to approximate anything not of interest, possibly
> without going to the server [Trond Myklebust, Ulrich Drepper].
>
> (3) Heavyweight stat: Force a netfs to go to the server, even if it thinks
> its
> cached attributes are up to date [Trond Myklebust].
>
> (4) Inode generation number: Useful for FUSE and userspace NFS servers [Bernd
> Schubert].
>
> (5) Data version number: Could be used by userspace NFS servers [Aneesh
> Kumar].
>
> Can also be used to modify fill_post_wcc() in NFSD which retrieves
> i_version directly, but has just called vfs_getattr(). It could get it
> from the kstat struct if it used vfs_xgetattr() instead.
>
> (6) BSD stat compatibility: Including more fields from the BSD stat such as
> creation time (st_btime) and inode generation number (st_gen) [Jeremy
> Allison, Bernd Schubert].
>
> (7) Extra coherency data may be useful in making backups [Andreas Dilger].
>
> (8) Allow the filesystem to indicate what it can/cannot provide: A filesystem
> can now say it doesn't support a standard stat feature if that isn't
> available, so if, for instance, inode numbers or UIDs don't exist...
>
> (9) Make the fields a consistent size on all arches and make them large.
>
> (10) Store a 16-byte volume ID in the superblock that can be returned in
> struct
> xstat [Steve French].
>
> (11) Include granularity fields in the time data to indicate the granularity
> of
> each of the times (NFSv4 time_delta) [Steve French].
It looks like you're including this with *each* time? But surely
there's no filesystem with different granularity (say) for ctime than
for mtime. Also, nfsd will want only one time_delta, not one for each
time.
Note also we need to document carefully what this means: I think it
should be the granularity that the filesystem is capable of
representing, but people are sometimes surprised to find out that the
actual time source is usually more coarse-grained than that.
--b.
>
> (12) FS_IOC_GETFLAGS value. These could be translated to BSD's st_flags.
>
> (13) Mask of features available on file (eg: ACLs, seclabel) [Brad Boyer,
> Michael Kerrisk].
>
> (14) Spare space, request flags and information flags are provided for future
> expansion.
>
>
> The following structures are defined for the use of these new system calls:
>
> struct xstat_dev {
> uint32_t major, minor;
> };
>
> struct xstat_time {
> uint64_t tv_sec;
> uint32_t tv_nsec;
> uint32_t tv_granularity;
> };
>
> struct xstat {
> uint32_t st_mask;
> uint32_t st_mode;
> uint32_t st_nlink;
> uint32_t st_uid;
> uint32_t st_gid;
> uint32_t st_information;
> uint32_t st_ioc_flags;
> uint32_t st_blksize;
> struct xstat_dev st_rdev;
> struct xstat_dev st_dev;
> struct xstat_time st_atime;
> struct xstat_time st_btime;
> struct xstat_time st_ctime;
> struct xstat_time st_mtime;
> uint64_t st_ino;
> uint64_t st_size;
> uint64_t st_blocks;
> uint64_t st_gen;
> uint64_t st_version;
> uint8_t st_volume_id[16];
> uint64_t __spares[11];
> };
>
> where st_information is local system information about the file, st_btime is
> the file creation time, st_gen is the inode generation (i_generation),
> st_data_version is the data version number (i_version), st_ioc_flags is the
> flags from FS_IOC_GETFLAGS, st_volume_id is where the volume identified is
> stored, st_result_mask is a bitmask indicating the data provided and
> __spares[]
> are where as-yet undefined fields can be placed.
>
> The defined bits in request_mask and st_mask are:
>
> XSTAT_MODE Want/got st_mode
> XSTAT_NLINK Want/got st_nlink
> XSTAT_UID Want/got st_uid
> XSTAT_GID Want/got st_gid
> XSTAT_RDEV Want/got st_rdev
> XSTAT_ATIME Want/got st_atime
> XSTAT_MTIME Want/got st_mtime
> XSTAT_CTIME Want/got st_ctime
> XSTAT_INO Want/got st_ino
> XSTAT_SIZE Want/got st_size
> XSTAT_BLOCKS Want/got st_blocks
> XSTAT_BASIC_STATS [The stuff in the normal stat struct]
> XSTAT_IOC_FLAGS Want/got FS_IOC_GETFLAGS
> XSTAT_BTIME Want/got st_btime
> XSTAT_GEN Want/got st_gen
> XSTAT_VERSION Want/got st_data_version
> XSTAT_VOLUME_ID Want/got st_volume_id
> XSTAT_ALL_STATS [All currently available stuff]
>
> The defined bits in st_ioc_flags are the usual FS_xxx_FL, plus some extra
> flags
> that might be supplied by the filesystem. Note that Ext4 returns flags
> outside
> of {EXT4,FS}_FL_USER_VISIBLE in response to FS_IOC_GETFLAGS. Should
> {EXT4,FS}_FL_USER_VISIBLE be extended to cover them? Or should the extra
> flags
> be suppressed?
>
> The defined bits in the st_information field give local system data on a file,
> how it is accessed, where it is and what it does:
>
> XSTAT_INFO_ENCRYPTED File is encrypted
> XSTAT_INFO_TEMPORARY File is temporary (NTFS/CIFS/deleted)
> XSTAT_INFO_FABRICATED File was made up by filesystem
> XSTAT_INFO_KERNEL_API File is kernel API (eg: procfs/sysfs)
> XSTAT_INFO_REMOTE File is remote
> XSTAT_INFO_OFFLINE File is offline (CIFS)
> XSTAT_INFO_AUTOMOUNT Dir is automount trigger
> XSTAT_INFO_AUTODIR Dir provides unlisted automounts
> XSTAT_INFO_NONSYSTEM_OWNERSHIP File has non-system ownership details
> XSTAT_INFO_HAS_ACL File has an ACL of some sort
> XSTAT_INFO_REPARSE_POINT File is reparse point (NTFS/CIFS)
> XSTAT_INFO_HIDDEN File is marked hidden (DOS+)
> XSTAT_INFO_SYSTEM File is marked system (DOS+)
> XSTAT_INFO_ARCHIVE File is marked archive (DOS+)
>
> These are for the use of GUI tools that might want to mark files specially,
> depending on what they are. I've tried not to provide overlap with
> st_ioc_flags where something usable exists there. Should Hidden, System and
> Archive flags be associated with ioc_flags, perhaps with ioc_flags extended to
> 64-bits?
>
>
> The system calls are:
>
> ssize_t ret = xstat(int dfd,
> const char *filename,
> unsigned int flags,
> unsigned int mask,
> struct xstat *buffer);
>
> ssize_t ret = fxstat(unsigned fd,
> unsigned int flags,
> unsigned int mask,
> struct xstat *buffer);
>
>
> The dfd, filename, flags and fd parameters indicate the file to query. There
> is no equivalent of lstat() as that can be emulated with xstat() by passing
> AT_SYMLINK_NOFOLLOW in flags.
>
> AT_FORCE_ATTR_SYNC can also be set in flags. This will require a network
> filesystem to synchronise its attributes with the server.
>
> mask is a bitmask indicating the fields in struct xstat that are of interest
> to
> the caller. The user should set this to XSTAT__BASIC_STATS to get the
> basic set returned by stat().
>
> Should there just be one xstat() syscall that does fxstat() if filename is
> NULL?
>
> The fields in struct xstat come in a number of classes:
>
> (0) st_dev, st_blksize, st_information.
>
> These are local data and are always available.
>
> (1) st_mode, st_nlinks, st_uid, st_gid, st_[amc]time, st_ino, st_size,
> st_blocks.
>
> These will be returned whether the caller asks for them or not. The
> corresponding bits in result_mask will be set to indicate their presence.
>
> If the caller didn't ask for them, then they may be approximated. For
> example, NFS won't waste any time updating them from the server, unless
> as
> a byproduct of updating something requested.
>
> If the values don't actually exist for the underlying object (such as UID
> or GID on a DOS file), then the bit won't be set in the result_mask, even
> if the caller asked for the value and the returned value will be a
> fabrication.
>
> (2) st_rdev.
>
> As for class (1), but this won't be returned if the file is not a
> blockdev
> or chardev. The bit will be cleared if the value is not returned.
>
> (3) File creation time (st_btime), inode generation (st_gen), data version
> (st_version), volume_id (st_volume_id) and inode flags (st_ioc_flags).
>
> These will be returned if available whether the caller asked for them or
> not. The corresponding bits in result_mask will be set or cleared as
> appropriate to indicate their presence.
>
> If the caller didn't ask for them, then they may be approximated. For
> example, NFS won't waste any time updating them from the server, unless
> as a byproduct of updating something requested.
>
> At the moment, this will only work on x86_64 and i386 as it requires system
> calls to be wired up.
>
>
> =======
> TESTING
> =======
>
> The following test program can be used to test the xstat system call:
>
> /* Test the xstat() system call
> *
> * Copyright (C) 2010 Red Hat, Inc. All Rights Reserved.
> * Written by David Howells (dhowe...@redhat.com)
> *
> * This program is free software; you can redistribute it and/or
> * modify it under the terms of the GNU General Public Licence
> * as published by the Free Software Foundation; either version
> * 2 of the Licence, or (at your option) any later version.
> */
>
> #define _GNU_SOURCE
> #define _ATFILE_SOURCE
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
> #include <unistd.h>
> #include <fcntl.h>
> #include <time.h>
> #include <sys/syscall.h>
> #include <sys/stat.h>
> #include <sys/types.h>
>
> #define AT_NO_AUTOMOUNT 0x800
> #define AT_FORCE_ATTR_SYNC 0x2000
>
> #define XSTAT_MODE 0x00000001U
> #define XSTAT_NLINK 0x00000002U
> #define XSTAT_UID 0x00000004U
> #define XSTAT_GID 0x00000008U
> #define XSTAT_RDEV 0x00000010U
> #define XSTAT_ATIME 0x00000020U
> #define XSTAT_MTIME 0x00000040U
> #define XSTAT_CTIME 0x00000080U
> #define XSTAT_INO 0x00000100U
> #define XSTAT_SIZE 0x00000200U
> #define XSTAT_BLOCKS 0x00000400U
> #define XSTAT_BASIC_STATS 0x000007ffU
> #define XSTAT_BTIME 0x00000800U
> #define XSTAT_GEN 0x00001000U
> #define XSTAT_VERSION 0x00002000U
> #define XSTAT_IOC_FLAGS 0x00004000U
> #define XSTAT_VOLUME_ID 0x00008000U
> #define XSTAT_ALL_STATS 0x0000ffffU
>
> struct xstat_dev {
> uint32_t major;
> uint32_t minor;
> };
>
> struct xstat_time {
> uint64_t tv_sec;
> uint32_t tv_nsec;
> uint32_t tv_granularity;
> };
>
> struct xstat {
> uint32_t st_mask;
> uint32_t st_mode;
> uint32_t st_nlink;
> uint32_t st_uid;
> uint32_t st_gid;
> uint32_t st_information;
> uint32_t st_ioc_flags;
> uint32_t st_blksize;
> struct xstat_dev st_rdev;
> struct xstat_dev st_dev;
> struct xstat_time st_atim;
> struct xstat_time st_btim;
> struct xstat_time st_ctim;
> struct xstat_time st_mtim;
> uint64_t st_ino;
> uint64_t st_size;
> uint64_t st_blksize;
> uint64_t st_blocks;
> uint64_t st_gen;
> uint64_t st_version;
> uint64_t st_volume_id[16];
> uint64_t st_spares[11];
> };
>
> #define XSTAT_INFO_ENCRYPTED 0x00000001U
> #define XSTAT_INFO_TEMPORARY 0x00000002U
> #define XSTAT_INFO_FABRICATED 0x00000004U
> #define XSTAT_INFO_KERNEL_API 0x00000008U
> #define XSTAT_INFO_REMOTE 0x00000010U
> #define XSTAT_INFO_OFFLINE 0x00000020U
> #define XSTAT_INFO_AUTOMOUNT 0x00000040U
> #define XSTAT_INFO_AUTODIR 0x00000080U
> #define XSTAT_INFO_NONSYSTEM_OWNERSHIP 0x00000100U
> #define XSTAT_INFO_HAS_ACL 0x00000200U
> #define XSTAT_INFO_REPARSE_POINT 0x00000400U
> #define XSTAT_INFO_HIDDEN 0x00000800U
> #define XSTAT_INFO_SYSTEM 0x00001000U
> #define XSTAT_INFO_ARCHIVE 0x00002000U
>
> #define __NR_xstat 312
> #define __NR_fxstat 313
>
> static __attribute__((unused))
> ssize_t xstat(int dfd, const char *filename, unsigned flags,
> unsigned int mask, struct xstat *buffer)
> {
> return syscall(__NR_xstat, dfd, filename, flags, mask, buffer);
> }
>
> static __attribute__((unused))
> ssize_t fxstat(int fd, unsigned flags,
> unsigned int mask, struct xstat *buffer)
> {
> return syscall(__NR_fxstat, fd, flags, mask, buffer);
> }
>
> static void print_time(const char *field, const struct xstat_time *xstm)
> {
> struct tm tm;
> time_t tim;
> char buffer[100];
> int len;
>
> tim = xstm->tv_sec;
> if (!localtime_r(&tim, &tm)) {
> perror("localtime_r");
> exit(1);
> }
> len = strftime(buffer, 100, "%F %T", &tm);
> if (len == 0) {
> perror("strftime");
> exit(1);
> }
> printf("%s", field);
> fwrite(buffer, 1, len, stdout);
> printf(".%09u", xstm->tv_nsec);
> len = strftime(buffer, 100, "%z", &tm);
> if (len == 0) {
> perror("strftime2");
> exit(1);
> }
> fwrite(buffer, 1, len, stdout);
> printf("\n");
> }
>
> static void dump_xstat(struct xstat *xst)
> {
> char buffer[256], ft;
>
> printf("results=%x\n", xst->st_mask);
>
> printf(" ");
> if (xst->st_mask & XSTAT_SIZE)
> printf(" Size: %-15llu", (unsigned long long)
> xst->st_size);
> if (xst->st_mask & XSTAT_BLOCKS)
> printf(" Blocks: %-10llu", (unsigned long long)
> xst->st_blocks);
> printf(" IO Block: %-6llu ", (unsigned long long)
> xst->st_blksize);
> if (xst->st_mask & XSTAT_MODE) {
> switch (xst->st_mode & S_IFMT) {
> case S_IFIFO: printf(" FIFO\n");
> ft = 'p'; break;
> case S_IFCHR: printf(" character special file\n");
> ft = 'c'; break;
> case S_IFDIR: printf(" directory\n");
> ft = 'd'; break;
> case S_IFBLK: printf(" block special file\n");
> ft = 'b'; break;
> case S_IFREG: printf(" regular file\n");
> ft = '-'; break;
> case S_IFLNK: printf(" symbolic link\n");
> ft = 'l'; break;
> case S_IFSOCK: printf(" socket\n");
> ft = 's'; break;
> default:
> printf("unknown type (%o)\n", xst->st_mode &
> S_IFMT);
> ft = '?';
> break;
> }
> }
>
> sprintf(buffer, "%02x:%02x", xst->st_dev.major,
> xst->st_dev.minor);
> printf("Device: %-15s", buffer);
> if (xst->st_mask & XSTAT_INO)
> printf(" Inode: %-11llu", (unsigned long long)
> xst->st_ino);
> if (xst->st_mask & XSTAT_SIZE)
> printf(" Links: %-5u", xst->st_nlink);
> if (xst->st_mask & XSTAT_RDEV)
> printf(" Device type: %u,%u",
> xst->st_rdev.major, xst->st_rdev.minor);
> printf("\n");
>
> if (xst->st_mask & XSTAT_MODE)
> printf("Access: (%04o/%c%c%c%c%c%c%c%c%c%c) ",
> xst->st_mode & 07777,
> ft,
> xst->st_mode & S_IRUSR ? 'r' : '-',
> xst->st_mode & S_IWUSR ? 'w' : '-',
> xst->st_mode & S_IXUSR ? 'x' : '-',
> xst->st_mode & S_IRGRP ? 'r' : '-',
> xst->st_mode & S_IWGRP ? 'w' : '-',
> xst->st_mode & S_IXGRP ? 'x' : '-',
> xst->st_mode & S_IROTH ? 'r' : '-',
> xst->st_mode & S_IWOTH ? 'w' : '-',
> xst->st_mode & S_IXOTH ? 'x' : '-');
> if (xst->st_mask & XSTAT_UID)
> printf("Uid: %d \n", xst->st_uid);
> if (xst->st_mask & XSTAT_GID)
> printf("Gid: %u\n", xst->st_gid);
>
> if (xst->st_mask & XSTAT_ATIME)
> print_time("Access: ", &xst->st_atim);
> if (xst->st_mask & XSTAT_MTIME)
> print_time("Modify: ", &xst->st_mtim);
> if (xst->st_mask & XSTAT_CTIME)
> print_time("Change: ", &xst->st_ctim);
> if (xst->st_mask & XSTAT_BTIME)
> print_time("Create: ", &xst->st_btim);
>
> if (xst->st_mask & XSTAT_GEN)
> printf("Inode version: %llxh\n", (unsigned long long)
> xst->st_gen);
> if (xst->st_mask & XSTAT_VERSION)
> printf("Data version: %llxh\n", (unsigned long long)
> xst->st_version);
>
> if (xst->st_mask & XSTAT_IOC_FLAGS) {
> unsigned char bits;
> int loop, byte;
>
> static char flag_representation[32 + 1] =
> /* FS_IOC_GETFLAGS flags: */
> "????????" /* 31-24
> 0x00000000-ff000000 */
> "????ehTD" /* 23-16
> 0x00000000-00ff0000 */
> "tj?IE?XZ" /* 15- 8
> 0x00000000-0000ff00 */
> "AdaiScus" /* 7- 0
> 0x00000000-000000ff */
> ;
>
> printf("Inode flags: %08x (", xst->st_ioc_flags);
> for (byte = 32 - 8; byte >= 0; byte -= 8) {
> bits = xst->st_ioc_flags >> byte;
> for (loop = 7; loop >= 0; loop--) {
> int bit = byte + loop;
>
> if (bits & 0x80)
> putchar(flag_representation[31
> - bit]);
> else
> putchar('-');
> bits <<= 1;
> }
> if (byte)
> putchar(' ');
> }
> printf(")\n");
> }
>
> if (xst->st_information) {
> unsigned char bits;
> int loop, byte;
>
> static char info_representation[32 + 1] =
> /* XSTAT_INFO_ flags: */
> "????????" /* 31-24
> 0x00000000-ff000000 */
> "????????" /* 23-16
> 0x00000000-00ff0000 */
> "??ASHRan" /* 15- 8
> 0x00000000-0000ff00 */
> "dmorkfte" /* 7- 0
> 0x00000000-000000ff */
> ;
>
> printf("Information: %08x (", xst->st_information);
> for (byte = 32 - 8; byte >= 0; byte -= 8) {
> bits = xst->st_information >> byte;
> for (loop = 7; loop >= 0; loop--) {
> int bit = byte + loop;
>
> if (bits & 0x80)
> putchar(info_representation[31
> - bit]);
> else
> putchar('-');
> bits <<= 1;
> }
> if (byte)
> putchar(' ');
> }
> printf(")\n");
> }
>
> if (xst->st_mask & XSTAT_VOLUME_ID) {
> int loop;
> printf("Volume ID: ");
> for (loop = 0; loop < sizeof(xst->st_volume_id);
> loop++) {
> printf("%02x", xst->st_volume_id[loop]);
> if (loop == 7)
> printf("-");
> }
> printf("\n");
> }
> }
>
> void dump_hex(unsigned long long *data, int from, int to)
> {
> unsigned offset, print_offset = 1, col = 0;
>
> from /= 8;
> to = (to + 7) / 8;
>
> for (offset = from; offset < to; offset++) {
> if (print_offset) {
> printf("%04x: ", offset * 8);
> print_offset = 0;
> }
> printf("%016llx", data[offset]);
> col++;
> if ((col & 3) == 0) {
> printf("\n");
> print_offset = 1;
> } else {
> printf(" ");
> }
> }
>
> if (!print_offset)
> printf("\n");
> }
>
> int main(int argc, char **argv)
> {
> struct xstat xst;
> int ret, raw = 0, atflag = AT_SYMLINK_NOFOLLOW;
>
> unsigned int mask = XSTAT_ALL_STATS;
>
> for (argv++; *argv; argv++) {
> if (strcmp(*argv, "-F") == 0) {
> atflag |= AT_FORCE_ATTR_SYNC;
> continue;
> }
> if (strcmp(*argv, "-L") == 0) {
> atflag &= ~AT_SYMLINK_NOFOLLOW;
> continue;
> }
> if (strcmp(*argv, "-O") == 0) {
> mask &= ~XSTAT_BASIC_STATS;
> continue;
> }
> if (strcmp(*argv, "-A") == 0) {
> atflag |= AT_NO_AUTOMOUNT;
> continue;
> }
> if (strcmp(*argv, "-R") == 0) {
> raw = 1;
> continue;
> }
>
> memset(&xst, 0xbf, sizeof(xst));
> ret = xstat(AT_FDCWD, *argv, atflag, mask, &xst);
> printf("xstat(%s) = %d\n", *argv, ret);
> if (ret < 0) {
> perror(*argv);
> exit(1);
> }
>
> if (raw)
> dump_hex((unsigned long long *)&xst, 0,
> sizeof(xst));
>
> dump_xstat(&xst);
> }
> return 0;
> }
>
> Just compile and run, passing it paths to the files you want to examine:
>
> [root@andromeda ~]# /tmp/xstat /proc/$$
> xstat(/proc/2074) = 160
> results=47ef
> Size: 0 Blocks: 0 IO Block: 1024 directory
> Device: 00:03 Inode: 9072 Links: 7
> Access: (0555/dr-xr-xr-x) Uid: 0
> Gid: 0
> Access: 2010-07-14 16:50:46.609336272+0100
> Modify: 2010-07-14 16:50:46.609336272+0100
> Change: 2010-07-14 16:50:46.609336272+0100
> Inode flags: 0000000100000000 (-------- -------- -------- -------S
> -------- -------- -------- --------)
> [root@andromeda ~]# /tmp/xstat
> /afs/archive/linuxdev/fedora9/x86_64/kernel-devel-2.6.25.10-86.fc9.x86_64.rpm
>
> xstat(/afs/archive/linuxdev/fedora9/x86_64/kernel-devel-2.6.25.10-86.fc9.x86_64.rpm)
> = 160
> results=77ef
> Size: 5413882 Blocks: 0 IO Block: 4096 regular
> file
> Device: 00:15 Inode: 2288 Links: 1
> Access: (0644/-rw-r--r--) Uid: 75338
> Gid: 0
> Access: 2008-11-05 19:47:22.000000000+0000
> Modify: 2008-11-05 19:47:22.000000000+0000
> Change: 2008-11-05 19:47:22.000000000+0000
> Inode version: 795h
> Data version: 2h
> Inode flags: 0000000800000000 (-------- -------- -------- ----r---
> -------- -------- -------- --------)
>
> Signed-off-by: David Howells <dhowe...@redhat.com>
> ---
>
> arch/x86/syscalls/syscall_32.tbl | 2
> arch/x86/syscalls/syscall_64.tbl | 2
> fs/stat.c | 350
> +++++++++++++++++++++++++++++++++++---
> include/linux/fcntl.h | 1
> include/linux/fs.h | 4
> include/linux/stat.h | 126 +++++++++++++-
> include/linux/syscalls.h | 7 +
> 7 files changed, 461 insertions(+), 31 deletions(-)
>
> diff --git a/arch/x86/syscalls/syscall_32.tbl
> b/arch/x86/syscalls/syscall_32.tbl
> index 29f9f05..980eb5a 100644
> --- a/arch/x86/syscalls/syscall_32.tbl
> +++ b/arch/x86/syscalls/syscall_32.tbl
> @@ -355,3 +355,5 @@
> 346 i386 setns sys_setns
> 347 i386 process_vm_readv sys_process_vm_readv
> compat_sys_process_vm_readv
> 348 i386 process_vm_writev sys_process_vm_writev
> compat_sys_process_vm_writev
> +349 i386 xstat sys_xstat
> +350 i386 fxstat sys_fxstat
> diff --git a/arch/x86/syscalls/syscall_64.tbl
> b/arch/x86/syscalls/syscall_64.tbl
> index dd29a9e..7ae24bb 100644
> --- a/arch/x86/syscalls/syscall_64.tbl
> +++ b/arch/x86/syscalls/syscall_64.tbl
> @@ -318,6 +318,8 @@
> 309 common getcpu sys_getcpu
> 310 64 process_vm_readv sys_process_vm_readv
> 311 64 process_vm_writev sys_process_vm_writev
> +312 common xstat sys_xstat
> +313 common fxstat sys_fxstat
> #
> # x32-specific system call numbers start at 512 to avoid cache impact
> # for native 64-bit operation.
> diff --git a/fs/stat.c b/fs/stat.c
> index c733dc5..af3ef33 100644
> --- a/fs/stat.c
> +++ b/fs/stat.c
> @@ -18,8 +18,20 @@
> #include <asm/uaccess.h>
> #include <asm/unistd.h>
>
> +/**
> + * generic_fillattr - Fill in the basic attributes from the inode struct
> + * @inode: Inode to use as the source
> + * @stat: Where to fill in the attributes
> + *
> + * Fill in the basic attributes in the kstat structure from data that's to be
> + * found on the VFS inode structure. This is the default if no getattr inode
> + * operation is supplied.
> + */
> void generic_fillattr(struct inode *inode, struct kstat *stat)
> {
> + struct super_block *sb = inode->i_sb;
> + u32 x;
> +
> stat->dev = inode->i_sb->s_dev;
> stat->ino = inode->i_ino;
> stat->mode = inode->i_mode;
> @@ -27,17 +39,61 @@ void generic_fillattr(struct inode *inode, struct kstat
> *stat)
> stat->uid = inode->i_uid;
> stat->gid = inode->i_gid;
> stat->rdev = inode->i_rdev;
> - stat->size = i_size_read(inode);
> - stat->atime = inode->i_atime;
> stat->mtime = inode->i_mtime;
> stat->ctime = inode->i_ctime;
> - stat->blksize = (1 << inode->i_blkbits);
> + stat->size = i_size_read(inode);
> stat->blocks = inode->i_blocks;
> -}
> + stat->blksize = (1 << inode->i_blkbits);
>
> + stat->result_mask |= XSTAT_BASIC_STATS & ~XSTAT_RDEV;
> + if (IS_NOATIME(inode))
> + stat->result_mask &= ~XSTAT_ATIME;
> + else
> + stat->atime = inode->i_atime;
> +
> + if (S_ISREG(stat->mode) && stat->nlink == 0)
> + stat->information |= XSTAT_INFO_TEMPORARY;
> + if (IS_AUTOMOUNT(inode))
> + stat->information |= XSTAT_INFO_AUTOMOUNT;
> + if (IS_POSIXACL(inode))
> + stat->information |= XSTAT_INFO_HAS_ACL;
> +
> + /* if unset, assume 1s granularity */
> + stat->tv_granularity = sb->s_time_gran ?: 1000000000U;
> +
> + if (unlikely(S_ISBLK(stat->mode) || S_ISCHR(stat->mode)))
> + stat->result_mask |= XSTAT_RDEV;
> +
> + x = ((u32*)&stat->volume_id)[0] = ((u32*)&sb->s_volume_id)[0];
> + x |= ((u32*)&stat->volume_id)[1] = ((u32*)&sb->s_volume_id)[1];
> + x |= ((u32*)&stat->volume_id)[2] = ((u32*)&sb->s_volume_id)[2];
> + x |= ((u32*)&stat->volume_id)[3] = ((u32*)&sb->s_volume_id)[3];
> + if (x)
> + stat->result_mask |= XSTAT_VOLUME_ID;
> +}
> EXPORT_SYMBOL(generic_fillattr);
>
> -int vfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat
> *stat)
> +/**
> + * vfs_xgetattr - Get the basic and extra attributes of a file
> + * @mnt: The mountpoint to which the dentry belongs
> + * @dentry: The file of interest
> + * @stat: Where to return the statistics
> + *
> + * Ask the filesystem for a file's attributes. The caller must have preset
> + * stat->request_mask and stat->query_flags to indicate what they want.
> + *
> + * If the file is remote, the filesystem can be forced to update the
> attributes
> + * from the backing store by passing AT_FORCE_ATTR_SYNC in query_flags.
> + *
> + * Bits must have been set in stat->request_mask to indicate which attributes
> + * the caller wants retrieving. Any such attribute not requested may be
> + * returned anyway, but the value may be approximate, and, if remote, may not
> + * have been synchronised with the server.
> + *
> + * 0 will be returned on success, and a -ve error code if unsuccessful.
> + */
> +int vfs_xgetattr(struct vfsmount *mnt, struct dentry *dentry,
> + struct kstat *stat)
> {
> struct inode *inode = dentry->d_inode;
> int retval;
> @@ -46,64 +102,184 @@ int vfs_getattr(struct vfsmount *mnt, struct dentry
> *dentry, struct kstat *stat)
> if (retval)
> return retval;
>
> + stat->result_mask = 0;
> + stat->information = 0;
> + stat->ioc_flags = 0;
> if (inode->i_op->getattr)
> return inode->i_op->getattr(mnt, dentry, stat);
>
> generic_fillattr(inode, stat);
> return 0;
> }
> +EXPORT_SYMBOL(vfs_xgetattr);
>
> +/**
> + * vfs_getattr - Get the basic attributes of a file
> + * @mnt: The mountpoint to which the dentry belongs
> + * @dentry: The file of interest
> + * @stat: Where to return the statistics
> + *
> + * Ask the filesystem for a file's attributes. If remote, the filesystem
> isn't
> + * forced to update its files from the backing store. Only the basic set of
> + * attributes will be retrieved; anyone wanting more must use vfs_getxattr(),
> + * as must anyone who wants to force attributes to be sync'd with the server.
> + *
> + * 0 will be returned on success, and a -ve error code if unsuccessful.
> + */
> +int vfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat
> *stat)
> +{
> + stat->query_flags = 0;
> + stat->request_mask = XSTAT_BASIC_STATS;
> + return vfs_xgetattr(mnt, dentry, stat);
> +}
> EXPORT_SYMBOL(vfs_getattr);
>
> -int vfs_fstat(unsigned int fd, struct kstat *stat)
> +/**
> + * vfs_fxstat - Get basic and extra attributes by file descriptor
> + * @fd: The file descriptor refering to the file of interest
> + * @stat: The result structure to fill in.
> + *
> + * This function is a wrapper around vfs_xgetattr(). The main difference is
> + * that it uses a file descriptor to determine the file location.
> + *
> + * The caller must have preset stat->query_flags and stat->request_mask as
> for
> + * vfs_xgetattr().
> + *
> + * 0 will be returned on success, and a -ve error code if unsuccessful.
> + */
> +int vfs_fxstat(unsigned int fd, struct kstat *stat)
> {
> struct file *f = fget(fd);
> int error = -EBADF;
>
> + if (stat->query_flags & ~KSTAT_QUERY_FLAGS)
> + return -EINVAL;
> if (f) {
> - error = vfs_getattr(f->f_path.mnt, f->f_path.dentry, stat);
> + error = vfs_xgetattr(f->f_path.mnt, f->f_path.dentry, stat);
> fput(f);
> }
> return error;
> }
> +EXPORT_SYMBOL(vfs_fxstat);
> +
> +/**
> + * vfs_fstat - Get basic attributes by file descriptor
> + * @fd: The file descriptor refering to the file of interest
> + * @stat: The result structure to fill in.
> + *
> + * This function is a wrapper around vfs_getattr(). The main difference is
> + * that it uses a file descriptor to determine the file location.
> + *
> + * 0 will be returned on success, and a -ve error code if unsuccessful.
> + */
> +int vfs_fstat(unsigned int fd, struct kstat *stat)
> +{
> + stat->query_flags = 0;
> + stat->request_mask = XSTAT_BASIC_STATS;
> + return vfs_fxstat(fd, stat);
> +}
> EXPORT_SYMBOL(vfs_fstat);
>
> -int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
> - int flag)
> +/**
> + * vfs_xstat - Get basic and extra attributes by filename
> + * @dfd: A file descriptor representing the base dir for a relative filename
> + * @filename: The name of the file of interest
> + * @flags: Flags to control the query
> + * @stat: The result structure to fill in.
> + *
> + * This function is a wrapper around vfs_xgetattr(). The main difference is
> + * that it uses a filename and base directory to determine the file location.
> + * Additionally, the addition of AT_SYMLINK_NOFOLLOW to flags will prevent a
> + * symlink at the given name from being referenced.
> + *
> + * The caller must have preset stat->request_mask as for vfs_xgetattr(). The
> + * flags are also used to load up stat->query_flags.
> + *
> + * 0 will be returned on success, and a -ve error code if unsuccessful.
> + */
> +int vfs_xstat(int dfd, const char __user *filename, int flags,
> + struct kstat *stat)
> {
> struct path path;
> - int error = -EINVAL;
> - int lookup_flags = 0;
> + int error, lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT;
>
> - if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
> - AT_EMPTY_PATH)) != 0)
> - goto out;
> + if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
> + AT_EMPTY_PATH | KSTAT_QUERY_FLAGS)) != 0)
> + return -EINVAL;
>
> - if (!(flag & AT_SYMLINK_NOFOLLOW))
> - lookup_flags |= LOOKUP_FOLLOW;
> - if (flag & AT_EMPTY_PATH)
> + if (flags & AT_SYMLINK_NOFOLLOW)
> + lookup_flags &= ~LOOKUP_FOLLOW;
> + if (flags & AT_NO_AUTOMOUNT)
> + lookup_flags &= ~LOOKUP_AUTOMOUNT;
> + if (flags & AT_EMPTY_PATH)
> lookup_flags |= LOOKUP_EMPTY;
>
> + stat->query_flags = flags & KSTAT_QUERY_FLAGS;
> error = user_path_at(dfd, filename, lookup_flags, &path);
> - if (error)
> - goto out;
> -
> - error = vfs_getattr(path.mnt, path.dentry, stat);
> - path_put(&path);
> -out:
> + if (!error) {
> + error = vfs_xgetattr(path.mnt, path.dentry, stat);
> + path_put(&path);
> + }
> return error;
> }
> +EXPORT_SYMBOL(vfs_xstat);
> +
> +/**
> + * vfs_fstatat - Get basic attributes by filename
> + * @dfd: A file descriptor representing the base dir for a relative filename
> + * @filename: The name of the file of interest
> + * @flags: Flags to control the query
> + * @stat: The result structure to fill in.
> + *
> + * This function is a wrapper around vfs_xstat(). The difference is that it
> + * preselects basic stats only. The flags are used to load up
> + * stat->query_flags in addition to indicating symlink handling during path
> + * resolution.
> + *
> + * 0 will be returned on success, and a -ve error code if unsuccessful.
> + */
> +int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
> + int flags)
> +{
> + stat->request_mask = XSTAT_BASIC_STATS;
> + return vfs_xstat(dfd, filename, flags, stat);
> +}
> EXPORT_SYMBOL(vfs_fstatat);
>
> -int vfs_stat(const char __user *name, struct kstat *stat)
> +/**
> + * vfs_stat - Get basic attributes by filename
> + * @filename: The name of the file of interest
> + * @stat: The result structure to fill in.
> + *
> + * This function is a wrapper around vfs_xstat(). The difference is that it
> + * preselects basic stats only, terminal symlinks are followed regardless
> and a
> + * remote filesystem can't be forced to query the server. If such is
> desired,
> + * vfs_xstat() should be used instead.
> + *
> + * 0 will be returned on success, and a -ve error code if unsuccessful.
> + */
> +int vfs_stat(const char __user *filename, struct kstat *stat)
> {
> - return vfs_fstatat(AT_FDCWD, name, stat, 0);
> + stat->request_mask = XSTAT_BASIC_STATS;
> + return vfs_xstat(AT_FDCWD, filename, 0, stat);
> }
> EXPORT_SYMBOL(vfs_stat);
>
> +/**
> + * vfs_stat - Get basic attributes by filename, without following terminal
> symlink
> + * @filename: The name of the file of interest
> + * @stat: The result structure to fill in.
> + *
> + * This function is a wrapper around vfs_xstat(). The difference is that it
> + * preselects basic stats only, terminal symlinks are note followed
> regardless
> + * and a remote filesystem can't be forced to query the server. If such is
> + * desired, vfs_xstat() should be used instead.
> + *
> + * 0 will be returned on success, and a -ve error code if unsuccessful.
> + */
> int vfs_lstat(const char __user *name, struct kstat *stat)
> {
> - return vfs_fstatat(AT_FDCWD, name, stat, AT_SYMLINK_NOFOLLOW);
> + return vfs_xstat(AT_FDCWD, name, AT_SYMLINK_NOFOLLOW, stat);
> }
> EXPORT_SYMBOL(vfs_lstat);
>
> @@ -118,7 +294,7 @@ static int cp_old_stat(struct kstat *stat, struct
> __old_kernel_stat __user * sta
> {
> static int warncount = 5;
> struct __old_kernel_stat tmp;
> -
> +
> if (warncount > 0) {
> warncount--;
> printk(KERN_WARNING "VFS: Warning: %s using old stat() call.
> Recompile your binary.\n",
> @@ -143,7 +319,7 @@ static int cp_old_stat(struct kstat *stat, struct
> __old_kernel_stat __user * sta
> #if BITS_PER_LONG == 32
> if (stat->size > MAX_NON_LFS)
> return -EOVERFLOW;
> -#endif
> +#endif
> tmp.st_size = stat->size;
> tmp.st_atime = stat->atime.tv_sec;
> tmp.st_mtime = stat->mtime.tv_sec;
> @@ -225,7 +401,7 @@ static int cp_new_stat(struct kstat *stat, struct stat
> __user *statbuf)
> #if BITS_PER_LONG == 32
> if (stat->size > MAX_NON_LFS)
> return -EOVERFLOW;
> -#endif
> +#endif
> tmp.st_size = stat->size;
> tmp.st_atime = stat->atime.tv_sec;
> tmp.st_mtime = stat->mtime.tv_sec;
> @@ -412,6 +588,122 @@ SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user
> *, filename,
> }
> #endif /* __ARCH_WANT_STAT64 */
>
> +/*
> + * Get the xstat parameters if supplied
> + */
> +static int xstat_get_params(unsigned int mask, struct xstat __user *buffer,
> + struct kstat *stat)
> +{
> + memset(stat, 0xde, sizeof(*stat)); // DEBUGGING
> +
> + if (!access_ok(VERIFY_WRITE, buffer, sizeof(*buffer)))
> + return -EFAULT;
> +
> + stat->request_mask = mask & XSTAT_ALL_STATS;
> + stat->result_mask = 0;
> + return 0;
> +}
> +
> +/*
> + * Set the xstat results.
> + *
> + * If the buffer size was 0, we just return the size of the buffer needed to
> + * return the full result.
> + *
> + * If bufsize indicates a buffer of insufficient size to hold the full
> result,
> + * we return -E2BIG.
> + *
> + * Otherwise we copy the extended stats to userspace and return the amount of
> + * data written into the buffer (or -EFAULT).
> + */
> +static long xstat_set_result(struct kstat *stat, struct xstat __user *buffer)
> +{
> + u32 mask = stat->result_mask, gran = stat->tv_granularity;
> +
> +#define __put_timestamp(kts, uts) ( \
> + __put_user(kts.tv_sec, uts.tv_sec ) || \
> + __put_user(kts.tv_nsec, uts.tv_nsec ) || \
> + __put_user(gran, uts.tv_granularity ))
> +
> + /* clear out anything we're not returning */
> + if (!(mask & XSTAT_IOC_FLAGS))
> + stat->ioc_flags = 0;
> + if (!(mask & XSTAT_BTIME))
> + memset(&stat->btime, 0, sizeof(stat->btime));
> + if (!(mask & XSTAT_GEN))
> + stat->gen = 0;
> + if (!(mask & XSTAT_VERSION))
> + stat->version = 0;
> + if (!(mask & XSTAT_VOLUME_ID))
> + memset(&stat->volume_id, 0, sizeof(stat->volume_id));
> +
> + /* transfer the results */
> + if (__put_user(mask, &buffer->st_mask ) ||
> + __put_user(stat->mode, &buffer->st_mode ) ||
> + __put_user(stat->nlink, &buffer->st_nlink ) ||
> + __put_user(stat->uid, &buffer->st_uid ) ||
> + __put_user(stat->gid, &buffer->st_gid ) ||
> + __put_user(stat->information, &buffer->st_information ) ||
> + __put_user(stat->ioc_flags, &buffer->st_ioc_flags ) ||
> + __put_user(stat->blksize, &buffer->st_blksize ) ||
> + __put_user(MAJOR(stat->rdev), &buffer->st_rdev.major ) ||
> + __put_user(MINOR(stat->rdev), &buffer->st_rdev.minor ) ||
> + __put_user(MAJOR(stat->dev), &buffer->st_dev.major ) ||
> + __put_user(MINOR(stat->dev), &buffer->st_dev.minor ) ||
> + __put_timestamp(stat->atime, &buffer->st_atime ) ||
> + __put_timestamp(stat->btime, &buffer->st_btime ) ||
> + __put_timestamp(stat->ctime, &buffer->st_ctime ) ||
> + __put_timestamp(stat->mtime, &buffer->st_mtime ) ||
> + __put_user(stat->ino, &buffer->st_ino ) ||
> + __put_user(stat->size, &buffer->st_size ) ||
> + __put_user(stat->blocks, &buffer->st_blocks ) ||
> + __put_user(stat->gen, &buffer->st_gen ) ||
> + __put_user(stat->version, &buffer->st_version ) ||
> + __copy_to_user(&buffer->st_volume_id, &stat->volume_id,
> + sizeof(buffer->st_volume_id) ) ||
> + __clear_user(&buffer->__spares, sizeof(buffer->__spares)))
> + return -EFAULT;
> + return 0;
> +}
> +
> +/*
> + * System call to get extended stats by path
> + */
> +SYSCALL_DEFINE5(xstat,
> + int, dfd, const char __user *, filename, unsigned, flags,
> + unsigned int, mask, struct xstat __user *, buffer)
> +{
> + struct kstat stat;
> + int error;
> +
> + error = xstat_get_params(mask, buffer, &stat);
> + if (error != 0)
> + return error;
> + error = vfs_xstat(dfd, filename, flags, &stat);
> + if (error)
> + return error;
> + return xstat_set_result(&stat, buffer);
> +}
> +
> +/*
> + * System call to get extended stats by file descriptor
> + */
> +SYSCALL_DEFINE4(fxstat, unsigned int, fd, unsigned int, flags,
> + unsigned int, mask, struct xstat __user *, buffer)
> +{
> + struct kstat stat;
> + int error;
> +
> + error = xstat_get_params(mask, buffer, &stat);
> + if (error < 0)
> + return error;
> + stat.query_flags = flags;
> + error = vfs_fxstat(fd, &stat);
> + if (error)
> + return error;
> + return xstat_set_result(&stat, buffer);
> +}
> +
> /* Caller is here responsible for sufficient locking (ie. inode->i_lock) */
> void __inode_add_bytes(struct inode *inode, loff_t bytes)
> {
> diff --git a/include/linux/fcntl.h b/include/linux/fcntl.h
> index f550f89..faa9e5d 100644
> --- a/include/linux/fcntl.h
> +++ b/include/linux/fcntl.h
> @@ -47,6 +47,7 @@
> #define AT_SYMLINK_FOLLOW 0x400 /* Follow symbolic links. */
> #define AT_NO_AUTOMOUNT 0x800 /* Suppress terminal automount
> traversal */
> #define AT_EMPTY_PATH 0x1000 /* Allow empty relative
> pathname */
> +#define AT_FORCE_ATTR_SYNC 0x2000 /* Force the attributes to be sync'd
> with the server */
>
> #ifdef __KERNEL__
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 8de6755..ec6c62e 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1467,6 +1467,7 @@ struct super_block {
>
> char s_id[32]; /* Informational name */
> u8 s_uuid[16]; /* UUID */
> + unsigned char s_volume_id[16]; /* Volume identifier */
>
> void *s_fs_info; /* Filesystem private info */
> unsigned int s_max_links;
> @@ -2470,6 +2471,7 @@ extern const struct inode_operations
> page_symlink_inode_operations;
> extern int generic_readlink(struct dentry *, char __user *, int);
> extern void generic_fillattr(struct inode *, struct kstat *);
> extern int vfs_getattr(struct vfsmount *, struct dentry *, struct kstat *);
> +extern int vfs_xgetattr(struct vfsmount *, struct dentry *, struct kstat *);
> void __inode_add_bytes(struct inode *inode, loff_t bytes);
> void inode_add_bytes(struct inode *inode, loff_t bytes);
> void inode_sub_bytes(struct inode *inode, loff_t bytes);
> @@ -2482,6 +2484,8 @@ extern int vfs_stat(const char __user *, struct kstat
> *);
> extern int vfs_lstat(const char __user *, struct kstat *);
> extern int vfs_fstat(unsigned int, struct kstat *);
> extern int vfs_fstatat(int , const char __user *, struct kstat *, int);
> +extern int vfs_xstat(int, const char __user *, int, struct kstat *);
> +extern int vfs_xfstat(unsigned int, struct kstat *);
>
> extern int do_vfs_ioctl(struct file *filp, unsigned int fd, unsigned int cmd,
> unsigned long arg);
> diff --git a/include/linux/stat.h b/include/linux/stat.h
> index 611c398..0ff561a 100644
> --- a/include/linux/stat.h
> +++ b/include/linux/stat.h
> @@ -3,6 +3,7 @@
>
> #ifdef __KERNEL__
>
> +#include <linux/types.h>
> #include <asm/stat.h>
>
> #endif
> @@ -46,6 +47,117 @@
>
> #endif
>
> +/*
> + * Query request/result mask
> + *
> + * Bits should be set in request_mask to request particular items when
> calling
> + * xstat() or fxstat().
> + *
> + * The bits in st_mask may or may not be set upon return, in part depending
> on
> + * what was set in the mask argument:
> + *
> + * - if not available at all, the bit will be cleared before returning and
> the
> + * field will be cleared; otherwise,
> + *
> + * - if AT_FORCE_ATTR_SYNC is set, then the datum will be synchronised to the
> + * server and the field and bit will be set on return; otherwise,
> + *
> + * - if explicitly requested, the datum will be synchronised to a server or
> + * other medium if out of date before being returned, and the bit will be
> set
> + * on return; otherwise,
> + *
> + * - if not requested, but available in approximate form without any effort,
> it
> + * will be filled in anyway, and the bit will be set upon return (it might
> + * not be up to date, however, and no attempt will be made to synchronise
> the
> + * internal state first); otherwise,
> + *
> + * - the field and the bit will be cleared before returning.
> + *
> + * Items in XSTAT_BASIC_STATS may be marked unavailable on return, but they
> + * will have a value installed for compatibility purposes so that stat() and
> + * co. can be emulated in userspace.
> + */
> +#define XSTAT_MODE 0x00000001U /* want/got st_mode */
> +#define XSTAT_NLINK 0x00000002U /* want/got st_nlink */
> +#define XSTAT_UID 0x00000004U /* want/got st_uid */
> +#define XSTAT_GID 0x00000008U /* want/got st_gid */
> +#define XSTAT_RDEV 0x00000010U /* want/got st_rdev */
> +#define XSTAT_ATIME 0x00000020U /* want/got st_atime */
> +#define XSTAT_MTIME 0x00000040U /* want/got st_mtime */
> +#define XSTAT_CTIME 0x00000080U /* want/got st_ctime */
> +#define XSTAT_INO 0x00000100U /* want/got st_ino */
> +#define XSTAT_SIZE 0x00000200U /* want/got st_size */
> +#define XSTAT_BLOCKS 0x00000400U /* want/got st_blocks */
> +#define XSTAT_BASIC_STATS 0x000007ffU /* the stuff in the normal stat
> struct */
> +#define XSTAT_IOC_FLAGS 0x00000800U /* want/got
> FS_IOC_GETFLAGS */
> +#define XSTAT_BTIME 0x00001000U /* want/got st_btime */
> +#define XSTAT_GEN 0x00002000U /* want/got st_gen */
> +#define XSTAT_VERSION 0x00004000U /* want/got st_version
> */
> +#define XSTAT_VOLUME_ID 0x00008000U /* want/got
> st_volume_id */
> +#define XSTAT_ALL_STATS 0x0000ffffU /* all supported stats
> */
> +
> +/*
> + * Extended stat structures
> + */
> +struct xstat_dev {
> + uint32_t major, minor;
> +};
> +
> +struct xstat_time {
> + int64_t tv_sec;
> + uint32_t tv_nsec;
> + uint32_t tv_granularity; /* time granularity (in nS) */
> +};
> +
> +struct xstat {
> + uint32_t st_mask; /* what results were written */
> + uint32_t st_mode; /* file mode */
> + uint32_t st_nlink; /* number of hard links */
> + uint32_t st_uid; /* user ID of owner */
> + uint32_t st_gid; /* group ID of owner */
> + uint32_t st_information; /* information about the file */
> + uint32_t st_ioc_flags; /* as FS_IOC_GETFLAGS */
> + uint32_t st_blksize; /* optimal size for filesystem
> I/O */
> + struct xstat_dev st_rdev; /* device ID of special file */
> + struct xstat_dev st_dev; /* ID of device containing file
> */
> + struct xstat_time st_atime; /* last access time */
> + struct xstat_time st_btime; /* file creation time */
> + struct xstat_time st_ctime; /* last attribute change time */
> + struct xstat_time st_mtime; /* last data modification time
> */
> + uint64_t st_ino; /* inode number */
> + uint64_t st_size; /* file size */
> + uint64_t st_blocks; /* number of 512-byte blocks
> allocated */
> + uint64_t st_gen; /* inode generation number */
> + uint64_t st_version; /* data version number */
> + uint8_t st_volume_id[16]; /* volume identifier */
> + uint64_t __spares[11]; /* spare space for future
> expansion */
> +};
> +
> +/*
> + * Flags to be found in st_information
> + *
> + * These give information about the features or the state of a file that
> might
> + * be of use to ordinary userspace programs such as GUIs or ls rather than
> + * specialised tools.
> + *
> + * Additional information may be found in st_ioc_flags and we try not to
> + * overlap with it.
> + */
> +#define XSTAT_INFO_ENCRYPTED 0x00000001U /* File is encrypted */
> +#define XSTAT_INFO_TEMPORARY 0x00000002U /* File is temporary
> (NTFS/CIFS) */
> +#define XSTAT_INFO_FABRICATED 0x00000004U /* File was made up
> by filesystem */
> +#define XSTAT_INFO_KERNEL_API 0x00000008U /* File is kernel
> API (eg: procfs/sysfs) */
> +#define XSTAT_INFO_REMOTE 0x00000010U /* File is remote */
> +#define XSTAT_INFO_OFFLINE 0x00000020U /* File is offline (CIFS) */
> +#define XSTAT_INFO_AUTOMOUNT 0x00000040U /* Dir is automount trigger
> */
> +#define XSTAT_INFO_AUTODIR 0x00000080U /* Dir provides unlisted
> automounts */
> +#define XSTAT_INFO_NONSYSTEM_OWNERSHIP 0x00000100U /* File has
> non-system ownership details */
> +#define XSTAT_INFO_HAS_ACL 0x00000200U /* File has an ACL of some
> sort */
> +#define XSTAT_INFO_REPARSE_POINT 0x00000400U /* File is reparse point
> (NTFS/CIFS) */
> +#define XSTAT_INFO_HIDDEN 0x00000800U /* File is marked hidden
> (DOS+) */
> +#define XSTAT_INFO_SYSTEM 0x00001000U /* File is marked system
> (DOS+) */
> +#define XSTAT_INFO_ARCHIVE 0x00002000U /* File is marked archive
> (DOS+) */
> +
> #ifdef __KERNEL__
> #define S_IRWXUGO (S_IRWXU|S_IRWXG|S_IRWXO)
> #define S_IALLUGO (S_ISUID|S_ISGID|S_ISVTX|S_IRWXUGO)
> @@ -60,6 +172,12 @@
> #include <linux/time.h>
>
> struct kstat {
> + u32 query_flags; /* operational flags */
> +#define KSTAT_QUERY_FLAGS (AT_FORCE_ATTR_SYNC)
> + u32 request_mask; /* what fields the user asked
> for */
> + u32 result_mask; /* what fields the user got */
> + u32 information;
> + u32 ioc_flags; /* inode flags
> (FS_IOC_GETFLAGS) */
> u64 ino;
> dev_t dev;
> umode_t mode;
> @@ -67,14 +185,18 @@ struct kstat {
> uid_t uid;
> gid_t gid;
> dev_t rdev;
> + unsigned int tv_granularity; /* granularity of times (in nS)
> */
> loff_t size;
> - struct timespec atime;
> + struct timespec atime;
> struct timespec mtime;
> struct timespec ctime;
> + struct timespec btime; /* file creation time */
> unsigned long blksize;
> unsigned long long blocks;
> + u64 gen; /* inode generation */
> + u64 version; /* data version */
> + unsigned char volume_id[16]; /* volume identifier */
> };
>
> #endif
> -
> #endif
> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> index 3de3acb..ff9f8d9 100644
> --- a/include/linux/syscalls.h
> +++ b/include/linux/syscalls.h
> @@ -45,6 +45,8 @@ struct shmid_ds;
> struct sockaddr;
> struct stat;
> struct stat64;
> +struct xstat_parameters;
> +struct xstat;
> struct statfs;
> struct statfs64;
> struct __sysctl_args;
> @@ -858,4 +860,9 @@ asmlinkage long sys_process_vm_writev(pid_t pid,
> unsigned long riovcnt,
> unsigned long flags);
>
> +asmlinkage long sys_xstat(int dfd, const char __user *path, unsigned flags,
> + unsigned mask, struct xstat __user *buffer);
> +asmlinkage long sys_fxstat(unsigned fd, unsigned flags,
> + unsigned mask, struct xstat __user *buffer);
> +
> #endif
>
> --
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