Re: [PATCH 1/6] statx: Add a system call to make enhanced file info available

From: Andreas Dilger
Date: Mon May 02 2016 - 18:46:58 EST

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On Apr 29, 2016, at 6:57 AM, David Howells <dhowells@xxxxxxxxxx> wrote:
>
> Add a system call to make extended file information available, including
> file creation time, inode version and data version where available through
> the underlying filesystem.

Hi David,
thanks for resubmitting the patch series. No requests to add features here,
just a couple of comments on the patches regarding the implementation...

> ========
> OVERVIEW
> ========
>
> The idea was initially proposed as a set of xattrs that could be retrieved
> with getxattr(), but the general preferance proved to be for a new syscall
> with an extended stat structure.
>
> This has a number of uses:
>
> (1) Better support for the y2038 problem [Arnd Bergmann].
>
> (2) 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].
>
> (3) 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, Andreas
> Dilger].
>
> (4) Heavyweight stat: Force a netfs to go to the server, even if it thinks
> its cached attributes are up to date [Trond Myklebust].
>
> (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) Inode generation number: Useful for FUSE and userspace NFS servers
> [Bernd Schubert]. This was asked for but later deemed unnecessary
> with the open-by-handle capability available
>
> (8) Extra coherency data may be useful in making backups [Andreas Dilger].
>
> (9) 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 or are fabricated locally...
>
> (10) Make the fields a consistent size on all arches and make them large.
>
> (11) Store a 16-byte volume ID in the superblock that can be returned in
> struct xstat [Steve French].
>
> (12) Include granularity fields in the time data to indicate the
> granularity of each of the times (NFSv4 time_delta) [Steve French].
>
> (13) FS_IOC_GETFLAGS value. These could be translated to BSD's st_flags.
> Note that the Linux IOC flags are a mess and filesystems such as Ext4
> define flags that aren't in linux/fs.h, so translation in the kernel
> may be a necessity (or, possibly, we provide the filesystem type too).
>
> (14) Mask of features available on file (eg: ACLs, seclabel) [Brad Boyer,
> Michael Kerrisk].
>
> (15) Spare space, request flags and information flags are provided for
> future expansion.
>
> Note that not all of the above are implemented here.
>
>
> ===============
> NEW SYSTEM CALL
> ===============
>
> The new system call is:
>
> int ret = statx(int dfd,
> const char *filename,
> unsigned int flags,
> unsigned int mask,
> struct statx *buffer);
>
> The dfd, filename and flags parameters indicate the file to query. There
> is no equivalent of lstat() as that can be emulated with statx() by passing
> AT_SYMLINK_NOFOLLOW in flags. There is also no equivalent of fstat() as
> that can be emulated by passing a NULL filename to statx() with the fd of
> interest in dfd.
>
> AT_FORCE_ATTR_SYNC can be set in flags. This will require a network
> filesystem to synchronise its attributes with the server.
>
> AT_NO_ATTR_SYNC can be set in flags. This will suppress synchronisation
> with the server in a network filesystem. The resulting values should be
> considered approximate.
>
> mask is a bitmask indicating the fields in struct statx that are of
> interest to the caller. The user should set this to STATX_BASIC_STATS to
> get the basic set returned by stat().
>
> buffer points to the destination for the data. This must be 256 bytes in
> size.
>
>
> ======================
> MAIN ATTRIBUTES RECORD
> ======================
>
> The following structures are defined in which to return the main attribute
> set:
>
> struct statx {
> __u32 st_mask;
> __u32 st_information;
> __u32 st_blksize;
> __u32 st_nlink;
> __u32 st_gen;
> __u32 st_uid;
> __u32 st_gid;
> __u16 st_mode;
> __u16 __spare0[1];
> __u64 st_ino;
> __u64 st_size;
> __u64 st_blocks;
> __u64 st_version;
> __s64 st_atime;
> __s64 st_btime;
> __s64 st_ctime;
> __s64 st_mtime;
> __s32 st_atime_ns;
> __s32 st_btime_ns;
> __s32 st_ctime_ns;
> __s32 st_mtime_ns;
> __u32 st_rdev_major;
> __u32 st_rdev_minor;
> __u32 st_dev_major;
> __u32 st_dev_minor;
> __u64 __spare1[16];
> };
>
> where st_information is local system information about the file, st_gen is
> the inode generation number, st_btime is the file creation time, st_version
> is the data version number (i_version), st_mask is a bitmask indicating the
> data provided and __spares*[] are where as-yet undefined fields can be
> placed.
>
> Time fields are split into separate seconds and nanoseconds fields to make
> packing easier and the granularities can be queried with the filesystem
> info system call. Note that times will be negative if before 1970; in such
> a case, the nanosecond fields should also be negative if not zero.
>
> The defined bits in request_mask and st_mask are:
>
> STATX_MODE Want/got st_mode
> STATX_NLINK Want/got st_nlink
> STATX_UID Want/got st_uid
> STATX_GID Want/got st_gid
> STATX_RDEV Want/got st_rdev_*
> STATX_ATIME Want/got st_atime
> STATX_MTIME Want/got st_mtime
> STATX_CTIME Want/got st_ctime
> STATX_INO Want/got st_ino
> STATX_SIZE Want/got st_size
> STATX_BLOCKS Want/got st_blocks
> STATX_BASIC_STATS [The stuff in the normal stat struct]
> STATX_BTIME Want/got st_btime
> STATX_VERSION Want/got st_data_version
> STATX_GEN Want/got st_gen
> STATX_ALL_STATS [All currently available stuff]
>
> 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:
>
> STATX_INFO_ENCRYPTED File is encrypted

This flag overlaps with FS_ENCRYPT_FL that is encoded in the FS_IOC_GETFLAGS
attributes. Are the FS_* flags expected to be translated into STATX_INFO_*
flags by each filesystem, or will they be partly duplicated in a separate
"st_attrs" field added in the future?

Cheers, Andreas

> STATX_INFO_TEMPORARY File is temporary
> STATX_INFO_FABRICATED File was made up by filesystem
> STATX_INFO_KERNEL_API File is kernel API (eg: procfs/sysfs)
> STATX_INFO_REMOTE File is remote
> STATX_INFO_AUTOMOUNT Dir is automount trigger
> STATX_INFO_AUTODIR Dir provides unlisted automounts
> STATX_INFO_NONSYSTEM_OWNERSHIP File has non-system ownership details
>
> These are for the use of GUI tools that might want to mark files specially,
> depending on what they are.
>
> Fields in struct statx come in a number of classes:
>
> (0) st_information, st_dev_*, st_blksize.
>
> These are local data and are always available.
>
> (1) 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 st_mask will be set to indicate whether they
> actually have valid values.
>
> 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 st_mask,
> even if the caller asked for the value. In such a case, the returned
> value will be a fabrication.
>
> (2) st_mode.
>
> The part of this that identifies the file type will always be
> available, irrespective of the setting of STATX_MODE. The access
> flags and sticky bit are as for class (1).
>
> (3) st_rdev_*.
>
> As for class (1), but this will be cleared if the file is not a
> blockdev or chardev. The bit will be cleared if the value is not
> returned.
>
> (4) File creation time (st_btime*), data version (st_version), inode
> generation number (st_gen).
>
> These will be returned if available whether the caller asked for them or
> not. The corresponding bits in st_mask will be set or cleared as
> appropriate to indicate a valid value.
>
> 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.
>
>
> =======
> TESTING
> =======
>
> The following test program can be used to test the statx system call:
>
> samples/statx/test-statx.c
>
> Just compile and run, passing it paths to the files you want to examine.
> The file is built automatically if CONFIG_SAMPLES is enabled.
>
> Here's some example output. Firstly, an NFS directory that crosses to
> another FSID. Note that the FABRICATED and AUTOMOUNT info flags are set.
> The former because the directory is invented locally as we don't see the
> underlying dir on the server, the latter because transiting this directory
> will cause d_automount to be invoked by the VFS.
>
> [root@andromeda tmp]# ./samples/statx/test-statx -A /warthog/data
> statx(/warthog/data) = 0
> results=4fef
> Size: 4096 Blocks: 8 IO Block: 1048576 directory
> Device: 00:1d Inode: 2 Links: 110
> Access: (3777/drwxrwxrwx) Uid: -2
> Gid: 4294967294
> Access: 2012-04-30 09:01:55.283819565+0100
> Modify: 2012-03-28 19:01:19.405465361+0100
> Change: 2012-03-28 19:01:19.405465361+0100
> Data version: ef51734f11e92a18h
> Information: 00000134 (-------- -------- -------a --mr-f--)
>
> Secondly, the result of automounting on that directory.
>
> [root@andromeda tmp]# ./samples/statx/test-statx /warthog/data
> statx(/warthog/data) = 0
> results=14fef
> Size: 4096 Blocks: 8 IO Block: 1048576 directory
> Device: 00:1e Inode: 2 Links: 110
> Access: (3777/drwxrwxrwx) Uid: -2
> Gid: 4294967294
> Access: 2012-04-30 09:01:55.283819565+0100
> Modify: 2012-03-28 19:01:19.405465361+0100
> Change: 2012-03-28 19:01:19.405465361+0100
> Data version: ef51734f11e92a18h
> Information: 00000110 (-------- -------- -------a ---r----)
>
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> ---
>
> arch/x86/entry/syscalls/syscall_32.tbl | 1
> arch/x86/entry/syscalls/syscall_64.tbl | 1
> fs/exportfs/expfs.c | 4
> fs/stat.c | 303 +++++++++++++++++++++++++++++---
> include/linux/fs.h | 5 -
> include/linux/stat.h | 15 +-
> include/linux/syscalls.h | 4
> include/uapi/linux/fcntl.h | 2
> include/uapi/linux/stat.h | 109 ++++++++++++
> samples/Makefile | 2
> samples/statx/Makefile | 10 +
> samples/statx/test-statx.c | 243 ++++++++++++++++++++++++++
> 12 files changed, 662 insertions(+), 37 deletions(-)
> create mode 100644 samples/statx/Makefile
> create mode 100644 samples/statx/test-statx.c
>
> diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
> index b30dd8154cc2..b99a6b3a167c 100644
> --- a/arch/x86/entry/syscalls/syscall_32.tbl
> +++ b/arch/x86/entry/syscalls/syscall_32.tbl
> @@ -386,3 +386,4 @@
> 377 i386 copy_file_range sys_copy_file_range
> 378 i386 preadv2 sys_preadv2
> 379 i386 pwritev2 sys_pwritev2
> +380 i386 statx sys_statx
> diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
> index cac6d17ce5db..6d5ef6c87cdc 100644
> --- a/arch/x86/entry/syscalls/syscall_64.tbl
> +++ b/arch/x86/entry/syscalls/syscall_64.tbl
> @@ -335,6 +335,7 @@
> 326 common copy_file_range sys_copy_file_range
> 327 64 preadv2 sys_preadv2
> 328 64 pwritev2 sys_pwritev2
> +329 common statx sys_statx
>
> #
> # x32-specific system call numbers start at 512 to avoid cache impact
> diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
> index c46f1a190b8d..cd6d9cbc9300 100644
> --- a/fs/exportfs/expfs.c
> +++ b/fs/exportfs/expfs.c
> @@ -295,7 +295,9 @@ static int get_name(const struct path *path, char *name, struct dentry *child)
> * filesystem supports 64-bit inode numbers. So we need to
> * actually call ->getattr, not just read i_ino:
> */
> - error = vfs_getattr_nosec(&child_path, &stat);
> + stat.query_flags = 0;
> + stat.request_mask = STATX_BASIC_STATS;
> + error = vfs_xgetattr_nosec(&child_path, &stat);
> if (error)
> return error;
> buffer.ino = stat.ino;
> diff --git a/fs/stat.c b/fs/stat.c
> index bc045c7994e1..c2f8370dab13 100644
> --- a/fs/stat.c
> +++ b/fs/stat.c
> @@ -18,6 +18,15 @@
> #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)
> {
> stat->dev = inode->i_sb->s_dev;
> @@ -27,87 +36,197 @@ 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 |= STATX_BASIC_STATS & ~STATX_RDEV;
> + if (IS_NOATIME(inode))
> + stat->result_mask &= ~STATX_ATIME;
> + else
> + stat->atime = inode->i_atime;
> +
> + if (S_ISREG(stat->mode) && stat->nlink == 0)
> + stat->information |= STATX_INFO_TEMPORARY;
> + if (IS_AUTOMOUNT(inode))
> + stat->information |= STATX_INFO_AUTOMOUNT;
> +
> + if (unlikely(S_ISBLK(stat->mode) || S_ISCHR(stat->mode)))
> + stat->result_mask |= STATX_RDEV;
> +}
> EXPORT_SYMBOL(generic_fillattr);
>
> /**
> - * vfs_getattr_nosec - getattr without security checks
> + * vfs_xgetattr_nosec - getattr without security checks
> * @path: file to get attributes from
> * @stat: structure to return attributes in
> *
> * Get attributes without calling security_inode_getattr.
> *
> - * Currently the only caller other than vfs_getattr is internal to the
> - * filehandle lookup code, which uses only the inode number and returns
> - * no attributes to any user. Any other code probably wants
> - * vfs_getattr.
> + * Currently the only caller other than vfs_xgetattr is internal to the
> + * filehandle lookup code, which uses only the inode number and returns no
> + * attributes to any user. Any other code probably wants vfs_xgetattr.
> + *
> + * The caller must set stat->request_mask to indicate what they want and
> + * stat->query_flags to indicate whether the server should be queried.
> */
> -int vfs_getattr_nosec(struct path *path, struct kstat *stat)
> +int vfs_xgetattr_nosec(struct path *path, struct kstat *stat)
> {
> struct inode *inode = d_backing_inode(path->dentry);
>
> + stat->query_flags &= ~KSTAT_QUERY_FLAGS;
> + if ((stat->query_flags & AT_FORCE_ATTR_SYNC) &&
> + (stat->query_flags & AT_NO_ATTR_SYNC))
> + return -EINVAL;
> +
> + stat->result_mask = 0;
> + stat->information = 0;
> if (inode->i_op->getattr)
> return inode->i_op->getattr(path->mnt, path->dentry, stat);
>
> generic_fillattr(inode, stat);
> return 0;
> }
> +EXPORT_SYMBOL(vfs_xgetattr_nosec);
>
> -EXPORT_SYMBOL(vfs_getattr_nosec);
> -
> -int vfs_getattr(struct path *path, struct kstat *stat)
> +/*
> + * vfs_xgetattr - Get the enhanced basic attributes of a file
> + * @path: 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 or can
> + * suppress the update by passing AT_NO_ATTR_SYNC.
> + *
> + * 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 path *path, struct kstat *stat)
> {
> int retval;
>
> retval = security_inode_getattr(path);
> if (retval)
> return retval;
> - return vfs_getattr_nosec(path, stat);
> + return vfs_xgetattr_nosec(path, stat);
> }
> +EXPORT_SYMBOL(vfs_xgetattr);
>
> +/**
> + * vfs_getattr - Get the basic attributes of a file
> + * @path: 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_xgetattr(),
> + * 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 path *path, struct kstat *stat)
> +{
> + stat->query_flags = 0;
> + stat->request_mask = STATX_BASIC_STATS;
> + return vfs_xgetattr(path, stat);
> +}
> EXPORT_SYMBOL(vfs_getattr);
>
> -int vfs_fstat(unsigned int fd, struct kstat *stat)
> +/**
> + * vfs_fstatx - Get the enhanced basic attributes by file descriptor
> + * @fd: The file descriptor referring 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_fstatx(unsigned int fd, struct kstat *stat)
> {
> struct fd f = fdget_raw(fd);
> int error = -EBADF;
>
> if (f.file) {
> - error = vfs_getattr(&f.file->f_path, stat);
> + error = vfs_xgetattr(&f.file->f_path, stat);
> fdput(f);
> }
> return error;
> }
> +EXPORT_SYMBOL(vfs_fstatx);
> +
> +/**
> + * vfs_fstat - Get basic attributes by file descriptor
> + * @fd: The file descriptor referring 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 = STATX_BASIC_STATS;
> + return vfs_fstatx(fd, stat);
> +}
> EXPORT_SYMBOL(vfs_fstat);
>
> -int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
> - int flag)
> +/**
> + * vfs_statx - 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_statx(int dfd, const char __user *filename, int flags,
> + struct kstat *stat)
> {
> struct path path;
> int error = -EINVAL;
> - unsigned int lookup_flags = 0;
> + unsigned int 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;
> +
> retry:
> error = user_path_at(dfd, filename, lookup_flags, &path);
> if (error)
> goto out;
>
> - error = vfs_getattr(&path, stat);
> + error = vfs_xgetattr(&path, stat);
> path_put(&path);
> if (retry_estale(error, lookup_flags)) {
> lookup_flags |= LOOKUP_REVAL;
> @@ -116,17 +235,65 @@ retry:
> out:
> return error;
> }
> +EXPORT_SYMBOL(vfs_statx);
> +
> +/**
> + * 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_statx(). 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 = STATX_BASIC_STATS;
> + return vfs_statx(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_statx(). 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_statx() 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 = STATX_BASIC_STATS;
> + return vfs_statx(AT_FDCWD, filename, 0, stat);
> }
> EXPORT_SYMBOL(vfs_stat);
>
> +/**
> + * vfs_lstat - Get basic attrs 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_statx(). 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_statx() 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);
> + stat->request_mask = STATX_BASIC_STATS;
> + return vfs_statx(AT_FDCWD, name, AT_SYMLINK_NOFOLLOW, stat);
> }
> EXPORT_SYMBOL(vfs_lstat);
>
> @@ -141,7 +308,7 @@ 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",
> @@ -166,7 +333,7 @@ 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;
> @@ -443,6 +610,80 @@ SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename,
> }
> #endif /* __ARCH_WANT_STAT64 || __ARCH_WANT_COMPAT_STAT64 */
>
> +/*
> + * Set the statx results.
> + */
> +static long statx_set_result(struct kstat *stat, struct statx __user *buffer)
> +{
> + uid_t uid = from_kuid_munged(current_user_ns(), stat->uid);
> + gid_t gid = from_kgid_munged(current_user_ns(), stat->gid);
> +
> +#define __put_timestamp(kts, uts) ( \
> + __put_user(kts.tv_sec, uts##_s ) || \
> + __put_user(kts.tv_nsec, uts##_ns ))
> +
> + if (__put_user(stat->result_mask, &buffer->st_mask ) ||
> + __put_user(stat->mode, &buffer->st_mode ) ||
> + __clear_user(&buffer->__spare0, sizeof(buffer->__spare0)) ||
> + __put_user(stat->nlink, &buffer->st_nlink ) ||
> + __put_user(uid, &buffer->st_uid ) ||
> + __put_user(gid, &buffer->st_gid ) ||
> + __put_user(stat->information, &buffer->st_information ) ||
> + __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->version, &buffer->st_version ) ||
> + __put_user(stat->gen, &buffer->st_gen ) ||
> + __clear_user(&buffer->__spare1, sizeof(buffer->__spare1)))
> + return -EFAULT;
> +
> + return 0;
> +}
> +
> +/**
> + * sys_statx - System call to get enhanced stats
> + * @dfd: Base directory to pathwalk from *or* fd to stat.
> + * @filename: File to stat *or* NULL.
> + * @flags: AT_* flags to control pathwalk.
> + * @mask: Parts of statx struct actually required.
> + * @buffer: Result buffer.
> + *
> + * Note that if filename is NULL, then it does the equivalent of fstat() using
> + * dfd to indicate the file of interest.
> + */
> +SYSCALL_DEFINE5(statx,
> + int, dfd, const char __user *, filename, unsigned, flags,
> + unsigned int, mask,
> + struct statx __user *, buffer)
> +{
> + struct kstat stat;
> + int error;
> +
> + if (!access_ok(VERIFY_WRITE, buffer, sizeof(*buffer)))
> + return -EFAULT;
> +
> + memset(&stat, 0, sizeof(stat));
> + stat.query_flags = flags;
> + stat.request_mask = mask & STATX_ALL_STATS;
> +
> + if (filename)
> + error = vfs_statx(dfd, filename, flags, &stat);
> + else
> + error = vfs_fstatx(dfd, &stat);
> + if (error)
> + return error;
> + return statx_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/fs.h b/include/linux/fs.h
> index 70e61b58baaf..8b2f6df924e9 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2827,8 +2827,9 @@ extern const struct inode_operations page_symlink_inode_operations;
> extern void kfree_link(void *);
> extern int generic_readlink(struct dentry *, char __user *, int);
> extern void generic_fillattr(struct inode *, struct kstat *);
> -int vfs_getattr_nosec(struct path *path, struct kstat *stat);
> +extern int vfs_xgetattr_nosec(struct path *path, struct kstat *stat);
> extern int vfs_getattr(struct path *, struct kstat *);
> +extern int vfs_xgetattr(struct path *, 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);
> @@ -2845,6 +2846,8 @@ 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 __generic_block_fiemap(struct inode *inode,
> struct fiemap_extent_info *fieinfo,
> diff --git a/include/linux/stat.h b/include/linux/stat.h
> index 075cb0c7eb2a..4f1902b0cb94 100644
> --- a/include/linux/stat.h
> +++ b/include/linux/stat.h
> @@ -19,6 +19,13 @@
> #include <linux/uidgid.h>
>
> struct kstat {
> + u32 query_flags; /* Operational flags */
> +#define KSTAT_QUERY_FLAGS (AT_FORCE_ATTR_SYNC | AT_NO_ATTR_SYNC)
> + u32 request_mask; /* What fields the user asked for */
> + u32 result_mask; /* What fields the user got */
> + u32 information;
> + u32 win_attrs; /* Windows file attributes */
> + u32 gen;
> u64 ino;
> dev_t dev;
> umode_t mode;
> @@ -27,11 +34,13 @@ struct kstat {
> kgid_t gid;
> dev_t rdev;
> loff_t size;
> - struct timespec atime;
> + struct timespec atime;
> struct timespec mtime;
> struct timespec ctime;
> - unsigned long blksize;
> - unsigned long long blocks;
> + struct timespec btime; /* File creation time */
> + uint32_t blksize; /* Preferred I/O size */
> + u64 blocks;
> + u64 version; /* Data version */
> };
>
> #endif
> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> index d795472c54d8..f6bfbf74e44d 100644
> --- a/include/linux/syscalls.h
> +++ b/include/linux/syscalls.h
> @@ -48,6 +48,7 @@ struct stat;
> struct stat64;
> struct statfs;
> struct statfs64;
> +struct statx;
> struct __sysctl_args;
> struct sysinfo;
> struct timespec;
> @@ -898,4 +899,7 @@ asmlinkage long sys_copy_file_range(int fd_in, loff_t __user *off_in,
>
> asmlinkage long sys_mlock2(unsigned long start, size_t len, int flags);
>
> +asmlinkage long sys_statx(int dfd, const char __user *path, unsigned flags,
> + unsigned mask, struct statx __user *buffer);
> +
> #endif
> diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
> index beed138bd359..5c8143b04ff7 100644
> --- a/include/uapi/linux/fcntl.h
> +++ b/include/uapi/linux/fcntl.h
> @@ -62,6 +62,8 @@
> #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 */
> +#define AT_NO_ATTR_SYNC 0x4000 /* Don't sync attributes with the server */
>
>
> #endif /* _UAPI_LINUX_FCNTL_H */
> diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h
> index 7fec7e36d921..55ce6607dab6 100644
> --- a/include/uapi/linux/stat.h
> +++ b/include/uapi/linux/stat.h
> @@ -1,6 +1,7 @@
> #ifndef _UAPI_LINUX_STAT_H
> #define _UAPI_LINUX_STAT_H
>
> +#include <linux/types.h>
>
> #if defined(__KERNEL__) || !defined(__GLIBC__) || (__GLIBC__ < 2)
>
> @@ -41,5 +42,113 @@
>
> #endif
>
> +/*
> + * Structures for the extended file attribute retrieval system call
> + * (statx()).
> + *
> + * The caller passes a mask of what they're specifically interested in as a
> + * parameter to statx(). What statx() actually got will be indicated in
> + * st_mask upon return.
> + *
> + * For each bit in the mask argument:
> + *
> + * - if the datum is not available at all, the field and the bit will both be
> + * cleared;
> + *
> + * - otherwise, if explicitly requested:
> + *
> + * - the datum will be synchronised to the server if AT_FORCE_ATTR_SYNC is
> + * set or if the datum is considered out of date, and
> + *
> + * - the field will be filled in and the bit will be set;
> + *
> + * - 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 STATX_BASIC_STATS may be marked unavailable on return, but they
> + * will have values installed for compatibility purposes so that stat() and
> + * co. can be emulated in userspace.
> + */
> +struct statx {
> + /* 0x00 */
> + __u32 st_mask; /* What results were written [uncond] */
> + __u32 st_information; /* Information about the file [uncond] */
> + __u32 st_blksize; /* Preferred general I/O size [uncond] */
> + __u32 st_nlink; /* Number of hard links */
> + /* 0x10 */
> + __u32 st_gen; /* Inode generation number */
> + __u32 st_uid; /* User ID of owner */
> + __u32 st_gid; /* Group ID of owner */
> + __u16 st_mode; /* File mode */
> + __u16 __spare0[1];
> + /* 0x20 */
> + __u64 st_ino; /* Inode number */
> + __u64 st_size; /* File size */
> + __u64 st_blocks; /* Number of 512-byte blocks allocated */
> + __u64 st_version; /* Data version number */
> + /* 0x40 */
> + __s64 st_atime_s; /* Last access time */
> + __s64 st_btime_s; /* File creation time */
> + __s64 st_ctime_s; /* Last attribute change time */
> + __s64 st_mtime_s; /* Last data modification time */
> + /* 0x60 */
> + __s32 st_atime_ns; /* Last access time (ns part) */
> + __s32 st_btime_ns; /* File creation time (ns part) */
> + __s32 st_ctime_ns; /* Last attribute change time (ns part) */
> + __s32 st_mtime_ns; /* Last data modification time (ns part) */
> + /* 0x70 */
> + __u32 st_rdev_major; /* Device ID of special file */
> + __u32 st_rdev_minor;
> + __u32 st_dev_major; /* ID of device containing file [uncond] */
> + __u32 st_dev_minor;
> + /* 0x80 */
> + __u64 __spare1[16]; /* Spare space for future expansion */
> + /* 0x100 */
> +};
> +
> +/*
> + * Flags to be st_mask
> + *
> + * Query request/result mask for statx() and struct statx::st_mask.
> + *
> + * These bits should be set in the mask argument of statx() to request
> + * particular items when calling statx().
> + */
> +#define STATX_MODE 0x00000001U /* Want/got st_mode */
> +#define STATX_NLINK 0x00000002U /* Want/got st_nlink */
> +#define STATX_UID 0x00000004U /* Want/got st_uid */
> +#define STATX_GID 0x00000008U /* Want/got st_gid */
> +#define STATX_RDEV 0x00000010U /* Want/got st_rdev */
> +#define STATX_ATIME 0x00000020U /* Want/got st_atime */
> +#define STATX_MTIME 0x00000040U /* Want/got st_mtime */
> +#define STATX_CTIME 0x00000080U /* Want/got st_ctime */
> +#define STATX_INO 0x00000100U /* Want/got st_ino */
> +#define STATX_SIZE 0x00000200U /* Want/got st_size */
> +#define STATX_BLOCKS 0x00000400U /* Want/got st_blocks */
> +#define STATX_BASIC_STATS 0x000007ffU /* The stuff in the normal stat struct */
> +#define STATX_BTIME 0x00000800U /* Want/got st_btime */
> +#define STATX_VERSION 0x00001000U /* Want/got st_version */
> +#define STATX_GEN 0x00002000U /* Want/got st_gen */
> +#define STATX_ALL_STATS 0x00003fffU /* All supported stats */
> +
> +/*
> + * 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.
> + */
> +#define STATX_INFO_ENCRYPTED 0x00000001U /* File is encrypted */
> +#define STATX_INFO_TEMPORARY 0x00000002U /* File is temporary */
> +#define STATX_INFO_FABRICATED 0x00000004U /* File was made up by filesystem */
> +#define STATX_INFO_KERNEL_API 0x00000008U /* File is kernel API (eg: procfs/sysfs) */
> +#define STATX_INFO_REMOTE 0x00000010U /* File is remote */
> +#define STATX_INFO_AUTOMOUNT 0x00000020U /* Dir is automount trigger */
> +#define STATX_INFO_AUTODIR 0x00000040U /* Dir provides unlisted automounts */
> +#define STATX_INFO_NONSYSTEM_OWNERSHIP 0x00000080U /* File has non-system ownership details */
>
> #endif /* _UAPI_LINUX_STAT_H */
> diff --git a/samples/Makefile b/samples/Makefile
> index 48001d7e23f0..d2ebb4e48d19 100644
> --- a/samples/Makefile
> +++ b/samples/Makefile
> @@ -2,4 +2,4 @@
>
> obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ trace_events/ livepatch/ \
> hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/ \
> - configfs/
> + configfs/ statx/
> diff --git a/samples/statx/Makefile b/samples/statx/Makefile
> new file mode 100644
> index 000000000000..6765dabc4c8d
> --- /dev/null
> +++ b/samples/statx/Makefile
> @@ -0,0 +1,10 @@
> +# kbuild trick to avoid linker error. Can be omitted if a module is built.
> +obj- := dummy.o
> +
> +# List of programs to build
> +hostprogs-y := test-statx
> +
> +# Tell kbuild to always build the programs
> +always := $(hostprogs-y)
> +
> +HOSTCFLAGS_test-statx.o += -I$(objtree)/usr/include
> diff --git a/samples/statx/test-statx.c b/samples/statx/test-statx.c
> new file mode 100644
> index 000000000000..38ef23c12e7d
> --- /dev/null
> +++ b/samples/statx/test-statx.c
> @@ -0,0 +1,243 @@
> +/* Test the statx() system call
> + *
> + * Copyright (C) 2015 Red Hat, Inc. All Rights Reserved.
> + * Written by David Howells (dhowells@xxxxxxxxxx)
> + *
> + * 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 <ctype.h>
> +#include <errno.h>
> +#include <time.h>
> +#include <sys/syscall.h>
> +#include <sys/types.h>
> +#include <linux/stat.h>
> +#include <linux/fcntl.h>
> +#include <sys/stat.h>
> +
> +#define AT_FORCE_ATTR_SYNC 0x2000
> +#define AT_NO_ATTR_SYNC 0x4000
> +
> +static __attribute__((unused))
> +ssize_t statx(int dfd, const char *filename, unsigned flags,
> + unsigned int mask, struct statx *buffer)
> +{
> + return syscall(__NR_statx, dfd, filename, flags, mask, buffer);
> +}
> +
> +static void print_time(const char *field, __s64 tv_sec, __s32 tv_nsec)
> +{
> + struct tm tm;
> + time_t tim;
> + char buffer[100];
> + int len;
> +
> + tim = 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", 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_statx(struct statx *stx)
> +{
> + char buffer[256], ft = '?';
> +
> + printf("results=%x\n", stx->st_mask);
> +
> + printf(" ");
> + if (stx->st_mask & STATX_SIZE)
> + printf(" Size: %-15llu", (unsigned long long)stx->st_size);
> + if (stx->st_mask & STATX_BLOCKS)
> + printf(" Blocks: %-10llu", (unsigned long long)stx->st_blocks);
> + printf(" IO Block: %-6llu ", (unsigned long long)stx->st_blksize);
> + if (stx->st_mask & STATX_MODE) {
> + switch (stx->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", stx->st_mode & S_IFMT);
> + break;
> + }
> + }
> +
> + sprintf(buffer, "%02x:%02x", stx->st_dev_major, stx->st_dev_minor);
> + printf("Device: %-15s", buffer);
> + if (stx->st_mask & STATX_INO)
> + printf(" Inode: %-11llu", (unsigned long long) stx->st_ino);
> + if (stx->st_mask & STATX_SIZE)
> + printf(" Links: %-5u", stx->st_nlink);
> + if (stx->st_mask & STATX_RDEV)
> + printf(" Device type: %u,%u", stx->st_rdev_major, stx->st_rdev_minor);
> + printf("\n");
> +
> + if (stx->st_mask & STATX_MODE)
> + printf("Access: (%04o/%c%c%c%c%c%c%c%c%c%c) ",
> + stx->st_mode & 07777,
> + ft,
> + stx->st_mode & S_IRUSR ? 'r' : '-',
> + stx->st_mode & S_IWUSR ? 'w' : '-',
> + stx->st_mode & S_IXUSR ? 'x' : '-',
> + stx->st_mode & S_IRGRP ? 'r' : '-',
> + stx->st_mode & S_IWGRP ? 'w' : '-',
> + stx->st_mode & S_IXGRP ? 'x' : '-',
> + stx->st_mode & S_IROTH ? 'r' : '-',
> + stx->st_mode & S_IWOTH ? 'w' : '-',
> + stx->st_mode & S_IXOTH ? 'x' : '-');
> + if (stx->st_mask & STATX_UID)
> + printf("Uid: %5d ", stx->st_uid);
> + if (stx->st_mask & STATX_GID)
> + printf("Gid: %5d\n", stx->st_gid);
> +
> + if (stx->st_mask & STATX_ATIME)
> + print_time("Access: ", stx->st_atime_s, stx->st_atime_ns);
> + if (stx->st_mask & STATX_MTIME)
> + print_time("Modify: ", stx->st_mtime_s, stx->st_mtime_ns);
> + if (stx->st_mask & STATX_CTIME)
> + print_time("Change: ", stx->st_ctime_s, stx->st_ctime_ns);
> + if (stx->st_mask & STATX_BTIME)
> + print_time(" Birth: ", stx->st_btime_s, stx->st_btime_ns);
> +
> + if (stx->st_mask & STATX_VERSION)
> + printf("Data version: %llxh\n",
> + (unsigned long long)stx->st_version);
> +
> + if (stx->st_mask & STATX_GEN)
> + printf("Inode gen : %xh\n", stx->st_gen);
> +
> + if (stx->st_information) {
> + unsigned char bits;
> + int loop, byte;
> +
> + static char info_representation[32 + 1] =
> + /* STATX_INFO_ flags: */
> + "????????" /* 31-24 0x00000000-ff000000 */
> + "????????" /* 23-16 0x00000000-00ff0000 */
> + "????????" /* 15- 8 0x00000000-0000ff00 */
> + "ndmrkfte" /* 7- 0 0x00000000-000000ff */
> + ;
> +
> + printf("Information: %08x (", stx->st_information);
> + for (byte = 32 - 8; byte >= 0; byte -= 8) {
> + bits = stx->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");
> + }
> +
> + printf("IO-blocksize: blksize=%u\n", stx->st_blksize);
> +}
> +
> +static 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 statx stx;
> + int ret, raw = 0, atflag = AT_SYMLINK_NOFOLLOW;
> +
> + unsigned int mask = STATX_ALL_STATS;
> +
> + for (argv++; *argv; argv++) {
> + if (strcmp(*argv, "-F") == 0) {
> + atflag |= AT_FORCE_ATTR_SYNC;
> + continue;
> + }
> + if (strcmp(*argv, "-N") == 0) {
> + atflag |= AT_NO_ATTR_SYNC;
> + continue;
> + }
> + if (strcmp(*argv, "-L") == 0) {
> + atflag &= ~AT_SYMLINK_NOFOLLOW;
> + continue;
> + }
> + if (strcmp(*argv, "-O") == 0) {
> + mask &= ~STATX_BASIC_STATS;
> + continue;
> + }
> + if (strcmp(*argv, "-A") == 0) {
> + atflag |= AT_NO_AUTOMOUNT;
> + continue;
> + }
> + if (strcmp(*argv, "-R") == 0) {
> + raw = 1;
> + continue;
> + }
> +
> + memset(&stx, 0xbf, sizeof(stx));
> + ret = statx(AT_FDCWD, *argv, atflag, mask, &stx);
> + printf("statx(%s) = %d\n", *argv, ret);
> + if (ret < 0) {
> + perror(*argv);
> + exit(1);
> + }
> +
> + if (raw)
> + dump_hex((unsigned long long *)&stx, 0, sizeof(stx));
> +
> + dump_statx(&stx);
> + }
> + return 0;
> +}
>
> --
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Cheers, Andreas

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