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From: Andreas Dilger <adilger@dilger.ca>
To: Jeff Layton <jlayton@redhat.com>
Cc: David Howells <dhowells@redhat.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/4] statx: Add a system call to make enhanced file info available
Date: Thu, 17 Nov 2016 19:32:08 -0700	[thread overview]
Message-ID: <2D8B8AAF-2016-45BD-9D70-A532DDDB23D2@dilger.ca> (raw)
In-Reply-To: <1479407964.4556.5.camel@redhat.com>

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> On Nov 17, 2016, at 11:39 AM, Jeff Layton <jlayton@redhat.com> wrote:
> 
> On Thu, 2016-11-17 at 13:35 +0000, David Howells wrote:
>> Add a system call to make extended file information available, including
>> file creation, data version and some attribute flags where available
>> through the underlying filesystem.
>> 
>> 
>> ========
>> 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_STATX_FORCE_SYNC can be set in flags.  This will require a network
>> filesystem to synchronise its attributes with the server.
>> 
>> AT_STATX_DONT_SYNC can be set in flags.  This will suppress synchronisation
>> with the server in a network filesystem.  The resulting values should be
>> considered approximate.
>> 
>> If neither AT_STATX_*_SYNC flag is set, the behaviour is the default for
>> stat() on that filesystem.
>> 
> 
> We also need to specify here what happens if both bits are set. Should
> that be -EINVAL?

If that is the case, then it doesn't make sense to have two contradictory
flags.

Pick a default behaviour (i.e. return what is known on the client), and
if this is 100% accurate (e.g. local filesystem or filesystem with strong
coherency) then it can optionally set the SYNC flag in the returned flags.
If the application needs 100% accurate size info, then it can set the SYNC
flag in the request and the filesystem may need to do extra work to fetch
accurate data from the server.

>> 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().  It should be note that asking for
>> more information may entail more I/O operations.
>> 
>> 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	stx_mask;
>> 		__u32	stx_blksize;
>> 		__u64	stx_attributes;
>> 		__u32	stx_nlink;
>> 		__u32	stx_uid;
>> 		__u32	stx_gid;
>> 		__u16	stx_mode;
>> 		__u16	__spare0[1];
>> 		__u64	stx_ino;
>> 		__u64	stx_size;
>> 		__u64	stx_blocks;
>> 		__u64	stx_version;
>> 		__s64	stx_atime;
>> 		__s64	stx_btime;
>> 		__s64	stx_ctime;
>> 		__s64	stx_mtime;
>> 		__s32	stx_atime_ns;
>> 		__s32	stx_btime_ns;
>> 		__s32	stx_ctime_ns;
>> 		__s32	stx_mtime_ns;
>> 		__u32	stx_rdev_major;
>> 		__u32	stx_rdev_minor;
>> 		__u32	stx_dev_major;
>> 		__u32	stx_dev_minor;
>> 		__u64	__spare1[16];
>> 	};
>> 
>> The defined bits in request_mask and stx_mask are:
>> 
>> 	STATX_TYPE		Want/got stx_mode & S_IFMT
>> 	STATX_MODE		Want/got stx_mode & ~S_IFMT
>> 	STATX_NLINK		Want/got stx_nlink
>> 	STATX_UID		Want/got stx_uid
>> 	STATX_GID		Want/got stx_gid
>> 	STATX_ATIME		Want/got stx_atime{,_ns}
>> 	STATX_MTIME		Want/got stx_mtime{,_ns}
>> 	STATX_CTIME		Want/got stx_ctime{,_ns}
>> 	STATX_INO		Want/got stx_ino
>> 	STATX_SIZE		Want/got stx_size
>> 	STATX_BLOCKS		Want/got stx_blocks
>> 	STATX_BASIC_STATS	[The stuff in the normal stat struct]
>> 	STATX_BTIME		Want/got stx_btime{,_ns}
>> 	STATX_VERSION		Want/got stx_version
>> 	STATX_ALL		[All currently available stuff]
>> 
>> stx_btime is the file creation time; stx_version is the data version number
>> (i_version); stx_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 will also be negative if not zero.
>> 
>> The bits defined in the stx_attributes field convey information about a
>> file, how it is accessed, where it is and what it does.  The following
>> attributes map to FS_*_FL flags and are the same numerical value:
>> 
>> 	STATX_ATTR_COMPRESSED		File is compressed by the fs
>> 	STATX_ATTR_IMMUTABLE		File is marked immutable
>> 	STATX_ATTR_APPEND		File is append-only
>> 	STATX_ATTR_NODUMP		File is not to be dumped
>> 	STATX_ATTR_ENCRYPTED		File requires key to decrypt in fs
>> 
>> The supported flags are listed by:
>> 
>> 	STATX_ATTR_FS_IOC_FLAGS
>> 
>> [Are any other IOC flags of sufficient general interest to be exposed
>> through this interface?]
>> 
>> New flags include:
>> 
>> 	STATX_ATTR_NONUNIX_OWNERSHIP	File doesn't have Unixy ownership
>> 	STATX_ATTR_HAS_ACL		File has an ACL
>> 	STATX_ATTR_KERNEL_API		File is kernel API (eg: procfs/sysfs)
>> 	STATX_ATTR_REMOTE		File is remote and needs network
>> 	STATX_ATTR_FABRICATED		File was made up by fs
>> 	STATX_ATTR_AUTOMOUNT		Object is an automount trigger
>> 	STATX_ATTR_UNLISTED_DENTS	Dir: Lookup may find files getdents doesn't
>> 
>> 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) stx_dev_*, stx_blksize.
>> 
>>     These are local system information and are always available.
>> 
>> (1) stx_mode, stx_nlinks, stx_uid, stx_gid, stx_[amc]time*, stx_ino,
>>     stx_size, stx_blocks.
>> 
>>     These will be returned whether the caller asks for them or not.  The
>>     corresponding bits in stx_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 stx_mask,
>>     even if the caller asked for the value.  In such a case, the returned
>>     value will be a fabrication.
>> 
>>     Note that there are instances where the type might not be valid, for
>>     instance Windows reparse points.
>> 
>> (2) stx_rdev_*.
>> 
>>     This will be set only if stx_mode indicates we're looking at a
>>     blockdev or a chardev, otherwise will be 0.
>> 
>> (3) stx_btime*, stx_version.
>> 
>>     Similar to (1), except these will be set to 0 if they don't exist.
>> 
>> 
>> =======
>> 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=17ff
>> 	  Size: 4096            Blocks: 8          IO Block: 1048576  directory
>> 	Device: 00:26           Inode: 1703937     Links: 124
>> 	Access: (3777/drwxrwxrwx)  Uid:     0   Gid:  4041
>> 	Access: 2016-11-10 15:52:11.219935864+0000
>> 	Modify: 2016-11-10 08:07:32.482314928+0000
>> 	Change: 2016-11-10 08:07:32.482314928+0000
>> 	Data version: 58242ac41cbf8ab0h
>> 	Attributes: 000000000000e000 (-------- -------- -------- -------- -------- -------- mfr----- --------)
>> 	IO-blocksize: blksize=1048576
>> 
>> Secondly, the result of automounting on that directory.
>> 
>> 	[root@andromeda tmp]# ./samples/statx/test-statx /warthog/data
>> 	statx(/warthog/data) = 0
>> 	results=17ff
>> 	  Size: 4096            Blocks: 8          IO Block: 1048576  directory
>> 	Device: 00:27           Inode: 2           Links: 124
>> 	Access: (3777/drwxrwxrwx)  Uid:     0   Gid:  4041
>> 	Access: 2016-11-10 15:52:11.219935864+0000
>> 	Modify: 2016-11-10 08:07:32.482314928+0000
>> 	Change: 2016-11-10 08:07:32.482314928+0000
>> 	Data version: 58242ac41cbf8ab0h
>> 	Attributes: 0000000000002000 (-------- -------- -------- -------- -------- -------- --r----- --------)
>> 	IO-blocksize: blksize=1048576
>> 
>> Signed-off-by: David Howells <dhowells@redhat.com>
>> ---
>> 
>> arch/x86/entry/syscalls/syscall_32.tbl |    1
>> arch/x86/entry/syscalls/syscall_64.tbl |    1
>> fs/exportfs/expfs.c                    |    4
>> fs/stat.c                              |  294 +++++++++++++++++++++++++++++---
>> include/linux/fs.h                     |    5 -
>> include/linux/stat.h                   |   19 +-
>> include/linux/syscalls.h               |    3
>> include/uapi/linux/fcntl.h             |    2
>> include/uapi/linux/stat.h              |  124 +++++++++++++
>> samples/Kconfig                        |    5 +
>> samples/Makefile                       |    3
>> samples/statx/Makefile                 |   10 +
>> samples/statx/test-statx.c             |  248 +++++++++++++++++++++++++++
>> 13 files changed, 679 insertions(+), 40 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 2b3618542544..9ba050fe47f3 100644
>> --- a/arch/x86/entry/syscalls/syscall_32.tbl
>> +++ b/arch/x86/entry/syscalls/syscall_32.tbl
>> @@ -389,3 +389,4 @@
>> 380	i386	pkey_mprotect		sys_pkey_mprotect
>> 381	i386	pkey_alloc		sys_pkey_alloc
>> 382	i386	pkey_free		sys_pkey_free
>> +383	i386	statx			sys_statx
>> diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
>> index e93ef0b38db8..5aef183e2f85 100644
>> --- a/arch/x86/entry/syscalls/syscall_64.tbl
>> +++ b/arch/x86/entry/syscalls/syscall_64.tbl
>> @@ -338,6 +338,7 @@
>> 329	common	pkey_mprotect		sys_pkey_mprotect
>> 330	common	pkey_alloc		sys_pkey_alloc
>> 331	common	pkey_free		sys_pkey_free
>> +332	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 a4b531be9168..2acc31751248 100644
>> --- a/fs/exportfs/expfs.c
>> +++ b/fs/exportfs/expfs.c
>> @@ -299,7 +299,9 @@ 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..78c0a5086038 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 +36,189 @@ 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;
>> +	if (IS_NOATIME(inode))
>> +		stat->result_mask &= ~STATX_ATIME;
>> +	else
>> +		stat->atime = inode->i_atime;
>> +
>> +	if (IS_AUTOMOUNT(inode))
>> +		stat->attributes |= STATX_ATTR_AUTOMOUNT;
>> +}
>> 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;
>> +
>> +	stat->result_mask = 0;
>> +	stat->attributes = 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 +227,65 @@ int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
>> 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 +300,7 @@ 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 +325,7 @@ 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 +602,79 @@ 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->stx_mask	) ||
>> +	    __put_user(stat->mode,		&buffer->stx_mode	) ||
>> +	    __clear_user(&buffer->__spare0, sizeof(buffer->__spare0))	  ||
>> +	    __put_user(stat->nlink,		&buffer->stx_nlink	) ||
>> +	    __put_user(uid,			&buffer->stx_uid	) ||
>> +	    __put_user(gid,			&buffer->stx_gid	) ||
>> +	    __put_user(stat->attributes,	&buffer->stx_attributes	) ||
>> +	    __put_user(stat->blksize,		&buffer->stx_blksize	) ||
>> +	    __put_user(MAJOR(stat->rdev),	&buffer->stx_rdev_major	) ||
>> +	    __put_user(MINOR(stat->rdev),	&buffer->stx_rdev_minor	) ||
>> +	    __put_user(MAJOR(stat->dev),	&buffer->stx_dev_major	) ||
>> +	    __put_user(MINOR(stat->dev),	&buffer->stx_dev_minor	) ||
>> +	    __put_timestamp(stat->atime,	&buffer->stx_atime	) ||
>> +	    __put_timestamp(stat->btime,	&buffer->stx_btime	) ||
>> +	    __put_timestamp(stat->ctime,	&buffer->stx_ctime	) ||
>> +	    __put_timestamp(stat->mtime,	&buffer->stx_mtime	) ||
>> +	    __put_user(stat->ino,		&buffer->stx_ino	) ||
>> +	    __put_user(stat->size,		&buffer->stx_size	) ||
>> +	    __put_user(stat->blocks,		&buffer->stx_blocks	) ||
>> +	    __put_user(stat->version,		&buffer->stx_version	) ||
>> +	    __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;
>> +
>> +	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 16d2b6e874d6..f153199566b4 100644
>> --- a/include/linux/fs.h
>> +++ b/include/linux/fs.h
>> @@ -2916,8 +2916,9 @@ 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);
>> @@ -2935,6 +2936,8 @@ 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 const char *vfs_get_link(struct dentry *, struct delayed_call *);
>> +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..cf25bb5cf754 100644
>> --- a/include/linux/stat.h
>> +++ b/include/linux/stat.h
>> @@ -19,19 +19,26 @@
>> #include <linux/uidgid.h>
>> 
>> struct kstat {
>> -	u64		ino;
>> -	dev_t		dev;
>> +	u32		query_flags;	/* Operational flags */
>> +#define KSTAT_QUERY_FLAGS (AT_STATX_FORCE_SYNC | AT_STATX_DONT_SYNC)
>> +	u32		request_mask;	/* What fields the user asked for */
>> +	u32		result_mask;	/* What fields the user got */
>> 	umode_t		mode;
>> 	unsigned int	nlink;
>> +	uint32_t	blksize;	/* Preferred I/O size */
>> +	u64		attributes;
>> +	u64		ino;
>> +	dev_t		dev;
>> +	dev_t		rdev;
>> 	kuid_t		uid;
>> 	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 */
>> +	u64		blocks;
>> +	u64		version;		/* Data version */
>> };
>> 
>> #endif
>> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
>> index 91a740f6b884..980c3c9b06f8 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;
>> @@ -902,5 +903,7 @@ asmlinkage long sys_pkey_mprotect(unsigned long start, size_t len,
>> 				  unsigned long prot, int pkey);
>> asmlinkage long sys_pkey_alloc(unsigned long flags, unsigned long init_val);
>> asmlinkage long sys_pkey_free(int pkey);
>> +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..c49cb6edaafa 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_STATX_FORCE_SYNC	0x2000	/* Force the attributes to be sync'd with the server */
>> +#define AT_STATX_DONT_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..32ea14c1c960 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 +42,128 @@
>> 
>> #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 supported:
>> + *
>> + *   - the bit will be cleared, and
>> + *
>> + *   - the datum will be set to an appropriate fabricated value if one is
>> + *     available (eg. CIFS can take a default uid and gid), otherwise
>> + *
>> + *   - the field will be cleared;
>> + *
>> + * - otherwise, if explicitly requested:
>> + *
>> + *   - the datum will be synchronised to the server if AT_STATX_FORCE_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	stx_mask;	/* What results were written [uncond] */
>> +	__u32	stx_blksize;	/* Preferred general I/O size [uncond] */
>> +	__u64	stx_attributes;	/* Flags conveying information about the file [uncond] */
>> +	/* 0x10 */
>> +	__u32	stx_nlink;	/* Number of hard links */
>> +	__u32	stx_uid;	/* User ID of owner */
>> +	__u32	stx_gid;	/* Group ID of owner */
>> +	__u16	stx_mode;	/* File mode */
>> +	__u16	__spare0[1];
>> +	/* 0x20 */
>> +	__u64	stx_ino;	/* Inode number */
>> +	__u64	stx_size;	/* File size */
>> +	__u64	stx_blocks;	/* Number of 512-byte blocks allocated */
>> +	__u64	stx_version;	/* Data version number */
>> +	/* 0x40 */
>> +	__s64	stx_atime_s;	/* Last access time */
>> +	__s64	stx_btime_s;	/* File creation time */
>> +	__s64	stx_ctime_s;	/* Last attribute change time */
>> +	__s64	stx_mtime_s;	/* Last data modification time */
>> +	/* 0x60 */
>> +	__s32	stx_atime_ns;	/* Last access time (ns part) */
>> +	__s32	stx_btime_ns;	/* File creation time (ns part) */
>> +	__s32	stx_ctime_ns;	/* Last attribute change time (ns part) */
>> +	__s32	stx_mtime_ns;	/* Last data modification time (ns part) */
>> +	/* 0x70 */
>> +	__u32	stx_rdev_major;	/* Device ID of special file [if bdev/cdev] */
>> +	__u32	stx_rdev_minor;
>> +	__u32	stx_dev_major;	/* ID of device containing file [uncond] */
>> +	__u32	stx_dev_minor;
>> +	/* 0x80 */
>> +	__u64	__spare1[16];	/* Spare space for future expansion */
>> +	/* 0x100 */
>> +};
>> +
>> +/*
>> + * Flags to be stx_mask
>> + *
>> + * Query request/result mask for statx() and struct statx::stx_mask.
>> + *
>> + * These bits should be set in the mask argument of statx() to request
>> + * particular items when calling statx().
>> + */
>> +#define STATX_TYPE		0x00000001U	/* Want/got stx_mode & S_IFMT */
>> +#define STATX_MODE		0x00000002U	/* Want/got stx_mode & ~S_IFMT */
>> +#define STATX_NLINK		0x00000004U	/* Want/got stx_nlink */
>> +#define STATX_UID		0x00000008U	/* Want/got stx_uid */
>> +#define STATX_GID		0x00000010U	/* Want/got stx_gid */
>> +#define STATX_ATIME		0x00000020U	/* Want/got stx_atime */
>> +#define STATX_MTIME		0x00000040U	/* Want/got stx_mtime */
>> +#define STATX_CTIME		0x00000080U	/* Want/got stx_ctime */
>> +#define STATX_INO		0x00000100U	/* Want/got stx_ino */
>> +#define STATX_SIZE		0x00000200U	/* Want/got stx_size */
>> +#define STATX_BLOCKS		0x00000400U	/* Want/got stx_blocks */
>> +#define STATX_BASIC_STATS	0x000007ffU	/* The stuff in the normal stat struct */
>> +#define STATX_BTIME		0x00000800U	/* Want/got stx_btime */
>> +#define STATX_VERSION		0x00001000U	/* Want/got stx_version */
>> +#define STATX_ALL		0x00001fffU	/* All currently supported flags */
>> +
>> +/*
>> + * Attributes to be found in stx_attributes
>> + *
>> + * 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.
>> + *
>> + * Note that the flags marked [I] correspond to generic FS_IOC_FLAGS
>> + * semantically.  Where possible, the numerical value is picked to correspond
>> + * also.
>> + */
>> +#define STATX_ATTR_COMPRESSED		0x00000004 /* [I] File is compressed by the fs */
>> +#define STATX_ATTR_IMMUTABLE		0x00000010 /* [I] File is marked immutable */
>> +#define STATX_ATTR_APPEND		0x00000020 /* [I] File is append-only */
>> +#define STATX_ATTR_NODUMP		0x00000040 /* [I] File is not to be dumped */
>> +#define STATX_ATTR_NONUNIX_OWNERSHIP	0x00000100 /* File has non-Unix ownership details */
>> +#define STATX_ATTR_HAS_ACL		0x00000200 /* File has an ACL */
>> +#define STATX_ATTR_ENCRYPTED		0x00000800 /* [I] File requires key to decrypt in fs */
>> +#define STATX_ATTR_FS_IOC_FLAGS		0x00000874 /* Attrs corresponding to FS_*_FL flags */
>> +
>> +#define STATX_ATTR_KERNEL_API		0x00001000 /* File is kernel API (eg: procfs/sysfs) */
>> +#define STATX_ATTR_REMOTE		0x00002000 /* File is remote and needs network */
>> +#define STATX_ATTR_FABRICATED		0x00004000 /* File was made up by fs and is transient */
>> +#define STATX_ATTR_AUTOMOUNT		0x00008000 /* Dir: Automount trigger */
>> +#define STATX_ATTR_UNLISTED_DENTS	0x00010000 /* Dir: Lookup may find files getdents doesn't */
>> +
>> 
>> #endif /* _UAPI_LINUX_STAT_H */
>> diff --git a/samples/Kconfig b/samples/Kconfig
>> index a6d2a43bbf2e..94a7488f14ae 100644
>> --- a/samples/Kconfig
>> +++ b/samples/Kconfig
>> @@ -105,4 +105,9 @@ config SAMPLE_BLACKFIN_GPTIMERS
>> 	help
>> 	  Build samples of blackfin gptimers sample module.
>> 
>> +config SAMPLE_STATX
>> +	bool "Build example extended-stat using code"
>> +	help
>> +	  Build example userspace program to use the new extended-stat syscall.
>> +
>> endif # SAMPLES
>> diff --git a/samples/Makefile b/samples/Makefile
>> index e17d66d77f09..8eeb15e13413 100644
>> --- a/samples/Makefile
>> +++ b/samples/Makefile
>> @@ -2,4 +2,5 @@
>> 
>> obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ trace_events/ livepatch/ \
>> 			   hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/ \
>> -			   configfs/ connector/ v4l/ trace_printk/ blackfin/
>> +			   configfs/ connector/ v4l/ trace_printk/ blackfin/ \
>> +			   statx/
>> diff --git a/samples/statx/Makefile b/samples/statx/Makefile
>> new file mode 100644
>> index 000000000000..1f80a3d8cf45
>> --- /dev/null
>> +++ b/samples/statx/Makefile
>> @@ -0,0 +1,10 @@
>> +# kbuild trick to avoid linker error. Can be omitted if a module is built.
>> +obj- := dummy.o
>> +
>> +# List of programs to build
>> +hostprogs-$(CONFIG_SAMPLE_STATX) := 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..2419b33fc15d
>> --- /dev/null
>> +++ b/samples/statx/test-statx.c
>> @@ -0,0 +1,248 @@
>> +/* Test the statx() system call
>> + *
>> + * Copyright (C) 2015 Red Hat, Inc. All Rights Reserved.
>> + * Written by David Howells (dhowells@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 <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_STATX_FORCE_SYNC	0x2000
>> +#define AT_STATX_DONT_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->stx_mask);
>> +
>> +	printf(" ");
>> +	if (stx->stx_mask & STATX_SIZE)
>> +		printf(" Size: %-15llu", (unsigned long long)stx->stx_size);
>> +	if (stx->stx_mask & STATX_BLOCKS)
>> +		printf(" Blocks: %-10llu", (unsigned long long)stx->stx_blocks);
>> +	printf(" IO Block: %-6llu ", (unsigned long long)stx->stx_blksize);
>> +	if (stx->stx_mask & STATX_MODE) {
>> +		switch (stx->stx_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->stx_mode & S_IFMT);
>> +			break;
>> +		}
>> +	}
>> +
>> +	sprintf(buffer, "%02x:%02x", stx->stx_dev_major, stx->stx_dev_minor);
>> +	printf("Device: %-15s", buffer);
>> +	if (stx->stx_mask & STATX_INO)
>> +		printf(" Inode: %-11llu", (unsigned long long) stx->stx_ino);
>> +	if (stx->stx_mask & STATX_SIZE)
>> +		printf(" Links: %-5u", stx->stx_nlink);
>> +	switch (stx->stx_mask & STATX_MODE) {
>> +	case S_IFBLK:
>> +	case S_IFCHR:
>> +		printf(" Device type: %u,%u", stx->stx_rdev_major, stx->stx_rdev_minor);
>> +		break;
>> +	}
>> +	printf("\n");
>> +
>> +	if (stx->stx_mask & STATX_MODE)
>> +		printf("Access: (%04o/%c%c%c%c%c%c%c%c%c%c)  ",
>> +		       stx->stx_mode & 07777,
>> +		       ft,
>> +		       stx->stx_mode & S_IRUSR ? 'r' : '-',
>> +		       stx->stx_mode & S_IWUSR ? 'w' : '-',
>> +		       stx->stx_mode & S_IXUSR ? 'x' : '-',
>> +		       stx->stx_mode & S_IRGRP ? 'r' : '-',
>> +		       stx->stx_mode & S_IWGRP ? 'w' : '-',
>> +		       stx->stx_mode & S_IXGRP ? 'x' : '-',
>> +		       stx->stx_mode & S_IROTH ? 'r' : '-',
>> +		       stx->stx_mode & S_IWOTH ? 'w' : '-',
>> +		       stx->stx_mode & S_IXOTH ? 'x' : '-');
>> +	if (stx->stx_mask & STATX_UID)
>> +		printf("Uid: %5d   ", stx->stx_uid);
>> +	if (stx->stx_mask & STATX_GID)
>> +		printf("Gid: %5d\n", stx->stx_gid);
>> +
>> +	if (stx->stx_mask & STATX_ATIME)
>> +		print_time("Access: ", stx->stx_atime_s, stx->stx_atime_ns);
>> +	if (stx->stx_mask & STATX_MTIME)
>> +		print_time("Modify: ", stx->stx_mtime_s, stx->stx_mtime_ns);
>> +	if (stx->stx_mask & STATX_CTIME)
>> +		print_time("Change: ", stx->stx_ctime_s, stx->stx_ctime_ns);
>> +	if (stx->stx_mask & STATX_BTIME)
>> +		print_time(" Birth: ", stx->stx_btime_s, stx->stx_btime_ns);
>> +
>> +	if (stx->stx_mask & STATX_VERSION)
>> +		printf("Data version: %llxh\n",
>> +		       (unsigned long long)stx->stx_version);
>> +
>> +	if (stx->stx_attributes) {
>> +		unsigned char bits;
>> +		int loop, byte;
>> +
>> +		static char attr_representation[64 + 1] =
>> +			/* STATX_ATTR_ flags: */
>> +			"????????"	/* 63-56 */
>> +			"????????"	/* 55-48 */
>> +			"????????"	/* 47-40 */
>> +			"????????"	/* 39-32 */
>> +			"????????"	/* 31-24	0x00000000-ff000000 */
>> +			"???????u"	/* 23-16	0x00000000-00ff0000 */
>> +			"mfrke?AU"	/* 15- 8	0x00000000-0000ff00 */
>> +			"?dai?c??"	/*  7- 0	0x00000000-000000ff */
>> +			;
>> +
>> +		printf("Attributes: %016llx (", stx->stx_attributes);
>> +		for (byte = 64 - 8; byte >= 0; byte -= 8) {
>> +			bits = stx->stx_attributes >> byte;
>> +			for (loop = 7; loop >= 0; loop--) {
>> +				int bit = byte + loop;
>> +
>> +				if (bits & 0x80)
>> +					putchar(attr_representation[63 - bit]);
>> +				else
>> +					putchar('-');
>> +				bits <<= 1;
>> +			}
>> +			if (byte)
>> +				putchar(' ');
>> +		}
>> +		printf(")\n");
>> +	}
>> +
>> +	printf("IO-blocksize: blksize=%u\n", stx->stx_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;
>> +
>> +	for (argv++; *argv; argv++) {
>> +		if (strcmp(*argv, "-F") == 0) {
>> +			atflag |= AT_STATX_FORCE_SYNC;
>> +			continue;
>> +		}
>> +		if (strcmp(*argv, "-D") == 0) {
>> +			atflag |= AT_STATX_DONT_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;
>> +}
>> 
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> --
> Jeff Layton <jlayton@redhat.com>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html


Cheers, Andreas






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  reply	other threads:[~2016-11-18  2:48 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-17 13:34 [RFC][PATCH 0/4] Enhanced file stat system call David Howells
2016-11-17 13:35 ` [PATCH 1/4] statx: Add a system call to make enhanced file info available David Howells
2016-11-17 18:39   ` Jeff Layton
2016-11-18  2:32     ` Andreas Dilger [this message]
2016-11-18  8:59     ` David Howells
2016-11-18  8:59       ` David Howells
2016-11-18  9:25       ` Andreas Dilger
2016-11-18  9:25         ` Andreas Dilger
2016-11-17 23:40   ` Dave Chinner
2016-11-18  3:28     ` Andreas Dilger
2016-11-18 22:07       ` Dave Chinner
2016-11-18 22:54       ` David Howells
2016-11-19 22:43         ` Dave Chinner
2016-11-21 14:30         ` One Thousand Gnomes
2016-11-21 20:43           ` Dave Chinner
2016-11-22 10:39         ` David Howells
2016-11-22 13:55           ` Jeff Layton
2016-11-22 20:58           ` Dave Chinner
2016-11-18  9:53     ` David Howells
2016-11-18  8:48   ` David Howells
2016-11-18 12:01     ` Jeff Layton
2016-11-18  9:36   ` David Howells
2016-11-18 17:17     ` Jeff Layton
2016-11-18 18:04     ` David Howells
2016-11-18 18:54       ` Jeff Layton
2016-11-18 19:08       ` David Howells
2016-11-18  9:43   ` David Howells
2016-11-18 21:41     ` Dave Chinner
2016-11-18 22:24     ` David Howells
2016-11-18 10:29   ` David Howells
2016-11-18 10:29     ` David Howells
2016-11-18 21:27     ` Dave Chinner
2016-11-18 21:48     ` David Howells
2016-11-18 21:48       ` David Howells
2016-11-18 22:17       ` Dave Chinner
2016-11-18 22:17         ` Dave Chinner
2016-11-19 10:21         ` Michael Kerrisk (man-pages)
2016-11-17 13:35 ` [PATCH 2/4] statx: Ext4: Return enhanced file attributes David Howells
2016-11-18  3:30   ` Andreas Dilger
2016-11-17 13:35 ` [PATCH 3/4] statx: NFS: " David Howells
2016-11-17 13:35 ` [PATCH 4/4] statx: AFS: " David Howells
2016-11-18  3:34   ` Andreas Dilger
2016-11-18  8:47   ` David Howells
2016-11-17 14:39 ` [RFC][PATCH 0/4] Enhanced file stat system call One Thousand Gnomes
2016-11-17 15:10 ` Michael Kerrisk
2016-11-17 16:33 ` David Howells
2016-11-17 16:45 ` David Howells
2016-11-17 20:00   ` J. Bruce Fields
2016-11-18  2:30     ` Andreas Dilger
2016-11-18  4:29       ` NeilBrown
2016-11-18 13:41   ` One Thousand Gnomes
2016-11-18 13:49   ` David Howells

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