1. 04 May, 2017 1 commit
  2. 03 Mar, 2017 1 commit
    • David Howells's avatar
      statx: Add a system call to make enhanced file info available · a528d35e
      David Howells authored
      Add a system call to make extended file information available, including
      file creation and some attribute flags where available through the
      underlying filesystem.
      
      The getattr inode operation is altered to take two additional arguments: a
      u32 request_mask and an unsigned int flags that indicate the
      synchronisation mode.  This change is propagated to the vfs_getattr*()
      function.
      
      Functions like vfs_stat() are now inline wrappers around new functions
      vfs_statx() and vfs_statx_fd() to reduce stack usage.
      
      ========
      OVERVIEW
      ========
      
      The idea was initially proposed as a set of xattrs that could be retrieved
      with getxattr(), but the general preference proved to be for a new syscall
      with an extended stat structure.
      
      A number of requests were gathered for features to be included.  The
      following have been included:
      
       (1) Make the fields a consistent size on all arches and make them large.
      
       (2) Spare space, request flags and information flags are provided for
           future expansion.
      
       (3) Better support for the y2038 problem [Arnd Bergmann] (tv_sec is an
           __s64).
      
       (4) 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 (stx_btime).
      
           This is also specified in NFSv4 as a recommended attribute and could
           be exported by NFSD [Steve French].
      
       (5) 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] (AT_STATX_DONT_SYNC).
      
       (6) Heavyweight stat: Force a netfs to go to the server, even if it thinks
           its cached attributes are up to date [Trond Myklebust]
           (AT_STATX_FORCE_SYNC).
      
      And the following have been left out for future extension:
      
       (7) 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.
      
           (There's disagreement on the exact semantics of a single field, since
           not all filesystems do this the same way).
      
       (8) 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].
      
       (9) 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 and caused disagreement as to
           whether it's a security hole or not).
      
      (10) Extra coherency data may be useful in making backups [Andreas Dilger].
      
           (No particular data were offered, but things like last backup
           timestamp, the data version number and the DOS archive bit would come
           into this category).
      
      (11) 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...
      
           (This requires a separate system call - I have an fsinfo() call idea
           for this).
      
      (12) Store a 16-byte volume ID in the superblock that can be returned in
           struct xstat [Steve French].
      
           (Deferred to fsinfo).
      
      (13) Include granularity fields in the time data to indicate the
           granularity of each of the times (NFSv4 time_delta) [Steve French].
      
           (Deferred to fsinfo).
      
      (14) 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).
      
           (Some attributes are made available in stx_attributes, but the general
           feeling was that the IOC flags were to ext[234]-specific and shouldn't
           be exposed through statx this way).
      
      (15) Mask of features available on file (eg: ACLs, seclabel) [Brad Boyer,
           Michael Kerrisk].
      
           (Deferred, probably to fsinfo.  Finding out if there's an ACL or
           seclabal might require extra filesystem operations).
      
      (16) Femtosecond-resolution timestamps [Dave Chinner].
      
           (A __reserved field has been left in the statx_timestamp struct for
           this - if there proves to be a need).
      
      (17) A set multiple attributes syscall to go with this.
      
      ===============
      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, in a
      similar way to fstatat().  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.
      
      Whether or not statx() synchronises the attributes with the backing store
      can be controlled by OR'ing a value into the flags argument (this typically
      only affects network filesystems):
      
       (1) AT_STATX_SYNC_AS_STAT tells statx() to behave as stat() does in this
           respect.
      
       (2) AT_STATX_FORCE_SYNC will require a network filesystem to synchronise
           its attributes with the server - which might require data writeback to
           occur to get the timestamps correct.
      
       (3) AT_STATX_DONT_SYNC 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().  It should be noted that asking for
      more information may entail extra 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_timestamp {
      		__s64	tv_sec;
      		__s32	tv_nsec;
      		__s32	__reserved;
      	};
      
      	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	__spare1[1];
      		struct statx_timestamp	stx_atime;
      		struct statx_timestamp	stx_btime;
      		struct statx_timestamp	stx_ctime;
      		struct statx_timestamp	stx_mtime;
      		__u32	stx_rdev_major;
      		__u32	stx_rdev_minor;
      		__u32	stx_dev_major;
      		__u32	stx_dev_minor;
      		__u64	__spare2[14];
      	};
      
      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_ALL		[All currently available stuff]
      
      stx_btime is the file creation time, stx_mask is a bitmask indicating the
      data provided and __spares*[] are where as-yet undefined fields can be
      placed.
      
      Time fields are structures with separate seconds and nanoseconds fields
      plus a reserved field in case we want to add even finer resolution.  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
      
      Within the kernel, the supported flags are listed by:
      
      	KSTAT_ATTR_FS_IOC_FLAGS
      
      [Are any other IOC flags of sufficient general interest to be exposed
      through this interface?]
      
      New flags include:
      
      	STATX_ATTR_AUTOMOUNT		Object is an automount trigger
      
      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.
      
           Similar to (1), except this will be set to 0 if it doesn'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 AUTOMOUNT attribute is set because transiting
      this directory will cause d_automount to be invoked by the VFS.
      
      	[root@andromeda ~]# /tmp/test-statx -A /warthog/data
      	statx(/warthog/data) = 0
      	results=7ff
      	  Size: 4096            Blocks: 8          IO Block: 1048576  directory
      	Device: 00:26           Inode: 1703937     Links: 125
      	Access: (3777/drwxrwxrwx)  Uid:     0   Gid:  4041
      	Access: 2016-11-24 09:02:12.219699527+0000
      	Modify: 2016-11-17 10:44:36.225653653+0000
      	Change: 2016-11-17 10:44:36.225653653+0000
      	Attributes: 0000000000001000 (-------- -------- -------- -------- -------- -------- ---m---- --------)
      
      Secondly, the result of automounting on that directory.
      
      	[root@andromeda ~]# /tmp/test-statx /warthog/data
      	statx(/warthog/data) = 0
      	results=7ff
      	  Size: 4096            Blocks: 8          IO Block: 1048576  directory
      	Device: 00:27           Inode: 2           Links: 125
      	Access: (3777/drwxrwxrwx)  Uid:     0   Gid:  4041
      	Access: 2016-11-24 09:02:12.219699527+0000
      	Modify: 2016-11-17 10:44:36.225653653+0000
      	Change: 2016-11-17 10:44:36.225653653+0000
      Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
      Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
      a528d35e
  3. 24 Feb, 2017 1 commit
  4. 20 Feb, 2017 4 commits
  5. 12 Dec, 2016 3 commits
  6. 29 Oct, 2016 2 commits
  7. 28 Jul, 2016 11 commits
  8. 01 Jun, 2016 1 commit
    • Yan, Zheng's avatar
      ceph: improve fscache revalidation · f7f7e7a0
      Yan, Zheng authored
      There are several issues in fscache revalidation code.
      - In ceph_revalidate_work(), fscache_invalidate() is called when
        fscache_check_consistency() return 0. This is complete wrong
        because 0 means cache is valid.
      - Handle_cap_grant() calls ceph_queue_revalidate() if client
        already has CAP_FILE_CACHE. This code is confusing. Client
        should revalidate the cache each time it got CAP_FILE_CACHE
        anew.
      - In Handle_cap_grant(), fscache_invalidate() is called if MDS
        revokes CAP_FILE_CACHE. This is inconsistency with the case
        that inode get evicted. In the later case, the cache is not
        discarded. Client may use the cache when inode is reloaded.
      
      This patch moves the fscache revalidation into ceph_get_caps().
      Client revalidates the cache after it gets CAP_FILE_CACHE.
      i_rdcache_gen should keep constance while CAP_FILE_CACHE is
      used. If i_fscache_gen is not equal to i_rdcache_gen, client
      needs to check cache's consistency.
      Signed-off-by: default avatarYan, Zheng <zyan@redhat.com>
      f7f7e7a0
  9. 25 May, 2016 6 commits
  10. 23 Apr, 2016 2 commits
  11. 11 Apr, 2016 1 commit
  12. 25 Mar, 2016 4 commits
    • Yan, Zheng's avatar
      ceph: kill ceph_get_dentry_parent_inode() · 641235d8
      Yan, Zheng authored
      use vfs helper dget_parent() instead
      Signed-off-by: default avatarYan, Zheng <zyan@redhat.com>
      641235d8
    • Yan, Zheng's avatar
      ceph: fix security xattr deadlock · 315f2408
      Yan, Zheng authored
      When security is enabled, security module can call filesystem's
      getxattr/setxattr callbacks during d_instantiate(). For cephfs,
      d_instantiate() is usually called by MDS' dispatch thread, while
      handling MDS reply. If the MDS reply does not include xattrs and
      corresponding caps, getxattr/setxattr need to send a new request
      to MDS and waits for the reply. This makes MDS' dispatch sleep,
      nobody handles later MDS replies.
      
      The fix is make sure lookup/atomic_open reply include xattrs and
      corresponding caps. So getxattr can be handled by cached xattrs.
      This requires some modification to both MDS and request message.
      (Client tells MDS what caps it wants; MDS encodes proper caps in
      the reply)
      
      Smack security module may call setxattr during d_instantiate().
      Unlike getxattr, we can't force MDS to issue CEPH_CAP_XATTR_EXCL
      to us. So just make setxattr return error when called by MDS'
      dispatch thread.
      Signed-off-by: default avatarYan, Zheng <zyan@redhat.com>
      315f2408
    • Ilya Dryomov's avatar
      ceph: kill ceph_empty_snapc · 34b759b4
      Ilya Dryomov authored
      ceph_empty_snapc->num_snaps == 0 at all times.  Passing such a snapc to
      ceph_osdc_alloc_request() (possibly through ceph_osdc_new_request()) is
      equivalent to passing NULL, as ceph_osdc_alloc_request() uses it only
      for sizing the request message.
      
      Further, in all four cases the subsequent ceph_osdc_build_request() is
      passed NULL for snapc, meaning that 0 is encoded for seq and num_snaps
      and making ceph_empty_snapc entirely useless.  The two cases where it
      actually mattered were removed in commits 86056090 ("ceph: avoid
      sending unnessesary FLUSHSNAP message") and 23078637 ("ceph: fix
      queuing inode to mdsdir's snaprealm").
      Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
      Reviewed-by: default avatarYan, Zheng <zyan@redhat.com>
      34b759b4
    • Yan, Zheng's avatar
      ceph: don't enable rbytes mount option by default · 133e9156
      Yan, Zheng authored
      When rbytes mount option is enabled, directory size is recursive
      size. Recursive size is not updated instantly. This can cause
      directory size to change between successive stat(1)
      Signed-off-by: default avatarYan, Zheng <zyan@redhat.com>
      133e9156
  13. 04 Mar, 2016 1 commit
  14. 02 Nov, 2015 1 commit
  15. 31 Jul, 2015 1 commit
    • Yan, Zheng's avatar
      ceph: always re-send cap flushes when MDS recovers · fc927cd3
      Yan, Zheng authored
      commit e548e9b9 makes the kclient
      only re-send cap flush once during MDS failover. If the kclient sends
      a cap flush after MDS enters reconnect stage but before MDS recovers.
      The kclient will skip re-sending the same cap flush when MDS recovers.
      
      This causes problem for newly created inode. The MDS handles cap
      flushes before replaying unsafe requests, so it's possible that MDS
      find corresponding inode is missing when handling cap flush. The fix
      is reverting to old behaviour: always re-send when MDS recovers
      Signed-off-by: default avatarYan, Zheng <zyan@redhat.com>
      Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
      fc927cd3