1. 18 4月, 2017 17 次提交
  2. 12 4月, 2017 4 次提交
    • L
      Btrfs: fix potential use-after-free for cloned bio · a967efb3
      Liu Bo 提交于
      KASAN reports that there is a use-after-free case of bio in btrfs_map_bio.
      
      If we need to submit IOs to several disks at a time, the original bio
      would get cloned and mapped to the destination disk, but we really should
      use the original bio instead of a cloned bio to do the sanity check
      because cloned bios are likely to be freed by its endio.
      Reported-by: NDiego <diegocg@gmail.com>
      Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
      Reviewed-by: NDavid Sterba <dsterba@suse.com>
      Signed-off-by: NDavid Sterba <dsterba@suse.com>
      a967efb3
    • L
      Btrfs: fix segmentation fault when doing dio read · 97bf5a55
      Liu Bo 提交于
      Commit 2dabb324 ("Btrfs: Direct I/O read: Work on sectorsized blocks")
      introduced this bug during iterating bio pages in dio read's endio hook,
      and it could end up with segment fault of the dio reading task.
      
      So the reason is 'if (nr_sectors--)', and it makes the code assume that
      there is one more block in the same page, so page offset is increased and
      the bio which is created to repair the bad block then has an incorrect
      bvec.bv_offset, and a later access of the page content would throw a
      segmentation fault.
      
      This also adds ASSERT to check page offset against page size.
      Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
      Reviewed-by: NDavid Sterba <dsterba@suse.com>
      Signed-off-by: NDavid Sterba <dsterba@suse.com>
      97bf5a55
    • L
      Btrfs: fix invalid dereference in btrfs_retry_endio · 2e949b0a
      Liu Bo 提交于
      When doing directIO repair, we have this oops:
      
      [ 1458.532816] general protection fault: 0000 [#1] SMP
      ...
      [ 1458.536291] Workqueue: btrfs-endio-repair btrfs_endio_repair_helper [btrfs]
      [ 1458.536893] task: ffff88082a42d100 task.stack: ffffc90002b3c000
      [ 1458.537499] RIP: 0010:btrfs_retry_endio+0x7e/0x1a0 [btrfs]
      ...
      [ 1458.543261] Call Trace:
      [ 1458.543958]  ? rcu_read_lock_sched_held+0xc4/0xd0
      [ 1458.544374]  bio_endio+0xed/0x100
      [ 1458.544750]  end_workqueue_fn+0x3c/0x40 [btrfs]
      [ 1458.545257]  normal_work_helper+0x9f/0x900 [btrfs]
      [ 1458.545762]  btrfs_endio_repair_helper+0x12/0x20 [btrfs]
      [ 1458.546224]  process_one_work+0x34d/0xb70
      [ 1458.546570]  ? process_one_work+0x29e/0xb70
      [ 1458.546938]  worker_thread+0x1cf/0x960
      [ 1458.547263]  ? process_one_work+0xb70/0xb70
      [ 1458.547624]  kthread+0x17d/0x180
      [ 1458.547909]  ? kthread_create_on_node+0x70/0x70
      [ 1458.548300]  ret_from_fork+0x31/0x40
      
      It turns out that btrfs_retry_endio is trying to get inode from a directIO
      page.
      
      This fixes the problem by using the saved inode pointer, done->inode.
      btrfs_retry_endio_nocsum has the same problem, and it's fixed as well.
      
      Also cleanup unused @start (which is too trivial for a separate patch).
      
      Cc: David Sterba <dsterba@suse.cz>
      Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
      Reviewed-by: NDavid Sterba <dsterba@suse.com>
      Signed-off-by: NDavid Sterba <dsterba@suse.com>
      2e949b0a
    • A
      btrfs: drop the nossd flag when remounting with -o ssd · 951e7966
      Adam Borowski 提交于
      The opposite case was already handled right in the very next switch entry.
      And also when turning on nossd, drop ssd_spread.
      Reported-by: NHans van Kranenburg <hans.van.kranenburg@mendix.com>
      Signed-off-by: NAdam Borowski <kilobyte@angband.pl>
      Reviewed-by: NDavid Sterba <dsterba@suse.com>
      Signed-off-by: NDavid Sterba <dsterba@suse.com>
      951e7966
  3. 29 3月, 2017 3 次提交
    • D
      Btrfs: fix an integer overflow check · 457ae726
      Dan Carpenter 提交于
      This isn't super serious because you need CAP_ADMIN to run this code.
      
      I added this integer overflow check last year but apparently I am
      rubbish at writing integer overflow checks...  There are two issues.
      First, access_ok() works on unsigned long type and not u64 so on 32 bit
      systems the access_ok() could be checking a truncated size.  The other
      issue is that we should be using a stricter limit so we don't overflow
      the kzalloc() setting ctx->clone_roots later in the function after the
      access_ok():
      
      	alloc_size = sizeof(struct clone_root) * (arg->clone_sources_count + 1);
      	sctx->clone_roots = kzalloc(alloc_size, GFP_KERNEL | __GFP_NOWARN);
      
      Fixes: f5ecec3c ("btrfs: send: silence an integer overflow warning")
      Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
      Reviewed-by: NDavid Sterba <dsterba@suse.com>
      [ added comment ]
      Signed-off-by: NDavid Sterba <dsterba@suse.com>
      457ae726
    • G
      btrfs: Change qgroup_meta_rsv to 64bit · ce0dcee6
      Goldwyn Rodrigues 提交于
      Using an int value is causing qg->reserved to become negative and
      exclusive -EDQUOT to be reached prematurely.
      
      This affects exclusive qgroups only.
      
      TEST CASE:
      
      DEVICE=/dev/vdb
      MOUNTPOINT=/mnt
      SUBVOL=$MOUNTPOINT/tmp
      
      umount $SUBVOL
      umount $MOUNTPOINT
      
      mkfs.btrfs -f $DEVICE
      mount /dev/vdb $MOUNTPOINT
      btrfs quota enable $MOUNTPOINT
      btrfs subvol create $SUBVOL
      umount $MOUNTPOINT
      mount /dev/vdb $MOUNTPOINT
      mount -o subvol=tmp $DEVICE $SUBVOL
      btrfs qgroup limit -e 3G $SUBVOL
      
      btrfs quota rescan /mnt -w
      
      for i in `seq 1 44000`; do
        dd if=/dev/zero of=/mnt/tmp/test_$i bs=10k count=1
        if [[ $? > 0 ]]; then
           btrfs qgroup show -pcref $SUBVOL
           exit 1
        fi
      done
      Signed-off-by: NGoldwyn Rodrigues <rgoldwyn@suse.com>
      [ add reproducer to changelog ]
      Signed-off-by: NDavid Sterba <dsterba@suse.com>
      ce0dcee6
    • L
      Btrfs: bring back repair during read · 9d0d1c8b
      Liu Bo 提交于
      Commit 20a7db8a ("btrfs: add dummy callback for readpage_io_failed
      and drop checks") made a cleanup around readpage_io_failed_hook, and
      it was supposed to keep the original sematics, but it also
      unexpectedly disabled repair during read for dup, raid1 and raid10.
      
      This fixes the problem by letting data's inode call the generic
      readpage_io_failed callback by returning -EAGAIN from its
      readpage_io_failed_hook in order to notify end_bio_extent_readpage to
      do the rest.  We don't call it directly because the generic one takes
      an offset from end_bio_extent_readpage() to calculate the index in the
      checksum array and inode's readpage_io_failed_hook doesn't offer that
      offset.
      
      Cc: David Sterba <dsterba@suse.cz>
      Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
      Reviewed-by: NDavid Sterba <dsterba@suse.com>
      [ keep the const function attribute ]
      Signed-off-by: NDavid Sterba <dsterba@suse.com>
      9d0d1c8b
  4. 18 3月, 2017 2 次提交
    • Z
      btrfs: add missing memset while reading compressed inline extents · e1699d2d
      Zygo Blaxell 提交于
      This is a story about 4 distinct (and very old) btrfs bugs.
      
      Commit c8b97818 ("Btrfs: Add zlib compression support") added
      three data corruption bugs for inline extents (bugs #1-3).
      
      Commit 93c82d57 ("Btrfs: zero page past end of inline file items")
      fixed bug #1:  uncompressed inline extents followed by a hole and more
      extents could get non-zero data in the hole as they were read.  The fix
      was to add a memset in btrfs_get_extent to zero out the hole.
      
      Commit 166ae5a4 ("btrfs: fix inline compressed read err corruption")
      fixed bug #2:  compressed inline extents which contained non-zero bytes
      might be replaced with zero bytes in some cases.  This patch removed an
      unhelpful memset from uncompress_inline, but the case where memset is
      required was missed.
      
      There is also a memset in the decompression code, but this only covers
      decompressed data that is shorter than the ram_bytes from the extent
      ref record.  This memset doesn't cover the region between the end of the
      decompressed data and the end of the page.  It has also moved around a
      few times over the years, so there's no single patch to refer to.
      
      This patch fixes bug #3:  compressed inline extents followed by a hole
      and more extents could get non-zero data in the hole as they were read
      (i.e. bug #3 is the same as bug #1, but s/uncompressed/compressed/).
      The fix is the same:  zero out the hole in the compressed case too,
      by putting a memset back in uncompress_inline, but this time with
      correct parameters.
      
      The last and oldest bug, bug #0, is the cause of the offending inline
      extent/hole/extent pattern.  Bug #0 is a subtle and mostly-harmless quirk
      of behavior somewhere in the btrfs write code.  In a few special cases,
      an inline extent and hole are allowed to persist where they normally
      would be combined with later extents in the file.
      
      A fast reproducer for bug #0 is presented below.  A few offending extents
      are also created in the wild during large rsync transfers with the -S
      flag.  A Linux kernel build (git checkout; make allyesconfig; make -j8)
      will produce a handful of offending files as well.  Once an offending
      file is created, it can present different content to userspace each
      time it is read.
      
      Bug #0 is at least 4 and possibly 8 years old.  I verified every vX.Y
      kernel back to v3.5 has this behavior.  There are fossil records of this
      bug's effects in commits all the way back to v2.6.32.  I have no reason
      to believe bug #0 wasn't present at the beginning of btrfs compression
      support in v2.6.29, but I can't easily test kernels that old to be sure.
      
      It is not clear whether bug #0 is worth fixing.  A fix would likely
      require injecting extra reads into currently write-only paths, and most
      of the exceptional cases caused by bug #0 are already handled now.
      
      Whether we like them or not, bug #0's inline extents followed by holes
      are part of the btrfs de-facto disk format now, and we need to be able
      to read them without data corruption or an infoleak.  So enough about
      bug #0, let's get back to bug #3 (this patch).
      
      An example of on-disk structure leading to data corruption found in
      the wild:
      
              item 61 key (606890 INODE_ITEM 0) itemoff 9662 itemsize 160
                      inode generation 50 transid 50 size 47424 nbytes 49141
                      block group 0 mode 100644 links 1 uid 0 gid 0
                      rdev 0 flags 0x0(none)
              item 62 key (606890 INODE_REF 603050) itemoff 9642 itemsize 20
                      inode ref index 3 namelen 10 name: DB_File.so
              item 63 key (606890 EXTENT_DATA 0) itemoff 8280 itemsize 1362
                      inline extent data size 1341 ram 4085 compress(zlib)
              item 64 key (606890 EXTENT_DATA 4096) itemoff 8227 itemsize 53
                      extent data disk byte 5367308288 nr 20480
                      extent data offset 0 nr 45056 ram 45056
                      extent compression(zlib)
      
      Different data appears in userspace during each read of the 11 bytes
      between 4085 and 4096.  The extent in item 63 is not long enough to
      fill the first page of the file, so a memset is required to fill the
      space between item 63 (ending at 4085) and item 64 (beginning at 4096)
      with zero.
      
      Here is a reproducer from Liu Bo, which demonstrates another method
      of creating the same inline extent and hole pattern:
      
      Using 'page_poison=on' kernel command line (or enable
      CONFIG_PAGE_POISONING) run the following:
      
      	# touch foo
      	# chattr +c foo
      	# xfs_io -f -c "pwrite -W 0 1000" foo
      	# xfs_io -f -c "falloc 4 8188" foo
      	# od -x foo
      	# echo 3 >/proc/sys/vm/drop_caches
      	# od -x foo
      
      This produce the following on my box:
      
      Correct output:  file contains 1000 data bytes followed
      by zeros:
      
      	0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
      	*
      	0001740 cdcd cdcd cdcd cdcd 0000 0000 0000 0000
      	0001760 0000 0000 0000 0000 0000 0000 0000 0000
      	*
      	0020000
      
      Actual output:  the data after the first 1000 bytes
      will be different each run:
      
      	0000000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd
      	*
      	0001740 cdcd cdcd cdcd cdcd 6c63 7400 635f 006d
      	0001760 5f74 6f43 7400 435f 0053 5f74 7363 7400
      	0002000 435f 0056 5f74 6164 7400 645f 0062 5f74
      	(...)
      Signed-off-by: NZygo Blaxell <ce3g8jdj@umail.furryterror.org>
      Reviewed-by: NLiu Bo <bo.li.liu@oracle.com>
      Reviewed-by: NChris Mason <clm@fb.com>
      Signed-off-by: NChris Mason <clm@fb.com>
      e1699d2d
    • L
      Btrfs: fix regression in lock_delalloc_pages · 49d4a334
      Liu Bo 提交于
      The bug is a regression after commit
      (da2c7009 "btrfs: teach __process_pages_contig about PAGE_LOCK operation")
      and commit
      (76c0021d "Btrfs: use helper to simplify lock/unlock pages").
      
      So if the dirty pages which are under writeback got truncated partially
      before we lock the dirty pages, we couldn't find all pages mapping to the
      delalloc range, and the bug didn't return an error so it kept going on and
      found that the delalloc range got truncated and got to unlock the dirty
      pages, and then the ASSERT could caught the error, and showed
      
      -----------------------------------------------------------------------------
      assertion failed: page_ops & PAGE_LOCK, file: fs/btrfs/extent_io.c, line: 1716
      -----------------------------------------------------------------------------
      
      This fixes the bug by returning the proper -EAGAIN.
      
      Cc: David Sterba <dsterba@suse.com>
      Reported-by: NDave Jones <davej@codemonkey.org.uk>
      Signed-off-by: NLiu Bo <bo.li.liu@oracle.com>
      Signed-off-by: NDavid Sterba <dsterba@suse.com>
      49d4a334
  5. 03 3月, 2017 1 次提交
    • D
      statx: Add a system call to make enhanced file info available · a528d35e
      David Howells 提交于
      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: NDavid Howells <dhowells@redhat.com>
      Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      a528d35e
  6. 02 3月, 2017 2 次提交
  7. 28 2月, 2017 11 次提交