Provided by: xfslibs-dev_5.0.0-1ubuntu1_amd64 bug

NAME

       ioctl_xfs_scrub_metadata - check XFS filesystem metadata

SYNOPSIS

       #include <xfs/xfs_fs.h>

       int ioctl(int dest_fd, XFS_IOC_SCRUB_METADATA, struct xfs_scrub_metadata *arg);

DESCRIPTION

       This XFS ioctl asks the kernel driver to examine a piece of filesystem metadata for errors
       or suboptimal metadata.  Examination includes running metadata verifiers, checking records
       for  obviously  incorrect or impossible values, and cross-referencing each record with any
       other available metadata in the filesystem.  This ioctl can also try to repair or optimize
       metadata,  though  this  may block normal filesystem operations for a long period of time.
       The type and location of the metadata to scrub is conveyed in a structure of the following
       form:

           struct xfs_scrub_metadata {
                __u32 sm_type;
                __u32 sm_flags;
                __u64 sm_ino;
                __u32 sm_gen;
                __u32 sm_agno;
                __u64 sm_reserved[5];
           };

       The field sm_reserved must be zero.

       The field sm_type indicates the type of metadata to check:

           XFS_SCRUB_TYPE_PROBE
                  Probe  the  kernel  to  see  if  it  is  willing to try to check or repair this
                  filesystem.  sm_agno, sm_ino, and sm_gen must be zero.

           XFS_SCRUB_TYPE_SB
           XFS_SCRUB_TYPE_AGF
           XFS_SCRUB_TYPE_AGFL
           XFS_SCRUB_TYPE_AGI
                  Examine a given allocation group's superblock, free space  header,  free  block
                  list,  or  inode  header,  respectively.   Headers  are  checked  for obviously
                  incorrect values and cross-referenced against the allocation  group's  metadata
                  btrees,  if  possible.   The  allocation group number must be given in sm_agno.
                  sm_ino and sm_gen must be zero.

           XFS_SCRUB_TYPE_BNOBT
           XFS_SCRUB_TYPE_CNTBT
           XFS_SCRUB_TYPE_INOBT
           XFS_SCRUB_TYPE_FINOBT
           XFS_SCRUB_TYPE_RMAPBT
           XFS_SCRUB_TYPE_REFCNTBT
                  Examine a given allocation group's two free space  btrees,  two  inode  btrees,
                  reverse  mapping  btrees, or reference count btrees, respectively.  Records are
                  checked  for  obviously  incorrect  values  and  cross-referenced  with   other
                  allocation  group  metadata records to ensure that there are no conflicts.  The
                  allocation group number must be given in sm_agno.  sm_ino and  sm_gen  must  be
                  zero.

           XFS_SCRUB_TYPE_INODE
                  Examine  a  given inode record for obviously incorrect values and discrepancies
                  with the  rest  of  filesystem  metadata.   Parent  pointers  are  checked  for
                  impossible  inode  values  and  are then followed up to the parent directory to
                  ensure that the linkage is correct.  The inode  to  examine  may  be  specified
                  either  through sm_ino and sm_gen; if not specified, then the file described by
                  dest_fd will be examined.  sm_agno must be zero.

           XFS_SCRUB_TYPE_BMBTD
           XFS_SCRUB_TYPE_BMBTA
           XFS_SCRUB_TYPE_BMBTC
           XFS_SCRUB_TYPE_PARENT
                  Examine a given inode's data block map, extended attribute block map,  copy  on
                  write  block  map,  or  parent  inode  pointer.  Inode records are examined for
                  obviously incorrect values and discrepancies with the three  block  map  types.
                  The block maps are checked for obviously wrong values and cross-referenced with
                  the allocation group space extent metadata for  discrepancies.   The  inode  to
                  examine can be specified in the same manner as XFS_SCRUB_TYPE_INODE.

           XFS_SCRUB_TYPE_XATTR
                  Examine  the  extended  attribute  records  and  indices  of  a given inode for
                  incorrect pointers and other signs of damage.  The  inode  to  examine  can  be
                  specified in the same manner as XFS_SCRUB_TYPE_INODE.

           XFS_SCRUB_TYPE_DIR
                  Examine the entries in a given directory for invalid data or dangling pointers.
                  The  directory  to  examine  can  be  specified   in   the   same   manner   as
                  XFS_SCRUB_TYPE_INODE.

           XFS_SCRUB_TYPE_SYMLINK
                  Examine  the target of a symbolic link for obvious pathname problems.  The link
                  to examine can be specified in the same manner as XFS_SCRUB_TYPE_INODE.

           XFS_SCRUB_TYPE_RTBITMAP
           XFS_SCRUB_TYPE_RTSUM
                  Examine the realtime block bitmap and realtime summary inodes for corruption.

           XFS_SCRUB_TYPE_UQUOTA
           XFS_SCRUB_TYPE_GQUOTA
           XFS_SCRUB_TYPE_PQUOTA
                  Examine all user, group, or project quota records for corruption.

       The field  sm_flags  control  the  behavior  of  the  scrub  operation  and  provide  more
       information  about  the  outcome of the operation.  If none of the XFS_SCRUB_OFLAG_* flags
       are set upon return, the metadata is clean.

           XFS_SCRUB_IFLAG_REPAIR
                  If the caller sets this flag, the kernel driver will examine the  metadata  and
                  try  to  fix all problems and to optimize metadata when possible.  If no errors
                  occur during the repair operation, the check is  performed  a  second  time  to
                  determine  whether  the repair succeeded.  If errors occur, the call returns an
                  error status immediately.

           XFS_SCRUB_OFLAG_CORRUPT
                  The metadata was corrupt when the call returned.  If XFS_SCRUB_IFLAG_REPAIR was
                  specified,  then  an  attempted  repair failed to fix the problem.  Unmount the
                  filesystem and run xfs_repair to fix the filesystem.

           XFS_SCRUB_OFLAG_PREEN
                  The metadata is ok, but some aspect of  the  metadata  could  be  optimized  to
                  increase  performance.   Call again with XFS_SCRUB_IFLAG_REPAIR to optimize the
                  metadata.

           XFS_SCRUB_OFLAG_XFAIL
                  Filesystem errors were encountered when  accessing  other  metadata  to  cross-
                  reference the records attached to this metadata object.

           XFS_SCRUB_OFLAG_XCORRUPT
                  Discrepancies  were  found  when cross-referencing the records attached to this
                  metadata object against all other available metadata in the system.

           XFS_SCRUB_OFLAG_INCOMPLETE
                  The checker was unable to complete its check of all records.

           XFS_SCRUB_OFLAG_WARNING
                  The checker encountered a metadata object with potentially problematic records.
                  However, the records were not obviously corrupt.

       For  metadata  checkers  that  operate  on inodes or inode metadata, the fields sm_ino and
       sm_gen are the inode number and generation number of the inode to  check.   If  the  inode
       number  is  zero,  the  inode  represented  by dest_fd is used instead.  If the generation
       number of the inode does not match sm_gen, the call will return  an  error  code  for  the
       invalid argument.  The sm_agno field must be zero.

       For  metadata  checkers  that  operate  on  allocation  group  metadata, the field sm_agno
       indicates the allocation group in which to find  the  metadata.   The  sm_ino  and  sm_gen
       fields must be zero.

       For  metadata  checkers that operate on filesystem-wide metadata, no further arguments are
       required.  sm_agno, sm_ino, and sm_gen must all be zero.

RETURN VALUE

       On error, -1 is returned, and errno is set to indicate the error.

ERRORS

       Error codes can be one of, but are not limited to, the following:

       EBUSY  The filesystem object is busy; the operation will have to be tried again.

       EFSCORRUPTED
              Severe filesystem corruption was detected and could not be repaired.   Unmount  the
              filesystem and run xfs_repair to fix the filesystem.

       EINVAL One or more of the arguments specified is invalid.

       ENOENT The  specified  metadata  object  does  not exist.  For example, this error code is
              returned for a XFS_SCRUB_TYPE_REFCNTBT  request  on  a  filesystem  that  does  not
              support reflink.

       ENOMEM There  was  not  sufficient  memory to perform the scrub or repair operation.  Some
              operations (most notably reference count checking) require large amounts of memory.

       ENOSPC There is not enough free disk space to attempt a repair.

       ENOTRECOVERABLE
              Filesystem was mounted in  norecovery  mode  and  therefore  has  an  unclean  log.
              Neither scrub nor repair operations can be attempted with an unclean log.

       ENOTTY Online scrubbing or repair were not enabled.

       EOPNOTSUPP
              Repairs of the requested metadata object are not supported.

       EROFS  Filesystem is read-only and a repair was requested.

       ESHUTDOWN
              Filesystem is shut down due to previous errors.

CONFORMING TO

       This API is specific to XFS filesystem on the Linux kernel.

NOTES

       These operations may block other filesystem operations for a long time.  A calling process
       can stop the operation by being sent a fatal signal, but non-fatal signals are blocked.

SEE ALSO

       ioctl(2) xfs_scrub(8) xfs_repair(8)