ioctl_xfs_getbmap(2) — Linux manual page


IOCTL-XFS-GETBMAPX(2)        System Calls Manual       IOCTL-XFS-GETBMAPX(2)

NAME         top

       ioctl_xfs_getbmapx - query extent information for an open file

SYNOPSIS         top

       #include <xfs/xfs_fs.h>

       int ioctl(int fd, XFS_IOC_GETBMAP, struct getbmap *arg);
       int ioctl(int fd, XFS_IOC_GETBMAPA, struct getbmap *arg);
       int ioctl(int fd, XFS_IOC_GETBMAPX, struct getbmapx *arg);

DESCRIPTION         top

       Get the block map for a segment of a file in an XFS file system.  The
       mapping information is conveyed via an array of structures of the
       following form:

           struct getbmap {
                __s64   bmv_offset;
                __s64   bmv_block;
                __s64   bmv_length;
                __s32   bmv_count;
                __s32   bmv_entries;

       The XFS_IOC_GETBMAPX ioctl uses a larger version of that structure:

           struct getbmapx {
                __s64   bmv_offset;
                __s64   bmv_block;
                __s64   bmv_length;
                __s32   bmv_count;
                __s32   bmv_entries;
                __s32   bmv_iflags;
                __s32   bmv_oflags;
                __s32   bmv_unused1;
                __s32   bmv_unused2;

       All sizes and offsets in the structure are in units of 512 bytes.

       The first structure in the array is a header and the remaining
       structures in the array contain block map information on return.  The
       header controls iterative calls to the command and should be filled
       out as follows:

              The file offset of the area of interest in the file.

              The length of the area of interest in the file.  If this value
              is set to -1, the length of the interesting area is the rest
              of the file.

              The number of elements in the array, including this header.
              The minimum value is 2.

              The number of entries actually filled in by the call.  This
              does not need to be filled out before the call.  This value
              may be zero if no extents were found in the requested range,
              or if iterated calls have reached the end of the requested

              For the XFS_IOC_GETBMAPX function, this is a bitmask
              containing a combination of the following flags:

                  Return information about the extended attribute fork.

                  Return information about unwritten pre-allocated segments.

                  Return information about delayed allocation reservation

                  Do not return information about holes.

       The other bmv_* fields in the header are ignored.

       On successful return from a call, the offset and length values in the
       header are updated so that the command can be reused to obtain more
       information.  The remaining elements of the array will be filled out
       by the call as follows:

              File offset of segment.

              Physical starting block of segment.  If this is -1, then the
              segment is a hole.

              Length of segment.

              The XFS_IOC_GETBMAPX function will fill this field with a
              combination of the following flags:

                  The segment is an unwritten pre-allocation.

                  The segment is a delayed allocation reservation.

                  This segment is the last in the file.

                  This segment shares blocks with other files.

       The other bmv_* fields are unused in the array of output records.

       The XFS_IOC_GETBMAPA command is identical to XFS_IOC_GETBMAP except
       that information about the attribute fork of the file is returned.

RETURN VALUE         top

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

ERRORS         top

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

       EFAULT The kernel was not able to copy into the userspace buffer.

              Metadata checksum validation failed while performing the

              Metadata corruption was encountered while performing the

       EINVAL One of the arguments was not valid.

       EIO    An I/O error was encountered while performing the query.

       ENOMEM There was insufficient memory to perform the query.

CONFORMING TO         top

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

SEE ALSO         top


COLOPHON         top

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XFS                              2019-06-17            IOCTL-XFS-GETBMAPX(2)

Pages that refer to this page: xfsctl(3)