preallocate near a specified block

["Roger Willcocks" <willcor@xxxxxxxxx>]

Hi folks,

I've put together a 'preallocate near' ioctl, which I've been using in
anger for several months now. The changes are pretty minimal, and boil
down to making xfs_bmap think it's extending a file instead of doing
an initial allocation.

From a user perspective it's a simple extension of the existing RESVSP
ioctl, with the flag bits (allocate near, allocate contiguous) hidden
in the 'whence' parameter.

       xfs_flock64_t flck;
       memset(&flck, 0, sizeof(flck));

       flck.l_whence = SEEK_SET;
       flck.l_start = 0LL;
       flck.l_len = (off64_t)extent;

       if (nearToBlock != 0) {
               flck.l_whence |= RESV_NEAR | RESV_CONTIG; /* if possible */
               flck.l_near = nearToBlock;
       }

       int status = ioctl(fd, XFS_IOC_RESVSP64, &flck);

Any interest?

--
Roger

xfs_near.patch
Description: Binary data