Readd zfs_holey() from OpenSolaris

This patch restores the zfs_holey() function from OpenSolaris.
This was removed by commit 3558fd7 because it wasn't clear we
had a use for it in ZoL.  However, this functionality is a
prerequisite for adding SEEK_DATA/SEEK_HOLE support to the ZPL.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <ryao@gentoo.org>
Issue #1384

diff --git a/module/zfs/zfs_vnops.c b/module/zfs/zfs_vnops.c
index 3b671b4..5a9c963 100644 (file)
--- a/module/zfs/zfs_vnops.c
+++ b/module/zfs/zfs_vnops.c
@@ -240,6 +240,51 @@ zfs_close(struct inode *ip, int flag, cred_t *cr)
 }
 EXPORT_SYMBOL(zfs_close);
 
+#if 0
+/*
+ * Lseek support for finding holes (cmd == _FIO_SEEK_HOLE) and
+ * data (cmd == _FIO_SEEK_DATA). "off" is an in/out parameter.
+ */
+static int
+zfs_holey(vnode_t *vp, int cmd, offset_t *off)
+{
+       znode_t *zp = VTOZ(vp);
+       uint64_t noff = (uint64_t)*off; /* new offset */
+       uint64_t file_sz;
+       int error;
+       boolean_t hole;
+
+       file_sz = zp->z_size;
+       if (noff >= file_sz)  {
+               return (SET_ERROR(ENXIO));
+       }
+
+       if (cmd == _FIO_SEEK_HOLE)
+               hole = B_TRUE;
+       else
+               hole = B_FALSE;
+
+       error = dmu_offset_next(zp->z_zfsvfs->z_os, zp->z_id, hole, &noff);
+
+       /* end of file? */
+       if ((error == ESRCH) || (noff > file_sz)) {
+               /*
+                * Handle the virtual hole at the end of file.
+                */
+               if (hole) {
+                       *off = file_sz;
+                       return (0);
+               }
+               return (SET_ERROR(ENXIO));
+       }
+
+       if (noff < *off)
+               return (error);
+       *off = noff;
+       return (error);
+}
+#endif
+
 #if defined(_KERNEL)
 /*
  * When a file is memory mapped, we must keep the IO data synchronized