kern/164445: [zfs][patch] WAS: lseek(2) always returns ENXIO with SEEK_DATA/SEEK_HOLE on 9.0 64bit ZFS

[Luis Garces-Erice]

Hi all

after digging a bit more into this
(http://www.freebsd.org/cgi/query-pr.cgi?pr=164445), I've found the
problem to be in ZFS or below. The patch attached addresses the
symptom, but the problem remains.

When invoking SEEK_DATA/SEEK_HOLE on a file on ZFS in FreeBSD 9.0 64
bit, the functions ddi_copyin and ddi_copyout in zfs_ioctl() do not
copy the offset passed from the application to the ioctl. The offset
is passed correctly to zfs_ioctl(), though, but those functions copy
garbage into the offset used by zfs_holey(). The corrupted offset is
often bigger than the file, and thus the ioctl returns ENXIO.

The patch does the copy of the offset passed from the application
correctly, and allows lseek(2) with SEEK_DATA/SEEK_HOLE to be used on
ZFS, but it is not a solution. I couldn't see a problem in the
assembler of the copyin and copyout functions in
sys/amd64/amd64/support.S, but I might be wrong, I'm no assembler
expert.


-- 
Luis
****
-------------- next part --------------
diff -w -u -r sys.orig/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c
--- sys.orig/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c	2012-01-03 04:27:03.000000000 +0100
+++ sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c	2012-03-06 11:26:27.000000000 +0100
@@ -296,6 +296,8 @@
 		if (ddi_copyin((void *)data, &off, sizeof (off), flag))
 			return (EFAULT);
 
+		// ddi_copyin did not copy the offset
+		off = (offset_t)*((offset_t *)data);
 		zp = VTOZ(vp);
 		zfsvfs = zp->z_zfsvfs;
 		ZFS_ENTER(zfsvfs);
@@ -308,6 +310,8 @@
 			return (error);
 		if (ddi_copyout(&off, (void *)data, sizeof (off), flag))
 			return (EFAULT);
+		// ddi_copyout did not copy the offset
+		*((offset_t *)data)=off;
 		return (0);
 	}
 	return (ENOTTY);