staging/lustre/lov: remove set_fs() call from lov_getstripe()

commit 0a33252e060e97ed3fbdcec9517672f1e91aaef3 upstream.

lov_getstripe() calls set_fs(KERNEL_DS) so that it can handle a struct
lov_user_md pointer from user- or kernel-space.  This changes the
behavior of copy_from_user() on SPARC and may result in a misaligned
access exception which in turn oopses the kernel.  In fact the
relevant argument to lov_getstripe() is never called with a
kernel-space pointer and so changing the address limits is unnecessary
and so we remove the calls to save, set, and restore the address
limits.

Signed-off-by: John L. Hammond <john.hammond@intel.com>
Reviewed-on: http://review.whamcloud.com/6150
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3221
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Li Wei <wei.g.li@intel.com>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/lustre/lustre/lov/lov_pack.c b/drivers/staging/lustre/lustre/lov/lov_pack.c
index be6e985..a6d1cc8 100644 (file)
--- a/drivers/staging/lustre/lustre/lov/lov_pack.c
+++ b/drivers/staging/lustre/lustre/lov/lov_pack.c
@@ -387,18 +387,10 @@ int lov_getstripe(struct lov_object *obj, struct lov_stripe_md *lsm,
        struct lov_mds_md *lmmk = NULL;
        int rc, lmmk_size, lmm_size;
        int lum_size;
-       mm_segment_t seg;
 
        if (!lsm)
                return -ENODATA;
 
-       /*
-        * "Switch to kernel segment" to allow copying from kernel space by
-        * copy_{to,from}_user().
-        */
-       seg = get_fs();
-       set_fs(KERNEL_DS);
-
        /* we only need the header part from user space to get lmm_magic and
         * lmm_stripe_count, (the header part is common to v1 and v3)
         */
@@ -478,6 +470,5 @@ int lov_getstripe(struct lov_object *obj, struct lov_stripe_md *lsm,
 out_free:
        kfree(lmmk);
 out:
-       set_fs(seg);
        return rc;
 }