Date: Mon, 04 Oct 2004 18:12:14 +0900 From: Takanori Watanabe <takawata@init-main.com> To: Uwe Doering <gemini@geminix.org> Cc: freebsd-current@FreeBSD.org Subject: Re: Your CVS fix 1.109 to union_vnops.c Message-ID: <200410040912.i949CEjk012965@sana.init-main.com> In-Reply-To: Your message of "Mon, 04 Oct 2004 09:29:29 %2B0200." <4160FBD9.10603@geminix.org>
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In message <4160FBD9.10603@geminix.org>, Uwe Doering wrote:
>takawata@jp.freebsd.org wrote:
>> In message <4160ED06.6070603@geminix.org>, Uwe Doering wrote:
>>
>>>Takanori Watanabe wrote:
>>>[...]
>>>>Ok, the issue Uwe says is when underlying filesystem and
>>>>wrapping filesystem are diffent and if there are two files
>>>>with same identifier exists.
>>>>And the issue I want to fix is when underlying filesystem and
>>>>wrapping filesystem are same so getcwd routine failed to distinguish
>>>>the mount point.
>>>>
>>>>So it can be solved by translating fsid if the fsid of a file is same as
>>>>that of mountpoint. True?
>>>
>>>Correct. In this case the inode number is guaranteed to be unique.
>>>This might be okay as a local patch, but it is IMHO not a fix suited for
>>>FreeBSD in general.
>>
>> Ok. How about this?
>
>This wouldn't be correct, either. Unionfs can be stacked, that is, you
>can't even be sure for a single layer that the passed up va_fsid will
>always be the same. The underlying unionfs can be comprised of two
>layers on two different file systems as well, and so on. You can
>override va_fsid only if the original file system id is guaranteed to be
>the same for all files in that layer (single file system case).
Ok, whats next?
Index: union.h
===================================================================
RCS file: /home/ncvs/src/sys/fs/unionfs/union.h,v
retrieving revision 1.28
diff -u -r1.28 union.h
--- union.h 7 Apr 2004 20:46:03 -0000 1.28
+++ union.h 4 Oct 2004 09:03:26 -0000
@@ -44,6 +44,7 @@
struct ucred *um_cred; /* Credentials of user calling mount */
int um_cmode; /* cmask from mount process */
int um_op; /* Operation mode */
+ dev_t um_upperdev; /* Upper root node fsid[0]*/
};
#ifdef _KERNEL
Index: union_vfsops.c
===================================================================
RCS file: /home/ncvs/src/sys/fs/unionfs/union_vfsops.c,v
retrieving revision 1.67
diff -u -r1.67 union_vfsops.c
--- union_vfsops.c 30 Jul 2004 22:08:51 -0000 1.67
+++ union_vfsops.c 4 Oct 2004 09:03:26 -0000
@@ -72,6 +72,7 @@
struct vnode *lowerrootvp = NULLVP;
struct vnode *upperrootvp = NULLVP;
struct union_mount *um = 0;
+ struct vattr va;
struct ucred *cred = 0;
char *cp = 0, *target;
int op;
@@ -190,6 +191,12 @@
M_UNIONFSMNT, M_WAITOK | M_ZERO);
um->um_op = op;
+
+ error = VOP_GETATTR(upperrootvp, &va, td->td_ucred, td);
+ if(error)
+ goto bad;
+
+ um->um_upperdev = va.va_fsid;
switch (um->um_op) {
case UNMNT_ABOVE:
Index: union_vnops.c
===================================================================
RCS file: /home/ncvs/src/sys/fs/unionfs/union_vnops.c,v
retrieving revision 1.109
diff -u -r1.109 union_vnops.c
--- union_vnops.c 2 Oct 2004 17:17:04 -0000 1.109
+++ union_vnops.c 4 Oct 2004 09:03:27 -0000
@@ -932,6 +932,7 @@
{
int error;
struct union_node *un = VTOUNION(ap->a_vp);
+ struct union_mount *um = MOUNTTOUNIONMOUNT(ap->a_vp->v_mount);
struct vnode *vp;
struct vattr *vap;
struct vattr va;
@@ -972,7 +973,8 @@
union_newsize(ap->a_vp, VNOVAL, vap->va_size);
}
- ap->a_vap->va_fsid = ap->a_vp->v_mount->mnt_stat.f_fsid.val[0];
+ if(vap->va_fsid == um->um_upperdev)
+ vap->va_fsid = ap->a_vp->v_mount->mnt_stat.f_fsid.val[0];
if ((vap != ap->a_vap) && (vap->va_type == VDIR))
ap->a_vap->va_nlink += vap->va_nlink;
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