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Allowed unionfs to use whiteout not supporting file system as

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upper layer. Until now, unionfs prevents to use that kind of
file system as upper layer. This time, I changed to allow
that kind of file system as upper layer. By this change, you
can use whiteout not supporting file system (e.g., especially
for tmpfs) as upper layer. It's very useful for combination of
tmpfs as upper layer and read only file system as lower layer.

By difinition, without whiteout support from the file system
backing the upper layer, there is no way that delete and rename
operations on lower layer objects can be done.  EOPNOTSUPP is
returned for this kind of operations as generated by VOP_WHITEOUT()
along with any others which would make modifica tions to the
lower layer, such as chmod(1).

This change is suggested by ed.

Submitted by:	ed
This commit is contained in:
daichi 2010-09-05 04:58:16 +00:00
parent e749c008a4
commit 6f5cfa0928
2 changed files with 4 additions and 24 deletions
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7
sbin/mount_unionfs/mount_unionfs.8
View File

@ -363,9 +363,10 @@ their intent to take it over.
Without whiteout support from the file system backing the upper layer,
there is no way that delete and rename operations on lower layer
objects can be done.
.Er EROFS
is returned for this kind of operations along with any others
which would make modifications to the lower layer, such as
.Er EOPNOTSUPP
is returned for this kind of operations as generated by VOP_WHITEOUT()
along with any others which would make modifications to the lower
layer, such as
.Xr chmod 1 .
.Pp
Running

21
sys/fs/unionfs/union_vfsops.c
View File

@ -89,7 +89,6 @@ unionfs_domount(struct mount *mp)
u_short ufile;
unionfs_copymode copymode;
unionfs_whitemode whitemode;
struct componentname fakecn;
struct nameidata nd, *ndp;
struct vattr va;
@ -279,26 +278,6 @@ unionfs_domount(struct mount *mp)
*/
mp->mnt_flag |= ump->um_uppervp->v_mount->mnt_flag & MNT_RDONLY;
/*
* Check whiteout
*/
if ((mp->mnt_flag & MNT_RDONLY) == 0) {
memset(&fakecn, 0, sizeof(fakecn));
fakecn.cn_nameiop = LOOKUP;
fakecn.cn_thread = td;
error = VOP_WHITEOUT(ump->um_uppervp, &fakecn, LOOKUP);
if (error) {
if (below) {
VOP_UNLOCK(ump->um_uppervp, 0);
vrele(upperrootvp);
} else
vput(ump->um_uppervp);
free(ump, M_UNIONFSMNT);
mp->mnt_data = NULL;
return (error);
}
}
/*
* Unlock the node
*/