Date: Sun, 13 Apr 2014 01:15:37 +0000 (UTC) From: Davide Italiano <davide@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r264392 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs Message-ID: <201404130115.s3D1FbNX048346@svn.freebsd.org>
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Author: davide Date: Sun Apr 13 01:15:37 2014 New Revision: 264392 URL: http://svnweb.freebsd.org/changeset/base/264392 Log: Fix a panic in zfs_rename(). this is due to a wrong dereference of a vnode when it's not locked and can be (potentially) recycled. 'sdvp' cannot be locked on zfs_rename() entry point because the VFS can't be sure that this scenario is LOR-free (it might violate the parent->child lock acquisition rule). Dereference 'tdvp' instead, which is already locked on entry, and access 'sdvp' fields only when it's safe, i.e. under ZFS_ENTER scope. While at it, remove the usage of VOP_REALVP, as long as this is a NOP on FreeBSD. Discussed with: avg Reviewed by: pjd Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c ============================================================================== --- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c Sun Apr 13 01:14:25 2014 (r264391) +++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vnops.c Sun Apr 13 01:15:37 2014 (r264392) @@ -3723,9 +3723,8 @@ static int zfs_rename(vnode_t *sdvp, char *snm, vnode_t *tdvp, char *tnm, cred_t *cr, caller_context_t *ct, int flags) { - znode_t *tdzp, *szp, *tzp; - znode_t *sdzp = VTOZ(sdvp); - zfsvfs_t *zfsvfs = sdzp->z_zfsvfs; + znode_t *tdzp, *sdzp, *szp, *tzp; + zfsvfs_t *zfsvfs; zilog_t *zilog; vnode_t *realvp; zfs_dirlock_t *sdl, *tdl; @@ -3736,24 +3735,27 @@ zfs_rename(vnode_t *sdvp, char *snm, vno int zflg = 0; boolean_t waited = B_FALSE; + tdzp = VTOZ(tdvp); + ZFS_VERIFY_ZP(tdzp); + zfsvfs = tdzp->z_zfsvfs; ZFS_ENTER(zfsvfs); - ZFS_VERIFY_ZP(sdzp); zilog = zfsvfs->z_log; + sdzp = VTOZ(sdvp); /* - * Make sure we have the real vp for the target directory. + * In case sdzp is not valid, let's be sure to exit from the right + * zfsvfs_t. */ - if (VOP_REALVP(tdvp, &realvp, ct) == 0) - tdvp = realvp; - - tdzp = VTOZ(tdvp); - ZFS_VERIFY_ZP(tdzp); + if (sdzp->z_sa_hdl == NULL) { + ZFS_EXIT(zfsvfs); + return (SET_ERROR(EIO)); + } /* * We check z_zfsvfs rather than v_vfsp here, because snapshots and the * ctldir appear to have the same v_vfsp. */ - if (tdzp->z_zfsvfs != zfsvfs || zfsctl_is_node(tdvp)) { + if (sdzp->z_zfsvfs != zfsvfs || zfsctl_is_node(tdvp)) { ZFS_EXIT(zfsvfs); return (SET_ERROR(EXDEV)); }
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