diff options
author | kato <kato@FreeBSD.org> | 1997-04-29 02:06:07 +0000 |
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committer | kato <kato@FreeBSD.org> | 1997-04-29 02:06:07 +0000 |
commit | d9ec773b46d66f5676cae1dc9868470019b769a1 (patch) | |
tree | ce92a09a0a9b3db678e16c3aaabfda0ebceceefd /sys/fs/unionfs/union_vnops.c | |
parent | 299d0a28fc28064d066cc2f1819d7f5ebb728e58 (diff) | |
download | FreeBSD-src-d9ec773b46d66f5676cae1dc9868470019b769a1.zip FreeBSD-src-d9ec773b46d66f5676cae1dc9868470019b769a1.tar.gz |
Revised fix for locking violation when unionfs calls vput with
UN_KLOCK flag.
When UN_KLOCK is set, VOP_UNLOCK should keep uppervp locked and clear
UN_ULOCK flag. To do this, when UN_KLOCK is set, (1) union_unlock
clears UN_ULOCK and does not clear UN_KLOCK, (2) union_lock() does not
access uppervp and does not clear UN_KLOCK, and (3) callers of
vput/VOP_UNLOCK should clear UN_KLOCK. For example, vput becomes:
SETKLOCK(union_node);
vput(vnode);
CLEARKLOCK(union_node);
where SETKLOCK macro sets UN_KLOCK and CLEARKLOCK macro clears
UN_KLOCK.
Diffstat (limited to 'sys/fs/unionfs/union_vnops.c')
-rw-r--r-- | sys/fs/unionfs/union_vnops.c | 68 |
1 files changed, 36 insertions, 32 deletions
diff --git a/sys/fs/unionfs/union_vnops.c b/sys/fs/unionfs/union_vnops.c index f8c8293..00e48622 100644 --- a/sys/fs/unionfs/union_vnops.c +++ b/sys/fs/unionfs/union_vnops.c @@ -35,7 +35,7 @@ * SUCH DAMAGE. * * @(#)union_vnops.c 8.32 (Berkeley) 6/23/95 - * $Id: union_vnops.c,v 1.29 1997/04/26 13:43:25 kato Exp $ + * $Id: union_vnops.c,v 1.30 1997/04/27 10:49:37 kato Exp $ */ #include <sys/param.h> @@ -61,6 +61,9 @@ } \ } +#define SETKLOCK(un) (un)->un_flags |= UN_KLOCK +#define CLEARKLOCK(un) (un)->un_flags &= ~UN_KLOCK + extern int union_abortop __P((struct vop_abortop_args *ap)); extern int union_access __P((struct vop_access_args *ap)); extern int union_advlock __P((struct vop_advlock_args *ap)); @@ -255,8 +258,9 @@ union_lookup(ap) */ if (cnp->cn_flags & ISDOTDOT) { /* retain lock on underlying VP: */ - dun->un_flags |= UN_KLOCK; + SETKLOCK(dun); VOP_UNLOCK(dvp, 0, p); + CLEARKLOCK(dun); } uerror = union_lookup1(um->um_uppervp, &upperdvp, &uppervp, cnp); @@ -459,9 +463,10 @@ union_create(ap) FIXUP(un, p); VREF(dvp); - un->un_flags |= UN_KLOCK; + SETKLOCK(un); mp = ap->a_dvp->v_mount; vput(ap->a_dvp); + CLEARKLOCK(un); error = VOP_CREATE(dvp, &vp, cnp, ap->a_vap); if (error) return (error); @@ -518,9 +523,10 @@ union_mknod(ap) FIXUP(un, p); VREF(dvp); - un->un_flags |= UN_KLOCK; + SETKLOCK(un); mp = ap->a_dvp->v_mount; vput(ap->a_dvp); + CLEARKLOCK(un); error = VOP_MKNOD(dvp, &vp, cnp, ap->a_vap); if (error) return (error); @@ -974,8 +980,8 @@ union_fsync(ap) if (dolock) VOP_UNLOCK(targetvp, 0, p); else if (isupperlocked) { - VOP_UNLOCK(targetvp, 0, p); un->un_flags &= ~UN_ULOCK; + VOP_UNLOCK(targetvp, 0, p); } } @@ -1020,12 +1026,14 @@ union_remove(ap) FIXUP(dun, p); VREF(dvp); - dun->un_flags |= UN_KLOCK; + SETKLOCK(dun); vput(ap->a_dvp); + CLEARKLOCK(dun); FIXUP(un, p); VREF(vp); - un->un_flags |= UN_KLOCK; + SETKLOCK(un); vput(ap->a_vp); + CLEARKLOCK(un); if (union_dowhiteout(un, cnp->cn_cred, cnp->cn_proc)) cnp->cn_flags |= DOWHITEOUT; @@ -1093,8 +1101,9 @@ union_link(ap) FIXUP(un, p); VREF(tdvp); - un->un_flags |= UN_KLOCK; + SETKLOCK(un); vput(ap->a_tdvp); + CLEARKLOCK(un); return (VOP_LINK(tdvp, vp, cnp)); } @@ -1116,6 +1125,7 @@ union_rename(ap) struct vnode *fvp = ap->a_fvp; struct vnode *tdvp = ap->a_tdvp; struct vnode *tvp = ap->a_tvp; + int isklockset = 0; if (fdvp->v_op == union_vnodeop_p) { /* always true */ struct union_node *un = VTOUNION(fdvp); @@ -1166,8 +1176,9 @@ union_rename(ap) tdvp = un->un_uppervp; VREF(tdvp); - un->un_flags |= UN_KLOCK; + SETKLOCK(un); vput(ap->a_tdvp); + CLEARKLOCK(un); } if (tvp != NULLVP && tvp->v_op == union_vnodeop_p) { @@ -1176,9 +1187,12 @@ union_rename(ap) tvp = un->un_uppervp; if (tvp != NULLVP) { VREF(tvp); - un->un_flags |= UN_KLOCK; + SETKLOCK(un); + isklockset = 1; } vput(ap->a_tvp); + if (isklockset) + CLEARKLOCK(un); } return (VOP_RENAME(fdvp, fvp, ap->a_fcnp, tdvp, tvp, ap->a_tcnp)); @@ -1213,8 +1227,9 @@ union_mkdir(ap) FIXUP(un, p); VREF(dvp); - un->un_flags |= UN_KLOCK; + SETKLOCK(un); VOP_UNLOCK(ap->a_dvp, 0, p); + CLEARKLOCK(un); error = VOP_MKDIR(dvp, &vp, cnp, ap->a_vap); if (error) { vrele(ap->a_dvp); @@ -1256,12 +1271,14 @@ union_rmdir(ap) FIXUP(dun, p); VREF(dvp); - dun->un_flags |= UN_KLOCK; + SETKLOCK(dun); vput(ap->a_dvp); + CLEARKLOCK(dun); FIXUP(un, p); VREF(vp); - un->un_flags |= UN_KLOCK; + SETKLOCK(un); vput(ap->a_vp); + CLEARKLOCK(un); if (union_dowhiteout(un, cnp->cn_cred, cnp->cn_proc)) cnp->cn_flags |= DOWHITEOUT; @@ -1301,8 +1318,9 @@ union_symlink(ap) FIXUP(un, p); VREF(dvp); - un->un_flags |= UN_KLOCK; + SETKLOCK(un); vput(ap->a_dvp); + CLEARKLOCK(un); error = VOP_SYMLINK(dvp, &vp, cnp, ap->a_vap, ap->a_target); *ap->a_vpp = NULLVP; return (error); @@ -1475,17 +1493,18 @@ start: un = VTOUNION(vp); if (un->un_uppervp != NULLVP) { - if (((un->un_flags & UN_ULOCK) == 0) && + if (((un->un_flags & (UN_ULOCK | UN_KLOCK)) == 0) && (vp->v_usecount != 0)) { if (VOP_ISLOCKED(un->un_uppervp)) { /* + * XXX * Erm, we find race! */ #ifdef DIAGNOSTIC panic("union_link: upper vnode is locked, " "but UN_UNLOCK is not set."); #endif - un->un_flags |= UN_ULOCK; /* XXX */ + un->un_flags |= UN_ULOCK; } else { error = vn_lock(un->un_uppervp, flags, p); if (error) @@ -1493,12 +1512,6 @@ start: un->un_flags |= UN_ULOCK; } } -#ifdef DIAGNOSTIC - if (un->un_flags & UN_KLOCK) { - vprint("union: dangling klock", vp); - panic("union: dangling upper lock (%lx)", vp); - } -#endif } if (un->un_flags & UN_LOCKED) { @@ -1558,16 +1571,7 @@ union_unlock(ap) if ((un->un_flags & (UN_ULOCK|UN_KLOCK)) == UN_ULOCK) VOP_UNLOCK(un->un_uppervp, 0, p); - if ((un->un_flags & UN_KLOCK) && (ap->a_vp->v_usecount == 1)) { - /* - * Do not clear UN_ULOCK here. Our vput will call - * VOP_LOCK for vm related reason. If we clear UN_ULOCK, - * VOP_LOCK will try to lock upper vnode, whic is not - * unlocked. - */ - un->un_flags &= ~UN_KLOCK; - } else - un->un_flags &= ~(UN_ULOCK|UN_KLOCK); + un->un_flags &= ~UN_ULOCK; if (un->un_flags & UN_WANT) { un->un_flags &= ~UN_WANT; |