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There is no need to upgrade the last dvp lock on lookups for modifying

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operations.  Instead of upgrading, assert that the lock is exclusive.
Explain the cause in comments.

This effectively reverts r209367.

Tested by:	pho
Reviewed by:	mckusick
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
This commit is contained in:
Konstantin Belousov 2016-09-08 12:04:45 +00:00
parent df4265774e
commit ccb19123e5
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=305593
1 changed files with 19 additions and 32 deletions
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51
sys/ufs/ufs/ufs_lookup.c
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@ -76,32 +76,6 @@ SYSCTL_INT(_debug, OID_AUTO, dircheck, CTLFLAG_RW, &dirchk, 0, "");
/* true if old FS format...*/
#define OFSFMT(vp) ((vp)->v_mount->mnt_maxsymlinklen <= 0)
#ifdef QUOTA
static int
ufs_lookup_upgrade_lock(struct vnode *vp)
{
int error;
ASSERT_VOP_LOCKED(vp, __FUNCTION__);
if (VOP_ISLOCKED(vp) == LK_EXCLUSIVE)
return (0);
error = 0;
/*
* Upgrade vnode lock, since getinoquota()
* requires exclusive lock to modify inode.
*/
vhold(vp);
vn_lock(vp, LK_UPGRADE | LK_RETRY);
VI_LOCK(vp);
if (vp->v_iflag & VI_DOOMED)
error = ENOENT;
vdropl(vp);
return (error);
}
#endif
static int
ufs_delete_denied(struct vnode *vdp, struct vnode *tdp, struct ucred *cred,
struct thread *td)
@ -259,12 +233,25 @@ ufs_lookup_ino(struct vnode *vdp, struct vnode **vpp, struct componentname *cnp,
vnode_create_vobject(vdp, DIP(dp, i_size), cnp->cn_thread);
bmask = VFSTOUFS(vdp->v_mount)->um_mountp->mnt_stat.f_iosize - 1;
#ifdef QUOTA
if ((nameiop == DELETE || nameiop == RENAME) && (flags & ISLASTCN)) {
error = ufs_lookup_upgrade_lock(vdp);
if (error != 0)
return (error);
}
#ifdef DEBUG_VFS_LOCKS
/*
* Assert that the directory vnode is locked, and locked
* exclusively for the last component lookup for modifying
* operations.
*
* The directory-modifying operations need to save
* intermediate state in the inode between namei() call and
* actual directory manipulations. See fields in the struct
* inode marked as 'used during directory lookup'. We must
* ensure that upgrade in namei() does not happen, since
* upgrade might need to unlock vdp. If quotas are enabled,
* getinoquota() also requires exclusive lock to modify inode.
*/
ASSERT_VOP_LOCKED(vdp, "ufs_lookup1");
if ((nameiop == CREATE || nameiop == DELETE || nameiop == RENAME) &&
(flags & (LOCKPARENT | ISLASTCN)) == (LOCKPARENT | ISLASTCN))
ASSERT_VOP_ELOCKED(vdp, "ufs_lookup2");
#endif
restart: