Date: Wed, 31 Dec 2014 00:34:38 +0000 (UTC) From: Rick Macklem <rmacklem@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r276436 - stable/10/sys/kern Message-ID: <201412310034.sBV0YcAs064519@svn.freebsd.org>
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Author: rmacklem Date: Wed Dec 31 00:34:37 2014 New Revision: 276436 URL: https://svnweb.freebsd.org/changeset/base/276436 Log: MFC: r276192, r276200 Modify vop_stdadvlock{async}() so that it only locks/unlocks the vnode and does a VOP_GETATTR() for the SEEK_END case. This is safe to do, since lf_advlock{async}() only uses the size argument for the SEEK_END case. The NFSv4 server needs this when vfs.nfsd.enable_locallocks!=0 since locking the vnode results in a LOR that can cause a deadlock for the nfsd threads. Modified: stable/10/sys/kern/vfs_default.c Directory Properties: stable/10/ (props changed) Modified: stable/10/sys/kern/vfs_default.c ============================================================================== --- stable/10/sys/kern/vfs_default.c Wed Dec 31 00:09:05 2014 (r276435) +++ stable/10/sys/kern/vfs_default.c Wed Dec 31 00:34:37 2014 (r276436) @@ -399,17 +399,24 @@ int vop_stdadvlock(struct vop_advlock_args *ap) { struct vnode *vp; - struct ucred *cred; struct vattr vattr; int error; vp = ap->a_vp; - cred = curthread->td_ucred; - vn_lock(vp, LK_SHARED | LK_RETRY); - error = VOP_GETATTR(vp, &vattr, cred); - VOP_UNLOCK(vp, 0); - if (error) - return (error); + if (ap->a_fl->l_whence == SEEK_END) { + /* + * The NFSv4 server must avoid doing a vn_lock() here, since it + * can deadlock the nfsd threads, due to a LOR. Fortunately + * the NFSv4 server always uses SEEK_SET and this code is + * only required for the SEEK_END case. + */ + vn_lock(vp, LK_SHARED | LK_RETRY); + error = VOP_GETATTR(vp, &vattr, curthread->td_ucred); + VOP_UNLOCK(vp, 0); + if (error) + return (error); + } else + vattr.va_size = 0; return (lf_advlock(ap, &(vp->v_lockf), vattr.va_size)); } @@ -418,17 +425,19 @@ int vop_stdadvlockasync(struct vop_advlockasync_args *ap) { struct vnode *vp; - struct ucred *cred; struct vattr vattr; int error; vp = ap->a_vp; - cred = curthread->td_ucred; - vn_lock(vp, LK_SHARED | LK_RETRY); - error = VOP_GETATTR(vp, &vattr, cred); - VOP_UNLOCK(vp, 0); - if (error) - return (error); + if (ap->a_fl->l_whence == SEEK_END) { + /* The size argument is only needed for SEEK_END. */ + vn_lock(vp, LK_SHARED | LK_RETRY); + error = VOP_GETATTR(vp, &vattr, curthread->td_ucred); + VOP_UNLOCK(vp, 0); + if (error) + return (error); + } else + vattr.va_size = 0; return (lf_advlockasync(ap, &(vp->v_lockf), vattr.va_size)); }
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