Date: Sat, 22 Nov 2008 13:11:11 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r185170 - head/sys/ufs/ufs Message-ID: <200811221311.mAMDBBU8018510@svn.freebsd.org>
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Author: kib Date: Sat Nov 22 13:11:11 2008 New Revision: 185170 URL: http://svn.freebsd.org/changeset/base/185170 Log: Busy ufs filesystem around block of code that does ".." lookup. Since mnt_lock is before lock of any vnode on the mp, it uses LK_NOWAIT. Since MNTK_UNMOUNT may be transient, pdp lock is dropped when vfs_busy() failed, and operation is retried after some time. This way, ffs_vget() is not called on the mp that may be in the process of being destroyed by unmount. Check for the VI_DOOMED flag on pdp after its lock is reacquired, to better detect some situations where directory containing ".." entry is removed during the lookup. Reviewed by: tegge, attilio (previous version) Tested by: pho MFC after: 1 month Modified: head/sys/ufs/ufs/ufs_lookup.c Modified: head/sys/ufs/ufs/ufs_lookup.c ============================================================================== --- head/sys/ufs/ufs/ufs_lookup.c Sat Nov 22 12:36:15 2008 (r185169) +++ head/sys/ufs/ufs/ufs_lookup.c Sat Nov 22 13:11:11 2008 (r185170) @@ -157,6 +157,8 @@ ufs_lookup(ap) int nameiop = cnp->cn_nameiop; ino_t ino; int ltype; + int pdoomed; + struct mount *mp; bp = NULL; slotoffset = -1; @@ -578,9 +580,32 @@ found: pdp = vdp; if (flags & ISDOTDOT) { ltype = VOP_ISLOCKED(pdp); + mp = pdp->v_mount; + for (;;) { + error = vfs_busy(mp, MBF_NOWAIT); + if (error == 0) + break; + VOP_UNLOCK(pdp, 0); + pause("ufs_dd", 1); + vn_lock(pdp, ltype | LK_RETRY); + VI_LOCK(pdp); + pdoomed = pdp->v_iflag & VI_DOOMED; + VI_UNLOCK(pdp); + if (pdoomed) + return (ENOENT); + } VOP_UNLOCK(pdp, 0); /* race to get the inode */ - error = VFS_VGET(pdp->v_mount, ino, cnp->cn_lkflags, &tdp); + error = VFS_VGET(mp, ino, cnp->cn_lkflags, &tdp); + vfs_unbusy(mp); vn_lock(pdp, ltype | LK_RETRY); + VI_LOCK(pdp); + pdoomed = pdp->v_iflag & VI_DOOMED; + VI_UNLOCK(pdp); + if (pdoomed) { + if (error == 0) + vput(tdp); + error = ENOENT; + } if (error) return (error); *vpp = tdp;
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