Date: Wed, 27 Mar 2013 11:47:52 +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: r248794 - head/sys/kern Message-ID: <201303271147.r2RBlqJX081355@svn.freebsd.org>
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Author: kib Date: Wed Mar 27 11:47:52 2013 New Revision: 248794 URL: http://svnweb.freebsd.org/changeset/base/248794 Log: Fix a race with the vnode reclamation in the aio_qphysio(). Obtain the thread reference on the vp->v_rdev and use the returned struct cdev *dev instead of using vp->v_rdev. Call dev_strategy_csw() instead of dev_strategy(), since we now own the reference. Since the csw was already calculated, test d_flags to avoid mapping the buffer if the driver supports unmapped requests [*]. Suggested by: kan [*] Reviewed by: kan (previous version) Sponsored by: The FreeBSD Foundation MFC after: 2 weeks Modified: head/sys/kern/vfs_aio.c Modified: head/sys/kern/vfs_aio.c ============================================================================== --- head/sys/kern/vfs_aio.c Wed Mar 27 11:42:36 2013 (r248793) +++ head/sys/kern/vfs_aio.c Wed Mar 27 11:47:52 2013 (r248794) @@ -1252,9 +1252,11 @@ aio_qphysio(struct proc *p, struct aiocb struct file *fp; struct buf *bp; struct vnode *vp; + struct cdevsw *csw; + struct cdev *dev; struct kaioinfo *ki; struct aioliojob *lj; - int error; + int error, ref; cb = &aiocbe->uaiocb; fp = aiocbe->fd_file; @@ -1282,9 +1284,6 @@ aio_qphysio(struct proc *p, struct aiocb if (cb->aio_nbytes % vp->v_bufobj.bo_bsize) return (-1); - if (cb->aio_nbytes > vp->v_rdev->si_iosize_max) - return (-1); - if (cb->aio_nbytes > MAXPHYS - (((vm_offset_t) cb->aio_buf) & PAGE_MASK)) return (-1); @@ -1293,6 +1292,15 @@ aio_qphysio(struct proc *p, struct aiocb if (ki->kaio_buffer_count >= ki->kaio_ballowed_count) return (-1); + ref = 0; + csw = devvn_refthread(vp, &dev, &ref); + if (csw == NULL) + return (ENXIO); + if (cb->aio_nbytes > dev->si_iosize_max) { + error = -1; + goto unref; + } + /* Create and build a buffer header for a transfer. */ bp = (struct buf *)getpbuf(NULL); BUF_KERNPROC(bp); @@ -1323,7 +1331,7 @@ aio_qphysio(struct proc *p, struct aiocb /* * Bring buffer into kernel space. */ - if (vmapbuf(bp, 1) < 0) { + if (vmapbuf(bp, (csw->d_flags & D_UNMAPPED_IO) == 0) < 0) { error = EFAULT; goto doerror; } @@ -1345,7 +1353,8 @@ aio_qphysio(struct proc *p, struct aiocb TASK_INIT(&aiocbe->biotask, 0, biohelper, aiocbe); /* Perform transfer. */ - dev_strategy(vp->v_rdev, bp); + dev_strategy_csw(dev, csw, bp); + dev_relthread(dev, ref); return (0); doerror: @@ -1357,6 +1366,8 @@ doerror: aiocbe->bp = NULL; AIO_UNLOCK(ki); relpbuf(bp, NULL); +unref: + dev_relthread(dev, ref); return (error); }
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