Date: Fri, 10 Nov 2017 12:45:09 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r325645 - stable/11/sys/vm Message-ID: <201711101245.vAACj9Ls083894@repo.freebsd.org>
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Author: kib Date: Fri Nov 10 12:45:09 2017 New Revision: 325645 URL: https://svnweb.freebsd.org/changeset/base/325645 Log: MFC r324807: Take the vm object lock in read mode in vnode_generic_putpages(). Modified: stable/11/sys/vm/vnode_pager.c Directory Properties: stable/11/ (props changed) Modified: stable/11/sys/vm/vnode_pager.c ============================================================================== --- stable/11/sys/vm/vnode_pager.c Fri Nov 10 12:42:50 2017 (r325644) +++ stable/11/sys/vm/vnode_pager.c Fri Nov 10 12:45:09 2017 (r325645) @@ -1211,8 +1211,14 @@ vnode_pager_generic_putpages(struct vnode *vp, vm_page * We do not under any circumstances truncate the valid bits, as * this will screw up bogus page replacement. */ - VM_OBJECT_WLOCK(object); + VM_OBJECT_RLOCK(object); if (maxsize + poffset > object->un_pager.vnp.vnp_size) { + if (!VM_OBJECT_TRYUPGRADE(object)) { + VM_OBJECT_RUNLOCK(object); + VM_OBJECT_WLOCK(object); + if (maxsize + poffset <= object->un_pager.vnp.vnp_size) + goto downgrade; + } if (object->un_pager.vnp.vnp_size > poffset) { maxsize = object->un_pager.vnp.vnp_size - poffset; ncount = btoc(maxsize); @@ -1237,6 +1243,8 @@ vnode_pager_generic_putpages(struct vnode *vp, vm_page } for (i = ncount; i < count; i++) rtvals[i] = VM_PAGER_BAD; +downgrade: + VM_OBJECT_LOCK_DOWNGRADE(object); } auio.uio_iov = &aiov; @@ -1283,7 +1291,7 @@ start_write: */ MPASS(prev_offset < next_offset); - VM_OBJECT_WUNLOCK(object); + VM_OBJECT_RUNLOCK(object); aiov.iov_base = NULL; auio.uio_iovcnt = 1; auio.uio_offset = prev_offset; @@ -1299,7 +1307,7 @@ start_write: "zero-length write at %ju resid %zd\n", auio.uio_offset, auio.uio_resid); } - VM_OBJECT_WLOCK(object); + VM_OBJECT_RLOCK(object); break; } @@ -1317,7 +1325,7 @@ start_write: vn_printf(vp, "vnode_pager_putpages: residual I/O %zd " "at %ju\n", auio.uio_resid, (uintmax_t)ma[0]->pindex); - VM_OBJECT_WLOCK(object); + VM_OBJECT_RLOCK(object); if (error != 0 || auio.uio_resid != 0) break; } @@ -1331,7 +1339,7 @@ write_done: /* Unwritten pages in range, free bonus if the page is clean. */ for (; i < ncount; i++) rtvals[i] = ma[i]->dirty == 0 ? VM_PAGER_OK : VM_PAGER_ERROR; - VM_OBJECT_WUNLOCK(object); + VM_OBJECT_RUNLOCK(object); PCPU_ADD(cnt.v_vnodepgsout, i); PCPU_INC(cnt.v_vnodeout); return (rtvals[0]);
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