Date: Tue, 4 Feb 2020 19:03:38 +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: r357514 - head/sys/vm Message-ID: <202002041903.014J3cIZ040033@repo.freebsd.org>
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Author: kib Date: Tue Feb 4 19:03:37 2020 New Revision: 357514 URL: https://svnweb.freebsd.org/changeset/base/357514 Log: Enable vm_object_mightbedirty() and vm_object_page_clean() for swap objects backing tmpfs vnodes data. The clean scan is limited to only remove write permissions from the mapped pages of the objects. This fixes the issue that tmpfs vnode mtime is not updated from writes to the mmaped area after the initial page-in. Noted by: mjg Reviewed by: markj Discussed with: jeff Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D23432 Modified: head/sys/vm/vm_object.c head/sys/vm/vm_object.h Modified: head/sys/vm/vm_object.c ============================================================================== --- head/sys/vm/vm_object.c Tue Feb 4 19:01:17 2020 (r357513) +++ head/sys/vm/vm_object.c Tue Feb 4 19:03:37 2020 (r357514) @@ -1017,6 +1017,10 @@ vm_object_page_remove_write(vm_page_t p, int flags, bo * write out pages with PGA_NOSYNC set (originally comes from MAP_NOSYNC), * leaving the object dirty. * + * For swap objects backing tmpfs regular files, do not flush anything, + * but remove write protection on the mapped pages to update mtime through + * mmaped writes. + * * When stuffing pages asynchronously, allow clustering. XXX we need a * synchronous clustering mode implementation. * @@ -1038,8 +1042,7 @@ vm_object_page_clean(vm_object_t object, vm_ooffset_t VM_OBJECT_ASSERT_WLOCKED(object); - if (object->type != OBJT_VNODE || !vm_object_mightbedirty(object) || - object->resident_page_count == 0) + if (!vm_object_mightbedirty(object) || object->resident_page_count == 0) return (TRUE); pagerflags = (flags & (OBJPC_SYNC | OBJPC_INVAL)) != 0 ? @@ -1072,32 +1075,36 @@ rescan: vm_page_xunbusy(p); continue; } + if (object->type == OBJT_VNODE) { + n = vm_object_page_collect_flush(object, p, pagerflags, + flags, &allclean, &eio); + if (eio) { + res = FALSE; + allclean = FALSE; + } + if (object->generation != curgeneration && + (flags & OBJPC_SYNC) != 0) + goto rescan; - n = vm_object_page_collect_flush(object, p, pagerflags, - flags, &allclean, &eio); - if (eio) { - res = FALSE; - allclean = FALSE; - } - if (object->generation != curgeneration && - (flags & OBJPC_SYNC) != 0) - goto rescan; - - /* - * If the VOP_PUTPAGES() did a truncated write, so - * that even the first page of the run is not fully - * written, vm_pageout_flush() returns 0 as the run - * length. Since the condition that caused truncated - * write may be permanent, e.g. exhausted free space, - * accepting n == 0 would cause an infinite loop. - * - * Forwarding the iterator leaves the unwritten page - * behind, but there is not much we can do there if - * filesystem refuses to write it. - */ - if (n == 0) { + /* + * If the VOP_PUTPAGES() did a truncated write, so + * that even the first page of the run is not fully + * written, vm_pageout_flush() returns 0 as the run + * length. Since the condition that caused truncated + * write may be permanent, e.g. exhausted free space, + * accepting n == 0 would cause an infinite loop. + * + * Forwarding the iterator leaves the unwritten page + * behind, but there is not much we can do there if + * filesystem refuses to write it. + */ + if (n == 0) { + n = 1; + allclean = FALSE; + } + } else { n = 1; - allclean = FALSE; + vm_page_xunbusy(p); } np = vm_page_find_least(object, pi + n); } @@ -1105,7 +1112,12 @@ rescan: VOP_FSYNC(vp, (pagerflags & VM_PAGER_PUT_SYNC) ? MNT_WAIT : 0); #endif - if (allclean) + /* + * Leave updating cleangeneration for tmpfs objects to tmpfs + * scan. It needs to update mtime, which happens for other + * filesystems during page writeouts. + */ + if (allclean && object->type == OBJT_VNODE) object->cleangeneration = curgeneration; return (res); } Modified: head/sys/vm/vm_object.h ============================================================================== --- head/sys/vm/vm_object.h Tue Feb 4 19:01:17 2020 (r357513) +++ head/sys/vm/vm_object.h Tue Feb 4 19:03:37 2020 (r357514) @@ -322,8 +322,15 @@ static __inline bool vm_object_mightbedirty(vm_object_t object) { - return (object->type == OBJT_VNODE && - object->generation != object->cleangeneration); + if (object->type != OBJT_VNODE) { + if ((object->flags & OBJ_TMPFS_NODE) == 0) + return (false); +#ifdef KASSERT + KASSERT(object->type == OBJT_SWAP, + ("TMPFS_NODE obj %p is not swap", object)); +#endif + } + return (object->generation != object->cleangeneration); } void vm_object_clear_flag(vm_object_t object, u_short bits);
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