From owner-freebsd-bugs@freebsd.org Fri Apr 26 20:48:04 2019 Return-Path: Delivered-To: freebsd-bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 43449159DD3E for ; Fri, 26 Apr 2019 20:48:04 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mailman.ysv.freebsd.org (mailman.ysv.freebsd.org [IPv6:2001:1900:2254:206a::50:5]) by mx1.freebsd.org (Postfix) with ESMTP id B606D85BA3 for ; Fri, 26 Apr 2019 20:48:03 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: by mailman.ysv.freebsd.org (Postfix) id 5A12D159DD2B; Fri, 26 Apr 2019 20:48:02 +0000 (UTC) Delivered-To: bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 37D97159DD29 for ; Fri, 26 Apr 2019 20:48:02 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from mxrelay.ysv.freebsd.org (mxrelay.ysv.freebsd.org [IPv6:2001:1900:2254:206a::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.ysv.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id BCC3185B57 for ; Fri, 26 Apr 2019 20:48:01 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2001:1900:2254:206a::16:76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.ysv.freebsd.org (Postfix) with ESMTPS id 4769317F21 for ; Fri, 26 Apr 2019 20:47:59 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id x3QKlxb5036629 for ; Fri, 26 Apr 2019 20:47:59 GMT (envelope-from bugzilla-noreply@freebsd.org) Received: (from www@localhost) by kenobi.freebsd.org (8.15.2/8.15.2/Submit) id x3QKlxOI036628 for bugs@FreeBSD.org; Fri, 26 Apr 2019 20:47:59 GMT (envelope-from bugzilla-noreply@freebsd.org) X-Authentication-Warning: kenobi.freebsd.org: www set sender to bugzilla-noreply@freebsd.org using -f From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 237588] [fusefs] data corruption when mixing normal writes and mmap writes with Write-through cache mode Date: Fri, 26 Apr 2019 20:47:59 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: kern X-Bugzilla-Version: CURRENT X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Many People X-Bugzilla-Who: asomers@FreeBSD.org X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 26 Apr 2019 20:48:04 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D237588 Bug ID: 237588 Summary: [fusefs] data corruption when mixing normal writes and mmap writes with Write-through cache mode Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Many People Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: asomers@FreeBSD.org fusefs supports three cache modes: uncached, write-through, and writeback.= =20 Write-through is the default. However, as currently implemented it's more = like "write-around" than true "write-through". That is, writes go directly to t= he fuse daemon and invalidate the cache, rather than fill it. This is merely a performance bug when using normal writes (write(2), pwrite= (2), aio_write(2), etc). But when mixing normal writes with mmap()'ed writes, it causes data corruption. The sequence goes like this: 1) A process mmaps a fusefs file 2) That process writes some data, but does not msync() it. 3) A process writes directly, such as with write(2) to a region of the file that overlaps what was written in step 2. fusefs invalidates all cached pa= ges that were part of the write. 4) If any bytes were written by step 2 and invalidated but not written by s= tep 3, then they will be lost. Steps to reproduce: =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D 1) Build the passthrough example from sysutils/libfuse and fsx from tools/regression/fsx 2) mkdir -p /tmp/mnt 3) /path/to/libfuse/build/example/passthrough -d /tmp/mnt 4) /path/to/fsx/fsx -P /tmp -S1333 -b5 -N 15 -U fsx.bin --=20 You are receiving this mail because: You are the assignee for the bug.=