Attachment 219896 Details for Bug 251320 – patch

[patch] patch

fix-mount-failure-panic.diff (text/plain), 1.64 KB, created by Tong Zhang on 2020-11-23 00:21:57 UTC

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Creator: Tong Zhang

Created: 2020-11-23 00:21:57 UTC

Size: 1.64 KB

patch

obsolete

>commit 6ab553e46cf3cb78d8a6fb1752235feadc9b3750
>Author: Tong Zhang <ztong0001@gmail.com>
>Date:   Sun Nov 22 18:50:16 2020 -0500
>
>    vfs_domount_first: do not crash on mount failure
>    
>    vfs_write_suspend_umnt() expect a non-zero vfs_write_suspend_umnt,
>    otherwise it will panic
>    
>     panic: vn_finished_write: neg cnt
>     cpuid = 7
>     time = 1606004193
>     KDB: stack backtrace:
>     #0 0xffffffff80c0a8f5 at kdb_backtrace+0x65
>     #1 0xffffffff80bbeb1b at vpanic+0x17b
>     #2 0xffffffff80bbe993 at panic+0x43
>     #3 0xffffffff80c9da05 at vn_finished_write+0xc5
>     #4 0xffffffff80c9f726 at vfs_write_suspend_umnt+0x16
>     #5 0xffffffff80ecdd31 at ffs_unmount+0x71
>     #6 0xffffffff80c844dd at vfs_domount+0xc0d
>     #7 0xffffffff80c83228 at vfs_donmount+0x988
>     #8 0xffffffff80c82871 at sys_nmount+0x71
>     #9 0xffffffff810904c7 at amd64_syscall+0x387
>     #10 0xffffffff8106785e at fast_syscall_common+0xf8
>     Uptime: 2h10m11s
>
>diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
>index afbb3e313d7..03e4394cf75 100644
>--- a/sys/kern/vfs_mount.c
>+++ b/sys/kern/vfs_mount.c
>@@ -895,6 +895,15 @@ vfs_domount_first(
> 	    (error1 = VFS_ROOT(mp, LK_EXCLUSIVE, &newdp)) != 0) {
> 		if (error1 != 0) {
> 			error = error1;
>+			/*
>+			 * if mounted as rw - we should increase mnt_writeopcount here
>+			 * since VFS_UNMOUNT will call vfs_write_suspend_umnt() and
>+			 * it expects a non-zero vfs_write_suspend_umnt
>+			 */
>+			if ((mp->mnt_flag & MNT_RDONLY) == 0) {
>+				if ((error = vn_start_write(NULL, &mp, V_WAIT)) != 0)
>+					return (error);
>+			}
> 			if ((error1 = VFS_UNMOUNT(mp, 0)) != 0)
> 				printf("VFS_UNMOUNT returned %d\n", error1);
> 		}

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Attachments on bug 251320: 219896