Date: Mon, 31 Aug 2009 10:20:52 +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: r196692 - head/sys/kern Message-ID: <200908311020.n7VAKqrG023585@svn.freebsd.org>
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Author: kib Date: Mon Aug 31 10:20:52 2009 New Revision: 196692 URL: http://svn.freebsd.org/changeset/base/196692 Log: Make the mnt_writeopcount and mnt_secondary_writes counters, used by the suspension code, not greater then mnt_ref reference counter value. Increment mnt_ref together with write counter in vn_start_write()/ vn_start_secondary_write(), releasing in vn_finished_write/vn_finished_secondary_write(). Since r186197, unmount code requires that no writers occured after all references are expired. We still could get write counter incremented for freed or reused struct mount, but it seems to be innocent, since corresponding vnode should be referenced and reclaimed then. Reported by: pho (last half a year), erwin Reviewed by: attilio Tested by: pho, erwin MFC after: 1 week Modified: head/sys/kern/vfs_vnops.c Modified: head/sys/kern/vfs_vnops.c ============================================================================== --- head/sys/kern/vfs_vnops.c Mon Aug 31 09:46:09 2009 (r196691) +++ head/sys/kern/vfs_vnops.c Mon Aug 31 10:20:52 2009 (r196692) @@ -999,7 +999,8 @@ vn_start_write(vp, mpp, flags) goto unlock; mp->mnt_writeopcount++; unlock: - MNT_REL(mp); + if (error != 0) + MNT_REL(mp); MNT_IUNLOCK(mp); return (error); } @@ -1049,7 +1050,6 @@ vn_start_secondary_write(vp, mpp, flags) if ((mp->mnt_kern_flag & (MNTK_SUSPENDED | MNTK_SUSPEND2)) == 0) { mp->mnt_secondary_writes++; mp->mnt_secondary_accwrites++; - MNT_REL(mp); MNT_IUNLOCK(mp); return (0); } @@ -1081,6 +1081,7 @@ vn_finished_write(mp) if (mp == NULL) return; MNT_ILOCK(mp); + MNT_REL(mp); mp->mnt_writeopcount--; if (mp->mnt_writeopcount < 0) panic("vn_finished_write: neg cnt"); @@ -1103,6 +1104,7 @@ vn_finished_secondary_write(mp) if (mp == NULL) return; MNT_ILOCK(mp); + MNT_REL(mp); mp->mnt_secondary_writes--; if (mp->mnt_secondary_writes < 0) panic("vn_finished_secondary_write: neg cnt");
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