Author: avg Date: Tue Jul 12 11:46:13 2016 New Revision: 302652 URL: https://svnweb.freebsd.org/changeset/base/302652
Log: 5768 zfsctl_snapshot_inactive() can leak a vnode hold illumos/illumos-gate@20a95fb2c4af266e063e0cf86037f910a303c710 https://github.com/illumos/illumos-gate/commit/20a95fb2c4af266e063e0cf86037f910a303c710 https://www.illumos.org/issues/5768 zfsctl_snapshot_inactive() leaks a hold on the dvp (directory vnode) if v_count > 1. reproduce by: create a fs with 100 snapshots. have a thread do: while true; do ls -l /test/snaps/.zfs/snapshot >/dev/null; done have another thread do: while true; do zfs promote test/clone; zfs promote test/snaps; done use dtrace to delay & observe: dtrace -w -xd \\ -n 'vn_rele:entry/args0 == (void*)0xffffff01dd42ce80ULL/{[stack()]=count(); chill(100000);}' \\ -n 'zfsctl_snapshot_inactive:entry{ if (args[0]->v_count > 1) trace(args[0]- >v_count); self->vp=args[0];}' \\ -n 'gfs_vop_inactive:entry/callers["zfsctl_snapshot_inactive"]/{self->good=1; [stack()]=count()}' \\ -n 'zfsctl_snapshot_inactive:return{if (self->good) self->good=0; else printf ("bad return");}' \\ -n 'gfs_dir_lookup:return/callers["zfsctl_snapshot_inactive"] && self->vp- >v_count > 1/{trace(self->vp->v_count)}' the address is found by selecting one of the output of this at random: dtrace -n 'zfsctl_snapshot_inactive:entry{print(args[0]);' when you see "bad return", we have hit the bug. Then doing "zfs umount test/ snaps" will fail with EBUSY. When we hit this case, we also leak the hold on the target vnode (vn). When the inactive callback is called on a vnode with v_count > 1, it needs to be decremented. Reviewed by: George Wilson <geo...@delphix.com> Reviewed by: Prakash Surya <prakash.su...@delphix.com> Reviewed by: Adam Leventhal <adam.levent...@delphix.com> Reviewed by: Bayard Bell <buffer.g.overf...@gmail.com> Approved by: Rich Lowe <richl...@richlowe.net> Author: Matthew Ahrens <mahr...@delphix.com> Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_ctldir.c Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_ctldir.c ============================================================================== --- vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_ctldir.c Tue Jul 12 11:37:19 2016 (r302651) +++ vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_ctldir.c Tue Jul 12 11:46:13 2016 (r302652) @@ -20,7 +20,7 @@ */ /* * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. - * Copyright (c) 2013 by Delphix. All rights reserved. + * Copyright (c) 2012, 2014 by Delphix. All rights reserved. * Copyright 2015, OmniTI Computer Consulting, Inc. All rights reserved. */ @@ -1214,10 +1214,15 @@ zfsctl_snapshot_inactive(vnode_t *vp, cr mutex_enter(&sdp->sd_lock); + mutex_enter(&vp->v_lock); if (vp->v_count > 1) { + vp->v_count--; + mutex_exit(&vp->v_lock); mutex_exit(&sdp->sd_lock); + VN_RELE(dvp); return; } + mutex_exit(&vp->v_lock); ASSERT(!vn_ismntpt(vp)); sep = avl_first(&sdp->sd_snaps); _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
