Date: Thu, 16 Oct 2014 02:23:28 +0000 (UTC) From: Steven Hartland <smh@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r273158 - head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs Message-ID: <201410160223.s9G2NSDu015140@svn.freebsd.org>
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Author: smh Date: Thu Oct 16 02:23:27 2014 New Revision: 273158 URL: https://svnweb.freebsd.org/changeset/base/273158 Log: Prevent ZFS leaking pool free space When processing async destroys ZFS would leak space every txg timeout (5 seconds by default), if no writes occurred, until the pool is totally full. At this point it would be unfixable without a pool recreation. In addition if the machine was rebooted with the pool in this situation would fail to import on boot, hanging indefinitely, as the import process requires the ability to write data to the pool. Any attempts to query the pool status during the hung import would not return as the import holds the pool lock. The only way to import such a pool would be to specify -o readonly=on to the zpool import. zdb -bb <pool> can be used to check for "deferred free" size which is where this lost space will be counted. MFC after: 3 days Sponsored by: Multiplay Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scan.c Modified: head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scan.c ============================================================================== --- head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scan.c Thu Oct 16 01:48:39 2014 (r273157) +++ head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dsl_scan.c Thu Oct 16 02:23:27 2014 (r273158) @@ -1459,13 +1459,6 @@ dsl_scan_sync(dsl_pool_t *dp, dmu_tx_t * "traverse_dataset_destroyed()", err); } - /* - * If we didn't make progress, mark the async destroy as - * stalled, so that we will not initiate a spa_sync() on - * its behalf. - */ - scn->scn_async_stalled = (scn->scn_visited_this_txg == 0); - if (bptree_is_empty(dp->dp_meta_objset, dp->dp_bptree_obj)) { /* finished; deactivate async destroy feature */ spa_feature_decr(spa, SPA_FEATURE_ASYNC_DESTROY, tx); @@ -1478,6 +1471,14 @@ dsl_scan_sync(dsl_pool_t *dp, dmu_tx_t * dp->dp_bptree_obj, tx)); dp->dp_bptree_obj = 0; scn->scn_async_destroying = B_FALSE; + } else { + /* + * If we didn't make progress, mark the async destroy as + * stalled, so that we will not initiate a spa_sync() on + * its behalf. + */ + scn->scn_async_stalled = + (scn->scn_visited_this_txg == 0); } } if (scn->scn_visited_this_txg) {
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