# HG changeset patch # User Matthew Ahrens # Date 1377058312 28800 # Node ID 189ec27885ae06605c1274067d89647d6648a6a8 # Parent 4b808fda2aace1c94582f2e967f4d128197f3eae 4047 panic from dbuf_free_range() from dmu_free_object() while doing zfs receive Reviewed by: Adam Leventhal Reviewed by: George Wilson Approved by: Dan McDonald diff -r 4b808fda2aac -r 189ec27885ae usr/src/uts/common/fs/zfs/dbuf.c --- a/usr/src/uts/common/fs/zfs/dbuf.c Wed Aug 07 17:58:15 2013 -0400 +++ b/usr/src/uts/common/fs/zfs/dbuf.c Tue Aug 20 20:11:52 2013 -0800 @@ -40,6 +40,12 @@ #include #include +/* + * Number of times that zfs_free_range() took the slow path while doing + * a zfs receive. A nonzero value indicates a potential performance problem. + */ +uint64_t zfs_free_range_recv_miss; + static void dbuf_destroy(dmu_buf_impl_t *db); static boolean_t dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx); static void dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx); @@ -819,20 +825,22 @@ } dprintf_dnode(dn, "start=%llu end=%llu\n", start, end); - if (dmu_objset_is_receiving(dn->dn_objset)) { + mutex_enter(&dn->dn_dbufs_mtx); + if (start >= dn->dn_unlisted_l0_blkid * dn->dn_datablksz) { + /* There can't be any dbufs in this range; no need to search. */ + mutex_exit(&dn->dn_dbufs_mtx); + return; + } else if (dmu_objset_is_receiving(dn->dn_objset)) { /* - * When processing a free record from a zfs receive, - * there should have been no previous modifications to the - * data in this range. Therefore there should be no dbufs - * in the range. Searching dn_dbufs for these non-existent - * dbufs can be very expensive, so simply ignore this. + * If we are receiving, we expect there to be no dbufs in + * the range to be freed, because receive modifies each + * block at most once, and in offset order. If this is + * not the case, it can lead to performance problems, + * so note that we unexpectedly took the slow path. */ - VERIFY3P(dbuf_find(dn, 0, start), ==, NULL); - VERIFY3P(dbuf_find(dn, 0, end), ==, NULL); - return; + atomic_inc_64(&zfs_free_range_recv_miss); } - mutex_enter(&dn->dn_dbufs_mtx); for (db = list_head(&dn->dn_dbufs); db; db = db_next) { db_next = list_next(&dn->dn_dbufs, db); ASSERT(db->db_blkid != DMU_BONUS_BLKID); @@ -1720,6 +1728,9 @@ return (odb); } list_insert_head(&dn->dn_dbufs, db); + if (db->db_level == 0 && db->db_blkid >= + dn->dn_unlisted_l0_blkid) + dn->dn_unlisted_l0_blkid = db->db_blkid + 1; db->db_state = DB_UNCACHED; mutex_exit(&dn->dn_dbufs_mtx); arc_space_consume(sizeof (dmu_buf_impl_t), ARC_SPACE_OTHER); diff -r 4b808fda2aac -r 189ec27885ae usr/src/uts/common/fs/zfs/dmu.c --- a/usr/src/uts/common/fs/zfs/dmu.c Wed Aug 07 17:58:15 2013 -0400 +++ b/usr/src/uts/common/fs/zfs/dmu.c Tue Aug 20 20:11:52 2013 -0800 @@ -569,98 +569,93 @@ * the end so that the file gets shorter over time (if we crashes in the * middle, this will leave us in a better state). We find allocated file * data by simply searching the allocated level 1 indirects. + * + * On input, *start should be the first offset that does not need to be + * freed (e.g. "offset + length"). On return, *start will be the first + * offset that should be freed. */ static int -get_next_chunk(dnode_t *dn, uint64_t *start, uint64_t limit) +get_next_chunk(dnode_t *dn, uint64_t *start, uint64_t minimum) { - uint64_t len = *start - limit; - uint64_t blkcnt = 0; - uint64_t maxblks = DMU_MAX_ACCESS / (1ULL << (dn->dn_indblkshift + 1)); + uint64_t maxblks = DMU_MAX_ACCESS >> (dn->dn_indblkshift + 1); + /* bytes of data covered by a level-1 indirect block */ uint64_t iblkrange = dn->dn_datablksz * EPB(dn->dn_indblkshift, SPA_BLKPTRSHIFT); - ASSERT(limit <= *start); + ASSERT3U(minimum, <=, *start); - if (len <= iblkrange * maxblks) { - *start = limit; + if (*start - minimum <= iblkrange * maxblks) { + *start = minimum; return (0); } ASSERT(ISP2(iblkrange)); - while (*start > limit && blkcnt < maxblks) { + for (uint64_t blks = 0; *start > minimum && blks < maxblks; blks++) { int err; - /* find next allocated L1 indirect */ + /* + * dnode_next_offset(BACKWARDS) will find an allocated L1 + * indirect block at or before the input offset. We must + * decrement *start so that it is at the end of the region + * to search. + */ + (*start)--; err = dnode_next_offset(dn, DNODE_FIND_BACKWARDS, start, 2, 1, 0); - /* if there are no more, then we are done */ + /* if there are no indirect blocks before start, we are done */ if (err == ESRCH) { - *start = limit; - return (0); - } else if (err) { + *start = minimum; + break; + } else if (err != 0) { return (err); } - blkcnt += 1; - /* reset offset to end of "next" block back */ + /* set start to the beginning of this L1 indirect */ *start = P2ALIGN(*start, iblkrange); - if (*start <= limit) - *start = limit; - else - *start -= 1; } + if (*start < minimum) + *start = minimum; return (0); } static int dmu_free_long_range_impl(objset_t *os, dnode_t *dn, uint64_t offset, - uint64_t length, boolean_t free_dnode) + uint64_t length) { - dmu_tx_t *tx; - uint64_t object_size, start, end, len; - boolean_t trunc = (length == DMU_OBJECT_END); - int align, err; + uint64_t object_size = (dn->dn_maxblkid + 1) * dn->dn_datablksz; + int err; - align = 1 << dn->dn_datablkshift; - ASSERT(align > 0); - object_size = align == 1 ? dn->dn_datablksz : - (dn->dn_maxblkid + 1) << dn->dn_datablkshift; + if (offset >= object_size) + return (0); - end = offset + length; - if (trunc || end > object_size) - end = object_size; - if (end <= offset) - return (0); - length = end - offset; + if (length == DMU_OBJECT_END || offset + length > object_size) + length = object_size - offset; - while (length) { - start = end; - /* assert(offset <= start) */ - err = get_next_chunk(dn, &start, offset); + while (length != 0) { + uint64_t chunk_end, chunk_begin; + + chunk_end = chunk_begin = offset + length; + + /* move chunk_begin backwards to the beginning of this chunk */ + err = get_next_chunk(dn, &chunk_begin, offset); if (err) return (err); - len = trunc ? DMU_OBJECT_END : end - start; + ASSERT3U(chunk_begin, >=, offset); + ASSERT3U(chunk_begin, <=, chunk_end); - tx = dmu_tx_create(os); - dmu_tx_hold_free(tx, dn->dn_object, start, len); + dmu_tx_t *tx = dmu_tx_create(os); + dmu_tx_hold_free(tx, dn->dn_object, + chunk_begin, chunk_end - chunk_begin); err = dmu_tx_assign(tx, TXG_WAIT); if (err) { dmu_tx_abort(tx); return (err); } - - dnode_free_range(dn, start, trunc ? -1 : len, tx); + dnode_free_range(dn, chunk_begin, chunk_end - chunk_begin, tx); + dmu_tx_commit(tx); - if (start == 0 && free_dnode) { - ASSERT(trunc); - dnode_free(dn, tx); - } - - length -= end - start; - - dmu_tx_commit(tx); - end = start; + length -= chunk_end - chunk_begin; } return (0); } @@ -675,38 +670,32 @@ err = dnode_hold(os, object, FTAG, &dn); if (err != 0) return (err); - err = dmu_free_long_range_impl(os, dn, offset, length, FALSE); + err = dmu_free_long_range_impl(os, dn, offset, length); dnode_rele(dn, FTAG); return (err); } int -dmu_free_object(objset_t *os, uint64_t object) +dmu_free_long_object(objset_t *os, uint64_t object) { - dnode_t *dn; dmu_tx_t *tx; int err; - err = dnode_hold_impl(os, object, DNODE_MUST_BE_ALLOCATED, - FTAG, &dn); + err = dmu_free_long_range(os, object, 0, DMU_OBJECT_END); if (err != 0) return (err); - if (dn->dn_nlevels == 1) { - tx = dmu_tx_create(os); - dmu_tx_hold_bonus(tx, object); - dmu_tx_hold_free(tx, dn->dn_object, 0, DMU_OBJECT_END); - err = dmu_tx_assign(tx, TXG_WAIT); - if (err == 0) { - dnode_free_range(dn, 0, DMU_OBJECT_END, tx); - dnode_free(dn, tx); - dmu_tx_commit(tx); - } else { - dmu_tx_abort(tx); - } + + tx = dmu_tx_create(os); + dmu_tx_hold_bonus(tx, object); + dmu_tx_hold_free(tx, object, 0, DMU_OBJECT_END); + err = dmu_tx_assign(tx, TXG_WAIT); + if (err == 0) { + err = dmu_object_free(os, object, tx); + dmu_tx_commit(tx); } else { - err = dmu_free_long_range_impl(os, dn, 0, DMU_OBJECT_END, TRUE); + dmu_tx_abort(tx); } - dnode_rele(dn, FTAG); + return (err); } diff -r 4b808fda2aac -r 189ec27885ae usr/src/uts/common/fs/zfs/dmu_send.c --- a/usr/src/uts/common/fs/zfs/dmu_send.c Wed Aug 07 17:58:15 2013 -0400 +++ b/usr/src/uts/common/fs/zfs/dmu_send.c Tue Aug 20 20:11:52 2013 -0800 @@ -1232,7 +1232,7 @@ if (dmu_object_info(os, obj, NULL) != 0) continue; - err = dmu_free_object(os, obj); + err = dmu_free_long_object(os, obj); if (err != 0) return (err); } diff -r 4b808fda2aac -r 189ec27885ae usr/src/uts/common/fs/zfs/dmu_tx.c --- a/usr/src/uts/common/fs/zfs/dmu_tx.c Wed Aug 07 17:58:15 2013 -0400 +++ b/usr/src/uts/common/fs/zfs/dmu_tx.c Tue Aug 20 20:11:52 2013 -0800 @@ -615,7 +615,8 @@ * if they are blocksize-aligned. */ if (dn->dn_datablkshift == 0) { - dmu_tx_count_write(txh, off, len); + if (off != 0 || len < dn->dn_datablksz) + dmu_tx_count_write(txh, off, len); } else { /* first block will be modified if it is not aligned */ if (!IS_P2ALIGNED(off, 1 << dn->dn_datablkshift)) diff -r 4b808fda2aac -r 189ec27885ae usr/src/uts/common/fs/zfs/dnode.c --- a/usr/src/uts/common/fs/zfs/dnode.c Wed Aug 07 17:58:15 2013 -0400 +++ b/usr/src/uts/common/fs/zfs/dnode.c Tue Aug 20 20:11:52 2013 -0800 @@ -115,6 +115,7 @@ dn->dn_id_flags = 0; dn->dn_dbufs_count = 0; + dn->dn_unlisted_l0_blkid = 0; list_create(&dn->dn_dbufs, sizeof (dmu_buf_impl_t), offsetof(dmu_buf_impl_t, db_link)); @@ -167,6 +168,7 @@ ASSERT0(dn->dn_id_flags); ASSERT0(dn->dn_dbufs_count); + ASSERT0(dn->dn_unlisted_l0_blkid); list_destroy(&dn->dn_dbufs); } @@ -472,6 +474,7 @@ dn->dn_newuid = 0; dn->dn_newgid = 0; dn->dn_id_flags = 0; + dn->dn_unlisted_l0_blkid = 0; dmu_zfetch_rele(&dn->dn_zfetch); kmem_cache_free(dnode_cache, dn); @@ -702,6 +705,7 @@ ASSERT(list_is_empty(&ndn->dn_dbufs)); list_move_tail(&ndn->dn_dbufs, &odn->dn_dbufs); ndn->dn_dbufs_count = odn->dn_dbufs_count; + ndn->dn_unlisted_l0_blkid = odn->dn_unlisted_l0_blkid; ndn->dn_bonus = odn->dn_bonus; ndn->dn_have_spill = odn->dn_have_spill; ndn->dn_zio = odn->dn_zio; @@ -736,6 +740,7 @@ list_create(&odn->dn_dbufs, sizeof (dmu_buf_impl_t), offsetof(dmu_buf_impl_t, db_link)); odn->dn_dbufs_count = 0; + odn->dn_unlisted_l0_blkid = 0; odn->dn_bonus = NULL; odn->dn_zfetch.zf_dnode = NULL; @@ -1523,7 +1528,7 @@ blkshift = dn->dn_datablkshift; epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT; - if (len == -1ULL) { + if (len == DMU_OBJECT_END) { len = UINT64_MAX - off; trunc = TRUE; } diff -r 4b808fda2aac -r 189ec27885ae usr/src/uts/common/fs/zfs/dsl_destroy.c --- a/usr/src/uts/common/fs/zfs/dsl_destroy.c Wed Aug 07 17:58:15 2013 -0400 +++ b/usr/src/uts/common/fs/zfs/dsl_destroy.c Tue Aug 20 20:11:52 2013 -0800 @@ -896,7 +896,7 @@ for (uint64_t obj = 0; error == 0; error = dmu_object_next(os, &obj, FALSE, prev_snap_txg)) - (void) dmu_free_object(os, obj); + (void) dmu_free_long_object(os, obj); /* sync out all frees */ txg_wait_synced(dmu_objset_pool(os), 0); dmu_objset_disown(os, FTAG); diff -r 4b808fda2aac -r 189ec27885ae usr/src/uts/common/fs/zfs/sys/dmu.h --- a/usr/src/uts/common/fs/zfs/sys/dmu.h Wed Aug 07 17:58:15 2013 -0400 +++ b/usr/src/uts/common/fs/zfs/sys/dmu.h Tue Aug 20 20:11:52 2013 -0800 @@ -21,7 +21,7 @@ /* * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. - * Copyright (c) 2012 by Delphix. All rights reserved. + * Copyright (c) 2013 by Delphix. All rights reserved. * Copyright 2011 Nexenta Systems, Inc. All rights reserved. * Copyright (c) 2012, Joyent, Inc. All rights reserved. */ @@ -581,7 +581,7 @@ uint64_t size, dmu_tx_t *tx); int dmu_free_long_range(objset_t *os, uint64_t object, uint64_t offset, uint64_t size); -int dmu_free_object(objset_t *os, uint64_t object); +int dmu_free_long_object(objset_t *os, uint64_t object); /* * Convenience functions. diff -r 4b808fda2aac -r 189ec27885ae usr/src/uts/common/fs/zfs/sys/dnode.h --- a/usr/src/uts/common/fs/zfs/sys/dnode.h Wed Aug 07 17:58:15 2013 -0400 +++ b/usr/src/uts/common/fs/zfs/sys/dnode.h Tue Aug 20 20:11:52 2013 -0800 @@ -20,7 +20,7 @@ */ /* * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. - * Copyright (c) 2012 by Delphix. All rights reserved. + * Copyright (c) 2013 by Delphix. All rights reserved. */ #ifndef _SYS_DNODE_H @@ -188,6 +188,8 @@ /* protected by dn_dbufs_mtx; declared here to fill 32-bit hole */ uint32_t dn_dbufs_count; /* count of dn_dbufs */ + /* There are no level-0 blocks of this blkid or higher in dn_dbufs */ + uint64_t dn_unlisted_l0_blkid; /* protected by os_lock: */ list_node_t dn_dirty_link[TXG_SIZE]; /* next on dataset's dirty */