Robert Evans a60214e792 dnode_next_offset: backtrack if lower level does not match ... This changes the basic search algorithm from a single search up and down the tree to a full depth-first traversal to handle conditions where the tree matches at a higher level but not a lower level. Normally higher level blocks always point to matching blocks, but there are cases where this does not happen: 1. Racing block pointer updates from dbuf_write_ready. Before f664f1ee7f (#8946), both dbuf_write_ready and dnode_next_offset held dn_struct_rwlock which protected against pointer writes from concurrent syncs. This no longer applies, so sync context can f.e. clear or fill all L1->L0 BPs before the L2->L1 BP and higher BP's are updated. dnode_free_range in particular can reach this case and skip over L1 blocks that need to be dirtied. Later, sync will panic in free_children when trying to clear a non-dirty indirect block. This case was found with ztest. 2. txg > 0, non-hole case. This is #11196. Freeing blocks/dnodes breaks the assumption that a match at a higher level implies a match at a lower level when filtering txg > 0. Whenever some but not all L0 blocks are freed, the parent L1 block is rewritten. Its updated L2->L1 BP reflects a newer birth txg. Later when searching by txg, if the L1 block matches since the txg is newer, it is possible that none of the remaining L1->L0 BPs match if none have been updated. The same behavior is possible with dnode search at L0. This is reachable from dsl_destroy_head for synchronous freeing. When this happens open context fails to free objects leaving sync context stuck freeing potentially many objects. This is also reachable from traverse_pool for extreme rewind where it is theoretically possible that datasets not dirtied after txg are skipped if the MOS has high enough indirection to trigger this case. In both of these cases, without backtracking the search ends prematurely as ESRCH result implies no more matches in the entire object. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Akash B <akash-b@hpe.com> Signed-off-by: Robert Evans <evansr@google.com> Closes #16025 Closes #11196		2025-10-21 11:30:30 -07:00
..
avl	SPDX: license tags: CDDL-1.0	2025-04-16 09:59:44 -07:00
icp	Linux build: silence objtool warnings	2025-06-17 10:50:26 -07:00
lua	SPDX: license tags: MIT	2025-04-16 09:59:44 -07:00
nvpair	SPDX: license tags: CDDL-1.0	2025-04-16 09:59:44 -07:00
os	zvol: verify IO type is supported	2025-10-21 11:02:42 -07:00
unicode	[2.3.2] uconv: add SPDX license tag	2025-04-16 09:59:45 -07:00
zcommon	GCC 15: Fix unterminated-string-initialization (#17244)	2025-04-16 09:59:45 -07:00
zfs	dnode_next_offset: backtrack if lower level does not match	2025-10-21 11:30:30 -07:00
zstd	Silence zstd large allocation warning	2025-08-12 17:24:26 -07:00
.gitignore	FreeBSD: Ignore symlink to i386 includes	2022-08-02 16:34:23 -07:00
Kbuild.in	linux: Fix out-of-src builds	2025-08-12 17:22:40 -07:00
Makefile.bsd	freebsd: unbreak module/Makefile.bsd build on 15-CURRENT-arm64	2025-04-16 09:59:45 -07:00
Makefile.in	objtool wrapper: use absolute path to call the wrapper	2025-08-07 13:10:58 -04:00