On 9/3/25 08:04, Zhiguo Niu wrote:
> Chao Yu via Linux-f2fs-devel <[email protected]>
> 于2025年9月1日周一 10:08写道：
>>
>> It reports a bug from device w/ zufs:
>>
>> F2FS-fs (dm-64): Inconsistent segment (173822) type [1, 0] in SSA and SIT
>> F2FS-fs (dm-64): Stopped filesystem due to reason: 4
>>
>> Thread A Thread B
>> - f2fs_expand_inode_data
>> - f2fs_allocate_pinning_section
>> - f2fs_gc_range
>> - do_garbage_collect w/ segno #x
>> - writepage
>> - f2fs_allocate_data_block
>> - new_curseg
>> - allocate segno #x
>>
>> The root cause is: fallocate on pinning file may race w/ block allocation
>> as above, result in do_garbage_collect() from fallocate() may migrate
>> segment which is just allocated by a log, the log will update segment type
>> in its in-memory structure, however GC will get segment type from on-disk
>> SSA block, once segment type changes by log, we can detect such
>> inconsistency, then shutdown filesystem.
>>
>> In this case, on-disk SSA shows type of segno #173822 is 1 (SUM_TYPE_NODE),
>> however segno #173822 was just allocated as data type segment, so in-memory
>> SIT shows type of segno #173822 is 0 (SUM_TYPE_DATA).
>>
>> Change as below to fix this issue:
>> - check whether current section is empty before gc
>> - add sanity checks on do_garbage_collect() to avoid any race case, result
>> in migrating segment used by log.
>> - btw, it fixes misc issue in printed logs: "SSA and SIT" -> "SIT and SSA".
>>
>> Fixes: 9703d69d9d15 ("f2fs: support file pinning for zoned devices")
>> Cc: Daeho Jeong <[email protected]>
>> Signed-off-by: Chao Yu <[email protected]>
>> ---
>> fs/f2fs/gc.c | 16 +++++++++++++++-
>> 1 file changed, 15 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
>> index ed3acbfc83ca..a7708cf80c04 100644
>> --- a/fs/f2fs/gc.c
>> +++ b/fs/f2fs/gc.c
>> @@ -1794,6 +1794,13 @@ static int do_garbage_collect(struct f2fs_sb_info
>> *sbi,
>> struct folio *sum_folio =
>> filemap_get_folio(META_MAPPING(sbi),
>> GET_SUM_BLOCK(sbi, segno));
>>
>> + if (is_cursec(sbi, GET_SEC_FROM_SEG(sbi, segno))) {
>> + f2fs_err(sbi, "%s: segment %u is used by log",
>> + __func__, segno);
>> + f2fs_bug_on(sbi, 1);
> Hi Chao,
> Do we need f2fs_bug_on here? or it is enough to skip current segno
> and let gc continue?
Zhiguo,
I think we should never select in-use segment as GC victim, so I add a
f2fs_bug_on() here to detect any potential bugs. Let's see what will we
find w/ this.
Thanks,
> Thanks!
>> + goto skip;
>> + }
>> +
>> if (get_valid_blocks(sbi, segno, false) == 0)
>> goto freed;
>> if (gc_type == BG_GC && __is_large_section(sbi) &&
>> @@ -1805,7 +1812,7 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>>
>> sum = folio_address(sum_folio);
>> if (type != GET_SUM_TYPE((&sum->footer))) {
>> - f2fs_err(sbi, "Inconsistent segment (%u) type [%d,
>> %d] in SSA and SIT",
>> + f2fs_err(sbi, "Inconsistent segment (%u) type [%d,
>> %d] in SIT and SSA",
>> segno, type, GET_SUM_TYPE((&sum->footer)));
>> f2fs_stop_checkpoint(sbi, false,
>> STOP_CP_REASON_CORRUPTED_SUMMARY);
>> @@ -2068,6 +2075,13 @@ int f2fs_gc_range(struct f2fs_sb_info *sbi,
>> .iroot = RADIX_TREE_INIT(gc_list.iroot, GFP_NOFS),
>> };
>>
>> + /*
>> + * avoid migrating empty section, as it can be allocated by
>> + * log in parallel.
>> + */
>> + if (!get_valid_blocks(sbi, segno, true))
>> + continue;
>> +
>> if (is_cursec(sbi, GET_SEC_FROM_SEG(sbi, segno)))
>> continue;
>>
>> --
>> 2.49.0
>>
>>
>>
>> _______________________________________________
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>> [email protected]
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