6.14-stable review patch. If anyone has any objections, please let me know.
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From: Chunhai Guo guochunhai@vivo.com
[ Upstream commit 21263d035ff21fa0ccf79adba20bab9cd8cca0f2 ]
During a checkpoint, the current active segment X may not be handled properly. This occurs when segment X has 0 valid blocks and a non-zero number of discard blocks, for the following reasons:
locate_dirty_segment() does not mark any active segment as a prefree segment. As a result, segment X is not included in dirty_segmap[PRE], and f2fs_clear_prefree_segments() skips it when handling prefree segments.
add_discard_addrs() skips any segment with 0 valid blocks, so segment X is also skipped.
Consequently, no `struct discard_cmd` is actually created for segment X. However, the ckpt_valid_map and cur_valid_map of segment X are synced by seg_info_to_raw_sit() during the current checkpoint process. As a result, it cannot find the missing discard bits even in subsequent checkpoints. Consequently, the value of sbi->discard_blks remains non-zero. Thus, when f2fs is umounted, CP_TRIMMED_FLAG will not be set due to the non-zero sbi->discard_blks.
Relevant code process:
f2fs_write_checkpoint() f2fs_flush_sit_entries() list_for_each_entry_safe(ses, tmp, head, set_list) { for_each_set_bit_from(segno, bitmap, end) { ... add_discard_addrs(sbi, cpc, false); // skip segment X due to its 0 valid blocks ... seg_info_to_raw_sit(); // sync ckpt_valid_map with cur_valid_map for segment X ... } } f2fs_clear_prefree_segments(); // segment X is not included in dirty_segmap[PRE] and is skipped
This issue is easy to reproduce with the following operations:
root # mkfs.f2fs -f /dev/f2fs_dev root # mount -t f2fs /dev/f2fs_dev /mnt_point root # dd if=/dev/blk_dev of=/mnt_point/1.bin bs=4k count=256 root # sync root # rm /mnt_point/1.bin root # umount /mnt_point root # dump.f2fs /dev/f2fs_dev | grep "checkpoint state" Info: checkpoint state = 45 : crc compacted_summary unmount ---- 'trimmed' flag is missing
Since add_discard_addrs() can handle active segments with non-zero valid blocks, it is reasonable to fix this issue by allowing it to also handle active segments with 0 valid blocks.
Fixes: b29555505d81 ("f2fs: add key functions for small discards") Signed-off-by: Chunhai Guo guochunhai@vivo.com Reviewed-by: Chao Yu chao@kernel.org Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/f2fs/segment.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 2b415926641f0..384bca002ec9a 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -2096,7 +2096,9 @@ static bool add_discard_addrs(struct f2fs_sb_info *sbi, struct cp_control *cpc, return false;
if (!force) { - if (!f2fs_realtime_discard_enable(sbi) || !se->valid_blocks || + if (!f2fs_realtime_discard_enable(sbi) || + (!se->valid_blocks && + !IS_CURSEG(sbi, cpc->trim_start)) || SM_I(sbi)->dcc_info->nr_discards >= SM_I(sbi)->dcc_info->max_discards) return false;