On 2024/6/25 1:53, Jaegeuk Kim wrote:
On 06/06, Chao Yu wrote:Commit 59c9081bc86e ("f2fs: allow write page cache when writting cp") allows write() to write data to page cache during checkpoint, so block count fields like .total_valid_block_count, .alloc_valid_block_count and .rf_node_block_count may encounter race condition as below:CP Thread A - write_checkpoint - block_operations - f2fs_down_write(&sbi->node_change) - __prepare_cp_block : ckpt->valid_block_count = .total_valid_block_count - f2fs_up_write(&sbi->node_change) - write - f2fs_preallocate_blocks - f2fs_map_blocks(,F2FS_GET_BLOCK_PRE_AIO) - f2fs_map_lock - f2fs_down_read(&sbi->node_change) - f2fs_reserve_new_blocks - inc_valid_block_count : percpu_counter_add(&sbi->alloc_valid_block_count, count) : sbi->total_valid_block_count += count - f2fs_up_read(&sbi->node_change) - do_checkpoint : sbi->last_valid_block_count = sbi->total_valid_block_count : percpu_counter_set(&sbi->alloc_valid_block_count, 0) : percpu_counter_set(&sbi->rf_node_block_count, 0) - fsync - need_do_checkpoint - f2fs_space_for_roll_forward : alloc_valid_block_count was reset to zero, so, it may missed last data during checkpoint Let's change to update .total_valid_block_count, .alloc_valid_block_count and .rf_node_block_count in block_operations(), then their access can be protected by .node_change and .cp_rwsem lock, so that it can avoid above race condition. Fixes: 59c9081bc86e ("f2fs: allow write page cache when writting cp") Cc: Yunlei He <heyun...@oppo.com> Signed-off-by: Chao Yu <c...@kernel.org> --- fs/f2fs/checkpoint.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c index 66eaad591b60..010bbd5af211 100644 --- a/fs/f2fs/checkpoint.c +++ b/fs/f2fs/checkpoint.c @@ -1298,6 +1298,12 @@ static int block_operations(struct f2fs_sb_info *sbi) * dirty node blocks and some checkpoint values by block allocation. */ __prepare_cp_block(sbi); + + /* update user_block_counts */ + sbi->last_valid_block_count = sbi->total_valid_block_count; + percpu_counter_set(&sbi->alloc_valid_block_count, 0); + percpu_counter_set(&sbi->rf_node_block_count, 0);Need to add this in __prepare_cp_block()?
Fine to me, will update in v2. Thanks,
+ f2fs_up_write(&sbi->node_change); return err; } @@ -1575,11 +1581,6 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc) start_blk += NR_CURSEG_NODE_TYPE; }- /* update user_block_counts */- sbi->last_valid_block_count = sbi->total_valid_block_count; - percpu_counter_set(&sbi->alloc_valid_block_count, 0); - percpu_counter_set(&sbi->rf_node_block_count, 0); - /* Here, we have one bio having CP pack except cp pack 2 page */ f2fs_sync_meta_pages(sbi, META, LONG_MAX, FS_CP_META_IO); /* Wait for all dirty meta pages to be submitted for IO */ -- 2.40.1
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