6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Chao Yu <chao@xxxxxxxxxx>
[ Upstream commit f06c0f82e38bbda7264d6ef3c90045ad2810e0f3 ]
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 <heyunlei@xxxxxxxx>
Signed-off-by: Chao Yu <chao@xxxxxxxxxx>
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/f2fs/checkpoint.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 13d8774706758..ad4073cde397b 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1178,6 +1178,11 @@ static void __prepare_cp_block(struct f2fs_sb_info *sbi)
ckpt->valid_node_count = cpu_to_le32(valid_node_count(sbi));
ckpt->valid_inode_count = cpu_to_le32(valid_inode_count(sbi));
ckpt->next_free_nid = cpu_to_le32(last_nid);
+
+ /* 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);
}
static bool __need_flush_quota(struct f2fs_sb_info *sbi)
@@ -1569,11 +1574,6 @@ 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 */
--
2.43.0
