On 02/04, Chao Yu wrote:
> There is potential hangtask happened during swapfile's writeback:
>
> - loop_kthread_worker_fn - do_checkpoint
> - kthread_worker_fn
> - loop_queue_work
> - lo_rw_aio
> - f2fs_file_write_iter
> - f2fs_preallocate_blocks
> - f2fs_map_blocks
> - down_write
> - down_read
> - rwsem_down_read_slowpath
> - schedule
>
> One cause is f2fs_preallocate_blocks() will always be called no matter
> the physical block addresses are allocated or not.
>
> This patch tries to check whether block addresses are all allocated with
> i_size and i_blocks of inode, it's rough because blocks can be allocated
> beyond i_size, however, we can afford skipping block preallocation in this
> condition since it's not necessary to do preallocation all the time.
>
> Signed-off-by: Chao Yu <[email protected]>
> ---
> v2:
> - check overwrite case with i_size and i_blocks roughly.
> fs/f2fs/file.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index cfdc41f87f5d..09565d10611d 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -4390,6 +4390,16 @@ static int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *iter,
> int flag;
> int ret;
>
> + /*
> + * It tries to check whether block addresses are all allocated,
> + * it's rough because blocks can be allocated beyond i_size,
> + * however, we can afford skipping block preallocation since
> + * it's not necessary all the time.
> + */
> + if (F2FS_BLK_ALIGN(i_size_read(inode)) ==
> + SECTOR_TO_BLOCK(inode->i_blocks))
Do we count i_blocks only for data?
> + return 0;
> +
> /* If it will be an out-of-place direct write, don't bother. */
> if (dio && f2fs_lfs_mode(sbi))
> return 0;
> --
> 2.32.0
On 2022/2/8 3:16, Jaegeuk Kim wrote:
> On 02/04, Chao Yu wrote:
>> There is potential hangtask happened during swapfile's writeback:
>>
>> - loop_kthread_worker_fn - do_checkpoint
>> - kthread_worker_fn
>> - loop_queue_work
>> - lo_rw_aio
>> - f2fs_file_write_iter
>> - f2fs_preallocate_blocks
>> - f2fs_map_blocks
>> - down_write
>> - down_read
>> - rwsem_down_read_slowpath
>> - schedule
>>
>> One cause is f2fs_preallocate_blocks() will always be called no matter
>> the physical block addresses are allocated or not.
>>
>> This patch tries to check whether block addresses are all allocated with
>> i_size and i_blocks of inode, it's rough because blocks can be allocated
>> beyond i_size, however, we can afford skipping block preallocation in this
>> condition since it's not necessary to do preallocation all the time.
>>
>> Signed-off-by: Chao Yu <[email protected]>
>> ---
>> v2:
>> - check overwrite case with i_size and i_blocks roughly.
>> fs/f2fs/file.c | 10 ++++++++++
>> 1 file changed, 10 insertions(+)
>>
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index cfdc41f87f5d..09565d10611d 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -4390,6 +4390,16 @@ static int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *iter,
>> int flag;
>> int ret;
>>
>> + /*
>> + * It tries to check whether block addresses are all allocated,
>> + * it's rough because blocks can be allocated beyond i_size,
>> + * however, we can afford skipping block preallocation since
>> + * it's not necessary all the time.
>> + */
>> + if (F2FS_BLK_ALIGN(i_size_read(inode)) ==
>> + SECTOR_TO_BLOCK(inode->i_blocks))
>
> Do we count i_blocks only for data?
Oops, it seems it's not...
Needs to introduce another function to calculate node block count based on i_size?
Thanks,
>
>> + return 0;
>> +
>> /* If it will be an out-of-place direct write, don't bother. */
>> if (dio && f2fs_lfs_mode(sbi))
>> return 0;
>> --
>> 2.32.0