Messages in this thread | | | Date | Tue, 14 Dec 2021 10:56:41 -0800 | From | Jaegeuk Kim <> | Subject | Re: [f2fs-dev] [PATCH] f2fs: skip f2fs_preallocate_blocks() for overwrite case |
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On 12/12, Chao Yu wrote: > Ping, > > On 2021/10/30 11:02, Chao Yu wrote: > > On 2021/10/30 1:43, Jaegeuk Kim wrote: > > > On 10/29, Chao Yu wrote: > > > > Ping, > > > > > > > > On 2021/9/29 8:05, Chao Yu wrote: > > > > > On 2021/9/29 3:08, Jaegeuk Kim wrote: > > > > > > On 09/28, Chao Yu wrote: > > > > > > > In f2fs_file_write_iter(), let's use f2fs_overwrite_io() to > > > > > > > check whethere it is overwrite case, for such case, we can skip > > > > > > > f2fs_preallocate_blocks() in order to avoid f2fs_do_map_lock(), > > > > > > > which may be blocked by checkpoint() potentially. > > > > > > > > > > > > > > Signed-off-by: Chao Yu <chao@kernel.org> > > > > > > > --- > > > > > > > fs/f2fs/file.c | 4 ++++ > > > > > > > 1 file changed, 4 insertions(+) > > > > > > > > > > > > > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > > > > > > > index 13deae03df06..51fecb2f4db5 100644 > > > > > > > --- a/fs/f2fs/file.c > > > > > > > +++ b/fs/f2fs/file.c > > > > > > > @@ -4321,6 +4321,10 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from) > > > > > > > preallocated = true; > > > > > > > target_size = iocb->ki_pos + iov_iter_count(from); > > > > > > > + if (f2fs_overwrite_io(inode, iocb->ki_pos, > > > > > > > + iov_iter_count(from))) > > > > > > > + goto write; > > > > > > > > > > > > This calls f2fs_map_blocks() which can be duplicate, if it's not the overwirte > > > > > > case. Do we have other benefit? > > > > > > > > > > f2fs_overwrite_io() will break for append write case w/ below check: > > > > > > > > > > if (pos + len > i_size_read(inode)) > > > > > return false; > > > > > > > > > > I guess we may only suffer double f2fs_map_blocks() for write hole > > > > > case, e.g. truncate to large size & write inside the filesize. For > > > > > this case, how about adding a condition to allow double f2fs_map_blocks() > > > > > only if write size is smaller than a threshold? > > > > > > I still don't see the benefit much to do double f2fs_map_blocks. What is the > > > problem here? > > > > There is potential hangtask happened during swapfile's writeback: > > > > - loop_kthread_worker_fn > > - kthread_worker_fn > > - loop_queue_work > > - lo_rw_aio > > - f2fs_file_write_iter > > - f2fs_preallocate_blocks > > - f2fs_map_blocks > > - down_read > > - rwsem_down_read_slowpath > > - schedule > > > > I try to mitigate such issue by preallocating swapfile's block address and > > avoid f2fs_do_map_lock() as much as possible in swapfile's writeback path...
How about checking i_blocks and i_size instead of checking the entire map?
> > > > Thanks, > > > > > > > > > > > > > > > Thanks, > > > > > > > > > > > > > > > > > > + > > > > > > > err = f2fs_preallocate_blocks(iocb, from); > > > > > > > if (err) { > > > > > > > out_err: > > > > > > > -- > > > > > > > 2.32.0 > > > > > > > > > > > > > > > _______________________________________________ > > > > > Linux-f2fs-devel mailing list > > > > > Linux-f2fs-devel@lists.sourceforge.net > > > > > https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flists.sourceforge.net%2Flists%2Flistinfo%2Flinux-f2fs-devel&data=04%7C01%7Cchao.yu%40oppo.com%7Cbb41006c3f6d4e4d600a08d99b51cbcd%7Cf1905eb1c35341c5951662b4a54b5ee6%7C0%7C0%7C637711597895400286%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=%2BlEAXWLpV5wGX2hL0Wj5p2qX0AqfUFI05Qiqdp8PK8g%3D&reserved=0 > > > > > > _______________________________________________ > > Linux-f2fs-devel mailing list > > Linux-f2fs-devel@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
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