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SubjectRe: [PATCH v2] f2fs: Fix direct IO handling
Date
On Dec 03, 2019 / 09:33, Jaegeuk Kim wrote:
> Thank you for checking the patch.
> I found some regressions in xfstests, so want to follow the Damien's one
> like below.
>
> Thanks,
>
> ===
> From 9df6f09e3a09ed804aba4b56ff7cd9524c002e69 Mon Sep 17 00:00:00 2001
> From: Jaegeuk Kim <jaegeuk@kernel.org>
> Date: Tue, 26 Nov 2019 15:01:42 -0800
> Subject: [PATCH] f2fs: preallocate DIO blocks when forcing buffered_io
>
> The previous preallocation and DIO decision like below.
>
> allow_outplace_dio !allow_outplace_dio
> f2fs_force_buffered_io (*) No_Prealloc / Buffered_IO Prealloc / Buffered_IO
> !f2fs_force_buffered_io No_Prealloc / DIO Prealloc / DIO
>
> But, Javier reported Case (*) where zoned device bypassed preallocation but
> fell back to buffered writes in f2fs_direct_IO(), resulting in stale data
> being read.
>
> In order to fix the issue, actually we need to preallocate blocks whenever
> we fall back to buffered IO like this. No change is made in the other cases.
>
> allow_outplace_dio !allow_outplace_dio
> f2fs_force_buffered_io (*) Prealloc / Buffered_IO Prealloc / Buffered_IO
> !f2fs_force_buffered_io No_Prealloc / DIO Prealloc / DIO
>
> Reported-and-tested-by: Javier Gonzalez <javier@javigon.com>
> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
> Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Using SMR disks, I reconfirmed that the reported problem goes away with this
modified patch also. Thanks.

> ---
> fs/f2fs/data.c | 13 -------------
> fs/f2fs/file.c | 43 +++++++++++++++++++++++++++++++++----------
> 2 files changed, 33 insertions(+), 23 deletions(-)
>
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index a034cd0ce021..fc40a72f7827 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -1180,19 +1180,6 @@ int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *from)
> int err = 0;
> bool direct_io = iocb->ki_flags & IOCB_DIRECT;
>
> - /* convert inline data for Direct I/O*/
> - if (direct_io) {
> - err = f2fs_convert_inline_inode(inode);
> - if (err)
> - return err;
> - }
> -
> - if (direct_io && allow_outplace_dio(inode, iocb, from))
> - return 0;
> -
> - if (is_inode_flag_set(inode, FI_NO_PREALLOC))
> - return 0;
> -
> map.m_lblk = F2FS_BLK_ALIGN(iocb->ki_pos);
> map.m_len = F2FS_BYTES_TO_BLK(iocb->ki_pos + iov_iter_count(from));
> if (map.m_len > map.m_lblk)
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index c0560d62dbee..0e1b12a4a4d6 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -3386,18 +3386,41 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
> ret = -EAGAIN;
> goto out;
> }
> - } else {
> - preallocated = true;
> - target_size = iocb->ki_pos + iov_iter_count(from);
> + goto write;
> + }
>
> - err = f2fs_preallocate_blocks(iocb, from);
> - if (err) {
> - clear_inode_flag(inode, FI_NO_PREALLOC);
> - inode_unlock(inode);
> - ret = err;
> - goto out;
> - }
> + if (is_inode_flag_set(inode, FI_NO_PREALLOC))
> + goto write;
> +
> + if (iocb->ki_flags & IOCB_DIRECT) {
> + /*
> + * Convert inline data for Direct I/O before entering
> + * f2fs_direct_IO().
> + */
> + err = f2fs_convert_inline_inode(inode);
> + if (err)
> + goto out_err;
> + /*
> + * If force_buffere_io() is true, we have to allocate
> + * blocks all the time, since f2fs_direct_IO will fall
> + * back to buffered IO.
> + */
> + if (!f2fs_force_buffered_io(inode, iocb, from) &&
> + allow_outplace_dio(inode, iocb, from))
> + goto write;
> + }
> + preallocated = true;
> + target_size = iocb->ki_pos + iov_iter_count(from);
> +
> + err = f2fs_preallocate_blocks(iocb, from);
> + if (err) {
> +out_err:
> + clear_inode_flag(inode, FI_NO_PREALLOC);
> + inode_unlock(inode);
> + ret = err;
> + goto out;
> }
> +write:
> ret = __generic_file_write_iter(iocb, from);
> clear_inode_flag(inode, FI_NO_PREALLOC);
>
> --
> 2.19.0.605.g01d371f741-goog
>
>

--
Best Regards,
Shin'ichiro Kawasaki
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