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SubjectRe: [PATCH v2] f2fs: Fix direct IO handling
On 03.12.2019 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>
>---
> 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
>
>

Looks good to me. It also fixes the problem we see in our end.

Reviewed-by: Javier González <javier@javigon.com>

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