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SubjectRe: [PATCH] f2fs: Fix direct IO handling
On 11/26, Damien Le Moal wrote:
> f2fs_preallocate_blocks() identifies direct IOs using the IOCB_DIRECT
> flag for a kiocb structure. However, the file system direct IO handler
> function f2fs_direct_IO() may have decided that a direct IO has to be
> exececuted as a buffered IO using the function f2fs_force_buffered_io().
> This is the case for instance for volumes including zoned block device
> and for unaligned write IOs with LFS mode enabled.
>
> These 2 different methods of identifying direct IOs can result in
> inconsistencies generating stale data access for direct reads after a
> direct IO write that is treated as a buffered write. Fix this
> inconsistency by combining the IOCB_DIRECT flag test with the result
> of f2fs_force_buffered_io().
>
> Reported-by: Javier Gonzalez <javier@javigon.com>
> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
> ---
> fs/f2fs/data.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 5755e897a5f0..8ac2d3b70022 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -1073,6 +1073,8 @@ int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *from)
> int flag;
> int err = 0;
> bool direct_io = iocb->ki_flags & IOCB_DIRECT;
> + bool do_direct_io = direct_io &&
> + !f2fs_force_buffered_io(inode, iocb, from);
>
> /* convert inline data for Direct I/O*/
> if (direct_io) {
> @@ -1081,7 +1083,7 @@ int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *from)
> return err;
> }
>
> - if (direct_io && allow_outplace_dio(inode, iocb, from))
> + if (do_direct_io && allow_outplace_dio(inode, iocb, from))

It seems f2fs_force_buffered_io() includes allow_outplace_dio().

How about this?
---
fs/f2fs/data.c | 13 -------------
fs/f2fs/file.c | 35 +++++++++++++++++++++++++----------
2 files changed, 25 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..6b32ac6c3382 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -3386,18 +3386,33 @@ 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*/
+ err = f2fs_convert_inline_inode(inode);
+ if (err)
+ goto out_err;
+
+ if (!f2fs_force_buffered_io(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
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