[PATCH 1/3] ext2: drain in-flight DIO before buffered write fallback

[PATCH 1/3] ext2: drain in-flight DIO before buffered write fallback

[Jiale Yao]

An asynchronous direct write can remain in flight after the inode lock is
released.  If another direct write falls back to buffered I/O while the
first write is still pending, generic_perform_write() can dirty pages
before the first write completes its post-I/O page cache invalidation.
The invalidation then finds dirty pages, reports a page cache invalidation
failure, and records -EIO in the mapping error sequence.  A later fsync()
therefore returns -EIO.

Commit 15cdefd0c0522f9d5e12d947fa04f4c11649b699 ("ext4: drain
in-flight DIO before buffered write fallback") fixed the same race in
ext4.  Ext2 has an equivalent fallback after iomap_dio_rw() returns
-ENOTBLK or a short write, but does not drain other in-flight DIO before
dirtying the page cache.

Wait for in-flight DIO before calling generic_perform_write() in the
fallback path.

A reproducer using concurrent AIO direct writes and buffered fallback
triggered the following warning and made a subsequent fsync() return
-EIO:

  Page cache invalidation failure on direct I/O.  Possible data corruption
  due to collision with buffered I/O!

Fixes: fb5de4358e1a ("ext2: Move direct-io to use iomap")
Link: https://lore.kernel.org/r/20260629113827.4074335-3-libaokun@linux.alibaba.com
Signed-off-by: Jiale Yao <yaojiale02@163.com>
---
 fs/ext2/file.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index b9020df7d89e..67fe423c3828 100644
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -135,6 +135,13 @@ static ssize_t ext2_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		int ret2;
 
 		iocb->ki_flags &= ~IOCB_DIRECT;
+
+		/*
+		 * Prevent concurrent direct I/O and buffered I/O to the same file
+		 * range. Wait for in-flight DIO to finish before dirtying pages.
+		 */
+		inode_dio_wait(inode);
+
 		pos = iocb->ki_pos;
 		status = generic_perform_write(iocb, from);
 		if (unlikely(status < 0)) {
-- 
2.34.1

[PATCH 2/3] ntfs: drain in-flight DIO before buffered write fallback

[Jiale Yao]

An asynchronous direct write can remain in flight after the inode lock is
released.  If another direct write falls back to buffered I/O while the
first write is still pending, iomap_file_buffered_write() can dirty pages
before the first write completes its post-I/O page cache invalidation.
The invalidation then finds dirty pages, reports a page cache invalidation
failure, and records -EIO in the mapping error sequence.  A later fsync()
therefore returns -EIO.

Commit 15cdefd0c0522f9d5e12d947fa04f4c11649b699 ("ext4: drain
in-flight DIO before buffered write fallback") fixed the same race in
ext4.  NTFS has an equivalent fallback after iomap_dio_rw() returns
-ENOTBLK or a short write, but does not drain other in-flight DIO before
dirtying the page cache.

Wait for in-flight DIO before calling iomap_file_buffered_write() in the
fallback path.

A reproducer using concurrent AIO direct writes and buffered fallback
triggered the following warning and made a subsequent fsync() return
-EIO:

  Page cache invalidation failure on direct I/O.  Possible data corruption
  due to collision with buffered I/O!

Fixes: 9c87959601e8 ("ntfs: update file operations")
Link: https://lore.kernel.org/r/20260629113827.4074335-3-libaokun@linux.alibaba.com
Signed-off-by: Jiale Yao <yaojiale02@163.com>
---
 fs/ntfs/file.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index 007d1614b9ac..2fc2ffde3846 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -527,6 +527,13 @@ static ssize_t ntfs_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 
 		offset = iocb->ki_pos;
 		iocb->ki_flags &= ~IOCB_DIRECT;
+
+		/*
+		 * Prevent concurrent direct I/O and buffered I/O to the same file
+		 * range. Wait for in-flight DIO to finish before dirtying pages.
+		 */
+		inode_dio_wait(file_inode(iocb->ki_filp));
+
 		written = iomap_file_buffered_write(iocb, from,
 				&ntfs_write_iomap_ops, &ntfs_iomap_folio_ops,
 				NULL);
-- 
2.34.1

[PATCH 3/3] exfat: drain in-flight DIO before buffered write fallback

[Jiale Yao]

An asynchronous direct write can remain in flight after the inode lock is
released.  If another direct write falls back to buffered I/O while the
first write is still pending, iomap_file_buffered_write() can dirty pages
before the first write completes its post-I/O page cache invalidation.
The invalidation then finds dirty pages, reports a page cache invalidation
failure, and records -EIO in the mapping error sequence.  A later fsync()
therefore returns -EIO.

Commit 15cdefd0c0522f9d5e12d947fa04f4c11649b699 ("ext4: drain
in-flight DIO before buffered write fallback") fixed the same race in
ext4.  ExFAT has an equivalent fallback after iomap_dio_rw() returns
-ENOTBLK or a short write, but does not drain other in-flight DIO before
dirtying the page cache.

Wait for in-flight DIO before calling iomap_file_buffered_write() in the
fallback path.

A reproducer using concurrent AIO direct writes and buffered fallback
triggered the following warning and made a subsequent fsync() return
-EIO:

  Page cache invalidation failure on direct I/O.  Possible data corruption
  due to collision with buffered I/O!

Fixes: 867b9c96dc83 ("exfat: add iomap direct I/O support")
Link: https://lore.kernel.org/r/20260629113827.4074335-3-libaokun@linux.alibaba.com
Signed-off-by: Jiale Yao <yaojiale02@163.com>
---
 fs/exfat/file.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index a2a9ee1a2004..cf5ccbd54823 100644
--- a/fs/exfat/file.c
+++ b/fs/exfat/file.c
@@ -807,6 +807,12 @@ static ssize_t exfat_fallback_buffered_write(struct kiocb *iocb,
 
 	iocb->ki_flags &= ~IOCB_DIRECT;
 
+	/*
+	 * Prevent concurrent direct I/O and buffered I/O to the same file
+	 * range. Wait for in-flight DIO to finish before dirtying pages.
+	 */
+	inode_dio_wait(file_inode(iocb->ki_filp));
+
 	written = iomap_file_buffered_write(iocb, from, &exfat_write_iomap_ops,
 			NULL, NULL);
 	if (written < 0)
-- 
2.34.1

Re: [PATCH 1/3] ext2: drain in-flight DIO before buffered write fallback

[Jan Kara]

On Thu 24-09-26 18:51:23, Jiale Yao wrote:
> An asynchronous direct write can remain in flight after the inode lock is
> released.  If another direct write falls back to buffered I/O while the
> first write is still pending, generic_perform_write() can dirty pages
> before the first write completes its post-I/O page cache invalidation.
> The invalidation then finds dirty pages, reports a page cache invalidation
> failure, and records -EIO in the mapping error sequence.  A later fsync()
> therefore returns -EIO.
> 
> Commit 15cdefd0c0522f9d5e12d947fa04f4c11649b699 ("ext4: drain
> in-flight DIO before buffered write fallback") fixed the same race in
> ext4.  Ext2 has an equivalent fallback after iomap_dio_rw() returns
> -ENOTBLK or a short write, but does not drain other in-flight DIO before
> dirtying the page cache.
> 
> Wait for in-flight DIO before calling generic_perform_write() in the
> fallback path.
> 
> A reproducer using concurrent AIO direct writes and buffered fallback
> triggered the following warning and made a subsequent fsync() return
> -EIO:
> 
>   Page cache invalidation failure on direct I/O.  Possible data corruption
>   due to collision with buffered I/O!
> 
> Fixes: fb5de4358e1a ("ext2: Move direct-io to use iomap")
> Link: https://lore.kernel.org/r/20260629113827.4074335-3-libaokun@linux.alibaba.com
> Signed-off-by: Jiale Yao <yaojiale02@163.com>

Thanks! Added to my tree.

								Honza

> ---
>  fs/ext2/file.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/fs/ext2/file.c b/fs/ext2/file.c
> index b9020df7d89e..67fe423c3828 100644
> --- a/fs/ext2/file.c
> +++ b/fs/ext2/file.c
> @@ -135,6 +135,13 @@ static ssize_t ext2_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
>  		int ret2;
>  
>  		iocb->ki_flags &= ~IOCB_DIRECT;
> +
> +		/*
> +		 * Prevent concurrent direct I/O and buffered I/O to the same file
> +		 * range. Wait for in-flight DIO to finish before dirtying pages.
> +		 */
> +		inode_dio_wait(inode);
> +
>  		pos = iocb->ki_pos;
>  		status = generic_perform_write(iocb, from);
>  		if (unlikely(status < 0)) {
> -- 
> 2.34.1
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

[PATCH 3/3] exfat: drain in-flight DIO before buffered write fallback

[Jiale Yao]

An asynchronous direct write can remain in flight after the inode lock is
released.  If another direct write falls back to buffered I/O while the
first write is still pending, iomap_file_buffered_write() can dirty pages
before the first write completes its post-I/O page cache invalidation.
The invalidation then finds dirty pages, reports a page cache invalidation
failure, and records -EIO in the mapping error sequence.  A later fsync()
therefore returns -EIO.

Commit 15cdefd0c0522f9d5e12d947fa04f4c11649b699 ("ext4: drain
in-flight DIO before buffered write fallback") fixed the same race in
ext4.  ExFAT has an equivalent fallback after iomap_dio_rw() returns
-ENOTBLK or a short write, but does not drain other in-flight DIO before
dirtying the page cache.

Wait for in-flight DIO before calling iomap_file_buffered_write() in the
fallback path.

A reproducer using concurrent AIO direct writes and buffered fallback
triggered the following warning and made a subsequent fsync() return
-EIO:

  Page cache invalidation failure on direct I/O.  Possible data corruption
  due to collision with buffered I/O!

Fixes: 867b9c96dc83 ("exfat: add iomap direct I/O support")
Link: https://lore.kernel.org/r/20260629113827.4074335-3-libaokun@linux.alibaba.com
Signed-off-by: Jiale Yao <yaojiale02@163.com>
---
 fs/exfat/file.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index a2a9ee1a2004..cf5ccbd54823 100644
--- a/fs/exfat/file.c
+++ b/fs/exfat/file.c
@@ -807,6 +807,12 @@ static ssize_t exfat_fallback_buffered_write(struct kiocb *iocb,
 
 	iocb->ki_flags &= ~IOCB_DIRECT;
 
+	/*
+	 * Prevent concurrent direct I/O and buffered I/O to the same file
+	 * range. Wait for in-flight DIO to finish before dirtying pages.
+	 */
+	inode_dio_wait(file_inode(iocb->ki_filp));
+
 	written = iomap_file_buffered_write(iocb, from, &exfat_write_iomap_ops,
 			NULL, NULL);
 	if (written < 0)
-- 
2.34.1