linux-kernel - [PATCH 1/4] fs: replace FOP_DIO_PARALLEL

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Message-ID: <20251029071537.1127397-2-hch@lst.de>
Date: Wed, 29 Oct 2025 08:15:02 +0100
From: Christoph Hellwig <hch@....de>
To: Carlos Maiolino <cem@...nel.org>,
	Christian Brauner <brauner@...nel.org>
Cc: Jan Kara <jack@...e.cz>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	linux-kernel@...r.kernel.org,
	linux-xfs@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	linux-raid@...r.kernel.org,
	linux-block@...r.kernel.org
Subject: [PATCH 1/4] fs: replace FOP_DIO_PARALLEL_WRITE with a fmode bits

To properly handle the direct to buffered I/O fallback for devices that
require stable writes, we need to be able to set the DIO_PARALLEL_WRITE
on a per-file basis and no statically for a given file_operations
instance.

This effectively reverts a part of 210a03c9d51a ("fs: claw back a few
FMODE_* bits").

Signed-off-by: Christoph Hellwig <hch@....de>
---
 fs/ext4/file.c      | 2 +-
 fs/xfs/xfs_file.c   | 4 ++--
 include/linux/fs.h  | 7 ++-----
 io_uring/io_uring.c | 2 +-
 4 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 7a8b30932189..b484e98b9c78 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -924,6 +924,7 @@ static int ext4_file_open(struct inode *inode, struct file *filp)
 		filp->f_mode |= FMODE_CAN_ATOMIC_WRITE;
 
 	filp->f_mode |= FMODE_NOWAIT | FMODE_CAN_ODIRECT;
+	filp->f_mode |= FMODE_DIO_PARALLEL_WRITE;
 	return dquot_file_open(inode, filp);
 }
 
@@ -978,7 +979,6 @@ const struct file_operations ext4_file_operations = {
 	.splice_write	= iter_file_splice_write,
 	.fallocate	= ext4_fallocate,
 	.fop_flags	= FOP_MMAP_SYNC | FOP_BUFFER_RASYNC |
-			  FOP_DIO_PARALLEL_WRITE |
 			  FOP_DONTCACHE,
 };
 
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 2702fef2c90c..5703b6681b1d 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1553,6 +1553,7 @@ xfs_file_open(
 	if (xfs_is_shutdown(XFS_M(inode->i_sb)))
 		return -EIO;
 	file->f_mode |= FMODE_NOWAIT | FMODE_CAN_ODIRECT;
+	file->f_mode |= FMODE_DIO_PARALLEL_WRITE;
 	if (xfs_get_atomic_write_min(XFS_I(inode)) > 0)
 		file->f_mode |= FMODE_CAN_ATOMIC_WRITE;
 	return generic_file_open(inode, file);
@@ -1951,8 +1952,7 @@ const struct file_operations xfs_file_operations = {
 	.fadvise	= xfs_file_fadvise,
 	.remap_file_range = xfs_file_remap_range,
 	.fop_flags	= FOP_MMAP_SYNC | FOP_BUFFER_RASYNC |
-			  FOP_BUFFER_WASYNC | FOP_DIO_PARALLEL_WRITE |
-			  FOP_DONTCACHE,
+			  FOP_BUFFER_WASYNC | FOP_DONTCACHE,
 };
 
 const struct file_operations xfs_dir_file_operations = {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index c895146c1444..09b47effc55e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -128,9 +128,8 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
 #define FMODE_WRITE_RESTRICTED	((__force fmode_t)(1 << 6))
 /* File supports atomic writes */
 #define FMODE_CAN_ATOMIC_WRITE	((__force fmode_t)(1 << 7))
-
-/* FMODE_* bit 8 */
-
+/* Supports non-exclusive O_DIRECT writes from multiple threads */
+#define FMODE_DIO_PARALLEL_WRITE ((__force fmode_t)(1 << 8))
 /* 32bit hashes as llseek() offset (for directories) */
 #define FMODE_32BITHASH         ((__force fmode_t)(1 << 9))
 /* 64bit hashes as llseek() offset (for directories) */
@@ -2317,8 +2316,6 @@ struct file_operations {
 #define FOP_BUFFER_WASYNC	((__force fop_flags_t)(1 << 1))
 /* Supports synchronous page faults for mappings */
 #define FOP_MMAP_SYNC		((__force fop_flags_t)(1 << 2))
-/* Supports non-exclusive O_DIRECT writes from multiple threads */
-#define FOP_DIO_PARALLEL_WRITE	((__force fop_flags_t)(1 << 3))
 /* Contains huge pages */
 #define FOP_HUGE_PAGES		((__force fop_flags_t)(1 << 4))
 /* Treat loff_t as unsigned (e.g., /dev/mem) */
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 296667ba712c..668937da27e8 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -469,7 +469,7 @@ static void io_prep_async_work(struct io_kiocb *req)
 
 		/* don't serialize this request if the fs doesn't need it */
 		if (should_hash && (req->file->f_flags & O_DIRECT) &&
-		    (req->file->f_op->fop_flags & FOP_DIO_PARALLEL_WRITE))
+		    (req->file->f_mode & FMODE_DIO_PARALLEL_WRITE))
 			should_hash = false;
 		if (should_hash || (ctx->flags & IORING_SETUP_IOPOLL))
 			io_wq_hash_work(&req->work, file_inode(req->file));
-- 
2.47.3