[PATCH 1/4] fs: replace FOP_DIO_PARALLEL_WRITE with a fmode bits

Christoph Hellwig
2025-10-29T07:15:48Z

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@lst.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