New flag, equivalent to removal of IOCB_DSYNC from iocb flags.
This mimics what btrfs is doing (and that's what btrfs will
switch to). However, I'm not at all sure that we want to
suppress REQ_FUA for those - all btrfs hack really cares about
is suppression of generic_write_sync(). For now let's keep
the existing behaviour, but I really want to hear more detailed
arguments pro or contra.
[folded brain fix from willy]
Suggested-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Christian Brauner (Microsoft) <brauner@xxxxxxxxxx>
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
fs/iomap/direct-io.c | 20 +++++++++++---------
include/linux/iomap.h | 6 ++++++
2 files changed, 17 insertions(+), 9 deletions(-)
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 370c3241618a..c10c69e2de24 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -548,17 +548,19 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
}
/* for data sync or sync, we need sync completion processing */
- if (iocb->ki_flags & IOCB_DSYNC)
+ if (iocb->ki_flags & IOCB_DSYNC &&
+ !(dio_flags & IOMAP_DIO_NOSYNC)) {
dio->flags |= IOMAP_DIO_NEED_SYNC;
- /*
- * For datasync only writes, we optimistically try using FUA for
- * this IO. Any non-FUA write that occurs will clear this flag,
- * hence we know before completion whether a cache flush is
- * necessary.
- */
- if ((iocb->ki_flags & (IOCB_DSYNC | IOCB_SYNC)) == IOCB_DSYNC)
- dio->flags |= IOMAP_DIO_WRITE_FUA;
+ /*
+ * For datasync only writes, we optimistically try
+ * using FUA for this IO. Any non-FUA write that
+ * occurs will clear this flag, hence we know before
+ * completion whether a cache flush is necessary.
+ */
+ if (!(iocb->ki_flags & IOCB_SYNC))
+ dio->flags |= IOMAP_DIO_WRITE_FUA;
+ }
}
if (dio_flags & IOMAP_DIO_OVERWRITE_ONLY) {
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index e552097c67e0..c8622d8f064e 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -353,6 +353,12 @@ struct iomap_dio_ops {
*/
#define IOMAP_DIO_PARTIAL (1 << 2)
+/*
+ * The caller will sync the write if needed; do not sync it within
+ * iomap_dio_rw. Overrides IOMAP_DIO_FORCE_WAIT.
+ */
+#define IOMAP_DIO_NOSYNC (1 << 3)
+
ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
unsigned int dio_flags, void *private, size_t done_before);
--
2.30.2
