iomap: iomap_dio_rw() handles all sync writes
Currently iomap_dio_rw() only handles (data)sync write completions
for AIO. This means we can't optimised non-AIO IO to minimise device
flushes as we can't tell the caller whether a flush is required or
not.
To solve this problem and enable further optimisations, make
iomap_dio_rw responsible for data sync behaviour for all IO, not
just AIO.
In doing so, the sync operation is now accounted as part of the DIO
IO by inode_dio_end(), hence post-IO data stability updates will no
long race against operations that serialise via inode_dio_wait()
such as truncate or hole punch.
Signed-Off-By: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
diff --git a/fs/iomap.c b/fs/iomap.c
index afd1635..b044d8e 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -685,6 +685,7 @@
* Private flags for iomap_dio, must not overlap with the public ones in
* iomap.h:
*/
+#define IOMAP_DIO_NEED_SYNC (1 << 29)
#define IOMAP_DIO_WRITE (1 << 30)
#define IOMAP_DIO_DIRTY (1 << 31)
@@ -759,6 +760,13 @@
dio_warn_stale_pagecache(iocb->ki_filp);
}
+ /*
+ * If this is a DSYNC write, make sure we push it to stable storage now
+ * that we've written data.
+ */
+ if (ret > 0 && (dio->flags & IOMAP_DIO_NEED_SYNC))
+ ret = generic_write_sync(iocb, ret);
+
inode_dio_end(file_inode(iocb->ki_filp));
kfree(dio);
@@ -769,13 +777,8 @@
{
struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work);
struct kiocb *iocb = dio->iocb;
- bool is_write = (dio->flags & IOMAP_DIO_WRITE);
- ssize_t ret;
- ret = iomap_dio_complete(dio);
- if (is_write && ret > 0)
- ret = generic_write_sync(iocb, ret);
- iocb->ki_complete(iocb, ret, 0);
+ iocb->ki_complete(iocb, iomap_dio_complete(dio), 0);
}
/*
@@ -961,6 +964,10 @@
return copied;
}
+/*
+ * iomap_dio_rw() always completes O_[D]SYNC writes regardless of whether the IO
+ * is being issued as AIO or not.
+ */
ssize_t
iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
const struct iomap_ops *ops, iomap_dio_end_io_t end_io)
@@ -1006,6 +1013,8 @@
dio->flags |= IOMAP_DIO_DIRTY;
} else {
dio->flags |= IOMAP_DIO_WRITE;
+ if (iocb->ki_flags & IOCB_DSYNC)
+ dio->flags |= IOMAP_DIO_NEED_SYNC;
flags |= IOMAP_WRITE;
}