[PATCH 6/7] aio: implement IOCB_CMD_FSYNC and IOCB_CMD_FDSYNC

[Christoph Hellwig]

Simple workqueue offload for now, but prepared for adding a real aio_fsync
method if the need arises.  Based on an earlier patch from Dave Chinner.

Signed-off-by: Christoph Hellwig <h...@lst.de>
Reviewed-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Reviewed-by: Darrick J. Wong <darrick.w...@oracle.com>
---
 fs/aio.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/fs/aio.c b/fs/aio.c
index d07c27b3fe88..61d2e6942951 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -156,6 +156,12 @@ struct kioctx {
        unsigned                id;
 };
 
+struct fsync_iocb {
+       struct work_struct      work;
+       struct file             *file;
+       bool                    datasync;
+};
+
 /*
  * We use ki_cancel == KIOCB_CANCELLED to indicate that a kiocb has been either
  * cancelled or completed (this makes a certain amount of sense because
@@ -172,6 +178,7 @@ struct kioctx {
 struct aio_kiocb {
        union {
                struct kiocb            rw;
+               struct fsync_iocb       fsync;
        };
 
        struct kioctx           *ki_ctx;
@@ -1573,6 +1580,36 @@ static ssize_t aio_write(struct kiocb *req, struct iocb 
*iocb, bool vectored,
        return ret;
 }
 
+static void aio_fsync_work(struct work_struct *work)
+{
+       struct fsync_iocb *req = container_of(work, struct fsync_iocb, work);
+       int ret;
+
+       ret = vfs_fsync(req->file, req->datasync);
+       fput(req->file);
+       aio_complete(container_of(req, struct aio_kiocb, fsync), ret, 0);
+}
+
+static int aio_fsync(struct fsync_iocb *req, struct iocb *iocb, bool datasync)
+{
+       if (unlikely(iocb->aio_buf || iocb->aio_offset || iocb->aio_nbytes ||
+                       iocb->aio_rw_flags))
+               return -EINVAL;
+
+       req->file = fget(iocb->aio_fildes);
+       if (unlikely(!req->file))
+               return -EBADF;
+       if (unlikely(!req->file->f_op->fsync)) {
+               fput(req->file);
+               return -EINVAL;
+       }
+
+       req->datasync = datasync;
+       INIT_WORK(&req->work, aio_fsync_work);
+       schedule_work(&req->work);
+       return -EIOCBQUEUED;
+}
+
 static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
                         struct iocb *iocb, bool compat)
 {
@@ -1636,6 +1673,12 @@ static int io_submit_one(struct kioctx *ctx, struct iocb 
__user *user_iocb,
        case IOCB_CMD_PWRITEV:
                ret = aio_write(&req->rw, iocb, true, compat);
                break;
+       case IOCB_CMD_FSYNC:
+               ret = aio_fsync(&req->fsync, iocb, false);
+               break;
+       case IOCB_CMD_FDSYNC:
+               ret = aio_fsync(&req->fsync, iocb, true);
+               break;
        default:
                pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode);
                ret = -EINVAL;
-- 
2.17.0