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Subject[RFC PATCH 12/22] dio: add dio_post_submission() helper function
Date
From: Zach Brown <zab@zabbo.net>

This creates a function that contains all the code that is executed
after IO is submitted. It takes code from the end of
do_blockdev_direct_IO(). This will be called by another entry point
that will be added in an upcoming patch.

Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Cc: Zach Brown <zab@zabbo.net>
---
fs/direct-io.c | 127 ++++++++++++++++++++++++++++++--------------------------
1 file changed, 68 insertions(+), 59 deletions(-)

diff --git a/fs/direct-io.c b/fs/direct-io.c
index e75b8d7..20bb84c 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -1187,6 +1187,73 @@ static int dio_lock_and_flush(struct dio *dio, loff_t offset, loff_t end)
return 0;
}

+static ssize_t dio_post_submission(int rw, loff_t offset, struct dio *dio,
+ struct dio_submit *sdio,
+ struct buffer_head *map_bh, ssize_t ret)
+{
+ if (ret == -ENOTBLK) {
+ /*
+ * The remaining part of the request will be
+ * be handled by buffered I/O when we return
+ */
+ ret = 0;
+ }
+ /*
+ * There may be some unwritten disk at the end of a part-written
+ * fs-block-sized block. Go zero that now.
+ */
+ dio_zero_block(dio, sdio, 1, map_bh);
+
+ if (sdio->cur_page) {
+ ssize_t ret2;
+
+ ret2 = dio_send_cur_page(dio, sdio, map_bh);
+ if (ret == 0)
+ ret = ret2;
+ page_cache_release(sdio->cur_page);
+ sdio->cur_page = NULL;
+ }
+ if (sdio->bio)
+ dio_bio_submit(dio, sdio);
+
+ /*
+ * It is possible that, we return short IO due to end of file.
+ * In that case, we need to release all the pages we got hold on.
+ */
+ dio_cleanup(dio, sdio);
+
+ /*
+ * All block lookups have been performed. For READ requests
+ * we can let i_mutex go now that its achieved its purpose
+ * of protecting us from looking up uninitialized blocks.
+ */
+ if (rw == READ && (dio->flags & DIO_LOCKING))
+ mutex_unlock(&dio->inode->i_mutex);
+
+ /*
+ * The only time we want to leave bios in flight is when a successful
+ * partial aio read or full aio write have been setup. In that case
+ * bio completion will call aio_complete. The only time it's safe to
+ * call aio_complete is when we return -EIOCBQUEUED, so we key on that.
+ * This had *better* be the only place that raises -EIOCBQUEUED.
+ */
+ BUG_ON(ret == -EIOCBQUEUED);
+ if (dio->is_async && ret == 0 && dio->result &&
+ ((rw & READ) || (dio->result == sdio->size)))
+ ret = -EIOCBQUEUED;
+
+ if (ret != -EIOCBQUEUED)
+ dio_await_completion(dio);
+
+ if (drop_refcount(dio) == 0) {
+ ret = dio_complete(dio, offset, ret, false);
+ kmem_cache_free(dio_cache, dio);
+ } else
+ BUG_ON(ret != -EIOCBQUEUED);
+
+ return ret;
+}
+
/*
* This is a library function for use by filesystem drivers.
*
@@ -1302,65 +1369,7 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
}
} /* end iovec loop */

- if (retval == -ENOTBLK) {
- /*
- * The remaining part of the request will be
- * be handled by buffered I/O when we return
- */
- retval = 0;
- }
- /*
- * There may be some unwritten disk at the end of a part-written
- * fs-block-sized block. Go zero that now.
- */
- dio_zero_block(dio, &sdio, 1, &map_bh);
-
- if (sdio.cur_page) {
- ssize_t ret2;
-
- ret2 = dio_send_cur_page(dio, &sdio, &map_bh);
- if (retval == 0)
- retval = ret2;
- page_cache_release(sdio.cur_page);
- sdio.cur_page = NULL;
- }
- if (sdio.bio)
- dio_bio_submit(dio, &sdio);
-
- /*
- * It is possible that, we return short IO due to end of file.
- * In that case, we need to release all the pages we got hold on.
- */
- dio_cleanup(dio, &sdio);
-
- /*
- * All block lookups have been performed. For READ requests
- * we can let i_mutex go now that its achieved its purpose
- * of protecting us from looking up uninitialized blocks.
- */
- if (rw == READ && (dio->flags & DIO_LOCKING))
- mutex_unlock(&dio->inode->i_mutex);
-
- /*
- * The only time we want to leave bios in flight is when a successful
- * partial aio read or full aio write have been setup. In that case
- * bio completion will call aio_complete. The only time it's safe to
- * call aio_complete is when we return -EIOCBQUEUED, so we key on that.
- * This had *better* be the only place that raises -EIOCBQUEUED.
- */
- BUG_ON(retval == -EIOCBQUEUED);
- if (dio->is_async && retval == 0 && dio->result &&
- ((rw & READ) || (dio->result == sdio.size)))
- retval = -EIOCBQUEUED;
-
- if (retval != -EIOCBQUEUED)
- dio_await_completion(dio);
-
- if (drop_refcount(dio) == 0) {
- retval = dio_complete(dio, offset, retval, false);
- kmem_cache_free(dio_cache, dio);
- } else
- BUG_ON(retval != -EIOCBQUEUED);
+ retval = dio_post_submission(rw, offset, dio, &sdio, &map_bh, retval);

out:
return retval;
--
1.7.9.2


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