[XFS] Delay direct I/O completion to a workqueue This is nessecary
because aio+dio completions may happen from irq context but we need
process context for converting unwritten extents. We also queue regular
direct I/O completions to workqueue for regularity, there's only one
queue_work call per syscall.
SGI-PV: 934766
SGI-Modid: xfs-linux:xfs-kern:196857a
Signed-off-by: Christoph Hellwig <hch@sgi.com>
Signed-off-by: Nathan Scott <nathans@sgi.com>
diff --git a/fs/xfs/linux-2.6/xfs_aops.c b/fs/xfs/linux-2.6/xfs_aops.c
index ed98c7a..2add9a8 100644
--- a/fs/xfs/linux-2.6/xfs_aops.c
+++ b/fs/xfs/linux-2.6/xfs_aops.c
@@ -126,7 +126,7 @@
/*
* Issue transactions to convert a buffer range from unwritten
- * to written extents (buffered IO).
+ * to written extents.
*/
STATIC void
xfs_end_bio_unwritten(
@@ -191,29 +191,6 @@
end_buffer_async_write(bh, uptodate);
}
-/*
- * Issue transactions to convert a buffer range from unwritten
- * to written extents (direct IO).
- */
-STATIC void
-linvfs_unwritten_convert_direct(
- struct kiocb *iocb,
- loff_t offset,
- ssize_t size,
- void *private)
-{
- struct inode *inode = iocb->ki_filp->f_dentry->d_inode;
- ASSERT(!private || inode == (struct inode *)private);
-
- /* private indicates an unwritten extent lay beneath this IO */
- if (private && size > 0) {
- vnode_t *vp = LINVFS_GET_VP(inode);
- int error;
-
- VOP_BMAP(vp, offset, size, BMAPI_UNWRITTEN, NULL, NULL, error);
- }
-}
-
STATIC int
xfs_map_blocks(
struct inode *inode,
@@ -1045,6 +1022,44 @@
create, 1, BMAPI_WRITE|BMAPI_DIRECT);
}
+STATIC void
+linvfs_end_io_direct(
+ struct kiocb *iocb,
+ loff_t offset,
+ ssize_t size,
+ void *private)
+{
+ xfs_ioend_t *ioend = iocb->private;
+
+ /*
+ * Non-NULL private data means we need to issue a transaction to
+ * convert a range from unwritten to written extents. This needs
+ * to happen from process contect but aio+dio I/O completion
+ * happens from irq context so we need to defer it to a workqueue.
+ * This is not nessecary for synchronous direct I/O, but we do
+ * it anyway to keep the code uniform and simpler.
+ *
+ * The core direct I/O code might be changed to always call the
+ * completion handler in the future, in which case all this can
+ * go away.
+ */
+ if (private && size > 0) {
+ ioend->io_offset = offset;
+ ioend->io_size = size;
+ xfs_finish_ioend(ioend);
+ } else {
+ ASSERT(size >= 0);
+ xfs_destroy_ioend(ioend);
+ }
+
+ /*
+ * blockdev_direct_IO can return an error even afer the I/O
+ * completion handler was called. Thus we need to protect
+ * against double-freeing.
+ */
+ iocb->private = NULL;
+}
+
STATIC ssize_t
linvfs_direct_IO(
int rw,
@@ -1059,16 +1074,23 @@
xfs_iomap_t iomap;
int maps = 1;
int error;
+ ssize_t ret;
VOP_BMAP(vp, offset, 0, BMAPI_DEVICE, &iomap, &maps, error);
if (error)
return -error;
- return blockdev_direct_IO_own_locking(rw, iocb, inode,
+ iocb->private = xfs_alloc_ioend(inode);
+
+ ret = blockdev_direct_IO_own_locking(rw, iocb, inode,
iomap.iomap_target->pbr_bdev,
iov, offset, nr_segs,
linvfs_get_blocks_direct,
- linvfs_unwritten_convert_direct);
+ linvfs_end_io_direct);
+
+ if (unlikely(ret <= 0 && iocb->private))
+ xfs_destroy_ioend(iocb->private);
+ return ret;
}
