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[PATCH 2/2] xfs: move aio completion after unwritten extent conversion

To: linux-fsdevel@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx, linux-ext4@xxxxxxxxxxxxxxx
Subject: [PATCH 2/2] xfs: move aio completion after unwritten extent conversion
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Tue, 22 Jun 2010 08:21:46 -0400
References: <20100622122144.302857146@xxxxxxxxxxxxxxxxxxxxxx>
User-agent: quilt/0.47-1
If we write into an unwritten extent using AIO we need to complete the AIO
request after the extent conversion has finished.  Without that a read could
race to see see the extent still unwritten and return zeros.   For synchronous
I/O we already take care of that by flushing the xfsconvertd workqueue (which
might be a bit of overkill).

To do that add iocb and result fields to struct xfs_ioend, so that we can
call aio_complete from xfs_end_io after the extent conversion has happened.
Note that we need a new result field as io_error is used for positive errno
values, while the AIO code can return negative error values and positive
transfer sizes.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>

Index: linux-2.6/fs/xfs/linux-2.6/xfs_aops.c
===================================================================
--- linux-2.6.orig/fs/xfs/linux-2.6/xfs_aops.c  2010-06-22 14:05:02.522005722 
+0200
+++ linux-2.6/fs/xfs/linux-2.6/xfs_aops.c       2010-06-22 14:08:30.065006205 
+0200
@@ -275,8 +275,11 @@ xfs_end_io(
                xfs_finish_ioend(ioend, 0);
                /* ensure we don't spin on blocked ioends */
                delay(1);
-       } else
+       } else {
+               if (ioend->io_iocb)
+                       aio_complete(ioend->io_iocb, ioend->io_result, 0);
                xfs_destroy_ioend(ioend);
+       }
 }
 
 /*
@@ -309,6 +312,8 @@ xfs_alloc_ioend(
        atomic_inc(&XFS_I(ioend->io_inode)->i_iocount);
        ioend->io_offset = 0;
        ioend->io_size = 0;
+       ioend->io_iocb = NULL;
+       ioend->io_result = 0;
 
        INIT_WORK(&ioend->io_work, xfs_end_io);
        return ioend;
@@ -1604,6 +1609,7 @@ xfs_end_io_direct(
        bool            is_async)
 {
        xfs_ioend_t     *ioend = iocb->private;
+       bool            complete_aio = is_async;
 
        /*
         * Non-NULL private data means we need to issue a transaction to
@@ -1629,7 +1635,14 @@ xfs_end_io_direct(
        if (ioend->io_type == IO_READ) {
                xfs_finish_ioend(ioend, 0);
        } else if (private && size > 0) {
-               xfs_finish_ioend(ioend, is_sync_kiocb(iocb));
+               if (is_async) {
+                       ioend->io_iocb = iocb;
+                       ioend->io_result = ret;
+                       complete_aio = false;
+                       xfs_finish_ioend(ioend, 0);
+               } else {
+                       xfs_finish_ioend(ioend, 1);
+               }
        } else {
                /*
                 * A direct I/O write ioend starts it's life in unwritten
@@ -1648,7 +1661,7 @@ xfs_end_io_direct(
         */
        iocb->private = NULL;
 
-       if (is_async)
+       if (complete_aio)
                aio_complete(iocb, ret, 0);
 }
 

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