Don't complete AIO file extension until i_size is updated
AIO O_DIRECT file extension has a bug where the IO is completed before i_size
is updated. direct_io_worker() calls aio_complete() after performing the
extension but before we get back up into generic_file_direct_write() which
updates i_size. Another thread in io_getevents() can catch the completion and
stat() the file before i_size is updated.
Previously the direct write path would always call aio_complete() and return
-EIOCBQUEUED. This fixes the bug by returning the bytes written in the sync
aio case which lets the aio core call aio_complete() after i_size has been
written. Now the only time -EIOCBQUEUED is returned and aio_complete() is
called is when bios are still in flight at the time direct_io_worker() returns.
Signed-off-by: Zach Brown <[email protected]>
---
This fixes the bug reported (with a test case!) in
http://bugzilla.kernel.org/show_bug.cgi?id=6831
light aio-stress runs work after the change but we all know that fs/direct-io.c
is incredibly fragile. Can you guys review this? Has anyone packaged the
tests at http://developer.osdl.org/daniel/AIO/ in a way that can be used to
check for regressions?
fs/direct-io.c | 15 ++++-----------
mm/filemap.c | 2 --
2 files changed, 4 insertions(+), 13 deletions(-)
Index: 2.6.18-rc1-mm2-odirextend/fs/direct-io.c
===================================================================
--- 2.6.18-rc1-mm2-odirextend.orig/fs/direct-io.c
+++ 2.6.18-rc1-mm2-odirextend/fs/direct-io.c
@@ -1094,8 +1094,6 @@ direct_io_worker(int rw, struct kiocb *i
dio->waiter = current;
should_wait = 1;
}
- if (ret == 0)
- ret = dio->result;
finished_one_bio(dio); /* This can free the dio */
blk_run_address_space(inode->i_mapping);
if (should_wait) {
@@ -1117,7 +1115,10 @@ direct_io_worker(int rw, struct kiocb *i
spin_unlock_irqrestore(&dio->bio_lock, flags);
set_current_state(TASK_RUNNING);
kfree(dio);
- }
+ if (ret == 0)
+ ret = dio->result;
+ } else
+ ret = -EIOCBQUEUED;
} else {
ssize_t transferred = 0;
@@ -1142,14 +1143,6 @@ direct_io_worker(int rw, struct kiocb *i
if (ret == 0)
ret = transferred;
- /* We could have also come here on an AIO file extend */
- if (!is_sync_kiocb(iocb) && (rw & WRITE) &&
- ret >= 0 && dio->result == dio->size)
- /*
- * For AIO writes where we have completed the
- * i/o, we have to mark the the aio complete.
- */
- aio_complete(iocb, ret, 0);
kfree(dio);
}
return ret;
Index: 2.6.18-rc1-mm2-odirextend/mm/filemap.c
===================================================================
--- 2.6.18-rc1-mm2-odirextend.orig/mm/filemap.c
+++ 2.6.18-rc1-mm2-odirextend/mm/filemap.c
@@ -2129,8 +2129,6 @@ generic_file_direct_write(struct kiocb *
if (err < 0)
written = err;
}
- if (written == count && !is_sync_kiocb(iocb))
- written = -EIOCBQUEUED;
return written;
}
EXPORT_SYMBOL(generic_file_direct_write);
-
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