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direct-io: add flag to allow aio writes beyond i_size 

Some filesystems can handle direct I/O writes beyond i_size safely,
so allow them to opt into receiving them.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
This commit is contained in:
Christoph Hellwig 2014-02-10 10:27:11 +11:00 committed by Dave Chinner
parent 38dbfb59d1
commit 6039257378
2 changed files with 15 additions and 6 deletions
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18
fs/direct-io.c
View File

@ -1194,13 +1194,19 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
}
/*
* For file extending writes updating i_size before data
* writeouts complete can expose uninitialized blocks. So
* even for AIO, we need to wait for i/o to complete before
* returning in this case.
* For file extending writes updating i_size before data writeouts
* complete can expose uninitialized blocks in dumb filesystems.
* In that case we need to wait for I/O completion even if asked
* for an asynchronous write.
*/
dio->is_async = !is_sync_kiocb(iocb) && !((rw & WRITE) &&
(end > i_size_read(inode)));
if (is_sync_kiocb(iocb))
dio->is_async = false;
else if (!(dio->flags & DIO_ASYNC_EXTEND) &&
(rw & WRITE) && end > i_size_read(inode))
dio->is_async = false;
else
dio->is_async = true;
dio->inode = inode;
dio->rw = rw;

3
include/linux/fs.h
View File

@ -2527,6 +2527,9 @@ enum {
/* filesystem does not support filling holes */
DIO_SKIP_HOLES = 0x02,
/* filesystem can handle aio writes beyond i_size */
DIO_ASYNC_EXTEND = 0x04,
};
void dio_end_io(struct bio *bio, int error);