From 0cefb29e6a63727bc7606c47fc538467594ef112 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Thu, 16 Apr 2015 22:03:27 +1000 Subject: [PATCH] xfs: using generic_file_direct_write() is unnecessary generic_file_direct_write() does all sorts of things to make DIO work "sorta ok" with mixed buffered IO workloads. We already do most of this work in xfs_file_aio_dio_write() because of the locking requirements, so there's only a couple of things it does for us. The first thing is that it does a page cache invalidation after the ->direct_IO callout. This can easily be added to the XFS code. The second thing it does is that if data was written, it updates the iov_iter structure to reflect the data written, and then does EOF size updates if necessary. For XFS, these EOF size updates are now not necessary, as we do them safely and race-free in IO completion context. That leaves just the iov_iter update, and that's also moved to the XFS code. Therefore we don't need to call generic_file_direct_write() and in doing so remove redundant buffered writeback and page cache invalidation calls from the DIO submission path. We also remove a racy EOF size update, and make the DIO submission code in XFS much easier to follow. Wins all round, really. Signed-off-by: Dave Chinner Reviewed-by: Brian Foster Signed-off-by: Dave Chinner --- fs/xfs/xfs_file.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index f6f0e9671919..79ffb3e74f49 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -659,6 +659,8 @@ xfs_file_dio_aio_write( int iolock; size_t count = iov_iter_count(from); loff_t pos = iocb->ki_pos; + loff_t end; + struct iov_iter data; struct xfs_buftarg *target = XFS_IS_REALTIME_INODE(ip) ? mp->m_rtdev_targp : mp->m_ddev_targp; @@ -698,10 +700,11 @@ xfs_file_dio_aio_write( if (ret) goto out; iov_iter_truncate(from, count); + end = pos + count - 1; if (mapping->nrpages) { ret = filemap_write_and_wait_range(VFS_I(ip)->i_mapping, - pos, pos + count - 1); + pos, end); if (ret) goto out; /* @@ -711,7 +714,7 @@ xfs_file_dio_aio_write( */ ret = invalidate_inode_pages2_range(VFS_I(ip)->i_mapping, pos >> PAGE_CACHE_SHIFT, - (pos + count - 1) >> PAGE_CACHE_SHIFT); + end >> PAGE_CACHE_SHIFT); WARN_ON_ONCE(ret); ret = 0; } @@ -728,8 +731,22 @@ xfs_file_dio_aio_write( } trace_xfs_file_direct_write(ip, count, iocb->ki_pos, 0); - ret = generic_file_direct_write(iocb, from, pos); + data = *from; + ret = mapping->a_ops->direct_IO(WRITE, iocb, &data, pos); + + /* see generic_file_direct_write() for why this is necessary */ + if (mapping->nrpages) { + invalidate_inode_pages2_range(mapping, + pos >> PAGE_CACHE_SHIFT, + end >> PAGE_CACHE_SHIFT); + } + + if (ret > 0) { + pos += ret; + iov_iter_advance(from, ret); + iocb->ki_pos = pos; + } out: xfs_rw_iunlock(ip, iolock);