Re: [PATCH v4 5/7] fs: prioritize and separate direct_io from dax_io
From: Christoph Hellwig <hch@infradead.org>
Date: 2016-05-02 14:56:06
Also in:
linux-ext4, linux-fsdevel, linux-mm, linux-xfs, lkml
quoted hunk ↗ jump to hunk
index 79defba..97a1f5f 100644--- a/fs/block_dev.c +++ b/fs/block_dev.c@@ -167,12 +167,21 @@ blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset) struct file *file = iocb->ki_filp; struct inode *inode = bdev_file_inode(file); - if (IS_DAX(inode)) + if (iocb_is_direct(iocb)) + return __blockdev_direct_IO(iocb, inode, I_BDEV(inode), iter, + offset, blkdev_get_block, NULL, + NULL, DIO_SKIP_DIO_COUNT); + else if (iocb_is_dax(iocb)) return dax_do_io(iocb, inode, iter, offset, blkdev_get_block, NULL, DIO_SKIP_DIO_COUNT); - return __blockdev_direct_IO(iocb, inode, I_BDEV(inode), iter, offset, - blkdev_get_block, NULL, NULL, - DIO_SKIP_DIO_COUNT); + else { + /* + * If we're in the direct_IO path, either the IOCB_DIRECT or + * IOCB_DAX flags must be set. + */ + WARN_ONCE(1, "Kernel Bug with iocb flags\n"); + return -ENXIO; + }
DAX should not even end up in ->direct_IO.
quoted hunk ↗ jump to hunk
--- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c@@ -300,7 +300,7 @@ xfs_file_read_iter( XFS_STATS_INC(mp, xs_read_calls); - if (unlikely(iocb->ki_flags & IOCB_DIRECT)) + if (unlikely(iocb->ki_flags & (IOCB_DIRECT | IOCB_DAX))) ioflags |= XFS_IO_ISDIRECT;
please also add a XFS_IO_ISDAX flag to propagate the information properly and allow tracing to display the actual I/O type.
+static inline bool iocb_is_dax(struct kiocb *iocb)
{
+ return IS_DAX(file_inode(iocb->ki_filp)) &&
+ (iocb->ki_flags & IOCB_DAX);
+}
+
+static inline bool iocb_is_direct(struct kiocb *iocb)
+{
+ return iocb->ki_flags & IOCB_DIRECT;
}No need for these helpers - especially as IOCB_DAX should never be set if IS_DAX is false.