Re: [PATCH 06/16] vfs: Rename generic_file_aio_write_nolock

[Christoph Hellwig <hch@lst.de>]

On Wed, Sep 02, 2009 at 03:59:16PM +0200, Jan Kara wrote:
> generic_file_aio_write_nolock() is now used only by block devices and raw
> character device. Filesystems should use __generic_file_aio_write() in case
> generic_file_aio_write() doesn't suit them. So rename the function to
> device_aio_write().

I would recommend this one on top:

Move it to fs/block_dev.c, rename it to blkdev_aio_write, export it _GPL
only and make it very clear it's only for block devices and raw.


And btw, I'm not actually sure it is the right thing for raw.  Raw is
supposed to do direct I/O only, and in fact forced O_DIRECT on.  Because
there are no holes it also can't fall back to direct I/O.  So strictly
spreaking we could just use __generic_file_aio_write directly.   That
is until we care about the hw disk caches..

Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: linux-2.6/drivers/char/raw.c
===================================================================
--- linux-2.6.orig/drivers/char/raw.c	2009-09-02 11:29:21.772122902 -0300
+++ linux-2.6/drivers/char/raw.c	2009-09-02 11:29:31.996123226 -0300
@@ -246,7 +246,7 @@ static const struct file_operations raw_
 	.read	=	do_sync_read,
 	.aio_read = 	generic_file_aio_read,
 	.write	=	do_sync_write,
-	.aio_write =	device_aio_write,
+	.aio_write =	blkdev_aio_write,
 	.open	=	raw_open,
 	.release=	raw_release,
 	.ioctl	=	raw_ioctl,
Index: linux-2.6/fs/block_dev.c
===================================================================
--- linux-2.6.orig/fs/block_dev.c	2009-09-02 11:26:33.344623333 -0300
+++ linux-2.6/fs/block_dev.c	2009-09-02 15:04:15.125012009 -0300
@@ -1405,6 +1405,33 @@ static long block_ioctl(struct file *fil
 }
 
 /*
+ * Write data to the block device.  Only intended for the block device itself
+ * and the raw driver which basically is a fake block device.
+ *
+ * Does not take i_mutex for the write and thus is not for general purpose
+ * use.
+ */
+ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
+			 unsigned long nr_segs, loff_t pos)
+{
+	struct file *file = iocb->ki_filp;
+	ssize_t ret;
+
+	BUG_ON(iocb->ki_pos != pos);
+
+	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
+	if (ret > 0 || ret == -EIOCBQUEUED) {
+		ssize_t err;
+
+		err = generic_write_sync(file, pos, ret);
+		if (err < 0 && ret > 0)
+			ret = err;
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(blkdev_aio_write);
+
+/*
  * Try to release a page associated with block device when the system
  * is under memory pressure.
  */
@@ -1436,7 +1463,7 @@ const struct file_operations def_blk_fop
 	.read		= do_sync_read,
 	.write		= do_sync_write,
   	.aio_read	= generic_file_aio_read,
-	.aio_write	= device_aio_write,
+	.aio_write	= blkdev_aio_write,
 	.mmap		= generic_file_mmap,
 	.fsync		= block_fsync,
 	.unlocked_ioctl	= block_ioctl,
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h	2009-09-02 11:28:36.464127763 -0300
+++ linux-2.6/include/linux/fs.h	2009-09-02 15:04:34.740769169 -0300
@@ -2196,8 +2196,6 @@ extern ssize_t generic_file_aio_read(str
 extern ssize_t __generic_file_aio_write(struct kiocb *, const struct iovec *, unsigned long,
 		loff_t *);
 extern ssize_t generic_file_aio_write(struct kiocb *, const struct iovec *, unsigned long, loff_t);
-extern ssize_t device_aio_write(struct kiocb *iocb, const struct iovec *iov,
-				unsigned long nr_segs, loff_t pos);
 extern ssize_t generic_file_direct_write(struct kiocb *, const struct iovec *,
 		unsigned long *, loff_t, loff_t *, size_t, size_t);
 extern ssize_t generic_file_buffered_write(struct kiocb *, const struct iovec *,
@@ -2207,6 +2205,10 @@ extern ssize_t do_sync_write(struct file
 extern int generic_segment_checks(const struct iovec *iov,
 		unsigned long *nr_segs, size_t *count, int access_flags);
 
+/* fs/block_dev.c */
+extern ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov,
+				unsigned long nr_segs, loff_t pos);
+
 /* fs/splice.c */
 extern ssize_t generic_file_splice_read(struct file *, loff_t *,
 		struct pipe_inode_info *, size_t, unsigned int);
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c	2009-09-02 11:26:33.240134550 -0300
+++ linux-2.6/mm/filemap.c	2009-09-02 11:27:03.488134215 -0300
@@ -2398,41 +2398,6 @@ out:
 EXPORT_SYMBOL(__generic_file_aio_write);
 
 /**
- * device_aio_write - write data
- * @iocb:	IO state structure
- * @iov:	vector with data to write
- * @nr_segs:	number of segments in the vector
- * @pos:	position in file where to write
- *
- * This is a wrapper around __generic_file_aio_write() which takes care of
- * syncing the file in case of O_SYNC file. It does not take i_mutex for the
- * write itself but may do so during syncing. It is meant for users like block
- * devices which do not need i_mutex during write. If your filesystem needs to
- * do a write but already holds i_mutex, use __generic_file_aio_write()
- * directly and then sync the file like generic_file_aio_write().
- */
-ssize_t device_aio_write(struct kiocb *iocb, const struct iovec *iov,
-			 unsigned long nr_segs, loff_t pos)
-{
-	struct file *file = iocb->ki_filp;
-	ssize_t ret;
-
-	BUG_ON(iocb->ki_pos != pos);
-
-	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
-
-	if (ret > 0 || ret == -EIOCBQUEUED) {
-		ssize_t err;
-
-		err = generic_write_sync(file, pos, ret);
-		if (err < 0 && ret > 0)
-			ret = err;
-	}
-	return ret;
-}
-EXPORT_SYMBOL(device_aio_write);
-
-/**
  * generic_file_aio_write - write data to a file
  * @iocb:	IO state structure
  * @iov:	vector with data to write