[PATCH -mm only] Pass IO size to batch_write() address space operation

[Badari Pulavarty <pbadari@us.ibm.com>]

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Hi,

Here is the patch to pass size of the remaining IO to batch_write() 
interface.
I would like to use it ext3/ext4 to allocate in chunks. Currently its 
passing
only the size of the current buffer (in the vector entry).

Comments ? Flames ? Looks reasonable ?

Thanks,
Badari



[-- Attachment #2: pass_io_size_to_batch_write.patch --]
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Pass remaining size of this IO to batch_write(). This
way filesystems could choose to allocate for the entire IO,
instead of current buffer size.

I would like to use this for setting ext3 reservation window
or allocating entire extent (ext4).


Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>

---
 include/linux/fs.h |    2 ++
 mm/filemap.c       |    1 +
 2 files changed, 3 insertions(+)

Index: linux-2.6.18-rc1/include/linux/fs.h
===================================================================
--- linux-2.6.18-rc1.orig/include/linux/fs.h	2006-07-24 10:12:18.000000000 -0700
+++ linux-2.6.18-rc1/include/linux/fs.h	2006-07-24 10:35:51.000000000 -0700
@@ -356,6 +356,7 @@ struct writeback_control;
  * struct write_descriptor - set of write arguments
  * @pos: offset from the start of the file to write to
  * @count: number of bytes to write
+ * @iosize: remaining number of bytes in the IO
  * @buf: pointer to data to be written
  * @lru_pvec: multipage container to batch adding pages to LRU list
  * @cached_page: allocated but not used on previous call
@@ -366,6 +367,7 @@ struct writeback_control;
 struct write_descriptor {
 	loff_t pos;
 	size_t count;
+	size_t iosize;
 	char __user *buf;
 	struct page *cached_page;
 	struct pagevec *lru_pvec;
Index: linux-2.6.18-rc1/mm/filemap.c
===================================================================
--- linux-2.6.18-rc1.orig/mm/filemap.c	2006-07-24 10:12:20.000000000 -0700
+++ linux-2.6.18-rc1/mm/filemap.c	2006-07-24 10:36:44.000000000 -0700
@@ -2278,6 +2278,7 @@ generic_file_buffered_write(struct kiocb
 	do {
 		/* do not walk over current segment */
 		desc.buf = cur_iov->iov_base + iov_base;
+		desc.iosize = count;
 		desc.count = min(count, cur_iov->iov_len - iov_base);
 		if (desc.count > 0)
 			status = (*batch_write)(file, &desc, &copied);