[PATCH] generic_osync_inode() with OSYNC_INODE only passed (Re: [PATCH 1/2] miss-sync changes on attributes)

["Machida, Hiroyuki" <machida@sm.sony.co.jp>]

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generic__inode() seems to do over-writing, if OSYNC_INODE only passed.
According comments of generic_osync_inode(), it is expected to write inode
itself only. Current implementation trys to write data page, even if
OSYNC_INODE only passed. This patch fixes it.

This patch is preparetion of other patch to fix "miss-sync changes on
attributes".


Machida, Hiroyuki wrote:
> 
> 
> OGAWA Hirofumi wrote:
> 
>> "Machida, Hiroyuki" <machida@sm.sony.co.jp> writes:
>>
>>
>>> OGAWA Hirofumi wrote:
>>>
>>>> Andrew Morton <akpm@osdl.org> writes:
>>>>
>>>>
>>>>> However there's not much point in writing a brand-new function when
>>>>> write_inode_now() almost does the right thing.  We can share the
>>>>> implementation within fs-writeback.c.
>>>>
>>>>
>>>> Indeed. We use the generic_osync_inode() for it?
>>>
>>>
>>> Please let me confirm.
>>> Using generic_osync_inode(inode, NULL, OSYNC_INODE) instaed of
>>> sync_inode_wodata(inode) is peferable for changes on fs/open.c,
>>> even it would write data. Is it correct?
>>
>>
>>
>> No, I only thought the interface is good. I don't know why it writes
>> data pages even if OSYNC_INODE only.
> 
> 
> 
> I checked 2.6.13 tree, following functions call generic_osync_inode().
> However noone calls it with OSYNC_INODE. SO I can't find intention of
> it's usage.
> 
> Does anyone know why generic_osync_inode() trys to write data page,
> even if OSYNC_INODE only passed ?
> 
>   - fs/reiserfs/file.c
>     reiserfs_file_write()        OSYNC_METADATA | OSYNC_DATA
>   - mm/filemap.c
>     sync_page_range()        OSYNC_METADATA
>     sync_page_range_nolock()    OSYNC_METADATA
>     generic_file_direct_write    OSYNC_METADATA
> 

-- 
Hiroyuki Machida		machida@sm.sony.co.jp		


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Signed-off-by: Hiroyuki Machida <machida@sm.sony.co.jp>

--- fs/fs-writeback.c.ORG	2005-08-29 08:41:01.000000000 +0900
+++ fs/fs-writeback.c	2005-10-14 21:22:37.329301605 +0900
@@ -614,6 +614,7 @@ int generic_osync_inode(struct inode *in
 	int err = 0;
 	int need_write_inode_now = 0;
 	int err2;
+	long nr_write;
 
 	current->flags |= PF_SYNCWRITE;
 	if (what & OSYNC_DATA)
@@ -632,13 +633,23 @@ int generic_osync_inode(struct inode *in
 
 	spin_lock(&inode_lock);
 	if ((inode->i_state & I_DIRTY) &&
-	    ((what & OSYNC_INODE) || (inode->i_state & I_DIRTY_DATASYNC)))
+	    ((what & OSYNC_INODE) || (inode->i_state & I_DIRTY_DATASYNC))) {
 		need_write_inode_now = 1;
+		nr_write = (what == OSYNC_INODE) ? 0 : LONG_MAX;
+	}
 	spin_unlock(&inode_lock);
 
-	if (need_write_inode_now) {
-		err2 = write_inode_now(inode, 1);
-		if (!err)
+	if (need_write_inode_now && 
+	    mapping_cap_writeback_dirty(inode->i_mapping)) {
+		struct writeback_control wbc = {
+			.sync_mode = WB_SYNC_ALL, 
+		};
+
+		wbc.nr_to_write = nr_write;
+		might_sleep();
+		err2 = sync_inode(inode, &wbc);
+		wait_on_inode(inode);
+		if (!err) 
 			err = err2;
 	}
 	else