Re: [PATCH] Btrfs: remove warning check in io_ctl_map_page

On 2012年11月30日 17:02, Liu Bo wrote:

On Fri, Nov 30, 2012 at 02:02:26PM +0800, shhuiw@gmail.com wrote:

quoted

From: Wang Sheng-Hui <redacted>

io_ctl_map_page is called by many functions in free-space-cache.
In some scenarios, the ->cur is not null, e.g. io_ctl_add_entry.
Remove the check here.

Hi Wang,

Seems to be impossible according to the code, even in io_ctl_add_entry().

So have you seen such a warning in your flight running?  If you do,
maybe you can post it here and we can figure out the whys.

Hi Liu Bo,

I just walked through the code. reread io_ctl_add_entry, and just noticed
that io_ctl_set_crc is called before io_ctl_map_page, which can guarantee
the ->cur is set to null before map.

Thanks for helping me understand the code.

Regards,
Sheng-Hui

thanks,
liubo

quoted

Signed-off-by: Wang Sheng-Hui <redacted>
---
 fs/btrfs/free-space-cache.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index c3318cb..4ea66d4 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c

@@ -307,7 +307,6 @@ static void io_ctl_unmap_page(struct io_ctl *io_ctl)
 
 static void io_ctl_map_page(struct io_ctl *io_ctl, int clear)
 {
-	WARN_ON(io_ctl->cur);
 	BUG_ON(io_ctl->index >= io_ctl->num_pages);
 	io_ctl->page = io_ctl->pages[io_ctl->index++];
 	io_ctl->cur = kmap(io_ctl->page);

-- 
1.6.0.2

--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html