[PATCH] Btrfs: release space on error in page_mkwrite

[PATCH] Btrfs: release space on error in page_mkwrite

[Josef Bacik]

If updating the inode gave us an ENOSPC we were just returning in page_mkwrite,
which is a problem since we make our reservation right before trying to update
the inode, so fix the out label so that we actually free our reservation.
Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
---
 fs/btrfs/inode.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index b0d7777..90a32f1 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6509,8 +6509,8 @@ out_unlock:
 	if (!ret)
 		return VM_FAULT_LOCKED;
 	unlock_page(page);
-	btrfs_delalloc_release_space(inode, PAGE_CACHE_SIZE);
 out:
+	btrfs_delalloc_release_space(inode, PAGE_CACHE_SIZE);
 	return ret;
 }
 
-- 
1.7.5.2

Re: [PATCH] Btrfs: release space on error in page_mkwrite

[David Sterba]

On Tue, Jan 10, 2012 at 02:20:18PM -0500, Josef Bacik wrote:
> If updating the inode gave us an ENOSPC we were just returning in page_mkwrite,
> which is a problem since we make our reservation right before trying to update
> the inode, so fix the out label so that we actually free our reservation.
> Thanks,
> 
> Signed-off-by: Josef Bacik <josef@redhat.com>
Tested-by: David Sterba <dsterba@suse.cz>

reproducer:

while :;do ./check 209;done

and some writeback activity, i used compilation or multithreaed random
writes via fio. the warning

WARNING: at fs/btrfs/extent-tree.c:7283 btrfs_free_block_groups+0x25b/0x370

appeared within minutes.


david

Re: [PATCH] Btrfs: release space on error in page_mkwrite

[David Sterba]

On Wed, Jan 11, 2012 at 03:27:09PM +0100, David Sterba wrote:
> On Tue, Jan 10, 2012 at 02:20:18PM -0500, Josef Bacik wrote:
> WARNING: at fs/btrfs/extent-tree.c:7283 btrfs_free_block_groups+0x25b/0x370
> 
> appeared within minutes.

Sorry, I spoke too soon, the test was running overnight and the warning
is there. I'll send you updated logs and traces.


david