[ 3.5.y.z extended stable ] Patch "Btrfs: limit the global reserve to 512mb" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    Btrfs: limit the global reserve to 512mb

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 4bcd6919db4571dffb53392d9145654e9ba8ae93 Mon Sep 17 00:00:00 2001
From: Josef Bacik <jbacik at fusionio.com>
Date: Tue, 26 Mar 2013 15:31:45 -0400
Subject: [PATCH] Btrfs: limit the global reserve to 512mb

commit fdf30d1c1b386e1b73116cc7e0fb14e962b763b0 upstream.

A user reported a problem where he was getting early ENOSPC with hundreds of
gigs of free data space and 6 gigs of free metadata space.  This is because the
global block reserve was taking up the entire free metadata space.  This is
ridiculous, we have infrastructure in place to throttle if we start using too
much of the global reserve, so instead of letting it get this huge just limit it
to 512mb so that users can still get work done.  This allowed the user to
complete his rsync without issues.  Thanks

Reported-and-tested-by: Stefan Priebe <s.priebe at profihost.ag>
Signed-off-by: Josef Bacik <jbacik at fusionio.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 fs/btrfs/extent-tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index fe6cec5..9e99ea0 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -4218,7 +4218,7 @@ static void update_global_block_rsv(struct btrfs_fs_info *fs_info)
 	spin_lock(&sinfo->lock);
 	spin_lock(&block_rsv->lock);

-	block_rsv->size = num_bytes;
+	block_rsv->size = min_t(u64, num_bytes, 512 * 1024 * 1024);

 	num_bytes = sinfo->bytes_used + sinfo->bytes_pinned +
 		    sinfo->bytes_reserved + sinfo->bytes_readonly +
--
1.8.1.2