On 02/27/2012 09:29 PM, Johannes Hirte wrote:

Am Tue, 17 Jan 2012 17:51:59 +0800
schrieb Liu Bo [off-list ref]:

quoted

I've kept hitting enospc warnings of global_rsv while running
defragment on files:
btrfs: block rsv returned -28
WARNING: at fs/btrfs/extent-tree.c:5984
btrfs_alloc_free_block+0x333/0x340 [btrfs]() ...

I used a fio jobs to create a file with lots of fragments:
$ filefrag /mnt/btrfs/foobar
/mnt/btrfs/foobar: 66964 extents found

and then "btrfs fi defrag /mnt/btrfs/foobar && sync" would pop the
warnings.

I found that the global_rsv size is just not enough for defragment,
and didn't find any space leak in using global_rsv, so double it and
go ahead.

Signed-off-by: Liu Bo <redacted>
---
 fs/btrfs/extent-tree.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 8603ee4..77ea23c 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c

@@ -3979,7 +3979,7 @@ static u64 calc_global_metadata_size(struct

btrfs_fs_info *fs_info) num_bytes += div64_u64(data_used + meta_used,
50); 
 	if (num_bytes * 3 > meta_used)
-		num_bytes = div64_u64(meta_used, 3);
+		num_bytes = div64_u64(meta_used, 3) * 2;
 
 	return ALIGN(num_bytes, fs_info->extent_root->leafsize <<
10); }

This patch breakes my system. With this applied all services fail on
boot with "no space left" messages.

It's weird since this patch is just aiming to enlarge our metadata reservation count.

so you've tried a revert or a bisect, right?  Can you show me the environment or any log messages?

thanks,
liubo