This patch introduces the quota override flag to btrfs_fs_info, and
a change to quota limit checking code to temporarily allow for quota
to be overridden for processes with cap_sys_resource.
It's useful for administrative programs, such as log rotation,
that may need to temporarily use more disk space in order to free up
a greater amount of overall disk space without yielding more disk
space to the rest of userland.
Eventually, we may want to add the idea of an operator-specific
quota, operator reserved space, or something else to allow for
administrative override, but this is perhaps the simplest
solution.
Signed-off-by: Sargun Dhillon <sar...@sargun.me>
---
fs/btrfs/ctree.h | 2 ++
fs/btrfs/qgroup.c | 5 +++++
2 files changed, 7 insertions(+)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 643c70d..e86cb7c 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -716,6 +716,8 @@ struct btrfs_delayed_root;
#define BTRFS_FS_BTREE_ERR 11
#define BTRFS_FS_LOG1_ERR 12
#define BTRFS_FS_LOG2_ERR 13
+#define BTRFS_FS_QUOTA_OVERRIDE 14
+
/*
* Indicate that a whole-filesystem exclusive operation is running
* (device replace, resize, device add/delete, balance)
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index deffbeb..458fec0 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -2338,6 +2338,11 @@ static int qgroup_reserve(struct btrfs_root *root, u64
num_bytes, bool enforce)
if (num_bytes == 0)
return 0;
+
+ if (test_bit(BTRFS_FS_QUOTA_OVERRIDE, &fs_info->flags) &&
+ capable(CAP_SYS_RESOURCE))
+ enforce = false;
+
retry:
spin_lock(&fs_info->qgroup_lock);
quota_root = fs_info->quota_root;
--
2.9.3
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