[PATCH 06/26] fs: Convert namespace IDAs to new API

From: Matthew Wilcox
Date: Thu Jun 21 2018 - 17:30:12 EST


We don't need to keep track of the starting value; the IDA is efficient.

Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
---
fs/namespace.c | 50 ++++++++++++--------------------------------------
1 file changed, 12 insertions(+), 38 deletions(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index 8ddd14806799..bfd33eaab5aa 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -61,9 +61,6 @@ __setup("mphash_entries=", set_mphash_entries);
static u64 event;
static DEFINE_IDA(mnt_id_ida);
static DEFINE_IDA(mnt_group_ida);
-static DEFINE_SPINLOCK(mnt_id_lock);
-static int mnt_id_start = 0;
-static int mnt_group_start = 1;

static struct hlist_head *mount_hashtable __read_mostly;
static struct hlist_head *mountpoint_hashtable __read_mostly;
@@ -101,50 +98,30 @@ static inline struct hlist_head *mp_hash(struct dentry *dentry)

static int mnt_alloc_id(struct mount *mnt)
{
- int res;
+ int res = ida_alloc(&mnt_id_ida, GFP_KERNEL);

-retry:
- ida_pre_get(&mnt_id_ida, GFP_KERNEL);
- spin_lock(&mnt_id_lock);
- res = ida_get_new_above(&mnt_id_ida, mnt_id_start, &mnt->mnt_id);
- if (!res)
- mnt_id_start = mnt->mnt_id + 1;
- spin_unlock(&mnt_id_lock);
- if (res == -EAGAIN)
- goto retry;
-
- return res;
+ if (res < 0)
+ return res;
+ mnt->mnt_id = res;
+ return 0;
}

static void mnt_free_id(struct mount *mnt)
{
- int id = mnt->mnt_id;
- spin_lock(&mnt_id_lock);
- ida_remove(&mnt_id_ida, id);
- if (mnt_id_start > id)
- mnt_id_start = id;
- spin_unlock(&mnt_id_lock);
+ ida_free(&mnt_id_ida, mnt->mnt_id);
}

/*
* Allocate a new peer group ID
- *
- * mnt_group_ida is protected by namespace_sem
*/
static int mnt_alloc_group_id(struct mount *mnt)
{
- int res;
+ int res = ida_alloc_min(&mnt_group_ida, 1, GFP_KERNEL);

- if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL))
- return -ENOMEM;
-
- res = ida_get_new_above(&mnt_group_ida,
- mnt_group_start,
- &mnt->mnt_group_id);
- if (!res)
- mnt_group_start = mnt->mnt_group_id + 1;
-
- return res;
+ if (res < 0)
+ return res;
+ mnt->mnt_group_id = res;
+ return 0;
}

/*
@@ -152,10 +129,7 @@ static int mnt_alloc_group_id(struct mount *mnt)
*/
void mnt_release_group_id(struct mount *mnt)
{
- int id = mnt->mnt_group_id;
- ida_remove(&mnt_group_ida, id);
- if (mnt_group_start > id)
- mnt_group_start = id;
+ ida_free(&mnt_group_ida, mnt->mnt_group_id);
mnt->mnt_group_id = 0;
}

--
2.17.1