Merge branch 'ida-4.19' of git://git.infradead.org/users/willy/linux-dax

Pull IDA updates from Matthew Wilcox:
 "A better IDA API:

      id = ida_alloc(ida, GFP_xxx);
      ida_free(ida, id);

  rather than the cumbersome ida_simple_get(), ida_simple_remove().

  The new IDA API is similar to ida_simple_get() but better named.  The
  internal restructuring of the IDA code removes the bitmap
  preallocation nonsense.

  I hope the net -200 lines of code is convincing"

* 'ida-4.19' of git://git.infradead.org/users/willy/linux-dax: (29 commits)
  ida: Change ida_get_new_above to return the id
  ida: Remove old API
  test_ida: check_ida_destroy and check_ida_alloc
  test_ida: Convert check_ida_conv to new API
  test_ida: Move ida_check_max
  test_ida: Move ida_check_leaf
  idr-test: Convert ida_check_nomem to new API
  ida: Start new test_ida module
  target/iscsi: Allocate session IDs from an IDA
  iscsi target: fix session creation failure handling
  drm/vmwgfx: Convert to new IDA API
  dmaengine: Convert to new IDA API
  ppc: Convert vas ID allocation to new IDA API
  media: Convert entity ID allocation to new IDA API
  ppc: Convert mmu context allocation to new IDA API
  Convert net_namespace to new IDA API
  cb710: Convert to new IDA API
  rsxx: Convert to new IDA API
  osd: Convert to new IDA API
  sd: Convert to new IDA API
  ...

3 files changed, 49 insertions, 115 deletions

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index e072e955ce33..c53814539070 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -46,7 +46,7 @@ static int pty_limit = NR_UNIX98_PTY_DEFAULT;
 static int pty_reserve = NR_UNIX98_PTY_RESERVE;
 static int pty_limit_min;
 static int pty_limit_max = INT_MAX;
-static int pty_count;
+static atomic_t pty_count = ATOMIC_INIT(0);
 
 static struct ctl_table pty_table[] = {
 	{
@@ -93,8 +93,6 @@ static struct ctl_table pty_root_table[] = {
 	{}
 };
 
-static DEFINE_MUTEX(allocated_ptys_lock);
-
 struct pts_mount_opts {
 	int setuid;
 	int setgid;
@@ -533,44 +531,25 @@ static struct file_system_type devpts_fs_type = {
 
 int devpts_new_index(struct pts_fs_info *fsi)
 {
-	int index;
-	int ida_ret;
-
-retry:
-	if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL))
-		return -ENOMEM;
-
-	mutex_lock(&allocated_ptys_lock);
-	if (pty_count >= (pty_limit -
-			  (fsi->mount_opts.reserve ? 0 : pty_reserve))) {
-		mutex_unlock(&allocated_ptys_lock);
-		return -ENOSPC;
-	}
+	int index = -ENOSPC;
 
-	ida_ret = ida_get_new(&fsi->allocated_ptys, &index);
-	if (ida_ret < 0) {
-		mutex_unlock(&allocated_ptys_lock);
-		if (ida_ret == -EAGAIN)
-			goto retry;
-		return -EIO;
-	}
+	if (atomic_inc_return(&pty_count) >= (pty_limit -
+			  (fsi->mount_opts.reserve ? 0 : pty_reserve)))
+		goto out;
 
-	if (index >= fsi->mount_opts.max) {
-		ida_remove(&fsi->allocated_ptys, index);
-		mutex_unlock(&allocated_ptys_lock);
-		return -ENOSPC;
-	}
-	pty_count++;
-	mutex_unlock(&allocated_ptys_lock);
+	index = ida_alloc_max(&fsi->allocated_ptys, fsi->mount_opts.max - 1,
+			GFP_KERNEL);
+
+out:
+	if (index < 0)
+		atomic_dec(&pty_count);
 	return index;
 }
 
 void devpts_kill_index(struct pts_fs_info *fsi, int idx)
 {
-	mutex_lock(&allocated_ptys_lock);
-	ida_remove(&fsi->allocated_ptys, idx);
-	pty_count--;
-	mutex_unlock(&allocated_ptys_lock);
+	ida_free(&fsi->allocated_ptys, idx);
+	atomic_dec(&pty_count);
 }
 
 /**
diff --git a/fs/namespace.c b/fs/namespace.c
index 725d6935fab9..99186556f8d3 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;
 }
 
diff --git a/fs/super.c b/fs/super.c
index 7429588d6b49..f3a8c008e164 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -981,58 +981,42 @@ void emergency_thaw_all(void)
 	}
 }
 
-/*
- * Unnamed block devices are dummy devices used by virtual
- * filesystems which don't use real block-devices.  -- jrs
- */
-
 static DEFINE_IDA(unnamed_dev_ida);
-static DEFINE_SPINLOCK(unnamed_dev_lock);/* protects the above */
-/* Many userspace utilities consider an FSID of 0 invalid.
- * Always return at least 1 from get_anon_bdev.
- */
-static int unnamed_dev_start = 1;
 
+/**
+ * get_anon_bdev - Allocate a block device for filesystems which don't have one.
+ * @p: Pointer to a dev_t.
+ *
+ * Filesystems which don't use real block devices can call this function
+ * to allocate a virtual block device.
+ *
+ * Context: Any context.  Frequently called while holding sb_lock.
+ * Return: 0 on success, -EMFILE if there are no anonymous bdevs left
+ * or -ENOMEM if memory allocation failed.
+ */
 int get_anon_bdev(dev_t *p)
 {
 	int dev;
-	int error;
 
- retry:
-	if (ida_pre_get(&unnamed_dev_ida, GFP_ATOMIC) == 0)
-		return -ENOMEM;
-	spin_lock(&unnamed_dev_lock);
-	error = ida_get_new_above(&unnamed_dev_ida, unnamed_dev_start, &dev);
-	if (!error)
-		unnamed_dev_start = dev + 1;
-	spin_unlock(&unnamed_dev_lock);
-	if (error == -EAGAIN)
-		/* We raced and lost with another CPU. */
-		goto retry;
-	else if (error)
-		return -EAGAIN;
-
-	if (dev >= (1 << MINORBITS)) {
-		spin_lock(&unnamed_dev_lock);
-		ida_remove(&unnamed_dev_ida, dev);
-		if (unnamed_dev_start > dev)
-			unnamed_dev_start = dev;
-		spin_unlock(&unnamed_dev_lock);
-		return -EMFILE;
-	}
-	*p = MKDEV(0, dev & MINORMASK);
+	/*
+	 * Many userspace utilities consider an FSID of 0 invalid.
+	 * Always return at least 1 from get_anon_bdev.
+	 */
+	dev = ida_alloc_range(&unnamed_dev_ida, 1, (1 << MINORBITS) - 1,
+			GFP_ATOMIC);
+	if (dev == -ENOSPC)
+		dev = -EMFILE;
+	if (dev < 0)
+		return dev;
+
+	*p = MKDEV(0, dev);
 	return 0;
 }
 EXPORT_SYMBOL(get_anon_bdev);
 
 void free_anon_bdev(dev_t dev)
 {
-	int slot = MINOR(dev);
-	spin_lock(&unnamed_dev_lock);
-	ida_remove(&unnamed_dev_ida, slot);
-	if (slot < unnamed_dev_start)
-		unnamed_dev_start = slot;
-	spin_unlock(&unnamed_dev_lock);
+	ida_free(&unnamed_dev_ida, MINOR(dev));
 }
 EXPORT_SYMBOL(free_anon_bdev);
 
@@ -1040,7 +1024,6 @@ int set_anon_super(struct super_block *s, void *data)
 {
 	return get_anon_bdev(&s->s_dev);
 }
-
 EXPORT_SYMBOL(set_anon_super);
 
 void kill_anon_super(struct super_block *sb)
@@ -1049,7 +1032,6 @@ void kill_anon_super(struct super_block *sb)
 	generic_shutdown_super(sb);
 	free_anon_bdev(dev);
 }
-
 EXPORT_SYMBOL(kill_anon_super);
 
 void kill_litter_super(struct super_block *sb)
@@ -1058,7 +1040,6 @@ void kill_litter_super(struct super_block *sb)
 		d_genocide(sb->s_root);
 	kill_anon_super(sb);
 }
-
 EXPORT_SYMBOL(kill_litter_super);
 
 static int ns_test_super(struct super_block *sb, void *data)