scoutfs: have per-fs inode nr allocators

We had previously seen lock contention between mounts that were either
resolving paths by looking up entries in directories or writing xattrs
in file inodes as they did archiving work.

The previous attempt to avoid this contention was to give each directory
its own inode number allocator which ensured that inodes created for
entries in the directory wouldn't share lock groups with inodes in other
directories.

But this creates the problem of operating on few files per lock for
reasonably small directories.  It also creates more server commits as
each new directory gets its inode allocation reservation.

The fix is to have mount-wide seperate allocators for directories and
for everything else.  This puts directories and files in seperate groups
and locks, regardless of directory population.

Signed-off-by: Zach Brown <zab@versity.com>

kmod/src/dir.c

@@ -642,7 +642,7 @@ static struct inode *lock_hold_create(struct inode *dir, struct dentry *dentry,
 	if (ret)
 		return ERR_PTR(ret);
 
-	ret = scoutfs_alloc_ino(dir, &ino);
+	ret = scoutfs_alloc_ino(sb, S_ISDIR(mode), &ino);
 	if (ret)
 		return ERR_PTR(ret);