/*
   *  fs/ext4/mballoc.h
   *
   *  Written by: Alex Tomas <alex@clusterfs.com>
   *
   */
  #ifndef _EXT4_MBALLOC_H
  #define _EXT4_MBALLOC_H
  
  #include <linux/time.h>
  #include <linux/fs.h>
  #include <linux/namei.h>
  #include <linux/quotaops.h>
  #include <linux/buffer_head.h>
  #include <linux/module.h>
  #include <linux/swap.h>
  #include <linux/proc_fs.h>
  #include <linux/pagemap.h>
  #include <linux/seq_file.h>
  #include <linux/blkdev.h>
  #include <linux/mutex.h>
  #include "ext4_jbd2.h"
  #include "ext4.h"
  
  /*
   * with AGGRESSIVE_CHECK allocator runs consistency checks over
   * structures. these checks slow things down a lot
   */
  #define AGGRESSIVE_CHECK__
  
  /*
   * with DOUBLE_CHECK defined mballoc creates persistent in-core
   * bitmaps, maintains and uses them to check for double allocations
   */
  #define DOUBLE_CHECK__
  
  /*
   */
  #ifdef CONFIG_EXT4_DEBUG
  extern ushort ext4_mballoc_debug;
  
  #define mb_debug(n, fmt, a...)	                                        \
  	do {								\
  		if ((n) <= ext4_mballoc_debug) {		        \
  			printk(KERN_DEBUG "(%s, %d): %s: ",		\
  			       __FILE__, __LINE__, __func__);		\
  			printk(fmt, ## a);				\
  		}							\
  	} while (0)
  #else
  #define mb_debug(n, fmt, a...)
  #endif
  
  #define EXT4_MB_HISTORY_ALLOC		1	/* allocation */
  #define EXT4_MB_HISTORY_PREALLOC	2	/* preallocated blocks used */
  
  /*
   * How long mballoc can look for a best extent (in found extents)
   */
  #define MB_DEFAULT_MAX_TO_SCAN		200
  
  /*
   * How long mballoc must look for a best extent
   */
  #define MB_DEFAULT_MIN_TO_SCAN		10
  
  /*
   * with 'ext4_mb_stats' allocator will collect stats that will be
   * shown at umount. The collecting costs though!
   */
  #define MB_DEFAULT_STATS		0
  
  /*
   * files smaller than MB_DEFAULT_STREAM_THRESHOLD are served
   * by the stream allocator, which purpose is to pack requests
   * as close each to other as possible to produce smooth I/O traffic
   * We use locality group prealloc space for stream request.
   * We can tune the same via /proc/fs/ext4/<parition>/stream_req
   */
  #define MB_DEFAULT_STREAM_THRESHOLD	16	/* 64K */
  
  /*
   * for which requests use 2^N search using buddies
   */
  #define MB_DEFAULT_ORDER2_REQS		2
  
  /*
   * default group prealloc size 512 blocks
   */
  #define MB_DEFAULT_GROUP_PREALLOC	512
  
  
  struct ext4_free_data {
  	/* MUST be the first member */
  	struct ext4_journal_cb_entry	efd_jce;
  
  	/* ext4_free_data private data starts from here */
  
  	/* this links the free block information from group_info */
  	struct rb_node			efd_node;
  
  	/* group which free block extent belongs */
  	ext4_group_t			efd_group;
  
  	/* free block extent */
  	ext4_grpblk_t			efd_start_cluster;
  	ext4_grpblk_t			efd_count;
  
  	/* transaction which freed this extent */
  	tid_t				efd_tid;
  };
  
  struct ext4_prealloc_space {
  	struct list_head	pa_inode_list;
  	struct list_head	pa_group_list;
  	union {
  		struct list_head pa_tmp_list;
  		struct rcu_head	pa_rcu;
  	} u;
  	spinlock_t		pa_lock;
  	atomic_t		pa_count;
  	unsigned		pa_deleted;
  	ext4_fsblk_t		pa_pstart;	/* phys. block */
  	ext4_lblk_t		pa_lstart;	/* log. block */
  	ext4_grpblk_t		pa_len;		/* len of preallocated chunk */
  	ext4_grpblk_t		pa_free;	/* how many blocks are free */
  	unsigned short		pa_type;	/* pa type. inode or group */
  	spinlock_t		*pa_obj_lock;
  	struct inode		*pa_inode;	/* hack, for history only */
  };
  
  enum {
  	MB_INODE_PA = 0,
  	MB_GROUP_PA = 1
  };
  
  struct ext4_free_extent {
  	ext4_lblk_t fe_logical;
  	ext4_grpblk_t fe_start;	/* In cluster units */
  	ext4_group_t fe_group;
  	ext4_grpblk_t fe_len;	/* In cluster units */
  };
  
  /*
   * Locality group:
   *   we try to group all related changes together
   *   so that writeback can flush/allocate them together as well
   *   Size of lg_prealloc_list hash is determined by MB_DEFAULT_GROUP_PREALLOC
   *   (512). We store prealloc space into the hash based on the pa_free blocks
   *   order value.ie, fls(pa_free)-1;
   */
  #define PREALLOC_TB_SIZE 10
  struct ext4_locality_group {
  	/* for allocator */
  	/* to serialize allocates */
  	struct mutex		lg_mutex;
  	/* list of preallocations */
  	struct list_head	lg_prealloc_list[PREALLOC_TB_SIZE];
  	spinlock_t		lg_prealloc_lock;
  };
  
  struct ext4_allocation_context {
  	struct inode *ac_inode;
  	struct super_block *ac_sb;
  
  	/* original request */
  	struct ext4_free_extent ac_o_ex;
  
  	/* goal request (normalized ac_o_ex) */
  	struct ext4_free_extent ac_g_ex;
  
  	/* the best found extent */
  	struct ext4_free_extent ac_b_ex;
  
  	/* copy of the best found extent taken before preallocation efforts */
  	struct ext4_free_extent ac_f_ex;
  
  	/* number of iterations done. we have to track to limit searching */
  	unsigned long ac_ex_scanned;
  	__u16 ac_groups_scanned;
  	__u16 ac_found;
  	__u16 ac_tail;
  	__u16 ac_buddy;
  	__u16 ac_flags;		/* allocation hints */
  	__u8 ac_status;
  	__u8 ac_criteria;
  	__u8 ac_2order;		/* if request is to allocate 2^N blocks and
  				 * N > 0, the field stores N, otherwise 0 */
  	__u8 ac_op;		/* operation, for history only */
  	struct page *ac_bitmap_page;
  	struct page *ac_buddy_page;
  	struct ext4_prealloc_space *ac_pa;
  	struct ext4_locality_group *ac_lg;
  };
  
  #define AC_STATUS_CONTINUE	1
  #define AC_STATUS_FOUND		2
  #define AC_STATUS_BREAK		3
  
  struct ext4_buddy {
  	struct page *bd_buddy_page;
  	void *bd_buddy;
  	struct page *bd_bitmap_page;
  	void *bd_bitmap;
  	struct ext4_group_info *bd_info;
  	struct super_block *bd_sb;
  	__u16 bd_blkbits;
  	ext4_group_t bd_group;
  };
  
  static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
  					struct ext4_free_extent *fex)
  {
  	return ext4_group_first_block_no(sb, fex->fe_group) +
  		(fex->fe_start << EXT4_SB(sb)->s_cluster_bits);
  }
  #endif