linux/fs/ext4/mballoc.h
Theodore Ts'o 53accfa9f8 ext4: teach mballoc preallocation code about bigalloc clusters
In most of mballoc.c, we do everything in units of clusters, since the
block allocation bitmaps and buddy bitmaps are all denominated in
clusters.  The one place where we do deal with absolute block numbers
is in the code that handles the preallocation regions, since in the
case of inode-based preallocation regions, the start of the
preallocation region can't be relative to the beginning of the group.

So this adds a bit of complexity, where pa_pstart and pa_lstart are
block numbers, while pa_free, pa_len, and fe_len are denominated in
units of clusters.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-09-09 18:48:51 -04:00

223 lines
5.5 KiB
C

/*
* 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 u8 mb_enable_debug;
#define mb_debug(n, fmt, a...) \
do { \
if ((n) <= mb_enable_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
/*
* How many groups mballoc will scan looking for the best chunk
*/
#define MB_DEFAULT_MAX_GROUPS_TO_SCAN 5
/*
* 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 {
/* this links the free block information from group_info */
struct rb_node node;
/* this links the free block information from ext4_sb_info */
struct list_head list;
/* group which free block extent belongs */
ext4_group_t group;
/* free block extent */
ext4_grpblk_t start_blk;
ext4_grpblk_t count;
/* transaction which freed this extent */
tid_t t_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 bext 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;
};
#define EXT4_MB_BITMAP(e4b) ((e4b)->bd_bitmap)
#define EXT4_MB_BUDDY(e4b) ((e4b)->bd_buddy)
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