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linux/fs/ext4/mballoc.h
Theodore Ts'o 3e624fc72f ext4: Replace hackish ext4_mb_poll_new_transaction with commit callback 
The multiblock allocator needs to be able to release blocks (and issue
a blkdev discard request) when the transaction which freed those
blocks is committed.  Previously this was done via a polling mechanism
when blocks are allocated or freed.  A much better way of doing things
is to create a jbd2 callback function and attaching the list of blocks
to be freed directly to the transaction structure.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2008-10-16 20:00:24 -04:00

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/*
* 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/version.h>
#include <linux/blkdev.h>
#include <linux/marker.h>
#include "ext4_jbd2.h"
#include "ext4.h"
#include "group.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__
/*
*/
#define MB_DEBUG__
#ifdef MB_DEBUG
#define mb_debug(fmt, a...) printk(fmt, ##a)
#else
#define mb_debug(fmt, a...)
#endif
/*
* with EXT4_MB_HISTORY mballoc stores last N allocations in memory
* and you can monitor it in /proc/fs/ext4/<dev>/mb_history
*/
#define EXT4_MB_HISTORY
#define EXT4_MB_HISTORY_ALLOC 1 /* allocation */
#define EXT4_MB_HISTORY_PREALLOC 2 /* preallocated blocks used */
#define EXT4_MB_HISTORY_DISCARD 4 /* preallocation discarded */
#define EXT4_MB_HISTORY_FREE 8 /* free */
#define EXT4_MB_HISTORY_DEFAULT (EXT4_MB_HISTORY_ALLOC | \
EXT4_MB_HISTORY_PREALLOC)
/*
* 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 1
/*
* 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
static struct kmem_cache *ext4_pspace_cachep;
static struct kmem_cache *ext4_ac_cachep;
static struct kmem_cache *ext4_free_ext_cachep;
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_group_info {
unsigned long bb_state;
struct rb_root bb_free_root;
unsigned short bb_first_free;
unsigned short bb_free;
unsigned short bb_fragments;
struct list_head bb_prealloc_list;
#ifdef DOUBLE_CHECK
void *bb_bitmap;
#endif
unsigned short bb_counters[];
};
#define EXT4_GROUP_INFO_NEED_INIT_BIT 0
#define EXT4_GROUP_INFO_LOCKED_BIT 1
#define EXT4_MB_GRP_NEED_INIT(grp) \
(test_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &((grp)->bb_state)))
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 */
unsigned short pa_len; /* len of preallocated chunk */
unsigned short pa_free; /* how many blocks are free */
unsigned short pa_linear; /* consumed in one direction
* strictly, for grp prealloc */
spinlock_t *pa_obj_lock;
struct inode *pa_inode; /* hack, for history only */
};
struct ext4_free_extent {
ext4_lblk_t fe_logical;
ext4_grpblk_t fe_start;
ext4_group_t fe_group;
int fe_len;
};
/*
* 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 (after normalization) */
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_repeats;
__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_mb_history {
struct ext4_free_extent orig; /* orig allocation */
struct ext4_free_extent goal; /* goal allocation */
struct ext4_free_extent result; /* result allocation */
unsigned pid;
unsigned ino;
__u16 found; /* how many extents have been found */
__u16 groups; /* how many groups have been scanned */
__u16 tail; /* what tail broke some buddy */
__u16 buddy; /* buddy the tail ^^^ broke */
__u16 flags;
__u8 cr:3; /* which phase the result extent was found at */
__u8 op:4;
__u8 merged:1;
};
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)
#ifndef EXT4_MB_HISTORY
static inline void ext4_mb_store_history(struct ext4_allocation_context *ac)
{
return;
}
#else
static void ext4_mb_store_history(struct ext4_allocation_context *ac);
#endif
#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
struct buffer_head *read_block_bitmap(struct super_block *, ext4_group_t);
static void ext4_mb_generate_from_pa(struct super_block *sb, void *bitmap,
ext4_group_t group);
static void ext4_mb_return_to_preallocation(struct inode *inode,
struct ext4_buddy *e4b, sector_t block,
int count);
static void ext4_mb_put_pa(struct ext4_allocation_context *,
struct super_block *, struct ext4_prealloc_space *pa);
static int ext4_mb_init_per_dev_proc(struct super_block *sb);
static int ext4_mb_destroy_per_dev_proc(struct super_block *sb);
static void release_blocks_on_commit(journal_t *journal, transaction_t *txn);
static inline void ext4_lock_group(struct super_block *sb, ext4_group_t group)
{
struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
bit_spin_lock(EXT4_GROUP_INFO_LOCKED_BIT, &(grinfo->bb_state));
}
static inline void ext4_unlock_group(struct super_block *sb,
ext4_group_t group)
{
struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
bit_spin_unlock(EXT4_GROUP_INFO_LOCKED_BIT, &(grinfo->bb_state));
}
static inline int ext4_is_group_locked(struct super_block *sb,
ext4_group_t group)
{
struct ext4_group_info *grinfo = ext4_get_group_info(sb, group);
return bit_spin_is_locked(EXT4_GROUP_INFO_LOCKED_BIT,
&(grinfo->bb_state));
}
static ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
struct ext4_free_extent *fex)
{
ext4_fsblk_t block;
block = (ext4_fsblk_t) fex->fe_group * EXT4_BLOCKS_PER_GROUP(sb)
+ fex->fe_start
+ le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
return block;
}
#endif
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