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[PATCH] md: remove personality numbering from md

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md supports multiple different RAID level, each being implemented by a
'personality' (which is often in a separate module).

These personalities have fairly artificial 'numbers'.  The numbers
are use to:
 1- provide an index into an array where the various personalities
    are recorded
 2- identify the module (via an alias) which implements are particular
    personality.

Neither of these uses really justify the existence of personality numbers.
The array can be replaced by a linked list which is searched (array lookup
only happens very rarely).  Module identification can be done using an alias
based on level rather than 'personality' number.

The current 'raid5' modules support two level (4 and 5) but only one
personality.  This slight awkwardness (which was handled in the mapping from
level to personality) can be better handled by allowing raid5 to register 2
personalities.

With this change in place, the core md module does not need to have an
exhaustive list of all possible personalities, so other personalities can be
added independently.

This patch also moves the check for chunksize being non-zero into the ->run
routines for the personalities that need it, rather than having it in core-md.
 This has a side effect of allowing 'faulty' and 'linear' not to have a
chunk-size set.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
NeilBrown
2006-01-06 00:20:36 -08:00
committed by Linus Torvalds
parent a24a8dd858
commit 2604b703b6
12 changed files with 125 additions and 155 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/raid/md.h
View File

@@ -71,8 +71,8 @@
*/
#define MD_PATCHLEVEL_VERSION 3
extern int register_md_personality (int p_num, mdk_personality_t *p);
extern int unregister_md_personality (int p_num);
extern int register_md_personality (struct mdk_personality *p);
extern int unregister_md_personality (struct mdk_personality *p);
extern mdk_thread_t * md_register_thread (void (*run) (mddev_t *mddev),
mddev_t *mddev, const char *name);
extern void md_unregister_thread (mdk_thread_t *thread);

63
include/linux/raid/md_k.h
View File

@@ -18,62 +18,19 @@
/* and dm-bio-list.h is not under include/linux because.... ??? */
#include "../../../drivers/md/dm-bio-list.h"
#define MD_RESERVED 0UL
#define LINEAR 1UL
#define RAID0 2UL
#define RAID1 3UL
#define RAID5 4UL
#define TRANSLUCENT 5UL
#define HSM 6UL
#define MULTIPATH 7UL
#define RAID6 8UL
#define RAID10 9UL
#define FAULTY 10UL
#define MAX_PERSONALITY 11UL
#define LEVEL_MULTIPATH (-4)
#define LEVEL_LINEAR (-1)
#define LEVEL_FAULTY (-5)
/* we need a value for 'no level specified' and 0
* means 'raid0', so we need something else. This is
* for internal use only
*/
#define LEVEL_NONE (-1000000)
#define MaxSector (~(sector_t)0)
#define MD_THREAD_NAME_MAX 14
static inline int pers_to_level (int pers)
{
switch (pers) {
case FAULTY: return LEVEL_FAULTY;
case MULTIPATH: return LEVEL_MULTIPATH;
case HSM: return -3;
case TRANSLUCENT: return -2;
case LINEAR: return LEVEL_LINEAR;
case RAID0: return 0;
case RAID1: return 1;
case RAID5: return 5;
case RAID6: return 6;
case RAID10: return 10;
}
BUG();
return MD_RESERVED;
}
static inline int level_to_pers (int level)
{
switch (level) {
case LEVEL_FAULTY: return FAULTY;
case LEVEL_MULTIPATH: return MULTIPATH;
case -3: return HSM;
case -2: return TRANSLUCENT;
case LEVEL_LINEAR: return LINEAR;
case 0: return RAID0;
case 1: return RAID1;
case 4:
case 5: return RAID5;
case 6: return RAID6;
case 10: return RAID10;
}
return MD_RESERVED;
}
typedef struct mddev_s mddev_t;
typedef struct mdk_rdev_s mdk_rdev_t;
@@ -140,12 +97,10 @@ struct mdk_rdev_s
*/
};
typedef struct mdk_personality_s mdk_personality_t;
struct mddev_s
{
void *private;
mdk_personality_t *pers;
struct mdk_personality *pers;
dev_t unit;
int md_minor;
struct list_head disks;
@@ -266,9 +221,11 @@ static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sect
atomic_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io);
}
struct mdk_personality_s
struct mdk_personality
{
char *name;
int level;
struct list_head list;
struct module *owner;
int (*make_request)(request_queue_t *q, struct bio *bio);
int (*run)(mddev_t *mddev);