alistair23-linux/drivers/md/dm-zoned.h
Damien Le Moal 3b8cafdd54 dm zoned: fix zone state management race
dm-zoned uses the zone flag DMZ_ACTIVE to indicate that a zone of the
backend device is being actively read or written and so cannot be
reclaimed. This flag is set as long as the zone atomic reference
counter is not 0. When this atomic is decremented and reaches 0 (e.g.
on BIO completion), the active flag is cleared and set again whenever
the zone is reused and BIO issued with the atomic counter incremented.
These 2 operations (atomic inc/dec and flag set/clear) are however not
always executed atomically under the target metadata mutex lock and
this causes the warning:

WARN_ON(!test_bit(DMZ_ACTIVE, &zone->flags));

in dmz_deactivate_zone() to be displayed. This problem is regularly
triggered with xfstests generic/209, generic/300, generic/451 and
xfs/077 with XFS being used as the file system on the dm-zoned target
device. Similarly, xfstests ext4/303, ext4/304, generic/209 and
generic/300 trigger the warning with ext4 use.

This problem can be easily fixed by simply removing the DMZ_ACTIVE flag
and managing the "ACTIVE" state by directly looking at the reference
counter value. To do so, the functions dmz_activate_zone() and
dmz_deactivate_zone() are changed to inline functions respectively
calling atomic_inc() and atomic_dec(), while the dmz_is_active() macro
is changed to an inline function calling atomic_read().

Fixes: 3b1a94c88b ("dm zoned: drive-managed zoned block device target")
Cc: stable@vger.kernel.org
Reported-by: Masato Suzuki <masato.suzuki@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
2019-07-17 11:03:48 -04:00

249 lines
7.1 KiB
C

/*
* Copyright (C) 2017 Western Digital Corporation or its affiliates.
*
* This file is released under the GPL.
*/
#ifndef DM_ZONED_H
#define DM_ZONED_H
#include <linux/types.h>
#include <linux/blkdev.h>
#include <linux/device-mapper.h>
#include <linux/dm-kcopyd.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/workqueue.h>
#include <linux/rwsem.h>
#include <linux/rbtree.h>
#include <linux/radix-tree.h>
#include <linux/shrinker.h>
/*
* dm-zoned creates block devices with 4KB blocks, always.
*/
#define DMZ_BLOCK_SHIFT 12
#define DMZ_BLOCK_SIZE (1 << DMZ_BLOCK_SHIFT)
#define DMZ_BLOCK_MASK (DMZ_BLOCK_SIZE - 1)
#define DMZ_BLOCK_SHIFT_BITS (DMZ_BLOCK_SHIFT + 3)
#define DMZ_BLOCK_SIZE_BITS (1 << DMZ_BLOCK_SHIFT_BITS)
#define DMZ_BLOCK_MASK_BITS (DMZ_BLOCK_SIZE_BITS - 1)
#define DMZ_BLOCK_SECTORS_SHIFT (DMZ_BLOCK_SHIFT - SECTOR_SHIFT)
#define DMZ_BLOCK_SECTORS (DMZ_BLOCK_SIZE >> SECTOR_SHIFT)
#define DMZ_BLOCK_SECTORS_MASK (DMZ_BLOCK_SECTORS - 1)
/*
* 4KB block <-> 512B sector conversion.
*/
#define dmz_blk2sect(b) ((sector_t)(b) << DMZ_BLOCK_SECTORS_SHIFT)
#define dmz_sect2blk(s) ((sector_t)(s) >> DMZ_BLOCK_SECTORS_SHIFT)
#define dmz_bio_block(bio) dmz_sect2blk((bio)->bi_iter.bi_sector)
#define dmz_bio_blocks(bio) dmz_sect2blk(bio_sectors(bio))
/*
* Zoned block device information.
*/
struct dmz_dev {
struct block_device *bdev;
char name[BDEVNAME_SIZE];
sector_t capacity;
unsigned int nr_zones;
sector_t zone_nr_sectors;
unsigned int zone_nr_sectors_shift;
sector_t zone_nr_blocks;
sector_t zone_nr_blocks_shift;
};
#define dmz_bio_chunk(dev, bio) ((bio)->bi_iter.bi_sector >> \
(dev)->zone_nr_sectors_shift)
#define dmz_chunk_block(dev, b) ((b) & ((dev)->zone_nr_blocks - 1))
/*
* Zone descriptor.
*/
struct dm_zone {
/* For listing the zone depending on its state */
struct list_head link;
/* Zone type and state */
unsigned long flags;
/* Zone activation reference count */
atomic_t refcount;
/* Zone write pointer block (relative to the zone start block) */
unsigned int wp_block;
/* Zone weight (number of valid blocks in the zone) */
unsigned int weight;
/* The chunk that the zone maps */
unsigned int chunk;
/*
* For a sequential data zone, pointer to the random zone
* used as a buffer for processing unaligned writes.
* For a buffer zone, this points back to the data zone.
*/
struct dm_zone *bzone;
};
/*
* Zone flags.
*/
enum {
/* Zone write type */
DMZ_RND,
DMZ_SEQ,
/* Zone critical condition */
DMZ_OFFLINE,
DMZ_READ_ONLY,
/* How the zone is being used */
DMZ_META,
DMZ_DATA,
DMZ_BUF,
/* Zone internal state */
DMZ_RECLAIM,
DMZ_SEQ_WRITE_ERR,
};
/*
* Zone data accessors.
*/
#define dmz_is_rnd(z) test_bit(DMZ_RND, &(z)->flags)
#define dmz_is_seq(z) test_bit(DMZ_SEQ, &(z)->flags)
#define dmz_is_empty(z) ((z)->wp_block == 0)
#define dmz_is_offline(z) test_bit(DMZ_OFFLINE, &(z)->flags)
#define dmz_is_readonly(z) test_bit(DMZ_READ_ONLY, &(z)->flags)
#define dmz_in_reclaim(z) test_bit(DMZ_RECLAIM, &(z)->flags)
#define dmz_seq_write_err(z) test_bit(DMZ_SEQ_WRITE_ERR, &(z)->flags)
#define dmz_is_meta(z) test_bit(DMZ_META, &(z)->flags)
#define dmz_is_buf(z) test_bit(DMZ_BUF, &(z)->flags)
#define dmz_is_data(z) test_bit(DMZ_DATA, &(z)->flags)
#define dmz_weight(z) ((z)->weight)
/*
* Message functions.
*/
#define dmz_dev_info(dev, format, args...) \
DMINFO("(%s): " format, (dev)->name, ## args)
#define dmz_dev_err(dev, format, args...) \
DMERR("(%s): " format, (dev)->name, ## args)
#define dmz_dev_warn(dev, format, args...) \
DMWARN("(%s): " format, (dev)->name, ## args)
#define dmz_dev_debug(dev, format, args...) \
DMDEBUG("(%s): " format, (dev)->name, ## args)
struct dmz_metadata;
struct dmz_reclaim;
/*
* Functions defined in dm-zoned-metadata.c
*/
int dmz_ctr_metadata(struct dmz_dev *dev, struct dmz_metadata **zmd);
void dmz_dtr_metadata(struct dmz_metadata *zmd);
int dmz_resume_metadata(struct dmz_metadata *zmd);
void dmz_lock_map(struct dmz_metadata *zmd);
void dmz_unlock_map(struct dmz_metadata *zmd);
void dmz_lock_metadata(struct dmz_metadata *zmd);
void dmz_unlock_metadata(struct dmz_metadata *zmd);
void dmz_lock_flush(struct dmz_metadata *zmd);
void dmz_unlock_flush(struct dmz_metadata *zmd);
int dmz_flush_metadata(struct dmz_metadata *zmd);
unsigned int dmz_id(struct dmz_metadata *zmd, struct dm_zone *zone);
sector_t dmz_start_sect(struct dmz_metadata *zmd, struct dm_zone *zone);
sector_t dmz_start_block(struct dmz_metadata *zmd, struct dm_zone *zone);
unsigned int dmz_nr_chunks(struct dmz_metadata *zmd);
#define DMZ_ALLOC_RND 0x01
#define DMZ_ALLOC_RECLAIM 0x02
struct dm_zone *dmz_alloc_zone(struct dmz_metadata *zmd, unsigned long flags);
void dmz_free_zone(struct dmz_metadata *zmd, struct dm_zone *zone);
void dmz_map_zone(struct dmz_metadata *zmd, struct dm_zone *zone,
unsigned int chunk);
void dmz_unmap_zone(struct dmz_metadata *zmd, struct dm_zone *zone);
unsigned int dmz_nr_rnd_zones(struct dmz_metadata *zmd);
unsigned int dmz_nr_unmap_rnd_zones(struct dmz_metadata *zmd);
/*
* Activate a zone (increment its reference count).
*/
static inline void dmz_activate_zone(struct dm_zone *zone)
{
atomic_inc(&zone->refcount);
}
/*
* Deactivate a zone. This decrement the zone reference counter
* indicating that all BIOs to the zone have completed when the count is 0.
*/
static inline void dmz_deactivate_zone(struct dm_zone *zone)
{
atomic_dec(&zone->refcount);
}
/*
* Test if a zone is active, that is, has a refcount > 0.
*/
static inline bool dmz_is_active(struct dm_zone *zone)
{
return atomic_read(&zone->refcount);
}
int dmz_lock_zone_reclaim(struct dm_zone *zone);
void dmz_unlock_zone_reclaim(struct dm_zone *zone);
struct dm_zone *dmz_get_zone_for_reclaim(struct dmz_metadata *zmd);
struct dm_zone *dmz_get_chunk_mapping(struct dmz_metadata *zmd,
unsigned int chunk, int op);
void dmz_put_chunk_mapping(struct dmz_metadata *zmd, struct dm_zone *zone);
struct dm_zone *dmz_get_chunk_buffer(struct dmz_metadata *zmd,
struct dm_zone *dzone);
int dmz_validate_blocks(struct dmz_metadata *zmd, struct dm_zone *zone,
sector_t chunk_block, unsigned int nr_blocks);
int dmz_invalidate_blocks(struct dmz_metadata *zmd, struct dm_zone *zone,
sector_t chunk_block, unsigned int nr_blocks);
int dmz_block_valid(struct dmz_metadata *zmd, struct dm_zone *zone,
sector_t chunk_block);
int dmz_first_valid_block(struct dmz_metadata *zmd, struct dm_zone *zone,
sector_t *chunk_block);
int dmz_copy_valid_blocks(struct dmz_metadata *zmd, struct dm_zone *from_zone,
struct dm_zone *to_zone);
int dmz_merge_valid_blocks(struct dmz_metadata *zmd, struct dm_zone *from_zone,
struct dm_zone *to_zone, sector_t chunk_block);
/*
* Functions defined in dm-zoned-reclaim.c
*/
int dmz_ctr_reclaim(struct dmz_dev *dev, struct dmz_metadata *zmd,
struct dmz_reclaim **zrc);
void dmz_dtr_reclaim(struct dmz_reclaim *zrc);
void dmz_suspend_reclaim(struct dmz_reclaim *zrc);
void dmz_resume_reclaim(struct dmz_reclaim *zrc);
void dmz_reclaim_bio_acc(struct dmz_reclaim *zrc);
void dmz_schedule_reclaim(struct dmz_reclaim *zrc);
#endif /* DM_ZONED_H */