linux/drivers/md/bcache/writeback.h
Coly Li 7a14812679 bcache: fix overflow in offset_to_stripe()
offset_to_stripe() returns the stripe number (in type unsigned int) from
an offset (in type uint64_t) by the following calculation,
	do_div(offset, d->stripe_size);
For large capacity backing device (e.g. 18TB) with small stripe size
(e.g. 4KB), the result is 4831838208 and exceeds UINT_MAX. The actual
returned value which caller receives is 536870912, due to the overflow.

Indeed in bcache_device_init(), bcache_device->nr_stripes is limited in
range [1, INT_MAX]. Therefore all valid stripe numbers in bcache are
in range [0, bcache_dev->nr_stripes - 1].

This patch adds a upper limition check in offset_to_stripe(): the max
valid stripe number should be less than bcache_device->nr_stripes. If
the calculated stripe number from do_div() is equal to or larger than
bcache_device->nr_stripe, -EINVAL will be returned. (Normally nr_stripes
is less than INT_MAX, exceeding upper limitation doesn't mean overflow,
therefore -EOVERFLOW is not used as error code.)

This patch also changes nr_stripes' type of struct bcache_device from
'unsigned int' to 'int', and return value type of offset_to_stripe()
from 'unsigned int' to 'int', to match their exact data ranges.

All locations where bcache_device->nr_stripes and offset_to_stripe() are
referenced also get updated for the above type change.

Reported-and-tested-by: Ken Raeburn <raeburn@redhat.com>
Signed-off-by: Coly Li <colyli@suse.de>
Cc: stable@vger.kernel.org
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1783075
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-25 07:38:20 -06:00

152 lines
3.6 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _BCACHE_WRITEBACK_H
#define _BCACHE_WRITEBACK_H
#define CUTOFF_WRITEBACK 40
#define CUTOFF_WRITEBACK_SYNC 70
#define CUTOFF_WRITEBACK_MAX 70
#define CUTOFF_WRITEBACK_SYNC_MAX 90
#define MAX_WRITEBACKS_IN_PASS 5
#define MAX_WRITESIZE_IN_PASS 5000 /* *512b */
#define WRITEBACK_RATE_UPDATE_SECS_MAX 60
#define WRITEBACK_RATE_UPDATE_SECS_DEFAULT 5
#define BCH_AUTO_GC_DIRTY_THRESHOLD 50
#define BCH_DIRTY_INIT_THRD_MAX 64
/*
* 14 (16384ths) is chosen here as something that each backing device
* should be a reasonable fraction of the share, and not to blow up
* until individual backing devices are a petabyte.
*/
#define WRITEBACK_SHARE_SHIFT 14
struct bch_dirty_init_state;
struct dirty_init_thrd_info {
struct bch_dirty_init_state *state;
struct task_struct *thread;
};
struct bch_dirty_init_state {
struct cache_set *c;
struct bcache_device *d;
int total_threads;
int key_idx;
spinlock_t idx_lock;
atomic_t started;
atomic_t enough;
wait_queue_head_t wait;
struct dirty_init_thrd_info infos[BCH_DIRTY_INIT_THRD_MAX];
};
static inline uint64_t bcache_dev_sectors_dirty(struct bcache_device *d)
{
uint64_t i, ret = 0;
for (i = 0; i < d->nr_stripes; i++)
ret += atomic_read(d->stripe_sectors_dirty + i);
return ret;
}
static inline int offset_to_stripe(struct bcache_device *d,
uint64_t offset)
{
do_div(offset, d->stripe_size);
/* d->nr_stripes is in range [1, INT_MAX] */
if (unlikely(offset >= d->nr_stripes)) {
pr_err("Invalid stripe %llu (>= nr_stripes %d).\n",
offset, d->nr_stripes);
return -EINVAL;
}
/*
* Here offset is definitly smaller than INT_MAX,
* return it as int will never overflow.
*/
return offset;
}
static inline bool bcache_dev_stripe_dirty(struct cached_dev *dc,
uint64_t offset,
unsigned int nr_sectors)
{
int stripe = offset_to_stripe(&dc->disk, offset);
if (stripe < 0)
return false;
while (1) {
if (atomic_read(dc->disk.stripe_sectors_dirty + stripe))
return true;
if (nr_sectors <= dc->disk.stripe_size)
return false;
nr_sectors -= dc->disk.stripe_size;
stripe++;
}
}
extern unsigned int bch_cutoff_writeback;
extern unsigned int bch_cutoff_writeback_sync;
static inline bool should_writeback(struct cached_dev *dc, struct bio *bio,
unsigned int cache_mode, bool would_skip)
{
unsigned int in_use = dc->disk.c->gc_stats.in_use;
if (cache_mode != CACHE_MODE_WRITEBACK ||
test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
in_use > bch_cutoff_writeback_sync)
return false;
if (bio_op(bio) == REQ_OP_DISCARD)
return false;
if (dc->partial_stripes_expensive &&
bcache_dev_stripe_dirty(dc, bio->bi_iter.bi_sector,
bio_sectors(bio)))
return true;
if (would_skip)
return false;
return (op_is_sync(bio->bi_opf) ||
bio->bi_opf & (REQ_META|REQ_PRIO) ||
in_use <= bch_cutoff_writeback);
}
static inline void bch_writeback_queue(struct cached_dev *dc)
{
if (!IS_ERR_OR_NULL(dc->writeback_thread))
wake_up_process(dc->writeback_thread);
}
static inline void bch_writeback_add(struct cached_dev *dc)
{
if (!atomic_read(&dc->has_dirty) &&
!atomic_xchg(&dc->has_dirty, 1)) {
if (BDEV_STATE(&dc->sb) != BDEV_STATE_DIRTY) {
SET_BDEV_STATE(&dc->sb, BDEV_STATE_DIRTY);
/* XXX: should do this synchronously */
bch_write_bdev_super(dc, NULL);
}
bch_writeback_queue(dc);
}
}
void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned int inode,
uint64_t offset, int nr_sectors);
void bch_sectors_dirty_init(struct bcache_device *d);
void bch_cached_dev_writeback_init(struct cached_dev *dc);
int bch_cached_dev_writeback_start(struct cached_dev *dc);
#endif