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block: set the zone size in blk_revalidate_disk_zones atomically

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The current zone revalidation code has a major problem in that it
doesn't update the zone size and q->nr_zones atomically, leading
to a short window where an out of bounds access to the zone arrays
is possible.

To fix this move the setting of the zone size into the crticial
sections blk_revalidate_disk_zones so that it gets updated together
with the zone bitmaps and q->nr_zones.  This also slightly simplifies
the caller as it deducts the zone size from the report_zones.

This change also allows to check for a power of two zone size in generic
code.

Reported-by: Hans Holmberg <hans@owltronix.com>
Reviewed-by: Javier González <javier@javigon.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2019-12-03 10:39:08 +01:00 committed by Jens Axboe
parent ae58954d87
commit 6c6b354914
3 changed files with 35 additions and 29 deletions
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59
block/blk-zoned.c
View File

@ -343,6 +343,7 @@ struct blk_revalidate_zone_args {
unsigned long *conv_zones_bitmap;
unsigned long *seq_zones_wlock;
unsigned int nr_zones;
sector_t zone_sectors;
sector_t sector;
};
@ -355,25 +356,33 @@ static int blk_revalidate_zone_cb(struct blk_zone *zone, unsigned int idx,
struct blk_revalidate_zone_args *args = data;
struct gendisk *disk = args->disk;
struct request_queue *q = disk->queue;
sector_t zone_sectors = blk_queue_zone_sectors(q);
sector_t capacity = get_capacity(disk);
/*
* All zones must have the same size, with the exception on an eventual
* smaller last zone.
*/
if (zone->start + zone_sectors < capacity &&
zone->len != zone_sectors) {
pr_warn("%s: Invalid zoned device with non constant zone size\n",
disk->disk_name);
return false;
}
if (zone->start == 0) {
if (zone->len == 0 || !is_power_of_2(zone->len)) {
pr_warn("%s: Invalid zoned device with non power of two zone size (%llu)\n",
disk->disk_name, zone->len);
return -ENODEV;
}
if (zone->start + zone->len >= capacity &&
zone->len > zone_sectors) {
pr_warn("%s: Invalid zoned device with larger last zone size\n",
disk->disk_name);
return -ENODEV;
args->zone_sectors = zone->len;
args->nr_zones = (capacity + zone->len - 1) >> ilog2(zone->len);
} else if (zone->start + args->zone_sectors < capacity) {
if (zone->len != args->zone_sectors) {
pr_warn("%s: Invalid zoned device with non constant zone size\n",
disk->disk_name);
return -ENODEV;
}
} else {
if (zone->len > args->zone_sectors) {
pr_warn("%s: Invalid zoned device with larger last zone size\n",
disk->disk_name);
return -ENODEV;
}
}
/* Check for holes in the zone report */
@ -428,9 +437,9 @@ int blk_revalidate_disk_zones(struct gendisk *disk)
struct request_queue *q = disk->queue;
struct blk_revalidate_zone_args args = {
.disk = disk,
.nr_zones = blkdev_nr_zones(disk),
};
int ret = 0;
unsigned int noio_flag;
int ret;
if (WARN_ON_ONCE(!blk_queue_is_zoned(q)))
return -EIO;
@ -438,24 +447,22 @@ int blk_revalidate_disk_zones(struct gendisk *disk)
return -EIO;
/*
* Ensure that all memory allocations in this context are done as
* if GFP_NOIO was specified.
* Ensure that all memory allocations in this context are done as if
* GFP_NOIO was specified.
*/
if (args.nr_zones) {
unsigned int noio_flag = memalloc_noio_save();
ret = disk->fops->report_zones(disk, 0, args.nr_zones,
blk_revalidate_zone_cb, &args);
memalloc_noio_restore(noio_flag);
}
noio_flag = memalloc_noio_save();
ret = disk->fops->report_zones(disk, 0, UINT_MAX,
blk_revalidate_zone_cb, &args);
memalloc_noio_restore(noio_flag);
/*
* Install the new bitmaps, making sure the queue is stopped and
* all I/Os are completed (i.e. a scheduler is not referencing the
* bitmaps).
* Install the new bitmaps and update nr_zones only once the queue is
* stopped and all I/Os are completed (i.e. a scheduler is not
* referencing the bitmaps).
*/
blk_mq_freeze_queue(q);
if (ret >= 0) {
blk_queue_chunk_sectors(q, args.zone_sectors);
q->nr_zones = args.nr_zones;
swap(q->seq_zones_wlock, args.seq_zones_wlock);
swap(q->conv_zones_bitmap, args.conv_zones_bitmap);

3
drivers/block/null_blk_main.c
View File

@ -1583,6 +1583,8 @@ static int null_gendisk_register(struct nullb *nullb)
if (ret)
return ret;
} else {
blk_queue_chunk_sectors(nullb->q,
nullb->dev->zone_size_sects);
nullb->q->nr_zones = blkdev_nr_zones(disk);
}
}
@ -1746,7 +1748,6 @@ static int null_add_dev(struct nullb_device *dev)
if (rv)
goto out_cleanup_blk_queue;
blk_queue_chunk_sectors(nullb->q, dev->zone_size_sects);
nullb->q->limits.zoned = BLK_ZONED_HM;
blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, nullb->q);
blk_queue_required_elevator_features(nullb->q,

2
drivers/scsi/sd_zbc.c
View File

@ -412,8 +412,6 @@ int sd_zbc_read_zones(struct scsi_disk *sdkp, unsigned char *buf)
goto err;
/* The drive satisfies the kernel restrictions: set it up */
blk_queue_chunk_sectors(sdkp->disk->queue,
logical_to_sectors(sdkp->device, zone_blocks));
blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, sdkp->disk->queue);
blk_queue_required_elevator_features(sdkp->disk->queue,
ELEVATOR_F_ZBD_SEQ_WRITE);