Commit 7cb10a4c authored by Bart Van Assche's avatar Bart Van Assche Committed by Greg Kroah-Hartman

scsi: sd_zbc: Avoid that resetting a zone fails sporadically

commit ccce20fc upstream.

Since SCSI scanning occurs asynchronously, since sd_revalidate_disk() is
called from sd_probe_async() and since sd_revalidate_disk() calls
sd_zbc_read_zones() it can happen that sd_zbc_read_zones() is called
concurrently with blkdev_report_zones() and/or blkdev_reset_zones().  That can
cause these functions to fail with -EIO because sd_zbc_read_zones() e.g. sets
q->nr_zones to zero before restoring it to the actual value, even if no drive
characteristics have changed.  Avoid that this can happen by making the
following changes:

- Protect the code that updates zone information with blk_queue_enter()
  and blk_queue_exit().
- Modify sd_zbc_setup_seq_zones_bitmap() and sd_zbc_setup() such that
  these functions do not modify struct scsi_disk before all zone
  information has been obtained.

Note: since commit 055f6e18 ("block: Make q_usage_counter also track
legacy requests"; kernel v4.15) the request queue freezing mechanism also
affects legacy request queues.

Fixes: 89d94756 ("sd: Implement support for ZBC devices")
Signed-off-by: default avatarBart Van Assche <bart.vanassche@wdc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: stable@vger.kernel.org # v4.16
Reviewed-by: default avatarDamien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: default avatarDamien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1110636e
......@@ -423,7 +423,16 @@ static int sd_zbc_check_capacity(struct scsi_disk *sdkp,
#define SD_ZBC_BUF_SIZE 131072
static int sd_zbc_check_zone_size(struct scsi_disk *sdkp)
/**
* sd_zbc_check_zone_size - Check the device zone sizes
* @sdkp: Target disk
*
* Check that all zones of the device are equal. The last zone can however
* be smaller. The zone size must also be a power of two number of LBAs.
*
* Returns the zone size in bytes upon success or an error code upon failure.
*/
static s64 sd_zbc_check_zone_size(struct scsi_disk *sdkp)
{
u64 zone_blocks = 0;
sector_t block = 0;
......@@ -434,8 +443,6 @@ static int sd_zbc_check_zone_size(struct scsi_disk *sdkp)
int ret;
u8 same;
sdkp->zone_blocks = 0;
/* Get a buffer */
buf = kmalloc(SD_ZBC_BUF_SIZE, GFP_KERNEL);
if (!buf)
......@@ -470,16 +477,17 @@ static int sd_zbc_check_zone_size(struct scsi_disk *sdkp)
/* Parse zone descriptors */
while (rec < buf + buf_len) {
zone_blocks = get_unaligned_be64(&rec[8]);
if (sdkp->zone_blocks == 0) {
sdkp->zone_blocks = zone_blocks;
} else if (zone_blocks != sdkp->zone_blocks &&
(block + zone_blocks < sdkp->capacity
|| zone_blocks > sdkp->zone_blocks)) {
u64 this_zone_blocks = get_unaligned_be64(&rec[8]);
if (zone_blocks == 0) {
zone_blocks = this_zone_blocks;
} else if (this_zone_blocks != zone_blocks &&
(block + this_zone_blocks < sdkp->capacity
|| this_zone_blocks > zone_blocks)) {
zone_blocks = 0;
goto out;
}
block += zone_blocks;
block += this_zone_blocks;
rec += 64;
}
......@@ -492,8 +500,6 @@ static int sd_zbc_check_zone_size(struct scsi_disk *sdkp)
} while (block < sdkp->capacity);
zone_blocks = sdkp->zone_blocks;
out:
if (!zone_blocks) {
if (sdkp->first_scan)
......@@ -513,8 +519,7 @@ static int sd_zbc_check_zone_size(struct scsi_disk *sdkp)
"Zone size too large\n");
ret = -ENODEV;
} else {
sdkp->zone_blocks = zone_blocks;
sdkp->zone_shift = ilog2(zone_blocks);
ret = zone_blocks;
}
out_free:
......@@ -523,23 +528,44 @@ static int sd_zbc_check_zone_size(struct scsi_disk *sdkp)
return ret;
}
static int sd_zbc_setup(struct scsi_disk *sdkp)
static int sd_zbc_setup(struct scsi_disk *sdkp, u32 zone_blocks)
{
struct request_queue *q = sdkp->disk->queue;
u32 zone_shift = ilog2(zone_blocks);
u32 nr_zones;
/* chunk_sectors indicates the zone size */
blk_queue_chunk_sectors(sdkp->disk->queue,
logical_to_sectors(sdkp->device, sdkp->zone_blocks));
sdkp->zone_shift = ilog2(sdkp->zone_blocks);
sdkp->nr_zones = sdkp->capacity >> sdkp->zone_shift;
if (sdkp->capacity & (sdkp->zone_blocks - 1))
sdkp->nr_zones++;
if (!sdkp->zones_wlock) {
sdkp->zones_wlock = kcalloc(BITS_TO_LONGS(sdkp->nr_zones),
sizeof(unsigned long),
GFP_KERNEL);
if (!sdkp->zones_wlock)
return -ENOMEM;
blk_queue_chunk_sectors(q,
logical_to_sectors(sdkp->device, zone_blocks));
nr_zones = round_up(sdkp->capacity, zone_blocks) >> zone_shift;
/*
* Initialize the disk zone write lock bitmap if the number
* of zones changed.
*/
if (nr_zones != sdkp->nr_zones) {
unsigned long *zones_wlock = NULL;
if (nr_zones) {
zones_wlock = kcalloc(BITS_TO_LONGS(nr_zones),
sizeof(unsigned long),
GFP_KERNEL);
if (!zones_wlock)
return -ENOMEM;
}
blk_mq_freeze_queue(q);
sdkp->zone_blocks = zone_blocks;
sdkp->zone_shift = zone_shift;
sdkp->nr_zones = nr_zones;
swap(sdkp->zones_wlock, zones_wlock);
blk_mq_unfreeze_queue(q);
kfree(zones_wlock);
/* READ16/WRITE16 is mandatory for ZBC disks */
sdkp->device->use_16_for_rw = 1;
sdkp->device->use_10_for_rw = 0;
}
return 0;
......@@ -548,6 +574,7 @@ static int sd_zbc_setup(struct scsi_disk *sdkp)
int sd_zbc_read_zones(struct scsi_disk *sdkp,
unsigned char *buf)
{
int64_t zone_blocks;
int ret;
if (!sd_is_zoned(sdkp))
......@@ -585,19 +612,19 @@ int sd_zbc_read_zones(struct scsi_disk *sdkp,
* Check zone size: only devices with a constant zone size (except
* an eventual last runt zone) that is a power of 2 are supported.
*/
ret = sd_zbc_check_zone_size(sdkp);
if (ret)
zone_blocks = sd_zbc_check_zone_size(sdkp);
ret = -EFBIG;
if (zone_blocks != (u32)zone_blocks)
goto err;
ret = zone_blocks;
if (ret < 0)
goto err;
/* The drive satisfies the kernel restrictions: set it up */
ret = sd_zbc_setup(sdkp);
ret = sd_zbc_setup(sdkp, zone_blocks);
if (ret)
goto err;
/* READ16/WRITE16 is mandatory for ZBC disks */
sdkp->device->use_16_for_rw = 1;
sdkp->device->use_10_for_rw = 0;
return 0;
err:
......@@ -610,6 +637,7 @@ void sd_zbc_remove(struct scsi_disk *sdkp)
{
kfree(sdkp->zones_wlock);
sdkp->zones_wlock = NULL;
sdkp->nr_zones = 0;
}
void sd_zbc_print_zones(struct scsi_disk *sdkp)
......
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