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 055f6e18e08f ("block: Make q_usage_counter also track legacy requests"; kernel v4.15) the request queue freezing mechanism also affects legacy request queues.

Signed-off-by: Bart 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 --- drivers/scsi/sd_zbc.c | 140 +++++++++++++++++++++++++++++-------------------- include/linux/blkdev.h | 5 ++ 2 files changed, 87 insertions(+), 58 deletions(-)

diff --git a/drivers/scsi/sd_zbc.c b/drivers/scsi/sd_zbc.c index f290e8a9923d..88e1e80fa497 100644 --- a/drivers/scsi/sd_zbc.c +++ b/drivers/scsi/sd_zbc.c @@ -378,8 +378,10 @@ static int sd_zbc_check_capacity(struct scsi_disk *sdkp, unsigned char *buf) * * 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 int sd_zbc_check_zone_size(struct scsi_disk *sdkp) +static s64 sd_zbc_check_zone_size(struct scsi_disk *sdkp) { u64 zone_blocks = 0; sector_t block = 0; @@ -390,8 +392,6 @@ 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) @@ -423,16 +423,17 @@ 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)) { - zone_blocks = 0; + 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)) { + this_zone_blocks = 0; goto out; } - block += zone_blocks; + block += this_zone_blocks; rec += 64; }

@@ -445,8 +446,6 @@ 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) @@ -466,8 +465,7 @@ 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: @@ -478,15 +476,14 @@ static int sd_zbc_check_zone_size(struct scsi_disk *sdkp)

/** * sd_zbc_alloc_zone_bitmap - Allocate a zone bitmap (one bit per zone). - * @sdkp: The disk of the bitmap + * @nr_zones: Number of zones to allocate space for. + * @numa_node: NUMA node to allocate the memory from. */ -static inline unsigned long *sd_zbc_alloc_zone_bitmap(struct scsi_disk *sdkp) +static inline unsigned long * +sd_zbc_alloc_zone_bitmap(u32 nr_zones, int numa_node) { - struct request_queue *q = sdkp->disk->queue; - - return kzalloc_node(BITS_TO_LONGS(sdkp->nr_zones) - * sizeof(unsigned long), - GFP_KERNEL, q->node); + return kzalloc_node(BITS_TO_LONGS(nr_zones) * sizeof(unsigned long), + GFP_KERNEL, numa_node); }

/** @@ -494,6 +491,7 @@ static inline unsigned long *sd_zbc_alloc_zone_bitmap(struct scsi_disk *sdkp) * @sdkp: disk used * @buf: report reply buffer * @buflen: length of @buf + * @zone_shift: logarithm base 2 of the number of blocks in a zone * @seq_zones_bitmap: bitmap of sequential zones to set * * Parse reported zone descriptors in @buf to identify sequential zones and @@ -503,7 +501,7 @@ static inline unsigned long *sd_zbc_alloc_zone_bitmap(struct scsi_disk *sdkp) * Return the LBA after the last zone reported. */ static sector_t sd_zbc_get_seq_zones(struct scsi_disk *sdkp, unsigned char *buf, - unsigned int buflen, + unsigned int buflen, u32 zone_shift, unsigned long *seq_zones_bitmap) { sector_t lba, next_lba = sdkp->capacity; @@ -522,7 +520,7 @@ static sector_t sd_zbc_get_seq_zones(struct scsi_disk *sdkp, unsigned char *buf, if (type != ZBC_ZONE_TYPE_CONV && cond != ZBC_ZONE_COND_READONLY && cond != ZBC_ZONE_COND_OFFLINE) - set_bit(lba >> sdkp->zone_shift, seq_zones_bitmap); + set_bit(lba >> zone_shift, seq_zones_bitmap); next_lba = lba + get_unaligned_be64(&rec[8]); rec += 64; } @@ -531,12 +529,16 @@ static sector_t sd_zbc_get_seq_zones(struct scsi_disk *sdkp, unsigned char *buf, }

/** - * sd_zbc_setup_seq_zones_bitmap - Initialize the disk seq zone bitmap. + * sd_zbc_setup_seq_zones_bitmap - Initialize a seq zone bitmap. * @sdkp: target disk + * @zone_shift: logarithm base 2 of the number of blocks in a zone + * @nr_zones: number of zones to set up a seq zone bitmap for * * Allocate a zone bitmap and initialize it by identifying sequential zones. */ -static int sd_zbc_setup_seq_zones_bitmap(struct scsi_disk *sdkp) +static unsigned long * +sd_zbc_setup_seq_zones_bitmap(struct scsi_disk *sdkp, u32 zone_shift, + u32 nr_zones) { struct request_queue *q = sdkp->disk->queue; unsigned long *seq_zones_bitmap; @@ -544,9 +546,9 @@ static int sd_zbc_setup_seq_zones_bitmap(struct scsi_disk *sdkp) unsigned char *buf; int ret = -ENOMEM;

- seq_zones_bitmap = sd_zbc_alloc_zone_bitmap(sdkp); + seq_zones_bitmap = sd_zbc_alloc_zone_bitmap(nr_zones, q->node); if (!seq_zones_bitmap) - return -ENOMEM; + return ERR_PTR(-ENOMEM);

buf = kmalloc(SD_ZBC_BUF_SIZE, GFP_KERNEL); if (!buf) @@ -557,7 +559,7 @@ static int sd_zbc_setup_seq_zones_bitmap(struct scsi_disk *sdkp) if (ret) goto out; lba = sd_zbc_get_seq_zones(sdkp, buf, SD_ZBC_BUF_SIZE, - seq_zones_bitmap); + zone_shift, seq_zones_bitmap); }

if (lba != sdkp->capacity) { @@ -569,12 +571,9 @@ static int sd_zbc_setup_seq_zones_bitmap(struct scsi_disk *sdkp) kfree(buf); if (ret) { kfree(seq_zones_bitmap); - return ret; + return ERR_PTR(ret); } - - q->seq_zones_bitmap = seq_zones_bitmap; - - return 0; + return seq_zones_bitmap; }

static void sd_zbc_cleanup(struct scsi_disk *sdkp) @@ -590,44 +589,64 @@ static void sd_zbc_cleanup(struct scsi_disk *sdkp) q->nr_zones = 0; }

-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; int ret;

- /* READ16/WRITE16 is mandatory for ZBC disks */ - sdkp->device->use_16_for_rw = 1; - sdkp->device->use_10_for_rw = 0; - /* chunk_sectors indicates the zone size */ - blk_queue_chunk_sectors(sdkp->disk->queue, - logical_to_sectors(sdkp->device, sdkp->zone_blocks)); - sdkp->nr_zones = - round_up(sdkp->capacity, sdkp->zone_blocks) >> sdkp->zone_shift; + blk_queue_chunk_sectors(q, + logical_to_sectors(sdkp->device, zone_blocks)); + nr_zones = round_up(sdkp->capacity, zone_blocks) >> zone_shift;

/* * Initialize the device request queue information if the number * of zones changed. */ - if (sdkp->nr_zones != q->nr_zones) { - - sd_zbc_cleanup(sdkp); - - q->nr_zones = sdkp->nr_zones; - if (sdkp->nr_zones) { - q->seq_zones_wlock = sd_zbc_alloc_zone_bitmap(sdkp); - if (!q->seq_zones_wlock) { + if (nr_zones != sdkp->nr_zones || nr_zones != q->nr_zones) { + unsigned long *seq_zones_wlock = NULL, *seq_zones_bitmap = NULL; + size_t zone_bitmap_size; + + if (nr_zones) { + seq_zones_wlock = sd_zbc_alloc_zone_bitmap(nr_zones, + q->node); + if (!seq_zones_wlock) { ret = -ENOMEM; goto err; }

- ret = sd_zbc_setup_seq_zones_bitmap(sdkp); - if (ret) { - sd_zbc_cleanup(sdkp); + seq_zones_bitmap = sd_zbc_setup_seq_zones_bitmap(sdkp, + zone_shift, nr_zones); + if (IS_ERR(seq_zones_bitmap)) { + ret = PTR_ERR(seq_zones_bitmap); + kfree(seq_zones_wlock); goto err; } } - + zone_bitmap_size = BITS_TO_LONGS(nr_zones) * + sizeof(unsigned long); + blk_mq_freeze_queue(q); + if (q->nr_zones != nr_zones) { + /* READ16/WRITE16 is mandatory for ZBC disks */ + sdkp->device->use_16_for_rw = 1; + sdkp->device->use_10_for_rw = 0; + + sdkp->zone_blocks = zone_blocks; + sdkp->zone_shift = zone_shift; + sdkp->nr_zones = nr_zones; + q->nr_zones = nr_zones; + swap(q->seq_zones_wlock, seq_zones_wlock); + swap(q->seq_zones_bitmap, seq_zones_bitmap); + } else if (memcmp(q->seq_zones_bitmap, seq_zones_bitmap, + zone_bitmap_size) != 0) { + memcpy(q->seq_zones_bitmap, seq_zones_bitmap, + zone_bitmap_size); + } + blk_mq_unfreeze_queue(q); + kfree(seq_zones_wlock); + kfree(seq_zones_bitmap); }

return 0; @@ -639,6 +658,7 @@ 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)) @@ -675,12 +695,16 @@ int sd_zbc_read_zones(struct scsi_disk *sdkp, unsigned char *buf) * 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;

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 9af3e0f430bc..21e21f273a21 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -605,6 +605,11 @@ struct request_queue { * initialized by the low level device driver (e.g. scsi/sd.c). * Stacking drivers (device mappers) may or may not initialize * these fields. + * + * Reads of this information must be protected with blk_queue_enter() / + * blk_queue_exit(). Modifying this information is only allowed while + * no requests are being processed. See also blk_mq_freeze_queue() and + * blk_mq_unfreeze_queue(). */ unsigned int nr_zones; unsigned long *seq_zones_bitmap;