An inactive nbd device may refuse any I/O operations. The nbd_config_put function calls invalidate_disk, which sets the device capacity to zero to reject all read and write I/O. For zero-sector flush I/O requests from blkdev_issue_flush, if the write cache is disabled, the zero-sector flush I/O immediately returns 0 in submit_bio_noacct. However, since nbd_config_put does not clear the write cache state, an inactive nbd device might still have the write cache enabled. In this situation, zero-sector flush I/O will return -EIO because there is no active socket. Additionally, BLK_FEAT_FUA and BLK_FEAT_ROTATIONAL flags may also remain stale, resetting all of them ensures consistent behavior. The limits update uses queue_limits_commit_update() (the non-freezing variant) because config_refs == 0 here means every fd is closed and recv threads have drained, so no in-flight I/O can read q->limits concurrently. Reviewed-by: Yu Kuai Signed-off-by: Yang Erkun --- drivers/block/nbd.c | 43 ++++++++++++++++++++++++++----------------- 1 file changed, 26 insertions(+), 17 deletions(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 7ec85f94f742..78df6f459da6 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -331,6 +331,26 @@ static void nbd_mark_nsock_dead(struct nbd_device *nbd, struct nbd_sock *nsock, nsock->sent = 0; } +static void nbd_apply_limits(struct queue_limits *lim, u32 flags) +{ + lim->features &= ~(BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA | BLK_FEAT_ROTATIONAL); + lim->max_hw_discard_sectors = 0; + lim->max_write_zeroes_sectors = 0; + + if (flags & NBD_FLAG_SEND_TRIM) + lim->max_hw_discard_sectors = UINT_MAX >> SECTOR_SHIFT; + if (flags & NBD_FLAG_SEND_FLUSH) { + lim->features |= BLK_FEAT_WRITE_CACHE; + if (flags & NBD_FLAG_SEND_FUA) + lim->features |= BLK_FEAT_FUA; + } + + if (flags & NBD_FLAG_ROTATIONAL) + lim->features |= BLK_FEAT_ROTATIONAL; + if (flags & NBD_FLAG_SEND_WRITE_ZEROES) + lim->max_write_zeroes_sectors = UINT_MAX >> SECTOR_SHIFT; +} + static int nbd_set_size(struct nbd_device *nbd, loff_t bytesize, loff_t blksize) { struct queue_limits lim; @@ -352,23 +372,7 @@ static int nbd_set_size(struct nbd_device *nbd, loff_t bytesize, loff_t blksize) return 0; lim = queue_limits_start_update(nbd->disk->queue); - if (nbd->config->flags & NBD_FLAG_SEND_TRIM) - lim.max_hw_discard_sectors = UINT_MAX >> SECTOR_SHIFT; - else - lim.max_hw_discard_sectors = 0; - if (!(nbd->config->flags & NBD_FLAG_SEND_FLUSH)) { - lim.features &= ~(BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA); - } else if (nbd->config->flags & NBD_FLAG_SEND_FUA) { - lim.features |= BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA; - } else { - lim.features |= BLK_FEAT_WRITE_CACHE; - lim.features &= ~BLK_FEAT_FUA; - } - if (nbd->config->flags & NBD_FLAG_ROTATIONAL) - lim.features |= BLK_FEAT_ROTATIONAL; - if (nbd->config->flags & NBD_FLAG_SEND_WRITE_ZEROES) - lim.max_write_zeroes_sectors = UINT_MAX >> SECTOR_SHIFT; - + nbd_apply_limits(&lim, nbd->config->flags); lim.logical_block_size = blksize; lim.physical_block_size = blksize; error = queue_limits_commit_update_frozen(nbd->disk->queue, &lim); @@ -1469,8 +1473,13 @@ static void nbd_config_put(struct nbd_device *nbd) if (refcount_dec_and_mutex_lock(&nbd->config_refs, &nbd->config_lock)) { struct nbd_config *config = nbd->config; + struct queue_limits lim; nbd_dev_dbg_close(nbd); invalidate_disk(nbd->disk); + /* reset queue limits to default */ + lim = queue_limits_start_update(nbd->disk->queue); + nbd_apply_limits(&lim, 0); + queue_limits_commit_update(nbd->disk->queue, &lim); if (nbd->config->bytesize) kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE); if (test_and_clear_bit(NBD_RT_HAS_PID_FILE, -- 2.52.0