From: =?UTF-8?q?Jan=20H=C3=B6ppner?= Date: Mon, 14 Sep 2020 13:56:47 +0200 Subject: s390/dasd: Fix zero write for FBA devices MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Git-commit: 709192d531e5b0a91f20aa14abfe2fc27ddd47af Patch-mainline: v5.9-rc7 References: bsc#1177808 LTC#188739 A discard request that writes zeros using the global kernel internal ZERO_PAGE will fail for machines with more than 2GB of memory due to the location of the ZERO_PAGE. Fix this by using a driver owned global zero page allocated with GFP_DMA flag set. Fixes: 28b841b3a7cb ("s390/dasd: Add discard support for FBA devices") Signed-off-by: Jan Höppner Reviewed-by: Stefan Haberland Cc: # 4.14+ Signed-off-by: Jens Axboe Acked-by: Petr Tesarik --- drivers/s390/block/dasd_fba.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/drivers/s390/block/dasd_fba.c +++ b/drivers/s390/block/dasd_fba.c @@ -39,6 +39,7 @@ MODULE_LICENSE("GPL"); static struct dasd_discipline dasd_fba_discipline; +static void *dasd_fba_zero_page; struct dasd_fba_private { struct dasd_fba_characteristics rdc_data; @@ -269,7 +270,7 @@ static void ccw_write_zero(struct ccw1 * ccw->cmd_code = DASD_FBA_CCW_WRITE; ccw->flags |= CCW_FLAG_SLI; ccw->count = count; - ccw->cda = (__u32) (addr_t) page_to_phys(ZERO_PAGE(0)); + ccw->cda = (__u32) (addr_t) dasd_fba_zero_page; } /* @@ -810,6 +811,11 @@ dasd_fba_init(void) int ret; ASCEBC(dasd_fba_discipline.ebcname, 4); + + dasd_fba_zero_page = (void *)get_zeroed_page(GFP_KERNEL | GFP_DMA); + if (!dasd_fba_zero_page) + return -ENOMEM; + ret = ccw_driver_register(&dasd_fba_driver); if (!ret) wait_for_device_probe(); @@ -821,6 +827,7 @@ static void __exit dasd_fba_cleanup(void) { ccw_driver_unregister(&dasd_fba_driver); + free_page((unsigned long)dasd_fba_zero_page); } module_init(dasd_fba_init);