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s390/dasd: Fix zero write for FBA devices 

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: 28b841b3a7 ("s390/dasd: Add discard support for FBA devices")
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Cc: <stable@vger.kernel.org> # 4.14+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jan Höppner 2020-09-14 13:56:47 +02:00 committed by Jens Axboe
parent fd04358e01
commit 709192d531
1 changed files with 8 additions and 1 deletions
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9
drivers/s390/block/dasd_fba.c
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@ -40,6 +40,7 @@
MODULE_LICENSE("GPL"); MODULE_LICENSE("GPL");
static struct dasd_discipline dasd_fba_discipline; static struct dasd_discipline dasd_fba_discipline;
static void *dasd_fba_zero_page;
struct dasd_fba_private { struct dasd_fba_private {
struct dasd_fba_characteristics rdc_data; struct dasd_fba_characteristics rdc_data;
@ -270,7 +271,7 @@ static void ccw_write_zero(struct ccw1 *ccw, int count)
ccw->cmd_code = DASD_FBA_CCW_WRITE; ccw->cmd_code = DASD_FBA_CCW_WRITE;
ccw->flags |= CCW_FLAG_SLI; ccw->flags |= CCW_FLAG_SLI;
ccw->count = count; ccw->count = count;
ccw->cda = (__u32) (addr_t) page_to_phys(ZERO_PAGE(0)); ccw->cda = (__u32) (addr_t) dasd_fba_zero_page;
} }
/* /*
@ -830,6 +831,11 @@ dasd_fba_init(void)
int ret; int ret;
ASCEBC(dasd_fba_discipline.ebcname, 4); 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); ret = ccw_driver_register(&dasd_fba_driver);
if (!ret) if (!ret)
wait_for_device_probe(); wait_for_device_probe();
@ -841,6 +847,7 @@ static void __exit
dasd_fba_cleanup(void) dasd_fba_cleanup(void)
{ {
ccw_driver_unregister(&dasd_fba_driver); ccw_driver_unregister(&dasd_fba_driver);
free_page((unsigned long)dasd_fba_zero_page);
} }
module_init(dasd_fba_init); module_init(dasd_fba_init);