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Commit 9ab4bc95 authored by Jan Höppner's avatar Jan Höppner Committed by Greg Kroah-Hartman
Browse files

s390/dasd: Fix zero write for FBA devices 



commit 709192d531e5b0a91f20aa14abfe2fc27ddd47af upstream.

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: 28b841b3 ("s390/dasd: Add discard support for FBA devices")
Signed-off-by: default avatarJan Höppner <hoeppner@linux.ibm.com>
Reviewed-by: default avatarStefan Haberland <sth@linux.ibm.com>
Cc: <stable@vger.kernel.org> # 4.14+
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 240dd511

drivers/s390/block/dasd_fba.c

+8 −1
Original line number Diff line number Diff line
@@ -40,6 +40,7 @@ 
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;
@@ -270,7 +271,7 @@ static void ccw_write_zero(struct ccw1 *ccw, int count) 
	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;

}



/*
@@ -811,6 +812,11 @@ 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();
@@ -822,6 +828,7 @@ 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);