Eric Blake 890cbccb08 nbd: Fix large trim/zero requests ... Although qemu as NBD client limits requests to <2G, the NBD protocol allows clients to send requests almost all the way up to 4G. But because our block layer is not yet 64-bit clean, we accidentally wrap such requests into a negative size, and fail with EIO instead of performing the intended operation. The bug is visible in modern systems with something as simple as: $ qemu-img create -f qcow2 /tmp/image.img 5G $ sudo qemu-nbd --connect=/dev/nbd0 /tmp/image.img $ sudo blkdiscard /dev/nbd0 or with user-space only: $ truncate --size=3G file $ qemu-nbd -f raw file $ nbdsh -u nbd://localhost:10809 -c 'h.trim(3*1024*1024*1024,0)' Although both blk_co_pdiscard and blk_pwrite_zeroes currently return 0 on success, this is also a good time to fix our code to a more robust paradigm that treats all non-negative values as success. Alas, our iotests do not currently make it easy to add external dependencies on blkdiscard or nbdsh, so we have to rely on manual testing for now. This patch can be reverted when we later improve the overall block layer to be 64-bit clean, but for now, a minimal fix was deemed less risky prior to release. CC: qemu-stable@nongnu.org Fixes: 1f4d6d18ed Fixes: 1c6c4bb7f0 Fixes: https://github.com/systemd/systemd/issues/16242 Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20200722212231.535072-1-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> [eblake: rework success tests to use >=0]		2020-07-28 08:49:29 -05:00
..
client.c	nbd: Use ERRP_GUARD()	2020-07-10 15:18:09 +02:00
common.c	nbd: Prepare for NBD_CMD_FLAG_FAST_ZERO	2019-09-05 16:03:13 -05:00
Makefile.objs	nbd: Split nbd.c	2016-01-15 18:58:02 +01:00
nbd-internal.h	Include qemu/main-loop.h less	2019-08-16 13:31:52 +02:00
server.c	nbd: Fix large trim/zero requests	2020-07-28 08:49:29 -05:00
trace-events	trace: Remove trailing newline in events	2019-09-18 10:19:47 +01:00