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Re: [Qemu-devel] [PATCH 1/2] glusterfs: fix max_discard
From: |
Peter Lieven |
Subject: |
Re: [Qemu-devel] [PATCH 1/2] glusterfs: fix max_discard |
Date: |
Mon, 02 Feb 2015 20:58:54 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 |
Am 02.02.2015 um 19:29 schrieb Denis V. Lunev:
> qemu_gluster_co_discard calculates size to discard as follows
> size_t size = nb_sectors * BDRV_SECTOR_SIZE;
> ret = glfs_discard_async(s->fd, offset, size, &gluster_finish_aiocb, acb);
>
> glfs_discard_async is declared as follows:
> int glfs_discard_async (glfs_fd_t *fd, off_t length, size_t lent,
> glfs_io_cbk fn, void *data) __THROW
> This is problematic on i686 as sizeof(size_t) == 4.
>
> Set bl_max_discard to SIZE_MAX >> BDRV_SECTOR_BITS to avoid overflow
> on i386.
>
> Signed-off-by: Denis V. Lunev <address@hidden>
> CC: Kevin Wolf <address@hidden>
> CC: Peter Lieven <address@hidden>
> ---
> block/gluster.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/block/gluster.c b/block/gluster.c
> index 1eb3a8c..47bf92d 100644
> --- a/block/gluster.c
> +++ b/block/gluster.c
> @@ -622,6 +622,13 @@ out:
> return ret;
> }
>
> +static void qemu_gluster_refresh_limits(BlockDriverState *bs, Error **errp)
> +{
> +#if SIZE_MAX == UINT_MAX
> + bs->bl.max_discard = SIZE_MAX >> BDRV_SECTOR_BITS;
> +#endif
I would write:
bs->bl.max_discard = MIN(SIZE_MAX >> BDRV_SECTOR_BITS, INT_MAX);
without the condition.
Peter
> +}
> +
> #ifdef CONFIG_GLUSTERFS_DISCARD
> static coroutine_fn int qemu_gluster_co_discard(BlockDriverState *bs,
> int64_t sector_num, int nb_sectors)
> @@ -735,6 +742,7 @@ static BlockDriver bdrv_gluster = {
> #ifdef CONFIG_GLUSTERFS_DISCARD
> .bdrv_co_discard = qemu_gluster_co_discard,
> #endif
> + .bdrv_refresh_limits = qemu_gluster_refresh_limits,
> #ifdef CONFIG_GLUSTERFS_ZEROFILL
> .bdrv_co_write_zeroes = qemu_gluster_co_write_zeroes,
> #endif
> @@ -762,6 +770,7 @@ static BlockDriver bdrv_gluster_tcp = {
> #ifdef CONFIG_GLUSTERFS_DISCARD
> .bdrv_co_discard = qemu_gluster_co_discard,
> #endif
> + .bdrv_refresh_limits = qemu_gluster_refresh_limits,
> #ifdef CONFIG_GLUSTERFS_ZEROFILL
> .bdrv_co_write_zeroes = qemu_gluster_co_write_zeroes,
> #endif
> @@ -789,6 +798,7 @@ static BlockDriver bdrv_gluster_unix = {
> #ifdef CONFIG_GLUSTERFS_DISCARD
> .bdrv_co_discard = qemu_gluster_co_discard,
> #endif
> + .bdrv_refresh_limits = qemu_gluster_refresh_limits,
> #ifdef CONFIG_GLUSTERFS_ZEROFILL
> .bdrv_co_write_zeroes = qemu_gluster_co_write_zeroes,
> #endif
> @@ -816,6 +826,7 @@ static BlockDriver bdrv_gluster_rdma = {
> #ifdef CONFIG_GLUSTERFS_DISCARD
> .bdrv_co_discard = qemu_gluster_co_discard,
> #endif
> + .bdrv_refresh_limits = qemu_gluster_refresh_limits,
> #ifdef CONFIG_GLUSTERFS_ZEROFILL
> .bdrv_co_write_zeroes = qemu_gluster_co_write_zeroes,
> #endif