On 6/16/26 9:45 PM, Niklas Cassel wrote:
> For zoned block devices with SWR zones, the order of the writes must be
> maintained to avoid write not at write pointer errors.
> Thus, cache.direct=on must be used to bypass the page cache, since the
> page cache uses write-back caching, where the physical order of the writes
> is not guaranteed.
>
> There is already a check for cache.direct=on in raw_open_common(),
> however, this check is done before raw_refresh_zoned_limits() has been
> called (which initializes bs->bl.zoned), so it is currently dead code.
>
> Fix this by moving the check to raw_refresh_zoned_limits(), such that the
> check is done after bs->bl.zoned has been initialized.
>
> Fixes: 774c726ceb2a ("block: add zoned BlockDriver check to block layer")
> Signed-off-by: Niklas Cassel <[email protected]>
> ---
> block/file-posix.c | 22 ++++++++++------------
> 1 file changed, 10 insertions(+), 12 deletions(-)
>
> diff --git a/block/file-posix.c b/block/file-posix.c
> index 5019ddade9..2cdae2d40c 100644
> --- a/block/file-posix.c
> +++ b/block/file-posix.c
> @@ -800,18 +800,6 @@ static int raw_open_common(BlockDriverState *bs, QDict
> *options,
> goto fail;
> }
> }
> -#ifdef CONFIG_BLKZONED
> - /*
> - * The kernel page cache does not reliably work for writes to SWR zones
> - * of zoned block device because it can not guarantee the order of
> writes.
> - */
> - if ((bs->bl.zoned != BLK_Z_NONE) &&
> - (!(s->open_flags & O_DIRECT))) {
> - error_setg(errp, "The driver supports zoned devices, and it requires
> "
> - "cache.direct=on, which was not specified.");
> - return -EINVAL; /* No host kernel page cache */
> - }
> -#endif
>
> #ifdef __FreeBSD__
> if (S_ISCHR(st.st_mode)) {
> @@ -1462,6 +1450,16 @@ static void raw_refresh_zoned_limits(BlockDriverState
> *bs, struct stat *st,
> }
> bs->bl.zoned = zoned;
>
> + /*
> + * The kernel page cache does not reliably work for writes to SWR zones
> + * of zoned block device because it can not guarantee the order of
> writes.
s/device/devices
Apart from that, looks OK to me.
Reviewed-by: Damien Le Moal <[email protected]>
> + */
> + if (!(s->open_flags & O_DIRECT)) {
> + error_setg(errp, "The driver supports zoned devices, and it requires
> "
> + "cache.direct=on, which was not specified.");
> + goto no_zoned;
> + }
> +
> ret = get_sysfs_long_val(st, "max_open_zones");
> if (ret >= 0) {
> bs->bl.max_open_zones = ret;
--
Damien Le Moal
Western Digital Research
