| Message ID | 20210805143603.59503-1-mreitz@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | gluster: Align block-status tail | expand |
On Thu, Aug 05, 2021 at 04:36:03PM +0200, Max Reitz wrote: > gluster's block-status implementation is basically a copy of that in > block/file-posix.c, there is only one thing missing, and that is > aligning trailing data extents to the request alignment (as added by > commit 9c3db310ff0). > > Note that 9c3db310ff0 mentions that "there seems to be no other block > driver that sets request_alignment and [...]", but while block/gluster.c > does indeed not set request_alignment, block/io.c's > bdrv_refresh_limits() will still default to an alignment of 512 because > block/gluster.c does not provide a byte-aligned read function. > Therefore, unaligned tails can conceivably occur, and so we should apply > the change from 9c3db310ff0 to gluster's block-status implementation. > > Reported-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> > Signed-off-by: Max Reitz <mreitz@redhat.com> > --- > block/gluster.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) Probably not a show-stopper for 6.1, so I'm fine if it sits until 6.2. Reviewed-by: Eric Blake <eblake@redhat.com>
On 05.08.21 16:36, Max Reitz wrote: > gluster's block-status implementation is basically a copy of that in > block/file-posix.c, there is only one thing missing, and that is > aligning trailing data extents to the request alignment (as added by > commit 9c3db310ff0). > > Note that 9c3db310ff0 mentions that "there seems to be no other block > driver that sets request_alignment and [...]", but while block/gluster.c > does indeed not set request_alignment, block/io.c's > bdrv_refresh_limits() will still default to an alignment of 512 because > block/gluster.c does not provide a byte-aligned read function. > Therefore, unaligned tails can conceivably occur, and so we should apply > the change from 9c3db310ff0 to gluster's block-status implementation. > > Reported-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> > Signed-off-by: Max Reitz <mreitz@redhat.com> > --- > block/gluster.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) Thanks for the review, applied to my block branch: https://github.com/XanClic/qemu/commits/block Hanna
diff --git a/block/gluster.c b/block/gluster.c index e8ee14c8e9..48a04417cf 100644 --- a/block/gluster.c +++ b/block/gluster.c @@ -1477,6 +1477,8 @@ static int coroutine_fn qemu_gluster_co_block_status(BlockDriverState *bs, off_t data = 0, hole = 0; int ret = -EINVAL; + assert(QEMU_IS_ALIGNED(offset | bytes, bs->bl.request_alignment)); + if (!s->fd) { return ret; } @@ -1501,6 +1503,20 @@ static int coroutine_fn qemu_gluster_co_block_status(BlockDriverState *bs, /* On a data extent, compute bytes to the end of the extent, * possibly including a partial sector at EOF. */ *pnum = MIN(bytes, hole - offset); + + /* + * We are not allowed to return partial sectors, though, so + * round up if necessary. + */ + if (!QEMU_IS_ALIGNED(*pnum, bs->bl.request_alignment)) { + int64_t file_length = qemu_gluster_getlength(bs); + if (file_length > 0) { + /* Ignore errors, this is just a safeguard */ + assert(hole == file_length); + } + *pnum = ROUND_UP(*pnum, bs->bl.request_alignment); + } + ret = BDRV_BLOCK_DATA; } else { /* On a hole, compute bytes to the beginning of the next extent. */
gluster's block-status implementation is basically a copy of that in block/file-posix.c, there is only one thing missing, and that is aligning trailing data extents to the request alignment (as added by commit 9c3db310ff0). Note that 9c3db310ff0 mentions that "there seems to be no other block driver that sets request_alignment and [...]", but while block/gluster.c does indeed not set request_alignment, block/io.c's bdrv_refresh_limits() will still default to an alignment of 512 because block/gluster.c does not provide a byte-aligned read function. Therefore, unaligned tails can conceivably occur, and so we should apply the change from 9c3db310ff0 to gluster's block-status implementation. Reported-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Max Reitz <mreitz@redhat.com> --- block/gluster.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)