On Mon, 20 Feb 2023, mingzhe wrote:
> 在 2023/2/19 17:39, Coly Li 写道:
> >> Subject: [PATCH v2] bcache: Add support for live resize of backing devices
> >>
> >> Signed-off-by: Andrea Tomassetti <andrea.tomassetti-opensource@devo.com>
> > 
> > Hi Andrea,
> > 
> > I am fine with this patch and added it in my test queue now. Do you have an
> > updated version, (e.g. more coding refine or adding commit log), then I can
> > update my local version.
> > 
> > 
> Hi, Coly
> 
> I posted some patchsets about online resize.
> 
> -[PATCH v5 1/3] bcache: add dirty_data in struct bcache_device
> -[PATCH v5 2/3] bcache: allocate stripe memory when partial_stripes_expensive
> is true
> -[PATCH v5 3/3] bcache: support online resizing of cached_dev
> 
> There are some differences:
> 1. Create /sys/block/bcache0/bcache/size in sysfs to trigger resize

Can the final version name the sysfs entry "resize", because "size" sounds 
like you are setting a specific size, not triggering a resize.

--
Eric Wheeler



> 2. Allocate stripe memory only if partial_stripes_expensive is true
> 3. Simplify bcache_dev_sectors_dirty()
> 
> Since the bcache superblock uses some sectors, the actual space of the bcache
> device is smaller than the backing. In order to provide a bcache device with a
> user-specified size, we need to create a backing device with a larger space,
> and then resize bcache. So resize can specify the size is very necessary.
> 
> 
> 
> 
> > 
> > 
> >> ---
> >> Hi Coly,
> >> this is the second version of the patch. As you correctly pointed out,
> >> I implemented roll-back functionalities in case of error.
> >> I'm testing this funcionality using QEMU/KVM vm via libvirt.
> >> Here the steps:
> >>   1. make-bcache --writeback -B /dev/vdb -C /dev/vdc
> >>   2. mkfs.xfs /dev/bcache0
> >>   3. mount /dev/bcache0 /mnt
> >>   3. dd if=/dev/random of=/mnt/random0 bs=1M count=1000
> >>   4. md5sum /mnt/random0 | tee /mnt/random0.md5
> >>   5. [HOST] virsh blockresize <vm-name> --path <disk-path> --size
> >>   <new-size>
> >>   6. xfs_growfs /dev/bcache0
> >>   6. Repeat steps 3 and 4 with a different file name (e.g. random1.md5)
> >>   7. umount/reboot/remount and check that the md5 hashes are correct with
> >>         md5sum -c /mnt/random?.md5
> >>
> >> drivers/md/bcache/super.c | 84 ++++++++++++++++++++++++++++++++++++++-
> >> 1 file changed, 83 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> >> index ba3909bb6bea..1435a3f605f8 100644
> >> --- a/drivers/md/bcache/super.c
> >> +++ b/drivers/md/bcache/super.c
> >>>
> > 
> > [snipped]
> > 
> > 
> 
>