When a disk changes size, udev rules are fired and register_bcache
function get called. With this patch, every time this happens, the
disk's capacity get checked: if it has changed then the new
bch_update_capacity function get called, otherwise it fails as before.
Signed-off-by: Andrea Tomassetti <andrea.tomassetti-opensource@xxxxxxxx>
---
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
@@ -2443,6 +2443,85 @@ static bool bch_is_open(dev_t dev)
return bch_is_open_cache(dev) || bch_is_open_backing(dev);
}
+static bool bch_update_capacity(dev_t dev)
+{
+ const size_t max_stripes = min_t(size_t, INT_MAX,
+ SIZE_MAX / sizeof(atomic_t));
+
+ uint64_t n, n_old, orig_cached_sectors = 0;
+ void *tmp_realloc;
+
+ int nr_stripes_old;
+ bool res = false;
+
+ struct bcache_device *d;
+ struct cache_set *c, *tc;
+ struct cached_dev *dcp, *t, *dc = NULL;
+
+ uint64_t parent_nr_sectors;
+
+ list_for_each_entry_safe(c, tc, &bch_cache_sets, list)
+ list_for_each_entry_safe(dcp, t, &c->cached_devs, list)
+ if (dcp->bdev->bd_dev == dev) {
+ dc = dcp;
+ goto dc_found;
+ }
+
+dc_found:
+ if (!dc)
+ return false;
+
+ parent_nr_sectors = bdev_nr_sectors(dc->bdev) - dc->sb.data_offset;
+
+ if (parent_nr_sectors == bdev_nr_sectors(dc->disk.disk->part0))
+ return false;
+
+ d = &dc->disk;
+ orig_cached_sectors = d->c->cached_dev_sectors;
+
+ /* Force cached device sectors re-calc */
+ calc_cached_dev_sectors(d->c);
+
+ /* Block writeback thread */
+ down_write(&dc->writeback_lock);
+ nr_stripes_old = d->nr_stripes;
+ n = DIV_ROUND_UP_ULL(parent_nr_sectors, d->stripe_size);
+ if (!n || n > max_stripes) {
+ pr_err("nr_stripes too large or invalid: %llu (start sector beyond end of disk?)\n",
+ n);
+ goto restore_dev_sectors;
+ }
+ d->nr_stripes = n;
+
+ n = d->nr_stripes * sizeof(atomic_t);
+ n_old = nr_stripes_old * sizeof(atomic_t);
+ tmp_realloc = kvrealloc(d->stripe_sectors_dirty, n_old,
+ n, GFP_KERNEL);
+ if (!tmp_realloc)
+ goto restore_nr_stripes;
+
+ d->stripe_sectors_dirty = (atomic_t *) tmp_realloc;
+
+ n = BITS_TO_LONGS(d->nr_stripes) * sizeof(unsigned long);
+ n_old = BITS_TO_LONGS(nr_stripes_old) * sizeof(unsigned long);
+ tmp_realloc = kvrealloc(d->full_dirty_stripes, n_old, n, GFP_KERNEL);
+ if (!tmp_realloc)
+ goto restore_nr_stripes;
+
+ d->full_dirty_stripes = (unsigned long *) tmp_realloc;
+
+ if ((res = set_capacity_and_notify(dc->disk.disk, parent_nr_sectors)))
+ goto unblock_and_exit;
+
+restore_nr_stripes:
+ d->nr_stripes = nr_stripes_old;
+restore_dev_sectors:
+ d->c->cached_dev_sectors = orig_cached_sectors;
+unblock_and_exit:
+ up_write(&dc->writeback_lock);
+ return res;
+}
+
struct async_reg_args {
struct delayed_work reg_work;
char *path;
@@ -2569,7 +2648,10 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
mutex_lock(&bch_register_lock);
if (lookup_bdev(strim(path), &dev) == 0 &&
bch_is_open(dev))
- err = "device already registered";
+ if (bch_update_capacity(dev))
+ err = "capacity changed";
+ else
+ err = "device already registered";
else
err = "device busy";
mutex_unlock(&bch_register_lock);
--
2.39.0
