On 7/9/25 22:06, Konstantin Khorenko wrote:
This reverts commit 34451d746b817b69b5e9df07bfef622bd4e1a2df.
The patch being reverted causes image size to be non-align to cluster
size (1Mb).
It's not yet clear why and if it really causes data loss/corruption,
but until we understand and fix this let's revert the patch.
Results with the patch reverted:
[root@localhost a1]# du -h .
0 .
[root@localhost a1]# ploop init -s 10G image
...
[root@localhost a1]# du -h .
129M .
[root@localhost a1]# ploop mount -m /mnt/fstrim/ DiskDescriptor.xml
...
[root@localhost a1]# dd if=/dev/urandom of=/mnt/fstrim/file bs=1M count=1024
oflag=direct
...
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 3.39694 s, 316 MB/s
[root@localhost a1]# ploop umount DiskDescriptor.xml
...
[root@localhost a1]# du -h .
1.2G .
[root@localhost a1]# ploop mount -m /mnt/fstrim/ DiskDescriptor.xml
...
[root@localhost a1]# rm -rf /mnt/fstrim/file
[root@localhost a1]# fstrim /mnt/fstrim
[root@localhost a1]# ploop umount DiskDescriptor.xml
...
[root@localhost a1]# du -h .
129M .
[root@localhost a1]# stat image
File: image
Size: 1207959552 Blocks: 262144 IO Block: 4096 regular file
...
Results before the revert:
[root@ptikh-hci fstrim]# du -h .
4.0K .
[root@ptikh-hci fstrim]# ploop init -s 10G image
[root@ptikh-hci fstrim]# du -h .
3.2M .
[root@ptikh-hci fstrim]# ploop mount -m /mnt/fstrim/ DiskDescriptor.xml
...
[root@ptikh-hci fstrim]# dd if=/dev/urandom of=/mnt/fstrim/file bs=1M
count=1024 oflag=direct
...
[root@ptikh-hci fstrim]# ploop umount DiskDescriptor.xml
...
[root@ptikh-hci fstrim]# du -h .
1.1G .
[root@ptikh-hci fstrim]# ploop mount -m /mnt/fstrim/ DiskDescriptor.xml
...
[root@ptikh-hci fstrim]# rm -rf /mnt/fstrim/file
[root@ptikh-hci fstrim]# fstrim /mnt/fstrim
[root@ptikh-hci fstrim]# ploop umount DiskDescriptor.xml
...
[root@ptikh-hci fstrim]# du -h .
4.2M .

So as expected after revert we do not truncate preallocated but not used
128Mb, but this time we don’t preallocate indefinitely and lose blocks.
https://virtuozzo.atlassian.net/browse/VSTOR-110285
Signed-off-by: Konstantin Khorenko <khore...@virtuozzo.com>
Feature: dm-ploop: ploop target driver
---
drivers/md/dm-ploop-map.c | 2 --
drivers/md/dm-ploop-target.c | 6 ------
2 files changed, 8 deletions(-)
diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index 828ae0b9c033..f21a3ae5ba4a 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -1332,8 +1332,6 @@ static int ploop_allocate_cluster(struct ploop *ploop,
u32 *dst_clu, struct file
}
}
- if (end > top->file_preallocated_area_start)
- top->file_preallocated_area_start = end;
We should probably leave this part.
First, we had it in 72.5 and in original patch (see d32286d80e91
("dm-ploop: Add ploop target driver")).
Second, we use file_preallocated_area_start in ploop_allocate_cluster(),
to determine if the area may contain dirty data and need to be cleared
on allocation. Dropping it may lead to data corruption (seeing non-zero
data where it should be zero).
spin_unlock_irqrestore(&ploop->bat_lock, flags);
return 0;
diff --git a/drivers/md/dm-ploop-target.c b/drivers/md/dm-ploop-target.c
index d0c519fdd97c..af0658a455ce 100644
--- a/drivers/md/dm-ploop-target.c
+++ b/drivers/md/dm-ploop-target.c
@@ -162,7 +162,6 @@ static bool ploop_empty_htable(struct hlist_head head[])
static void ploop_destroy(struct ploop *ploop)
{
- struct ploop_delta *top = ploop_top_delta(ploop);
int i;
if (ploop->kt_worker) {
@@ -202,11 +201,6 @@ static void ploop_destroy(struct ploop *ploop)
for (i = 0; i < 2; i++)
percpu_ref_exit(&ploop->inflight_bios_ref[i]);
-
- if (top->file_preallocated_area_start < top->file_size &&
- vfs_truncate2(&top->file->f_path, top->file_preallocated_area_start,
top->file))
- PL_ERR("Unable to truncate preallocated area on destroy");
-
/* Nobody uses it after destroy_workqueue() */
while (ploop->nr_deltas-- > 0) {
if (ploop->deltas[ploop->nr_deltas].file) {
--
Best regards, Pavel Tikhomirov
Senior Software Developer, Virtuozzo.
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