Current sheep cannot handle a case like this:
1. iterate snapshot creation and let latest working VDI have VID 0xffffff
2. create one more snapshot
(The situation can be reproduced with the below sequence:
$ dog vdi create 00471718 1G
$ dog vdi snapshot 00471718 (repeat 7 times) )
In this case, new VID becomes 0x000000. Current fill_vdi_info() and
fill_vdi_info_range() cannot handle this case. It comes from the below
two reasons:
1. Recent change 00ecfb24ee46f2 introduced a bug which breaks
fill_vdi_info_range() in a case of underflow of its variable i.
2. fill_vdi_info_range() assumes that its parameters, left and right,
are obtained from get_vdi_bitmap_range(). get_vdi_bitmap_range()
obtains left and right which mean the range of existing VIDs is
[left, right), in other words, [left, right - 1]. So
fill_vdi_info_range() starts checking from right - 1 to left. But
it means fill_vdi_info_range() cannot check VID 0xffffff even VID
overflow happens. So this patch lets fill_vdi_info_range() check
from right to left, and also change callers' manner (it passes left
and right - 1 in ordinal cases).
Signed-off-by: Hitoshi Mitake <mitake.hito...@lab.ntt.co.jp>
---
sheep/vdi.c | 30 +++++++++++++++++++++++-------
1 file changed, 23 insertions(+), 7 deletions(-)
diff --git a/sheep/vdi.c b/sheep/vdi.c
index 2889df6..3d14ccf 100644
--- a/sheep/vdi.c
+++ b/sheep/vdi.c
@@ -1404,9 +1404,11 @@ static int fill_vdi_info_range(uint32_t left, uint32_t
right,
ret = SD_RES_NO_MEM;
goto out;
}
- for (i = right - 1; i && i >= left; i--) {
+
+ i = right;
+ while (i >= left) {
if (!test_bit(i, sys->vdi_inuse))
- continue;
+ goto next;
ret = sd_read_object(vid_to_vdi_oid(i), (char *)inode,
SD_INODE_HEADER_SIZE, 0);
@@ -1420,10 +1422,10 @@ static int fill_vdi_info_range(uint32_t left, uint32_t
right,
/* Read, delete, clone on snapshots */
if (!vdi_is_snapshot(inode)) {
vdi_found = true;
- continue;
+ goto next;
}
if (!vdi_tag_match(iocb, inode))
- continue;
+ goto next;
} else {
/*
* Rollback & snap create, read, delete on
@@ -1438,6 +1440,10 @@ static int fill_vdi_info_range(uint32_t left, uint32_t
right,
info->vid = inode->vdi_id;
goto out;
}
+next:
+ if (!i)
+ break;
+ i--;
}
ret = vdi_found ? SD_RES_NO_TAG : SD_RES_NO_VDI;
out:
@@ -1452,13 +1458,23 @@ static int fill_vdi_info(unsigned long left, unsigned
long right,
int ret;
if (left < right)
- return fill_vdi_info_range(left, right, iocb, info);
+ return fill_vdi_info_range(left, right - 1, iocb, info);
+
+ if (!right)
+ /*
+ * a special case right == 0
+ * because the variables left and right have values obtained by
+ * get_vdi_bitmap_range(), they mean used bitmap range is
+ * [left, right). If right == 0, it means used bitmap range is
+ * [left, SD_NR_VDIS].
+ */
+ return fill_vdi_info_range(left, SD_NR_VDIS, iocb, info);
- ret = fill_vdi_info_range(0, right, iocb, info);
+ ret = fill_vdi_info_range(0, right - 1, iocb, info);
switch (ret) {
case SD_RES_NO_VDI:
case SD_RES_NO_TAG:
- ret = fill_vdi_info_range(left, SD_NR_VDIS - 1, iocb, info);
+ ret = fill_vdi_info_range(left, SD_NR_VDIS, iocb, info);
break;
default:
break;
--
1.9.1
--
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