On 2019-01-07 21:37, bugfood-ml@xxxxxxxxxx wrote:
From: Corey Hickey <bugfood-c@xxxxxxxxxx>
...when not changing the number of disks.
This patch needs context to explain. These are the relevant parts of
the original code (condensed and annotated):
if (dir > 0) {
/* Increase data offset (reshape backwards) */
if (data_offset < sd->data_offset + min) {
pr_err("--data-offset too small on %s\n",
dn);
goto release;
}
} else {
/* Decrease data offset (reshape forwards) */
if (data_offset < sd->data_offset - min) {
pr_err("--data-offset too small on %s\n",
dn);
goto release;
}
}
When this code is reached, mdadm has already decided on a reshape
direction. When increasing the data offset, the reshape runs backwards
(dir==1); when decreasing the data offset, the reshape runs forwards
(dir==-1).
The conditional within the backwards reshape is correct: the requested
offset must be larger than the old offset plus a minimum delta; thus the
reshape has room to work.
For the forwards reshape, the requested offset needs to be smaller than
the old offset minus a minimum delta; to do this correctly, the
comparison must be reversed.
Also update the error message.
Note: I have tested this change on a RAID 5 on Linux 4.18.0 and verified
that there were no errors from the kernel and that the device data
remained intact. I do not know if there are considerations for different
RAID levels.
---
Grow.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/Grow.c b/Grow.c
index 363b209..c2cae00 100644
--- a/Grow.c
+++ b/Grow.c
@@ -2613,8 +2613,8 @@ static int set_new_data_offset(struct mdinfo *sra, struct supertype *st,
goto release;
}
if (data_offset != INVALID_SECTORS &&
- data_offset < sd->data_offset - min) {
- pr_err("--data-offset too small on %s\n",
+ data_offset > sd->data_offset - min) {
+ pr_err("--data-offset too large on %s\n",
dn);
goto release;
}
Hi,
Sorry to pester, but is this patch acceptable?
Thanks,
Corey
