md_bitmap_get_counter() has code:
```
if (bitmap->bp[page].hijacked ||
bitmap->bp[page].map == NULL)
csize = ((sector_t)1) << (bitmap->chunkshift +
PAGE_COUNTER_SHIFT - 1);
```
the minus 1 is wrong, this branch should report 2048 bits of space.
with "-1" action, this only report 1024 bit of space.
this bug code returns wrong blocks, but it doesn't inflence bitmap logic:
1. most callers focus this function return value (the counter of offset),
not the parameter blocks.
2. the bug is only triggered when hijacked is true or map is NULL.
the hijacked true condition is very rare.
the "map == null" only true when array is creating or resizing.
3. even the caller gets wrong blocks, current code makes caller just to
call md_bitmap_get_counter() one more time.
Signed-off-by: Zhao Heming <heming.zhao@xxxxxxxx>
---
v2:
- shorten patch Subject
---
drivers/md/md-bitmap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index 553b6406ba1c..11c75e727b49 100644
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -1367,7 +1367,7 @@ __acquires(bitmap->lock)
if (bitmap->bp[page].hijacked ||
bitmap->bp[page].map == NULL)
csize = ((sector_t)1) << (bitmap->chunkshift +
- PAGE_COUNTER_SHIFT - 1);
+ PAGE_COUNTER_SHIFT);
else
csize = ((sector_t)1) << bitmap->chunkshift;
*blocks = csize - (offset & (csize - 1));
--
2.27.0
