After the DAX configuration locking was converted to rwsems, successful
lock acquisition leaves rc set to zero in mapping_store(). Two error
paths can return this stale value: an unbound region driver and a
misaligned range size. The sysfs write therefore reports success without
allocating the requested range.
Return -ENXIO when the region driver is not bound and -EINVAL when the
range size is misaligned.
Fixes: c05ae9d85b47 ("dax/bus.c: replace driver-core lock usage by a local
rwsem")
Assisted-by: LLM
Signed-off-by: Muchun Song <[email protected]>
---
v2:
- Return explicit errors before Device DAX range allocation
(suggested by Dave Jiang)
- Move the patch before range alignment validation for independent
backports (suggested by Dave Jiang)
---
drivers/dax/bus.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index b809e1a264af..e40c25401cf0 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -1192,7 +1192,7 @@ static ssize_t mapping_store(struct device *dev, struct
device_attribute *attr,
return rc;
if (!dax_region->dev->driver) {
up_write(&dax_region_rwsem);
- return rc;
+ return -ENXIO;
}
rc = down_write_killable(&dax_dev_rwsem);
if (rc) {
@@ -1201,8 +1201,12 @@ static ssize_t mapping_store(struct device *dev, struct
device_attribute *attr,
}
to_alloc = range_len(&r);
- if (alloc_is_aligned(dev_dax, to_alloc))
+ if (!alloc_is_aligned(dev_dax, to_alloc)) {
+ dev_dbg(dev, "%s: size: %zu misaligned\n", __func__, to_alloc);
+ rc = -EINVAL;
+ } else {
rc = alloc_dev_dax_range(dev_dax, r.start, to_alloc);
+ }
up_write(&dax_dev_rwsem);
up_write(&dax_region_rwsem);
--
2.54.0
