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-rw-r--r--include/linux/blk_types.h18
1 files changed, 18 insertions, 0 deletions
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index c5d3db0d83f8..bf18b95ed92d 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -39,6 +39,24 @@ typedef u8 __bitwise blk_status_t;
#define BLK_STS_AGAIN ((__force blk_status_t)12)
+/*
+ * BLK_STS_DEV_RESOURCE is returned from the driver to the block layer if
+ * device related resources are unavailable, but the driver can guarantee
+ * that the queue will be rerun in the future once resources become
+ * available again. This is typically the case for device specific
+ * resources that are consumed for IO. If the driver fails allocating these
+ * resources, we know that inflight (or pending) IO will free these
+ * resource upon completion.
+ *
+ * This is different from BLK_STS_RESOURCE in that it explicitly references
+ * a device specific resource. For resources of wider scope, allocation
+ * failure can happen without having pending IO. This means that we can't
+ * rely on request completions freeing these resources, as IO may not be in
+ * flight. Examples of that are kernel memory allocations, DMA mappings, or
+ * any other system wide resources.
+ */
+#define BLK_STS_DEV_RESOURCE ((__force blk_status_t)13)
+
/**
* blk_path_error - returns true if error may be path related
* @error: status the request was completed with

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