Re: [PATCH v12 09/14] block: modify the comment for BDRV_REQ_PREFETCH flag

[Vladimir Sementsov-Ogievskiy]

22.10.2020 21:13, Andrey Shinkevich wrote:

Modify the comment for the flag BDRV_REQ_PREFETCH as we are going to
use it alone and pass it to the COR-filter driver for further
processing.

Signed-off-by: Andrey Shinkevich 
---
  include/block/block.h | 8 +---
  1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/include/block/block.h b/include/block/block.h
index ae7612f..1b6742f 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -81,9 +81,11 @@ typedef enum {
  BDRV_REQ_NO_FALLBACK= 0x100,
  
  /*

- * BDRV_REQ_PREFETCH may be used only together with BDRV_REQ_COPY_ON_READ
- * on read request and means that caller doesn't really need data to be
- * written to qiov parameter which may be NULL.
+ * BDRV_REQ_PREFETCH makes sense only in the context of copy-on-read
+ * (i.e., together with the BDRV_REQ_COPY_ON_READ flag or when a COR
+ * filter is involved), in which case it signals that the COR operation
+ * need not read the data into memory (qiov) but only ensure they are
+ * copied to the top layer (i.e., that COR operation is done).
   */
  BDRV_REQ_PREFETCH  = 0x200,
  /* Mask of valid flags */



I like the wording.. I think this patch should be merged together with 11 and 
12 to make sense.

--
Best regards,
Vladimir

[PATCH v12 09/14] block: modify the comment for BDRV_REQ_PREFETCH flag

[Andrey Shinkevich via]

Modify the comment for the flag BDRV_REQ_PREFETCH as we are going to
use it alone and pass it to the COR-filter driver for further
processing.

Signed-off-by: Andrey Shinkevich 
---
 include/block/block.h | 8 +---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/include/block/block.h b/include/block/block.h
index ae7612f..1b6742f 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -81,9 +81,11 @@ typedef enum {
 BDRV_REQ_NO_FALLBACK= 0x100,
 
 /*
- * BDRV_REQ_PREFETCH may be used only together with BDRV_REQ_COPY_ON_READ
- * on read request and means that caller doesn't really need data to be
- * written to qiov parameter which may be NULL.
+ * BDRV_REQ_PREFETCH makes sense only in the context of copy-on-read
+ * (i.e., together with the BDRV_REQ_COPY_ON_READ flag or when a COR
+ * filter is involved), in which case it signals that the COR operation
+ * need not read the data into memory (qiov) but only ensure they are
+ * copied to the top layer (i.e., that COR operation is done).
  */
 BDRV_REQ_PREFETCH  = 0x200,
 /* Mask of valid flags */
-- 
1.8.3.1