[Xen-devel] [PATCH 1/3] xen-blkfront: remove type check from blkfront_setup_discard

[Olaf Hering <olaf@xxxxxxxxx>]

In its initial implementation a check for "type" was added, but only phy
and file are handled. This breaks advertised discard support for other
type values such as qdisk.

Fix and simplify this function: If the backend advertises discard
support it is supposed to implement it properly, so enable
feature_discard unconditionally. If the backend advertises the need for
a certain granularity and alignment then propagate both properties to
the blocklayer. The discard-secure property is a boolean, update the code
to reflect that.

Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
---
 drivers/block/xen-blkfront.c | 40 ++++++++++++++--------------------------
 1 file changed, 14 insertions(+), 26 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 8dcfb54..4d8ddea 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1635,36 +1635,24 @@ blkfront_closing(struct blkfront_info *info)
 static void blkfront_setup_discard(struct blkfront_info *info)
 {
        int err;
-       char *type;
        unsigned int discard_granularity;
        unsigned int discard_alignment;
        unsigned int discard_secure;
 
-       type = xenbus_read(XBT_NIL, info->xbdev->otherend, "type", NULL);
-       if (IS_ERR(type))
-               return;
-
-       info->feature_secdiscard = 0;
-       if (strncmp(type, "phy", 3) == 0) {
-               err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
-                       "discard-granularity", "%u", &discard_granularity,
-                       "discard-alignment", "%u", &discard_alignment,
-                       NULL);
-               if (!err) {
-                       info->feature_discard = 1;
-                       info->discard_granularity = discard_granularity;
-                       info->discard_alignment = discard_alignment;
-               }
-               err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
-                           "discard-secure", "%d", &discard_secure,
-                           NULL);
-               if (!err)
-                       info->feature_secdiscard = discard_secure;
-
-       } else if (strncmp(type, "file", 4) == 0)
-               info->feature_discard = 1;
-
-       kfree(type);
+       info->feature_discard = 1;
+       err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
+               "discard-granularity", "%u", &discard_granularity,
+               "discard-alignment", "%u", &discard_alignment,
+               NULL);
+       if (!err) {
+               info->discard_granularity = discard_granularity;
+               info->discard_alignment = discard_alignment;
+       }
+       err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
+                   "discard-secure", "%d", &discard_secure,
+                   NULL);
+       if (!err)
+               info->feature_secdiscard = !!discard_secure;
 }
 
 static int blkfront_setup_indirect(struct blkfront_info *info)

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