[Libguestfs] [PATCH 2/3] New API: guestfs_blockdev_setra: Adjust readahead for filesystems and devices.

[Richard W.M. Jones]

This adds a binding for 'blockdev --setra', allowing you to adjust the
readahead parameter for filesystems and devices.
---
 daemon/blockdev.c    | 30 ++++++++++++++++++++----------
 generator/actions.ml | 14 ++++++++++++++
 2 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/daemon/blockdev.c b/daemon/blockdev.c
index 8a7b1a8..6e8821d 100644
--- a/daemon/blockdev.c
+++ b/daemon/blockdev.c
@@ -62,7 +62,7 @@ call_blockdev (const char *device, const char *switc, int extraarg, int prints)
    */
   udev_settle ();
 
-  if (extraarg > 0) {
+  if (extraarg >= 0) {
     snprintf (buf, sizeof buf, "%d", extraarg);
     argv[2] = buf;
     argv[3] = device;
@@ -89,33 +89,43 @@ call_blockdev (const char *device, const char *switc, int extraarg, int prints)
 }
 
 int
+do_blockdev_setra (const char *device, int sectors)
+{
+  if (sectors < 0) {
+    reply_with_error ("readahead sectors must be >= 0");
+    return -1;
+  }
+  return (int) call_blockdev (device, "--setra", sectors, 0);
+}
+
+int
 do_blockdev_setro (const char *device)
 {
-  return (int) call_blockdev (device, "--setro", 0, 0);
+  return (int) call_blockdev (device, "--setro", -1, 0);
 }
 
 int
 do_blockdev_setrw (const char *device)
 {
-  return (int) call_blockdev (device, "--setrw", 0, 0);
+  return (int) call_blockdev (device, "--setrw", -1, 0);
 }
 
 int
 do_blockdev_getro (const char *device)
 {
-  return (int) call_blockdev (device, "--getro", 0, 1);
+  return (int) call_blockdev (device, "--getro", -1, 1);
 }
 
 int
 do_blockdev_getss (const char *device)
 {
-  return (int) call_blockdev (device, "--getss", 0, 1);
+  return (int) call_blockdev (device, "--getss", -1, 1);
 }
 
 int
 do_blockdev_getbsz (const char *device)
 {
-  return (int) call_blockdev (device, "--getbsz", 0, 1);
+  return (int) call_blockdev (device, "--getbsz", -1, 1);
 }
 
 int
@@ -128,23 +138,23 @@ do_blockdev_setbsz (const char *device, int blocksize)
 int64_t
 do_blockdev_getsz (const char *device)
 {
-  return call_blockdev (device, "--getsz", 0, 1);
+  return call_blockdev (device, "--getsz", -1, 1);
 }
 
 int64_t
 do_blockdev_getsize64 (const char *device)
 {
-  return call_blockdev (device, "--getsize64", 0, 1);
+  return call_blockdev (device, "--getsize64", -1, 1);
 }
 
 int
 do_blockdev_flushbufs (const char *device)
 {
-  return call_blockdev (device, "--flushbufs", 0, 0);
+  return call_blockdev (device, "--flushbufs", -1, 0);
 }
 
 int
 do_blockdev_rereadpt (const char *device)
 {
-  return call_blockdev (device, "--rereadpt", 0, 0);
+  return call_blockdev (device, "--rereadpt", -1, 0);
 }
diff --git a/generator/actions.ml b/generator/actions.ml
index fe492e6..baa7679 100644
--- a/generator/actions.ml
+++ b/generator/actions.ml
@@ -12003,6 +12003,20 @@ This is the same as the C<lstat(2)> system call." };
     longdesc = "\
 This is the internal call which implements C<guestfs_lstatnslist>." };
 
+  { defaults with
+    name = "blockdev_setra";
+    style = RErr, [Device "device"; Int "sectors"], [];
+    proc_nr = Some 424;
+    tests = [
+      InitEmpty, Always, TestRun (
+        [["blockdev_setra"; "/dev/sda"; "1024" ]]), []
+    ];
+    shortdesc = "set readahead";
+    longdesc = "\
+Set readahead (in 512-byte sectors) for the device.
+
+This uses the L<blockdev(8)> command." };
+
 ]
 
 (* Non-API meta-commands available only in guestfish.
-- 
2.1.0