From: Karel Zak <kzak@redhat.com>
Date: Fri, 29 Jun 2007 09:38:54 +0000 (+0200)
Subject: blockdev: add BLKFRAGET/BLKFRASET ioctls
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c2a1e7880895bbd0ecdd50984ebbf9e68b745e8e;p=util-linux

blockdev: add BLKFRAGET/BLKFRASET ioctls

In Linux 2.6 the BLKRASET ioctl has the desired effect for mounted
file-systems.  In Linux 2.4 it appears to set the number of blocks to
read-ahead on the *device* as opposed to within a *file*, and the
maximum value of this number is 255.  As a result the invocation of
blockdev will fail on Linux 2.4 for any usefully large value of
READAHEAD, and will not in any case have the desired affect for
fragmented files.

(Based on the blockdev-getfra-setfra.patch Debian patch.)

Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/disk-utils/blockdev.8 b/disk-utils/blockdev.8
index bde64265..86c29dd2 100644
--- a/disk-utils/blockdev.8
+++ b/disk-utils/blockdev.8
@@ -48,6 +48,12 @@ Set readahead to
 .B \--getra
 Print readahead (in 512-byte sectors).
 .TP
+.BI \--setfra " N"
+Set filesystem readahead (same like --setra on 2.6 kernels).
+.TP
+.B \--getfra
+Get filesystem readahead.
+.TP
 .B \--flushbufs
 Flush buffers.
 .TP
diff --git a/disk-utils/blockdev.c b/disk-utils/blockdev.c
index c07fb30a..6cd038f1 100644
--- a/disk-utils/blockdev.c
+++ b/disk-utils/blockdev.c
@@ -23,6 +23,8 @@
 #define BLKFLSBUF  _IO(0x12,97)
 #define BLKRASET   _IO(0x12,98)
 #define BLKRAGET   _IO(0x12,99)
+#define BLKFRASET  _IO(0x12,100)
+#define BLKFRAGET  _IO(0x12,101)
 #define BLKSSZGET  _IO(0x12,104)
 #define BLKBSZGET  _IOR(0x12,112,size_t)
 #define BLKBSZSET  _IOW(0x12,113,size_t)
@@ -86,6 +88,12 @@ struct bdc {
 #ifdef BLKRAGET
 	{ "--getra", "BLKRAGET", BLKRAGET, ARGLINTG, -1, NULL, N_("get readahead") },
 #endif
+#ifdef BLKFRASET
+	{ "--setfra", "BLKFRASET", BLKFRASET, ARGINTA, 0, "FSREADAHEAD", N_("set filesystem readahead") },
+#endif
+#ifdef BLKFRAGET
+	{ "--getfra", "BLKFRAGET", BLKFRAGET, ARGLINTG, -1, NULL, N_("get filesystem readahead") },
+#endif
 #ifdef BLKFLSBUF
 	{ "--flushbufs", "BLKFLSBUF", BLKFLSBUF, ARGNONE, 0, NULL, N_("flush buffers") },
 #endif