Re: [PATCH] mkfs: add discard support

Christoph Hellwig
2009-10-07T01:17:26Z

> It might be a bit cleaner to add this in with the existing platform-
> specific code in libxfs/linux.c (or perhaps include/platform_defs.h)
> with wrappers for the other platforms, rather than putting it directly
> in mkfs like this? repair may want to use this someday too, I guess.

How about this one?

--

Subject: [PATCH] mkfs: add discard support
From: Christoph Hellwig <hch@lst.de>

Cal the BLKDISCARD ioctl to mark the whole disk as unused before creating
a new filesystem. This will allow SSDs, Arrays with thin provisioning support
and virtual machines to make smarter allocation decisions.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: xfsprogs-dev/mkfs/xfs_mkfs.c
===================================================================
--- xfsprogs-dev.orig/mkfs/xfs_mkfs.c 2009-10-06 18:46:06.000000000 +0000
+++ xfsprogs-dev/mkfs/xfs_mkfs.c 2009-10-07 01:09:49.000000000 +0000
@@ -605,6 +605,20 @@ done:
free(buf);
}

+static void
+discard_blocks(dev_t dev, __uint64_t nsectors)
+{
+ int fd;
+
+ /*
+ * We intentionally ignore errors from the discard ioctl. It is
+ * not nessecary for the mkfs functionality but just an optimization.
+ */
+ fd = libxfs_device_to_fd(dev);
+ if (fd > 0)
+ platform_discard_blocks(fd, 0, nsectors << 9);
+}
+
int
main(
int argc,
@@ -1645,6 +1659,12 @@ main(
}
}

+ discard_blocks(xi.ddev, xi.dsize);
+ if (xi.rtdev)
+ discard_blocks(xi.rtdev, xi.rtsize);
+ if (xi.logdev && xi.logdev != xi.ddev)
+ discard_blocks(xi.logdev, xi.logBBsize);
+
if (!liflag && !ldflag)
loginternal = xi.logdev == 0;
if (xi.logname)
Index: xfsprogs-dev/include/linux.h
===================================================================
--- xfsprogs-dev.orig/include/linux.h 2009-10-07 01:06:00.000000000 +0000
+++ xfsprogs-dev/include/linux.h 2009-10-07 01:13:12.000000000 +0000
@@ -93,6 +93,20 @@ static __inline__ void platform_uuid_cop
uuid_copy(*dst, *src);
}

+#ifndef BLKDISCARD
+#define BLKDISCARD _IO(0x12,119)
+#endif
+
+static __inline__ int
+platform_discard_blocks(int fd, off64_t start, off64_t end)
+{
+ __uint64_t range[2] = { start, end };
+
+ if (ioctl(fd, BLKDISCARD, &range) < 0)
+ return errno;
+ return 0;
+}
+
#if (__GLIBC__ < 2) || ((__GLIBC__ == 2) && (__GLIBC_MINOR__ <= 1))
# define constpp const char * const *
#else
Index: xfsprogs-dev/include/darwin.h
===================================================================
--- xfsprogs-dev.orig/include/darwin.h 2009-10-07 01:15:38.000000000 +0000
+++ xfsprogs-dev/include/darwin.h 2009-10-07 01:16:19.000000000 +0000
@@ -154,4 +154,10 @@ typedef unsigned char uchar_t;

#define HAVE_FID 1

+static __inline__ int
+platform_discard_blocks(int fd, off64_t start, off64_t end)
+{
+ return 0;
+}
+
#endif /* __XFS_DARWIN_H__ */
Index: xfsprogs-dev/include/freebsd.h
===================================================================
--- xfsprogs-dev.orig/include/freebsd.h 2009-10-07 01:15:38.000000000 +0000
+++ xfsprogs-dev/include/freebsd.h 2009-10-07 01:16:06.000000000 +0000
@@ -139,4 +139,10 @@ static __inline__ void platform_uuid_cop
memcpy(dst, src, sizeof(uuid_t));
}

+static __inline__ int
+platform_discard_blocks(int fd, off64_t start, off64_t end)
+{
+ return 0;
+}
+
#endif /* __XFS_FREEBSD_H__ */
Index: xfsprogs-dev/include/irix.h
===================================================================
--- xfsprogs-dev.orig/include/irix.h 2009-10-07 01:15:38.000000000 +0000
+++ xfsprogs-dev/include/irix.h 2009-10-07 01:16:29.000000000 +0000
@@ -337,6 +337,12 @@ static __inline__ void platform_uuid_cop
memcpy(dst, src, sizeof(uuid_t));
}

+static __inline__ int
+platform_discard_blocks(int fd, off64_t start, off64_t end)
+{
+ return 0;
+}
+
static __inline__ char * strsep(char **s, const char *ct)
{
char *sbegin = *s, *end;