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raw-posix: support discard on more filesystems

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Linux 2.6.38 introduced the filesystem independent interface to
deallocate part of a file. As of Linux 3.7, btrfs, ext4, ocfs2,
tmpfs and xfs support it.

Even though the system calls here are in practice issued on Linux,
the code is structured to allow plugging in alternatives for other Unix
variants.  EOPNOTSUPP is used unconditionally in this patch, but it is
supported in both OpenBSD and Mac OS X since forever (see for example
http://lists.debian.org/debian-glibc/2006/02/msg00337.html).

Signed-off-by: Kusanagi Kouichi <slash@ac.auone-net.jp>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kusanagi Kouichi 2013-01-14 16:26:52 +01:00 • committed by Stefan Hajnoczi
parent 029d091e49
commit 3d4fa43e64
2 changed files with 43 additions and 2 deletions
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26
block/raw-posix.c
View file

@ -59,6 +59,9 @@
#ifdef CONFIG_FIEMAP
#include <linux/fiemap.h>
#endif
#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
#include <linux/falloc.h>
#endif
#if defined (__FreeBSD__) || defined(__FreeBSD_kernel__)
#include <sys/disk.h>
#include <sys/cdio.h>
@ -1074,15 +1077,34 @@ static int xfs_discard(BDRVRawState *s, int64_t sector_num, int nb_sectors)
static coroutine_fn int raw_co_discard(BlockDriverState *bs,
int64_t sector_num, int nb_sectors)
{
#ifdef CONFIG_XFS
int ret = -EOPNOTSUPP;
#if defined(CONFIG_FALLOCATE_PUNCH_HOLE) || defined(CONFIG_XFS)
BDRVRawState *s = bs->opaque;
#ifdef CONFIG_XFS
if (s->is_xfs) {
return xfs_discard(s, sector_num, nb_sectors);
}
#endif
return 0;
#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
do {
if (fallocate(s->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
sector_num << BDRV_SECTOR_BITS,
(int64_t)nb_sectors << BDRV_SECTOR_BITS) == 0) {
return 0;
}
} while (errno == EINTR);
ret = -errno;
#endif
#endif
if (ret == -EOPNOTSUPP) {
return 0;
}
return ret;
}
static QEMUOptionParameter raw_create_options[] = {