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.
Signed-off-by: Kusanagi Kouichi <sl...@ac.auone-net.jp> --- block/raw-posix.c | 22 ++++++++++++++++++++-- configure | 19 +++++++++++++++++++ 2 files changed, 39 insertions(+), 2 deletions(-) diff --git a/block/raw-posix.c b/block/raw-posix.c index 87d888e..66ba0b5 100644 --- a/block/raw-posix.c +++ b/block/raw-posix.c @@ -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> @@ -1098,15 +1101,30 @@ 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 +#if defined(CONFIG_FALLOCATE_PUNCH_HOLE) || defined(CONFIG_XFS) BDRVRawState *s = bs->opaque; +#endif + int ret = 0; +#ifdef CONFIG_FALLOCATE_PUNCH_HOLE + do { + if (fallocate(s->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, + sector_num << BDRV_SECTOR_BITS, + nb_sectors << BDRV_SECTOR_BITS) == 0) { + return 0; + } + } while (errno == EINTR); + + ret = -errno; +#endif + +#ifdef CONFIG_XFS if (s->is_xfs) { return xfs_discard(s, sector_num, nb_sectors); } #endif - return 0; + return ret; } static QEMUOptionParameter raw_create_options[] = { diff --git a/configure b/configure index 837a84a..ff2e373 100755 --- a/configure +++ b/configure @@ -2576,6 +2576,22 @@ if compile_prog "" "" ; then fallocate=yes fi +# check for fallocate hole punching +fallocate_punch_hole=no +cat > $TMPC << EOF +#include <fcntl.h> +#include <linux/falloc.h> + +int main(void) +{ + fallocate(0, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, 0, 0); + return 0; +} +EOF +if compile_prog "" "" ; then + fallocate_punch_hole=yes +fi + # check for sync_file_range sync_file_range=no cat > $TMPC << EOF @@ -3485,6 +3501,9 @@ fi if test "$fallocate" = "yes" ; then echo "CONFIG_FALLOCATE=y" >> $config_host_mak fi +if test "$fallocate_punch_hole" = "yes" ; then + echo "CONFIG_FALLOCATE_PUNCH_HOLE=y" >> $config_host_mak +fi if test "$sync_file_range" = "yes" ; then echo "CONFIG_SYNC_FILE_RANGE=y" >> $config_host_mak fi -- 1.7.10.4