Commit b953f075 authored by Denis V. Lunev's avatar Denis V. Lunev Committed by Kevin Wolf
Browse files

block: use fallocate(FALLOC_FL_ZERO_RANGE) in handle_aiocb_write_zeroes 



This efficiently writes zeroes on Linux if the kernel is capable enough.
FALLOC_FL_ZERO_RANGE correctly handles all cases, including and not
including file expansion.

CC: Kevin Wolf <kwolf@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Peter Lieven <pl@kamp.de>
CC: Fam Zheng <famz@redhat.com>
Signed-off-by: default avatarDenis V. Lunev <den@openvz.org>
Reviewed-by: default avatarMax Reitz <mreitz@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 37cc9f7f

block/raw-posix.c

+13 −2
Original line number Diff line number Diff line
@@ -60,7 +60,7 @@ 
#define FS_NOCOW_FL                     0x00800000 /* Do not cow file */

#endif

#endif

#ifdef CONFIG_FALLOCATE_PUNCH_HOLE

#if defined(CONFIG_FALLOCATE_PUNCH_HOLE) || defined(CONFIG_FALLOCATE_ZERO_RANGE)

#include <linux/falloc.h>

#endif

#if defined (__FreeBSD__) || defined(__FreeBSD_kernel__)
@@ -902,7 +902,7 @@ static int translate_err(int err) 
    return err;

}



#if defined(CONFIG_FALLOCATE_PUNCH_HOLE)

#if defined(CONFIG_FALLOCATE_PUNCH_HOLE) || defined(CONFIG_FALLOCATE_ZERO_RANGE)

static int do_fallocate(int fd, int mode, off_t offset, off_t len)

{

    do {
@@ -954,6 +954,17 @@ static ssize_t handle_aiocb_write_zeroes(RawPosixAIOData *aiocb) 
    }

#endif



#ifdef CONFIG_FALLOCATE_ZERO_RANGE

    if (s->has_write_zeroes) {

        int ret = do_fallocate(s->fd, FALLOC_FL_ZERO_RANGE,

                               aiocb->aio_offset, aiocb->aio_nbytes);

        if (ret == 0 || ret != -ENOTSUP) {

            return ret;

        }

        s->has_write_zeroes = false;

    }

#endif



    return -ENOTSUP;

}

configure

+19 −0
Original line number Diff line number Diff line
@@ -3335,6 +3335,22 @@ if compile_prog "" "" ; then 
  fallocate_punch_hole=yes

fi



# check that fallocate supports range zeroing inside the file

fallocate_zero_range=no

cat > $TMPC << EOF

#include <fcntl.h>

#include <linux/falloc.h>



int main(void)

{

    fallocate(0, FALLOC_FL_ZERO_RANGE, 0, 0);

    return 0;

}

EOF

if compile_prog "" "" ; then

  fallocate_zero_range=yes

fi



# check for posix_fallocate

posix_fallocate=no

cat > $TMPC << EOF
@@ -4567,6 +4583,9 @@ fi 
if test "$fallocate_punch_hole" = "yes" ; then

  echo "CONFIG_FALLOCATE_PUNCH_HOLE=y" >> $config_host_mak

fi

if test "$fallocate_zero_range" = "yes" ; then

  echo "CONFIG_FALLOCATE_ZERO_RANGE=y" >> $config_host_mak

fi

if test "$posix_fallocate" = "yes" ; then

  echo "CONFIG_POSIX_FALLOCATE=y" >> $config_host_mak

fi