| Message ID | 1422366699-17473-5-git-send-email-den@openvz.org |
|---|---|
| State | New |
| Headers | show |
On 2015-01-27 at 08:51, Denis V. Lunev wrote: > 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. > > Signed-off-by: Denis V. Lunev <den@openvz.org> > CC: Kevin Wolf <kwolf@redhat.com> > CC: Stefan Hajnoczi <stefanha@redhat.com> > CC: Peter Lieven <pl@kamp.de> > CC: Fam Zheng <famz@redhat.com> > --- > block/raw-posix.c | 16 ++++++++++++++-- > configure | 19 +++++++++++++++++++ > 2 files changed, 33 insertions(+), 2 deletions(-) Okay, now the "ret" in handle_aiocb_write_zeroes() is necessary, so please disregard my statement about removing it in patch 3. > diff --git a/block/raw-posix.c b/block/raw-posix.c > index 24e1fab..3c35b2f 100644 > --- a/block/raw-posix.c > +++ b/block/raw-posix.c > @@ -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 { > @@ -955,6 +955,18 @@ static ssize_t handle_aiocb_write_zeroes(RawPosixAIOData *aiocb) > } > #endif > > +#ifdef CONFIG_FALLOCATE_ZERO_RANGE > + if (s->has_write_zeroes) { > + 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; > + return ret; > + } First, you probably want to simply fall through here; right now, you are immediately failing with -ENOTSUP on the first call, but falling through on the second call. After this patch, it doesn't make a difference, but after the next one, it might. Second, while using s->has_write_zeroes here seems correct to me, I personally don't like sharing it with handle_aiocb_write_zeroes_block(); and if you do introduce a new flag like "has_zero_range", please don't make it a bit field (I will give you an R-b regardless of whether you make it a bit field or not, I just won't like it). Feel free to keep has_write_zeroes, though, while it doesn't look good to me it certainly is correct from a technical perspective. Max
diff --git a/block/raw-posix.c b/block/raw-posix.c index 24e1fab..3c35b2f 100644 --- a/block/raw-posix.c +++ b/block/raw-posix.c @@ -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 { @@ -955,6 +955,18 @@ static ssize_t handle_aiocb_write_zeroes(RawPosixAIOData *aiocb) } #endif +#ifdef CONFIG_FALLOCATE_ZERO_RANGE + if (s->has_write_zeroes) { + 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; + return ret; + } +#endif + s->has_write_zeroes = false; return ret; } diff --git a/configure b/configure index f185dd0..e00e03a 100755 --- a/configure +++ b/configure @@ -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
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. Signed-off-by: Denis V. Lunev <den@openvz.org> CC: Kevin Wolf <kwolf@redhat.com> CC: Stefan Hajnoczi <stefanha@redhat.com> CC: Peter Lieven <pl@kamp.de> CC: Fam Zheng <famz@redhat.com> --- block/raw-posix.c | 16 ++++++++++++++-- configure | 19 +++++++++++++++++++ 2 files changed, 33 insertions(+), 2 deletions(-)