search for: round_up

...nding of the internals. > > And it looks to me like the use case you want this for is very much > probably a power of two. In which case division is all kinds of just > stupid. > > And we already have a power-of-two round up function that works on > u64. It's called "round_up()". > > I wish we had a better visual warning about the differences between > "round_up()" (limited to powers-of-two, but efficient, and works with > any size) and "roundup()" (generic, potentially horribly slow, and > doesn't work for 64-bit on 32-bit)....

...<string.h> #include <limits.h> #include <errno.h> +#include <inttypes.h> #include <nbdkit-filter.h> @@ -172,8 +173,14 @@ truncate_prepare (struct nbdkit_next_ops *next_ops, void *nxdata, */ if (truncate_size >= 0) h->size = truncate_size; - if (round_up > 0) + if (round_up > 0) { + if (ROUND_UP (h->size, round_up) > INT64_MAX) { + nbdkit_error ("cannot round size %" PRId64 " up to next boundary of %u", + h->size, round_up); + return -1; + } h->size = ROUND_UP (h->siz...

Since we're using ({ .. }) gcc/clang extension, let's rewrite the rounding.h change too. Rich.

...ltiple of C<N>. > +Use either C<round-up=N> or C<round-down=N>. Worth mentioning that N must be a power of 2. > + > +#define THREAD_MODEL NBDKIT_THREAD_MODEL_PARALLEL > + > +/* These are the parameters. */ > +static int64_t truncate = -1; > +static unsigned round_up = 0, round_down = 0; > + > +/* The real size of the underlying plugin. */ > +static uint64_t real_size; > + > +/* The calculated size after applying the parameters. */ > +static uint64_t size; > + > +/* This lock protects the real_size and size fields. */ > +static pthrea...

...g: > > So that at least handles the constant case that the normal "roundup()" > case also handles. > > At the same time, in the case you are talking about, I really do > suspect that we have a (non-constant) power of two, and that you > should have just used "round_up()" which works fine regardless of > size, and is always efficient. I think you are correct in this. act_size = roundup_64(attr->length, MLX5_SW_ICM_BLOCK_SIZE(dm_db->dev)); Where we have: #define MLX5_SW_ICM_BLOCK_SIZE(dev) (1 << MLX5_LOG_SW_ICM_BLOCK_SIZE(dev)) Whic...

From: Steven Rostedt (VMware) <rostedt at goodmis.org> In discussing a build failure on x86_32 due to the use of roundup() on a 64 bit number, I realized that there's no generic equivalent roundup_64(). It is implemented in two separate places in the kernel, but there really should be just one that all can use. Although the other implementations are a static inline function, this

...| 2 +- > filters/cow/Makefile.am | 3 +- > filters/cow/cow.c | 2 +- > filters/truncate/truncate.c | 5 ++-- > 6 files changed, 68 insertions(+), 6 deletions(-) > > +/* Round up i to next multiple of n (n must be a power of 2). > + */ > +#define ROUND_UP(i, n) ({ \ > + assert (is_power_of_2 (n)); \ > + ((i) + (n) - 1) & ~((n) - 1); \ > +}) Potential bug: if n is 32-bit unsigned, but i is 64-bit, the bitmask on the right half of & will be inappropriately truncated...

...S SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#ifndef NBDKIT_ROUNDING_H +#define NBDKIT_ROUNDING_H + +#include <stdint.h> +#include <assert.h> + +#include "ispowerof2.h" + +/* Round up i to next multiple of n (n must be a power of 2). + */ +#define ROUND_UP(i, n) ({ \ + assert (is_power_of_2 (n)); \ + ((i) + (n) - 1) & ~((n) - 1); \ +}) + +/* Round down i to next multiple of n (n must be a power of 2). + */ +#define ROUND_DOWN(i, n) ({ \ + assert (is_po...

...hat about something like the following: So that at least handles the constant case that the normal "roundup()" case also handles. At the same time, in the case you are talking about, I really do suspect that we have a (non-constant) power of two, and that you should have just used "round_up()" which works fine regardless of size, and is always efficient. On a slight tangent.. Maybe we should have something like this: #define size_fn(x, prefix, ...) ({ \ typeof(x) __ret; \ switch (sizeof(x)) {...

...Y OUT + * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#ifndef NBDKIT_ROUNDING_H +#define NBDKIT_ROUNDING_H + +#include <assert.h> + +#include "ispowerof2.h" + +/* Round up i to next multiple of n (n must be a power of 2). + */ +#define ROUND_UP(i, n) ({ \ + assert (is_power_of_2 (n)); \ + ((i) + (n) - 1) & -((typeof (i))n); \ +}) + +/* Round down i to next multiple of n (n must be a power of 2). + */ +#define ROUND_DOWN(i, n) ({ \ + assert (is_po...

...- * Copyright (C) 2018 Red Hat Inc. + * Copyright (C) 2018-2019 Red Hat Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are @@ -54,15 +54,6 @@ static int64_t truncate_size = -1; static unsigned round_up = 0, round_down = 0; -/* The real size of the underlying plugin. */ -static uint64_t real_size; - -/* The calculated size after applying the parameters. */ -static uint64_t size; - -/* This lock protects the real_size and size fields. */ -static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER; -...

...c/ext2fs-c.c b/src/ext2fs-c.c index f01ca9d..e45980a 100644 --- a/src/ext2fs-c.c +++ b/src/ext2fs-c.c @@ -52,6 +52,9 @@ /* fts.h in glibc is broken, forcing us to use the GNUlib alternative. */ #include "fts_.h" +/* How many blocks of size S are needed for storing N bytes. */ +#define ROUND_UP(N, S) (((N) + (S) - 1) / (S)) + struct ext2_data { ext2_filsys fs; @@ -629,6 +632,7 @@ ext2_copy_file (struct ext2_data *data, const char *src, const char *dest) errcode_t err; struct stat statbuf; struct statvfs statvfsbuf; + size_t blocks; if (data->debug >= 3) prin...

...fig.h> + +#include <stdio.h> +#include <stdlib.h> +#include <stdint.h> +#include <string.h> +#include <errno.h> + +#include <nbdkit-filter.h> + +#define THREAD_MODEL NBDKIT_THREAD_MODEL_PARALLEL + +/* These are the parameters. */ +static int64_t truncate = -1, round_up = -1, round_down = -1; + +/* The real size of the underlying plugin. */ +static int64_t real_size; + +/* The calculated size after applying the parameters. */ +static int64_t size; + +/* Called for each key=value passed on the command line. */ +static int +truncate_config (nbdkit_next_config *next,...

...piler doesn't have any understanding of the internals. And it looks to me like the use case you want this for is very much probably a power of two. In which case division is all kinds of just stupid. And we already have a power-of-two round up function that works on u64. It's called "round_up()". I wish we had a better visual warning about the differences between "round_up()" (limited to powers-of-two, but efficient, and works with any size) and "roundup()" (generic, potentially horribly slow, and doesn't work for 64-bit on 32-bit). Side note: "round_...

...05/2019 16:27, Steven Rostedt wrote: > > I haven't yet tested this, but what about something like the following: > > ...perhaps forget about the constant check, and just force > the power of two check: > > \ > if (!(__y & (__y >> 1))) { \ > __x = round_up(x, y); \ > } else { \ You probably want            if (!(__y & (__y - 1)) -- Roger

...able_space(unsigned long end) { - unsigned long puds, pmds, ptes, tables; + unsigned long puds, pmds, ptes, tables, fixmap_tables; puds = (end + PUD_SIZE - 1) >> PUD_SHIFT; pmds = (end + PMD_SIZE - 1) >> PMD_SHIFT; @@ -660,7 +682,16 @@ static void __init find_early_table_spac round_up(pmds * 8, PAGE_SIZE) + round_up(ptes * 8, PAGE_SIZE); - extend_init_mapping(tables); + /* Also reserve pages for fixmaps that need to be set up early. + * Their pud is shared with the kernel pud. + */ + pmds = (PMD_SIZE - 1 - FIXADDR_START) >> PMD_SHIFT; + ptes = (PTE_SIZE - 1 - FIXA...

While working on adding assertions to pthread_mutex_lock calls, I noticed that the truncate filter's use of mutex didn't really protect us, and isn't really necessary. Cleaning that up also spotted a couple of other potential cleanups. Eric Blake (4): filters: Drop useless .open callbacks truncate: Fix corruption when plugin changes per-connection size truncate: Test for safe

...gt; +#include <errno.h> + +#include <pthread.h> + +#include <nbdkit-filter.h> + +#include "ispowerof2.h" +#include "iszero.h" + +#define THREAD_MODEL NBDKIT_THREAD_MODEL_PARALLEL + +/* These are the parameters. */ +static int64_t truncate = -1; +static unsigned round_up = 0, round_down = 0; + +/* The real size of the underlying plugin. */ +static uint64_t real_size; + +/* The calculated size after applying the parameters. */ +static uint64_t size; + +/* This lock protects the real_size and size fields. */ +static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER; +...

...; > > I haven't yet tested this, but what about something like the following: > > > > ...perhaps forget about the constant check, and just force > > the power of two check: > > > > \ > > if (!(__y & (__y >> 1))) { \ > > __x = round_up(x, y); \ > > } else { \ > > You probably want > >            if (!(__y & (__y - 1)) > > -- Yes I do. I corrected it in my next email. http://lkml.kernel.org/r/20190523133648.591f9e78 at gandalf.local.home > #define roundup(x, y) ( \ > { \...

...39;t yet tested this, but what about something like the following: >>> >>> ...perhaps forget about the constant check, and just force >>> the power of two check: >>> >>> \ >>> if (!(__y & (__y >> 1))) { \ >>> __x = round_up(x, y); \ >>> } else { \ >> >> You probably want >> >>            if (!(__y & (__y - 1)) >> >> -- > > Yes I do. I corrected it in my next email. > > http://lkml.kernel.org/r/20190523133648.591f9e78 at gandalf.local.home Or pe...