Hi Mauro, Mauro Condarelli <mc5...@mclink.it> wrote on Thu, 8 Oct 2020 00:30:21 +0200:
> Use macros in linux/kernel.h to avoid 64-bit divisions. s/in/from/? > > These divisions are needed to convert from file length (potentially > over 32-bit range) to block number, so result and remainder are > guaranteed to fit in 32-bit integers. > > Some 32bit architectures (notably mipsel) lack an implementation of > __udivdi3() compiler helper function in reduced libgcc. > > Standard strategy is to use macros and do_div() inline. You don't use do_div(), here, is it a leftover or do you mean that this is a generic solution? > > Signed-off-by: Mauro Condarelli <mc5...@mclink.it> > --- > > Changes in v3: > - converted to use DIV_ROUND_(UP|DOWN)_ULL() macros (Miquel Raynal). > - split commits to handle unrelated Kconfig warning (Thomas Petazzoni). > > Changes in v2: > - replace division with right shift (Daniel Schwierzeck). > - remove vocore2-specific change (Daniel Schwierzeck). > - add warning to Kconfig about CONFIG_SYS_MALLOC_LEN (Tom Rini). > > fs/squashfs/sqfs.c | 32 ++++++++++++++++---------------- > fs/squashfs/sqfs_inode.c | 7 ++++--- > 2 files changed, 20 insertions(+), 19 deletions(-) > > diff --git a/fs/squashfs/sqfs.c b/fs/squashfs/sqfs.c > index 15208b4dab..ef9f5e3449 100644 > --- a/fs/squashfs/sqfs.c > +++ b/fs/squashfs/sqfs.c > @@ -10,14 +10,14 @@ > #include <asm/unaligned.h> > #include <errno.h> > #include <fs.h> > -#include <linux/types.h> > +#include <linux/kernel.h> > +#include <div64.h> > #include <linux/byteorder/little_endian.h> > #include <linux/byteorder/generic.h> > #include <memalign.h> > #include <stdlib.h> > #include <string.h> > #include <squashfs.h> > -#include <part.h> > > #include "sqfs_decompressor.h" > #include "sqfs_filesystem.h" > @@ -85,10 +85,10 @@ static int sqfs_calc_n_blks(__le64 start, __le64 end, u64 > *offset) > u64 start_, table_size; > > table_size = le64_to_cpu(end) - le64_to_cpu(start); > - start_ = le64_to_cpu(start) / ctxt.cur_dev->blksz; > + start_ = DIV_ROUND_DOWN_ULL(le64_to_cpu(start), ctxt.cur_dev->blksz); > *offset = le64_to_cpu(start) - (start_ * ctxt.cur_dev->blksz); > > - return DIV_ROUND_UP(table_size + *offset, ctxt.cur_dev->blksz); > + return (table_size + *offset + ctxt.cur_dev->blksz - 1) >> > ctxt.cur_dev->log2blksz; I don't recall Joao using this kind of structure but I might be wrong. Can you just verify that this is not a leftover from a previous change? Also, as you state in the commit message, all these divisions serve the same purpose: translating a file length to a block number. I think a helper would be very nice here, something like sqfs_length_to_block_id(ctxt, length); Thanks, Miquèl