nilfs2: Use div64_ul() instead of do_div()
Commit Message
Fixes Coccinelle/coccicheck warning reported by do_div.cocci.
Compared to do_div(), div64_ul() does not implicitly cast the divisor and
does not unnecessarily calculate the remainder.
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
---
fs/nilfs2/cpfile.c | 2 +-
fs/nilfs2/dat.c | 2 +-
fs/nilfs2/ioctl.c | 4 ++--
fs/nilfs2/sufile.c | 2 +-
4 files changed, 5 insertions(+), 5 deletions(-)
Comments
On Thu, Feb 29, 2024 at 9:19 PM Thorsten Blum wrote:
>
> Fixes Coccinelle/coccicheck warning reported by do_div.cocci.
>
> Compared to do_div(), div64_ul() does not implicitly cast the divisor and
> does not unnecessarily calculate the remainder.
>
> Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
> ---
> fs/nilfs2/cpfile.c | 2 +-
> fs/nilfs2/dat.c | 2 +-
> fs/nilfs2/ioctl.c | 4 ++--
> fs/nilfs2/sufile.c | 2 +-
> 4 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/fs/nilfs2/cpfile.c b/fs/nilfs2/cpfile.c
> index 39136637f715..bafbdca1a17d 100644
> --- a/fs/nilfs2/cpfile.c
> +++ b/fs/nilfs2/cpfile.c
> @@ -28,7 +28,7 @@ nilfs_cpfile_get_blkoff(const struct inode *cpfile, __u64 cno)
> {
> __u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
>
> - do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
> + tcno = div64_ul(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
> return (unsigned long)tcno;
> }
>
> diff --git a/fs/nilfs2/dat.c b/fs/nilfs2/dat.c
> index 9cf6ba58f585..df5324b0c0cd 100644
> --- a/fs/nilfs2/dat.c
> +++ b/fs/nilfs2/dat.c
> @@ -460,7 +460,7 @@ ssize_t nilfs_dat_get_vinfo(struct inode *dat, void *buf, unsigned int visz,
> kaddr = kmap_atomic(entry_bh->b_page);
> /* last virtual block number in this block */
> first = vinfo->vi_vblocknr;
> - do_div(first, entries_per_block);
> + first = div64_ul(first, entries_per_block);
> first *= entries_per_block;
> last = first + entries_per_block - 1;
> for (j = i, n = 0;
> diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
> index cfb6aca5ec38..f1a01c191cf5 100644
> --- a/fs/nilfs2/ioctl.c
> +++ b/fs/nilfs2/ioctl.c
> @@ -1111,7 +1111,7 @@ static int nilfs_ioctl_set_alloc_range(struct inode *inode, void __user *argp)
> segbytes = nilfs->ns_blocks_per_segment * nilfs->ns_blocksize;
>
> minseg = range[0] + segbytes - 1;
> - do_div(minseg, segbytes);
> + minseg = div64_ul(minseg, segbytes);
>
> if (range[1] < 4096)
> goto out;
> @@ -1120,7 +1120,7 @@ static int nilfs_ioctl_set_alloc_range(struct inode *inode, void __user *argp)
> if (maxseg < segbytes)
> goto out;
>
> - do_div(maxseg, segbytes);
> + maxseg = div64_ul(maxseg, segbytes);
> maxseg--;
>
> ret = nilfs_sufile_set_alloc_range(nilfs->ns_sufile, minseg, maxseg);
> diff --git a/fs/nilfs2/sufile.c b/fs/nilfs2/sufile.c
> index 0a8119456c21..c02b523d9c7e 100644
> --- a/fs/nilfs2/sufile.c
> +++ b/fs/nilfs2/sufile.c
> @@ -48,7 +48,7 @@ nilfs_sufile_get_blkoff(const struct inode *sufile, __u64 segnum)
> {
> __u64 t = segnum + NILFS_MDT(sufile)->mi_first_entry_offset;
>
> - do_div(t, nilfs_sufile_segment_usages_per_block(sufile));
> + t = div64_ul(t, nilfs_sufile_segment_usages_per_block(sufile));
> return (unsigned long)t;
> }
>
> --
> 2.44.0
>
All of the fixes in this patch seem to be correct, but this doesn't
cover nilfs_resize_fs(), nilfs_max_segment_count(), and
nilfs_sb2_bad_offset(), which also have do_div() that doesn't use the
return value.
Did do_div.cocci make a difference ?
Thanks,
Ryusuke Konishi
> On Feb 29, 2024, at 19:45, Ryusuke Konishi <konishi.ryusuke@gmail.com> wrote:
>
> All of the fixes in this patch seem to be correct, but this doesn't
> cover nilfs_resize_fs(), nilfs_max_segment_count(), and
> nilfs_sb2_bad_offset(), which also have do_div() that doesn't use the
> return value.
I just tested this, and Coccinelle didn't report nilfs_resize_fs() or
nilfs_max_segment_count() because both divisors are fields of a struct. I will
refactor this and submit a v2.
For nilfs_sb2_bad_offset(), where the dividend is u64 and the divisor is u32, we
would need a dedicated function like div64_u32() that doesn't calculate the
remainder, which doesn't seem to exist. What do you think?
Thanks,
Thorsten
> On Feb 29, 2024, at 20:41, Thorsten Blum <thorsten.blum@toblux.com> wrote:
>
>> On Feb 29, 2024, at 19:45, Ryusuke Konishi <konishi.ryusuke@gmail.com> wrote:
>>
>> All of the fixes in this patch seem to be correct, but this doesn't
>> cover nilfs_resize_fs(), nilfs_max_segment_count(), and
>> nilfs_sb2_bad_offset(), which also have do_div() that doesn't use the
>> return value.
>
> For nilfs_sb2_bad_offset(), where the dividend is u64 and the divisor is u32, we
> would need a dedicated function like div64_u32() that doesn't calculate the
> remainder, which doesn't seem to exist. What do you think?
Never mind, there is div_u64(u64, u32). I'll submit a v2 shortly.
Thorsten
> On Feb 29, 2024, at 21:40, Thorsten Blum <thorsten.blum@toblux.com> wrote:
>
>> On Feb 29, 2024, at 20:41, Thorsten Blum <thorsten.blum@toblux.com> wrote:
>>
>>> On Feb 29, 2024, at 19:45, Ryusuke Konishi <konishi.ryusuke@gmail.com> wrote:
>>>
>>> All of the fixes in this patch seem to be correct, but this doesn't
>>> cover nilfs_resize_fs(), nilfs_max_segment_count(), and
>>> nilfs_sb2_bad_offset(), which also have do_div() that doesn't use the
>>> return value.
>>
>> For nilfs_sb2_bad_offset(), where the dividend is u64 and the divisor is u32, we
>> would need a dedicated function like div64_u32() that doesn't calculate the
>> remainder, which doesn't seem to exist. What do you think?
>
> Never mind, there is div_u64(u64, u32). I'll submit a v2 shortly.
I left nilfs_sb2_bad_offset() unchanged in v2 because div_u64() still calculates
the remainder.
Thorsten
@@ -28,7 +28,7 @@ nilfs_cpfile_get_blkoff(const struct inode *cpfile, __u64 cno)
{
__u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
- do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
+ tcno = div64_ul(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
return (unsigned long)tcno;
}
@@ -460,7 +460,7 @@ ssize_t nilfs_dat_get_vinfo(struct inode *dat, void *buf, unsigned int visz,
kaddr = kmap_atomic(entry_bh->b_page);
/* last virtual block number in this block */
first = vinfo->vi_vblocknr;
- do_div(first, entries_per_block);
+ first = div64_ul(first, entries_per_block);
first *= entries_per_block;
last = first + entries_per_block - 1;
for (j = i, n = 0;
@@ -1111,7 +1111,7 @@ static int nilfs_ioctl_set_alloc_range(struct inode *inode, void __user *argp)
segbytes = nilfs->ns_blocks_per_segment * nilfs->ns_blocksize;
minseg = range[0] + segbytes - 1;
- do_div(minseg, segbytes);
+ minseg = div64_ul(minseg, segbytes);
if (range[1] < 4096)
goto out;
@@ -1120,7 +1120,7 @@ static int nilfs_ioctl_set_alloc_range(struct inode *inode, void __user *argp)
if (maxseg < segbytes)
goto out;
- do_div(maxseg, segbytes);
+ maxseg = div64_ul(maxseg, segbytes);
maxseg--;
ret = nilfs_sufile_set_alloc_range(nilfs->ns_sufile, minseg, maxseg);
@@ -48,7 +48,7 @@ nilfs_sufile_get_blkoff(const struct inode *sufile, __u64 segnum)
{
__u64 t = segnum + NILFS_MDT(sufile)->mi_first_entry_offset;
- do_div(t, nilfs_sufile_segment_usages_per_block(sufile));
+ t = div64_ul(t, nilfs_sufile_segment_usages_per_block(sufile));
return (unsigned long)t;
}