| Message ID | 20221222143353.598042-2-shikemeng@huaweicloud.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | A few bugfix and cleanup patches for sbitmap | expand |
On Thu 22-12-22 22:33:49, Kemeng Shi wrote: > We calculate allow_hint in next word as following: > > /* low sb->shift bit of alloc_hint will be 0 after this shift */ > alloc_hint = index << sb->shift; > > /* get low sb->shift bit of alloc_hit */ > SB_NR_TO_BIT(sb, alloc_hint) > > So alloc_hit in next word will always be zero. Simpfy alloc_hit calculation > in __sbitmap_get_shallow according to the alloc_hit calculation in > __sbitmap_get. > > Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com> Looks good to me, nice cleanup. I'd just somewhat rephrase the changelog to: Updates to alloc_hint in the loop in __sbitmap_get_shallow() are mostly pointless and equivalent to setting alloc_hint to zero (because SB_NR_TO_BIT() considers only low sb->shift bits from alloc_hint). So simplify the logic. Anyway, feel free to add: Reviewed-by: Jan Kara <jack@suse.cz> Honza > --- > lib/sbitmap.c | 11 ++++------- > 1 file changed, 4 insertions(+), 7 deletions(-) > > diff --git a/lib/sbitmap.c b/lib/sbitmap.c > index 586deb333237..cb5e03a2d65b 100644 > --- a/lib/sbitmap.c > +++ b/lib/sbitmap.c > @@ -243,6 +243,7 @@ static int __sbitmap_get_shallow(struct sbitmap *sb, > int nr = -1; > > index = SB_NR_TO_INDEX(sb, alloc_hint); > + alloc_hint = SB_NR_TO_BIT(sb, alloc_hint); > > for (i = 0; i < sb->map_nr; i++) { > again: > @@ -250,7 +251,7 @@ static int __sbitmap_get_shallow(struct sbitmap *sb, > min_t(unsigned int, > __map_depth(sb, index), > shallow_depth), > - SB_NR_TO_BIT(sb, alloc_hint), true); > + alloc_hint, true); > if (nr != -1) { > nr += index << sb->shift; > break; > @@ -260,13 +261,9 @@ static int __sbitmap_get_shallow(struct sbitmap *sb, > goto again; > > /* Jump to next index. */ > - index++; > - alloc_hint = index << sb->shift; > - > - if (index >= sb->map_nr) { > + alloc_hint = 0; > + if (++index >= sb->map_nr) > index = 0; > - alloc_hint = 0; > - } > } > > return nr; > -- > 2.30.0 >
diff --git a/lib/sbitmap.c b/lib/sbitmap.c index 586deb333237..cb5e03a2d65b 100644 --- a/lib/sbitmap.c +++ b/lib/sbitmap.c @@ -243,6 +243,7 @@ static int __sbitmap_get_shallow(struct sbitmap *sb, int nr = -1; index = SB_NR_TO_INDEX(sb, alloc_hint); + alloc_hint = SB_NR_TO_BIT(sb, alloc_hint); for (i = 0; i < sb->map_nr; i++) { again: @@ -250,7 +251,7 @@ static int __sbitmap_get_shallow(struct sbitmap *sb, min_t(unsigned int, __map_depth(sb, index), shallow_depth), - SB_NR_TO_BIT(sb, alloc_hint), true); + alloc_hint, true); if (nr != -1) { nr += index << sb->shift; break; @@ -260,13 +261,9 @@ static int __sbitmap_get_shallow(struct sbitmap *sb, goto again; /* Jump to next index. */ - index++; - alloc_hint = index << sb->shift; - - if (index >= sb->map_nr) { + alloc_hint = 0; + if (++index >= sb->map_nr) index = 0; - alloc_hint = 0; - } } return nr;
We calculate allow_hint in next word as following: /* low sb->shift bit of alloc_hint will be 0 after this shift */ alloc_hint = index << sb->shift; /* get low sb->shift bit of alloc_hit */ SB_NR_TO_BIT(sb, alloc_hint) So alloc_hit in next word will always be zero. Simpfy alloc_hit calculation in __sbitmap_get_shallow according to the alloc_hit calculation in __sbitmap_get. Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com> --- lib/sbitmap.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-)