Messages in this thread | | | Date | Fri, 13 May 2022 23:20:57 +0800 | Subject | Re: [PATCH] bcache: fix wrong BITMASK offset value for BDEV_CACHE_MODE | From | Coly Li <> |
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On 7/20/21 6:32 PM, Lin Feng wrote: > Original codes: > BITMASK(CACHE_SYNC, struct cache_sb, flags, 0, 1); > BITMASK(CACHE_DISCARD, struct cache_sb, flags, 1, 1); > BITMASK(CACHE_REPLACEMENT, struct cache_sb, flags, 2, 3); > ... > BITMASK(BDEV_CACHE_MODE, struct cache_sb, flags, 0, 4); > > Should BDEV_CACHE_MODE bits start from bit-nr 5(2+3) else it overlaps > with previous defined bit chunks, since we have 4 types of cache modes, > BDEV_CACHE_MODE will overwrite CACHE_SYNC and CACHE_DISCARD bits.
The overlap won't happen, previous lines are for cache device, and what you modified is for backing device.
And your patch changes the on-disk format, which is unacceptable anyway.
Coly Li
> > This bug stays there since first upstream version of bcache, don't know > why it lives so long, or am i missing something, please point me out > if I'm wrong, thanks! > > Signed-off-by: Lin Feng <linf@wangsu.com> > --- > include/uapi/linux/bcache.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/uapi/linux/bcache.h b/include/uapi/linux/bcache.h > index cf7399f03b71..dccd89756451 100644 > --- a/include/uapi/linux/bcache.h > +++ b/include/uapi/linux/bcache.h > @@ -288,7 +288,7 @@ BITMASK(CACHE_REPLACEMENT, struct cache_sb, flags, 2, 3); > #define CACHE_REPLACEMENT_FIFO 1U > #define CACHE_REPLACEMENT_RANDOM 2U > > -BITMASK(BDEV_CACHE_MODE, struct cache_sb, flags, 0, 4); > +BITMASK(BDEV_CACHE_MODE, struct cache_sb, flags, 5, 4); > #define CACHE_MODE_WRITETHROUGH 0U > #define CACHE_MODE_WRITEBACK 1U > #define CACHE_MODE_WRITEAROUND 2U
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