forked from Minki/linux
dm space map: disallow decrementing a reference count below zero
The old behaviour, returning -EINVAL if a ref_count of 0 would be
decremented, was removed in commit f722063
("dm space map: optimise
sm_ll_dec and sm_ll_inc"). To fix this regression we return an error
code from the mutator function pointer passed to sm_ll_mutate() and have
dec_ref_count() return -EINVAL if the old ref_count is 0.
Add a DMERR to reflect the potential seriousness of this error.
Also, add missing dm_tm_unlock() to sm_ll_mutate()'s error path.
With this fix the following dmts regression test now passes:
dmtest run --suite cache -n /metadata_use_kernel/
The next patch fixes the higher-level dm-array code that exposed this
regression.
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # 3.12+
This commit is contained in:
parent
76f5bee5c3
commit
5b564d80f8
@ -381,7 +381,7 @@ int sm_ll_find_free_block(struct ll_disk *ll, dm_block_t begin,
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}
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static int sm_ll_mutate(struct ll_disk *ll, dm_block_t b,
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uint32_t (*mutator)(void *context, uint32_t old),
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int (*mutator)(void *context, uint32_t old, uint32_t *new),
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void *context, enum allocation_event *ev)
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{
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int r;
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@ -410,11 +410,17 @@ static int sm_ll_mutate(struct ll_disk *ll, dm_block_t b,
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if (old > 2) {
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r = sm_ll_lookup_big_ref_count(ll, b, &old);
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if (r < 0)
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if (r < 0) {
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dm_tm_unlock(ll->tm, nb);
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return r;
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}
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}
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ref_count = mutator(context, old);
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r = mutator(context, old, &ref_count);
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if (r) {
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dm_tm_unlock(ll->tm, nb);
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return r;
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}
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if (ref_count <= 2) {
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sm_set_bitmap(bm_le, bit, ref_count);
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@ -465,9 +471,10 @@ static int sm_ll_mutate(struct ll_disk *ll, dm_block_t b,
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return ll->save_ie(ll, index, &ie_disk);
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}
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static uint32_t set_ref_count(void *context, uint32_t old)
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static int set_ref_count(void *context, uint32_t old, uint32_t *new)
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{
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return *((uint32_t *) context);
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*new = *((uint32_t *) context);
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return 0;
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}
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int sm_ll_insert(struct ll_disk *ll, dm_block_t b,
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@ -476,9 +483,10 @@ int sm_ll_insert(struct ll_disk *ll, dm_block_t b,
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return sm_ll_mutate(ll, b, set_ref_count, &ref_count, ev);
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}
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static uint32_t inc_ref_count(void *context, uint32_t old)
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static int inc_ref_count(void *context, uint32_t old, uint32_t *new)
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{
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return old + 1;
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*new = old + 1;
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return 0;
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}
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int sm_ll_inc(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
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@ -486,9 +494,15 @@ int sm_ll_inc(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
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return sm_ll_mutate(ll, b, inc_ref_count, NULL, ev);
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}
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static uint32_t dec_ref_count(void *context, uint32_t old)
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static int dec_ref_count(void *context, uint32_t old, uint32_t *new)
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{
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return old - 1;
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if (!old) {
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DMERR_LIMIT("unable to decrement a reference count below 0");
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return -EINVAL;
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}
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*new = old - 1;
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return 0;
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}
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int sm_ll_dec(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
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