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| author | Joe Thornber <ejt@redhat.com> | 2013-12-13 12:31:08 (GMT) |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2013-12-13 19:22:09 (GMT) |
| commit | 5b564d80f8bc21094c0cd2b19b679d983aabcc29 (patch) | |
| tree | 942293da24619a5befb57d03e4a94db9b243710c | |
| parent | 76f5bee5c3b45c617f91243e85547fc8f67bc678 (diff) | |
| download | linux-5b564d80f8bc21094c0cd2b19b679d983aabcc29.tar.xz | |
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+
| -rw-r--r-- | drivers/md/persistent-data/dm-space-map-common.c | 32 |
1 files changed, 23 insertions, 9 deletions
diff --git a/drivers/md/persistent-data/dm-space-map-common.c b/drivers/md/persistent-data/dm-space-map-common.c index 6058569..466a60b 100644 --- a/drivers/md/persistent-data/dm-space-map-common.c +++ b/drivers/md/persistent-data/dm-space-map-common.c @@ -381,7 +381,7 @@ int sm_ll_find_free_block(struct ll_disk *ll, dm_block_t begin, } static int sm_ll_mutate(struct ll_disk *ll, dm_block_t b, - uint32_t (*mutator)(void *context, uint32_t old), + int (*mutator)(void *context, uint32_t old, uint32_t *new), void *context, enum allocation_event *ev) { int r; @@ -410,11 +410,17 @@ static int sm_ll_mutate(struct ll_disk *ll, dm_block_t b, if (old > 2) { r = sm_ll_lookup_big_ref_count(ll, b, &old); - if (r < 0) + if (r < 0) { + dm_tm_unlock(ll->tm, nb); return r; + } } - ref_count = mutator(context, old); + r = mutator(context, old, &ref_count); + if (r) { + dm_tm_unlock(ll->tm, nb); + return r; + } if (ref_count <= 2) { sm_set_bitmap(bm_le, bit, ref_count); @@ -465,9 +471,10 @@ static int sm_ll_mutate(struct ll_disk *ll, dm_block_t b, return ll->save_ie(ll, index, &ie_disk); } -static uint32_t set_ref_count(void *context, uint32_t old) +static int set_ref_count(void *context, uint32_t old, uint32_t *new) { - return *((uint32_t *) context); + *new = *((uint32_t *) context); + return 0; } int sm_ll_insert(struct ll_disk *ll, dm_block_t b, @@ -476,9 +483,10 @@ int sm_ll_insert(struct ll_disk *ll, dm_block_t b, return sm_ll_mutate(ll, b, set_ref_count, &ref_count, ev); } -static uint32_t inc_ref_count(void *context, uint32_t old) +static int inc_ref_count(void *context, uint32_t old, uint32_t *new) { - return old + 1; + *new = old + 1; + return 0; } int sm_ll_inc(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev) @@ -486,9 +494,15 @@ int sm_ll_inc(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev) return sm_ll_mutate(ll, b, inc_ref_count, NULL, ev); } -static uint32_t dec_ref_count(void *context, uint32_t old) +static int dec_ref_count(void *context, uint32_t old, uint32_t *new) { - return old - 1; + if (!old) { + DMERR_LIMIT("unable to decrement a reference count below 0"); + return -EINVAL; + } + + *new = old - 1; + return 0; } int sm_ll_dec(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev) |