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Address warnings about possible division by zero from clangsa 

* The complaint in ztest_replay_write() is only possible if something
   went horribly wrong. An assertion will silence this and if it goes
   off, we will know that something is wrong.
 * The complaint in spa_estimate_metaslabs_to_flush() is not impossible,
   but seems very unlikely. We resolve this by passing the value from
   the `MIN()` that does not go to infinity when the variable is zero.

There was a third report from Clang's scan-build, but that was a
definite false positive and disappeared when checked again through
Clang's static analyzer with Z3 refution via CodeChecker.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14124
This commit is contained in:
Richard Yao 2022-11-03 12:58:14 -04:00 committed by Tony Hutter
parent ac01b876c9
commit 256b74d0b0
2 changed files with 3 additions and 1 deletions
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1
cmd/ztest/ztest.c
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@ -2193,6 +2193,7 @@ ztest_replay_write(void *arg1, void *arg2, boolean_t byteswap)
* but not always, because we also want to verify correct * but not always, because we also want to verify correct
* behavior when the data was not recently read into cache. * behavior when the data was not recently read into cache.
*/ */
ASSERT(doi.doi_data_block_size);
ASSERT0(offset % doi.doi_data_block_size); ASSERT0(offset % doi.doi_data_block_size);
if (ztest_random(4) != 0) { if (ztest_random(4) != 0) {
int prefetch = ztest_random(2) ? int prefetch = ztest_random(2) ?

3
module/zfs/spa_log_spacemap.c
View File

@ -690,7 +690,8 @@ spa_estimate_metaslabs_to_flush(spa_t *spa)
* based on the incoming rate until we exceed it. * based on the incoming rate until we exceed it.
*/ */
if (available_blocks >= 0 && available_txgs >= 0) { if (available_blocks >= 0 && available_txgs >= 0) {
uint64_t skip_txgs = MIN(available_txgs + 1, uint64_t skip_txgs = (incoming == 0) ?
available_txgs + 1 : MIN(available_txgs + 1,
(available_blocks / incoming) + 1); (available_blocks / incoming) + 1);
available_blocks -= (skip_txgs * incoming); available_blocks -= (skip_txgs * incoming);
available_txgs -= skip_txgs; available_txgs -= skip_txgs;