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| author | Qu Wenruo <wqu@suse.com> | 2023-10-28 05:58:45 +0300 |
|---|---|---|
| committer | David Sterba <dsterba@suse.com> | 2023-11-03 18:40:15 +0300 |
| commit | 47e2b06b7b5cb356a987ba3429550c3a89ea89d6 (patch) | |
| tree | d1415f4cad3a193ec3a2259ee07d134ce7dbe62a /fs/btrfs/scrub.c | |
| parent | d8ba2a91fc3cd0347823435971f58f473cbba7aa (diff) | |
| download | linux-47e2b06b7b5cb356a987ba3429550c3a89ea89d6.tar.xz | |
btrfs: make found_logical_ret parameter mandatory for function queue_scrub_stripe()
[BUG]
There is a compilation warning reported on commit ae76d8e3e135 ("btrfs:
scrub: fix grouping of read IO"), where gcc (14.0.0 20231022 experimental)
is reporting the following uninitialized variable:
fs/btrfs/scrub.c: In function ‘scrub_simple_mirror.isra’:
fs/btrfs/scrub.c:2075:29: error: ‘found_logical’ may be used uninitialized [-Werror=maybe-uninitialized[https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wmaybe-uninitialized]]
2075 | cur_logical = found_logical + BTRFS_STRIPE_LEN;
fs/btrfs/scrub.c:2040:21: note: ‘found_logical’ was declared here
2040 | u64 found_logical;
| ^~~~~~~~~~~~~
[CAUSE]
This is a false alert, as @found_logical is passed as parameter
@found_logical_ret of function queue_scrub_stripe().
As long as queue_scrub_stripe() returned 0, we would update
@found_logical_ret. And if queue_scrub_stripe() returned >0 or <0, the
caller would not utilized @found_logical, thus there should be nothing
wrong.
Although the triggering gcc is still experimental, it looks like the
extra check on "if (found_logical_ret)" can sometimes confuse the
compiler.
Meanwhile the only caller of queue_scrub_stripe() is always passing a
valid pointer, there is no need for such check at all.
[FIX]
Although the report itself is a false alert, we can still make it more
explicit by:
- Replace the check for @found_logical_ret with ASSERT()
- Initialize @found_logical to U64_MAX
- Add one extra ASSERT() to make sure @found_logical got updated
Link: https://lore.kernel.org/linux-btrfs/87fs1x1p93.fsf@gentoo.org/
Fixes: ae76d8e3e135 ("btrfs: scrub: fix grouping of read IO")
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/scrub.c')
| -rw-r--r-- | fs/btrfs/scrub.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index 9ce5be21b036..f62a408671cb 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -1868,6 +1868,9 @@ static int queue_scrub_stripe(struct scrub_ctx *sctx, struct btrfs_block_group * */ ASSERT(sctx->cur_stripe < SCRUB_TOTAL_STRIPES); + /* @found_logical_ret must be specified. */ + ASSERT(found_logical_ret); + stripe = &sctx->stripes[sctx->cur_stripe]; scrub_reset_stripe(stripe); ret = scrub_find_fill_first_stripe(bg, &sctx->extent_path, @@ -1876,8 +1879,7 @@ static int queue_scrub_stripe(struct scrub_ctx *sctx, struct btrfs_block_group * /* Either >0 as no more extents or <0 for error. */ if (ret) return ret; - if (found_logical_ret) - *found_logical_ret = stripe->logical; + *found_logical_ret = stripe->logical; sctx->cur_stripe++; /* We filled one group, submit it. */ @@ -2080,7 +2082,7 @@ static int scrub_simple_mirror(struct scrub_ctx *sctx, /* Go through each extent items inside the logical range */ while (cur_logical < logical_end) { - u64 found_logical; + u64 found_logical = U64_MAX; u64 cur_physical = physical + cur_logical - logical_start; /* Canceled? */ @@ -2115,6 +2117,8 @@ static int scrub_simple_mirror(struct scrub_ctx *sctx, if (ret < 0) break; + /* queue_scrub_stripe() returned 0, @found_logical must be updated. */ + ASSERT(found_logical != U64_MAX); cur_logical = found_logical + BTRFS_STRIPE_LEN; /* Don't hold CPU for too long time */ |