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chore: fallocate test #513

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chore: fallocate test #513

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41 changes: 41 additions & 0 deletions util/fibers/uring_file_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -165,5 +165,46 @@ TEST_F(UringFileTest, FSync) {
});
}

TEST_F(UringFileTest, FAllocate) {
string path = base::GetTestTempPath("1.log");
proactor_->Await([this, path] {
auto res = OpenLinux(path, O_RDWR | O_CREAT | O_TRUNC, 0666);
ASSERT_TRUE(res);
LinuxFile* wf = (*res).get();

struct statx stat;
auto ec = StatX(path.c_str(), &stat, wf->fd());
ASSERT_FALSE(ec);
// File size remained zero even if we allocated block size
ASSERT_EQ(stat.stx_size, 0);
const off_t fsize = 128 * 1024 * 1024; // 128 MB

{
util::fb2::FiberCall fc(proactor_.get());
fc->PrepFallocate(wf->fd(), FALLOC_FL_KEEP_SIZE, 0, fsize);
FiberCall::IoResult io_res = fc.Get();
ASSERT_EQ(io_res, 0);
}

ec = StatX(path.c_str(), &stat, wf->fd());
ASSERT_FALSE(ec);
ASSERT_EQ(stat.stx_size, 0);
ASSERT_NE(stat.stx_blocks, 0);

const int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
util::fb2::FiberCall fc(proactor_.get());
fc->PrepFallocate(wf->fd(), mode, 0, fsize);
FiberCall::IoResult io_res = fc.Get();
ASSERT_EQ(io_res, 0);

ec = StatX(path.c_str(), &stat, wf->fd());
ASSERT_FALSE(ec);
ASSERT_EQ(stat.stx_size, 0);
ASSERT_EQ(stat.stx_blocks, 0);
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@kostasrim kostasrim Dec 11, 2025

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This fires but I don't understand why 🤔

const int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;

Means that we will punch a hole on all the blocks so at least we should see a reduction yet it does not change at all 🤔

Based on my understanding, PUCH_HOLE is not hint meaning that we should see a reduction in block size

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@romange romange Dec 11, 2025

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I do not know but I would first use fallocate + stat shell commands and play with them. no need to write code to explore their behavior


ASSERT_FALSE(wf->Close());
});
}

} // namespace fb2
} // namespace util
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