+++ /dev/null
-From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
-From: Alwin Antreich <a.antreich@proxmox.com>
-Date: Thu, 6 Dec 2018 12:14:04 +0100
-Subject: [PATCH] os/bluestore: handle spurious read errors
-
-Some kernels (4.9+) sometime fail to return data when reading
-from a block device under memory pressure. This patch retries
-the read if the checksum verification fails, tests show that
-the first retried read succeeds in ~99.5% of the cases, so
-3 attempts are made by default before giving up on the data.
-
-Works-around: http://tracker.ceph.com/issues/22464
-Signed-off-by: Paul Emmerich <paul.emmerich@croit.io>
-(cherry picked from commit cffcbc73aaaa874829d5fc9091af3042b887f9a7)
-
- Conflicts:
- src/common/legacy_config_opts.h
-- adjacent options
- src/common/options.cc
-- no RUNTIME flag in luminous
- src/os/bluestore/BlueStore.cc
- src/os/bluestore/BlueStore.h
-- adjacent perfcounter
- src/test/objectstore/store_test.cc
-- adjacent tests, no #ifdef
-- g_conf, not g_conf()
-- no create_new_collection
-- queue_transaction etc take osr, not ch
-
-Signed-off-by: Alwin Antreich <a.antreich@proxmox.com>
----
- src/common/legacy_config_opts.h | 2 +
- src/common/options.cc | 10 +++++
- src/os/bluestore/BlueStore.cc | 35 ++++++++++++++--
- src/os/bluestore/BlueStore.h | 4 +-
- src/test/objectstore/store_test.cc | 67 ++++++++++++++++++++++++++++++
- 5 files changed, 114 insertions(+), 4 deletions(-)
-
-diff --git a/src/common/legacy_config_opts.h b/src/common/legacy_config_opts.h
-index a51870ef6..54d2b578b 100644
---- a/src/common/legacy_config_opts.h
-+++ b/src/common/legacy_config_opts.h
-@@ -1031,6 +1031,7 @@ OPTION(bluestore_block_preallocate_file, OPT_BOOL) //whether preallocate space i
- OPTION(bluestore_csum_type, OPT_STR) // none|xxhash32|xxhash64|crc32c|crc32c_16|crc32c_8
- OPTION(bluestore_csum_min_block, OPT_U32)
- OPTION(bluestore_csum_max_block, OPT_U32)
-+OPTION(bluestore_retry_disk_reads, OPT_U64)
- OPTION(bluestore_min_alloc_size, OPT_U32)
- OPTION(bluestore_min_alloc_size_hdd, OPT_U32)
- OPTION(bluestore_min_alloc_size_ssd, OPT_U32)
-@@ -1124,6 +1125,7 @@ OPTION(bluestore_debug_omit_kv_commit, OPT_BOOL)
- OPTION(bluestore_debug_permit_any_bdev_label, OPT_BOOL)
- OPTION(bluestore_shard_finishers, OPT_BOOL)
- OPTION(bluestore_debug_random_read_err, OPT_DOUBLE)
-+OPTION(bluestore_debug_inject_csum_err_probability, OPT_FLOAT)
-
- OPTION(kstore_max_ops, OPT_U64)
- OPTION(kstore_max_bytes, OPT_U64)
-diff --git a/src/common/options.cc b/src/common/options.cc
-index ff3bb1a1b..8983210d9 100644
---- a/src/common/options.cc
-+++ b/src/common/options.cc
-@@ -3422,6 +3422,12 @@ std::vector<Option> get_global_options() {
- .set_description("Maximum block size to checksum")
- .add_see_also("bluestore_csum_min_block"),
-
-+ Option("bluestore_retry_disk_reads", Option::TYPE_UINT, Option::LEVEL_ADVANCED)
-+ .set_default(3)
-+ .set_min_max(0, 255)
-+ .set_description("Number of read retries on checksum validation error")
-+ .set_long_description("Retries to read data from the disk this many times when checksum validation fails to handle spurious read errors gracefully."),
-+
- Option("bluestore_min_alloc_size", Option::TYPE_UINT, Option::LEVEL_ADVANCED)
- .set_default(0)
- .add_tag("mkfs")
-@@ -3791,6 +3797,10 @@ std::vector<Option> get_global_options() {
- .set_default(0)
- .set_description(""),
-
-+ Option("bluestore_debug_inject_csum_err_probability", Option::TYPE_FLOAT, Option::LEVEL_DEV)
-+ .set_default(0.0)
-+ .set_description("inject crc verification errors into bluestore device reads"),
-+
- // -----------------------------------------
- // kstore
-
-diff --git a/src/os/bluestore/BlueStore.cc b/src/os/bluestore/BlueStore.cc
-index b326d39bc..28ababbe5 100644
---- a/src/os/bluestore/BlueStore.cc
-+++ b/src/os/bluestore/BlueStore.cc
-@@ -4171,6 +4171,8 @@ void BlueStore::_init_logger()
- "collection");
- b.add_u64_counter(l_bluestore_read_eio, "bluestore_read_eio",
- "Read EIO errors propagated to high level callers");
-+ b.add_u64_counter(l_bluestore_reads_with_retries, "bluestore_reads_with_retries",
-+ "Read operations that required at least one retry due to failed checksum validation");
- logger = b.create_perf_counters();
- cct->get_perfcounters_collection()->add(logger);
- }
-@@ -6698,7 +6700,8 @@ int BlueStore::_do_read(
- uint64_t offset,
- size_t length,
- bufferlist& bl,
-- uint32_t op_flags)
-+ uint32_t op_flags,
-+ uint64_t retry_count)
- {
- FUNCTRACE();
- int r = 0;
-@@ -6919,7 +6922,14 @@ int BlueStore::_do_read(
- bufferlist& compressed_bl = *p++;
- if (_verify_csum(o, &bptr->get_blob(), 0, compressed_bl,
- b2r_it->second.front().logical_offset) < 0) {
-- return -EIO;
-+ // Handles spurious read errors caused by a kernel bug.
-+ // We sometimes get all-zero pages as a result of the read under
-+ // high memory pressure. Retrying the failing read succeeds in most cases.
-+ // See also: http://tracker.ceph.com/issues/22464
-+ if (retry_count >= cct->_conf->bluestore_retry_disk_reads) {
-+ return -EIO;
-+ }
-+ return _do_read(c, o, offset, length, bl, op_flags, retry_count + 1);
- }
- bufferlist raw_bl;
- r = _decompress(compressed_bl, &raw_bl);
-@@ -6937,7 +6947,14 @@ int BlueStore::_do_read(
- for (auto& reg : b2r_it->second) {
- if (_verify_csum(o, &bptr->get_blob(), reg.r_off, reg.bl,
- reg.logical_offset) < 0) {
-- return -EIO;
-+ // Handles spurious read errors caused by a kernel bug.
-+ // We sometimes get all-zero pages as a result of the read under
-+ // high memory pressure. Retrying the failing read succeeds in most cases.
-+ // See also: http://tracker.ceph.com/issues/22464
-+ if (retry_count >= cct->_conf->bluestore_retry_disk_reads) {
-+ return -EIO;
-+ }
-+ return _do_read(c, o, offset, length, bl, op_flags, retry_count + 1);
- }
- if (buffered) {
- bptr->shared_blob->bc.did_read(bptr->shared_blob->get_cache(),
-@@ -6981,6 +6998,11 @@ int BlueStore::_do_read(
- assert(pos == length);
- assert(pr == pr_end);
- r = bl.length();
-+ if (retry_count) {
-+ logger->inc(l_bluestore_reads_with_retries);
-+ dout(5) << __func__ << " read at 0x" << std::hex << offset << "~" << length
-+ << " failed " << std::dec << retry_count << " times before succeeding" << dendl;
-+ }
- return r;
- }
-
-@@ -6993,6 +7015,13 @@ int BlueStore::_verify_csum(OnodeRef& o,
- uint64_t bad_csum;
- utime_t start = ceph_clock_now();
- int r = blob->verify_csum(blob_xoffset, bl, &bad, &bad_csum);
-+ if (cct->_conf->bluestore_debug_inject_csum_err_probability > 0 &&
-+ (rand() % 10000) < cct->_conf->bluestore_debug_inject_csum_err_probability * 10000.0) {
-+ derr << __func__ << " injecting bluestore checksum verifcation error" << dendl;
-+ bad = blob_xoffset;
-+ r = -1;
-+ bad_csum = 0xDEADBEEF;
-+ }
- if (r < 0) {
- if (r == -1) {
- PExtentVector pex;
-diff --git a/src/os/bluestore/BlueStore.h b/src/os/bluestore/BlueStore.h
-index 6a14042df..70050a567 100644
---- a/src/os/bluestore/BlueStore.h
-+++ b/src/os/bluestore/BlueStore.h
-@@ -118,6 +118,7 @@ enum {
- l_bluestore_extent_compress,
- l_bluestore_gc_merged,
- l_bluestore_read_eio,
-+ l_bluestore_reads_with_retries,
- l_bluestore_last
- };
-
-@@ -2366,7 +2367,8 @@ public:
- uint64_t offset,
- size_t len,
- bufferlist& bl,
-- uint32_t op_flags = 0);
-+ uint32_t op_flags = 0,
-+ uint64_t retry_count = 0);
-
- private:
- int _fiemap(CollectionHandle &c_, const ghobject_t& oid,
-diff --git a/src/test/objectstore/store_test.cc b/src/test/objectstore/store_test.cc
-index d2152d456..326c9785d 100644
---- a/src/test/objectstore/store_test.cc
-+++ b/src/test/objectstore/store_test.cc
-@@ -6855,6 +6855,73 @@ TEST_P(StoreTestSpecificAUSize, fsckOnUnalignedDevice2) {
- g_conf->apply_changes(NULL);
- }
-
-+TEST_P(StoreTest, SpuriousReadErrorTest) {
-+ if (string(GetParam()) != "bluestore")
-+ return;
-+
-+ ObjectStore::Sequencer osr("test");
-+ int r;
-+ auto logger = store->get_perf_counters();
-+ coll_t cid;
-+ ghobject_t hoid(hobject_t(sobject_t("foo", CEPH_NOSNAP)));
-+ {
-+ ObjectStore::Transaction t;
-+ t.create_collection(cid, 0);
-+ cerr << "Creating collection " << cid << std::endl;
-+ r = store->queue_transaction(&osr, std::move(t), nullptr);
-+ ASSERT_EQ(r, 0);
-+ }
-+ bufferlist test_data;
-+ bufferptr ap(0x2000);
-+ memset(ap.c_str(), 'a', 0x2000);
-+ test_data.append(ap);
-+ {
-+ ObjectStore::Transaction t;
-+ t.write(cid, hoid, 0, 0x2000, test_data);
-+ r = store->queue_transaction(&osr, std::move(t), nullptr);
-+ ASSERT_EQ(r, 0);
-+ // force cache clear
-+ EXPECT_EQ(store->umount(), 0);
-+ EXPECT_EQ(store->mount(), 0);
-+ }
-+
-+ cerr << "Injecting CRC error with no retry, expecting EIO" << std::endl;
-+ g_conf->set_val("bluestore_retry_disk_reads", "0");
-+ g_conf->set_val("bluestore_debug_inject_csum_err_probability", "1");
-+ g_ceph_context->_conf->apply_changes(nullptr);
-+ {
-+ bufferlist in;
-+ r = store->read(cid, hoid, 0, 0x2000, in, CEPH_OSD_OP_FLAG_FADVISE_NOCACHE);
-+ ASSERT_EQ(-EIO, r);
-+ ASSERT_EQ(logger->get(l_bluestore_read_eio), 1u);
-+ ASSERT_EQ(logger->get(l_bluestore_reads_with_retries), 0u);
-+ }
-+
-+ cerr << "Injecting CRC error with retries, expecting success after several retries" << std::endl;
-+ g_conf->set_val("bluestore_retry_disk_reads", "255");
-+ g_conf->set_val("bluestore_debug_inject_csum_err_probability", "0.8");
-+ /**
-+ * Probabilistic test: 25 reads, each has a 80% chance of failing with 255 retries
-+ * Probability of at least one retried read: 1 - (0.2 ** 25) = 100% - 3e-18
-+ * Probability of a random test failure: 1 - ((1 - (0.8 ** 255)) ** 25) ~= 5e-24
-+ */
-+ g_ceph_context->_conf->apply_changes(nullptr);
-+ {
-+ for (int i = 0; i < 25; ++i) {
-+ bufferlist in;
-+ r = store->read(cid, hoid, 0, 0x2000, in, CEPH_OSD_OP_FLAG_FADVISE_NOCACHE);
-+ ASSERT_EQ(0x2000, r);
-+ ASSERT_TRUE(bl_eq(test_data, in));
-+ }
-+ ASSERT_GE(logger->get(l_bluestore_reads_with_retries), 1u);
-+ }
-+
-+ // revert
-+ g_conf->set_val("bluestore_retry_disk_reads", "3");
-+ g_conf->set_val("bluestore_debug_inject_csum_err_probability", "0");
-+ g_ceph_context->_conf->apply_changes(nullptr);
-+}
-+
- int main(int argc, char **argv) {
- vector<const char*> args;
- argv_to_vec(argc, (const char **)argv, args);
---
-2.19.2
-
projects / ceph.git / commitdiff