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blobfs: ensure length xattr is written even if all data is flushed

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Data can get implicitly flushed as cache buffers are filled.  But
the length xattr is only written in response to a sync or close
operation.  So we cannot just look at the amount of data flushed,
and ignore the sync operation if all of the data written has been
flushed - we still need to write the length xattr.

This also adds a unit test which reproduces the original problem.

Fixes issue #297.

Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: Icca6ef4d1544f72e9bc31c4ee77d26b4b7f0cce4

Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/455692
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Ziye Yang <ziye.yang@intel.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
This commit is contained in:
Jim Harris 2019-05-24 08:11:09 -07:00 committed by Changpeng Liu
parent fec9d4146b
commit e967dcd245
2 changed files with 112 additions and 2 deletions
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20
lib/blobfs/blobfs.c
View File

@ -121,6 +121,7 @@ struct spdk_file {
bool is_deleted;
bool open_for_writing;
uint64_t length_flushed;
uint64_t length_xattr;
uint64_t append_pos;
uint64_t seq_byte_count;
uint64_t next_seq_offset;
@ -212,9 +213,16 @@ struct spdk_fs_cb_args {
uint64_t offset;
} readahead;
struct {
/* offset of the file when the sync request was made */
uint64_t offset;
TAILQ_ENTRY(spdk_fs_request) tailq;
bool xattr_in_progress;
/* length written to the xattr for this file - this should
* always be the same as the offset if only one thread is
* writing to the file, but could differ if multiple threads
* are appending
*/
uint64_t length;
} sync;
struct {
uint32_t num_clusters;
@ -720,6 +728,7 @@ iter_cb(void *ctx, struct spdk_blob *blob, int rc)
f->blobid = spdk_blob_get_id(blob);
f->length = *length;
f->length_flushed = *length;
f->length_xattr = *length;
f->append_pos = *length;
SPDK_DEBUGLOG(SPDK_LOG_BLOBFS, "added file %s length=%ju\n", f->name, f->length);
} else {
@ -2024,6 +2033,7 @@ __file_cache_finish_sync(void *ctx, int bserrno)
sync_args = &sync_req->args;
file = sync_args->file;
pthread_spin_lock(&file->lock);
file->length_xattr = sync_args->op.sync.length;
assert(sync_args->op.sync.offset <= file->length_flushed);
spdk_trace_record(TRACE_BLOBFS_XATTR_END, 0, sync_args->op.sync.offset,
0, file->trace_arg_name);
@ -2055,6 +2065,7 @@ __check_sync_reqs(struct spdk_file *file)
if (sync_req != NULL && !sync_req->args.op.sync.xattr_in_progress) {
BLOBFS_TRACE(file, "set xattr length 0x%jx\n", file->length_flushed);
sync_req->args.op.sync.xattr_in_progress = true;
sync_req->args.op.sync.length = file->length_flushed;
spdk_blob_set_xattr(file->blob, "length", &file->length_flushed,
sizeof(file->length_flushed));
@ -2147,6 +2158,11 @@ __file_flush(void *ctx)
if (length == 0) {
free_fs_request(req);
pthread_spin_unlock(&file->lock);
/*
* There is no data to flush, but we still need to check for any
* outstanding sync requests to make sure metadata gets updated.
*/
__check_sync_reqs(file);
return;
}
args->op.flush.length = length;
@ -2542,8 +2558,8 @@ _file_sync(struct spdk_file *file, struct spdk_fs_channel *channel,
BLOBFS_TRACE(file, "offset=%jx\n", file->append_pos);
pthread_spin_lock(&file->lock);
if (file->append_pos <= file->length_flushed) {
BLOBFS_TRACE(file, "done - no data to flush\n");
if (file->append_pos <= file->length_xattr) {
BLOBFS_TRACE(file, "done - file already synced\n");
pthread_spin_unlock(&file->lock);
cb_fn(cb_arg, 0);
return;

94
test/unit/lib/blobfs/blobfs_sync_ut/blobfs_sync_ut.c
View File

@ -140,6 +140,24 @@ _fs_init(void *arg)
CU_ASSERT(g_fserrno == 0);
}
static void
_fs_load(void *arg)
{
struct spdk_thread *thread;
struct spdk_bs_dev *dev;
g_fs = NULL;
g_fserrno = -1;
dev = init_dev();
spdk_fs_load(dev, send_request, fs_op_with_handle_complete, NULL);
thread = spdk_get_thread();
while (spdk_thread_poll(thread, 0, 0) > 0) {}
SPDK_CU_ASSERT_FATAL(g_fs != NULL);
SPDK_CU_ASSERT_FATAL(g_fs->bdev == dev);
CU_ASSERT(g_fserrno == 0);
}
static void
_fs_unload(void *arg)
{
@ -208,6 +226,81 @@ cache_read_after_write(void)
ut_send_request(_fs_unload, NULL);
}
static void
file_length(void)
{
int rc;
char *buf;
uint64_t buf_length;
struct spdk_fs_thread_ctx *channel;
struct spdk_file_stat stat = {0};
ut_send_request(_fs_init, NULL);
channel = spdk_fs_alloc_thread_ctx(g_fs);
g_file = NULL;
rc = spdk_fs_open_file(g_fs, channel, "testfile", SPDK_BLOBFS_OPEN_CREATE, &g_file);
CU_ASSERT(rc == 0);
SPDK_CU_ASSERT_FATAL(g_file != NULL);
/* Write slightly more than one CACHE_BUFFER. Filling at least one cache
* buffer triggers a flush to disk. Currently when that cache buffer is written,
* it will proceed to write the final byte, even though there's been no explicit
* sync for it yet. We will fix that eventually, but for now test with this
* behavior since it matches a subtle RocksDB failure scenario.
*/
buf_length = CACHE_BUFFER_SIZE + 1;
buf = calloc(1, buf_length);
spdk_file_write(g_file, channel, buf, 0, buf_length);
free(buf);
/* Spin until all of the data has been flushed to the SSD. There's been no
* sync operation yet, so the xattr on the file is still 0.
*/
while (g_file->length_flushed != buf_length) {}
/* Close the file. This causes an implicit sync which should write the
* length_flushed value as the "length" xattr on the file.
*/
spdk_file_close(g_file, channel);
rc = spdk_fs_file_stat(g_fs, channel, "testfile", &stat);
CU_ASSERT(rc == 0);
CU_ASSERT(buf_length == stat.size);
spdk_fs_free_thread_ctx(channel);
/* Unload and reload the filesystem. The file length will be
* read during load from the length xattr. We want to make sure
* it matches what was written when the file was originally
* written and closed.
*/
ut_send_request(_fs_unload, NULL);
ut_send_request(_fs_load, NULL);
channel = spdk_fs_alloc_thread_ctx(g_fs);
rc = spdk_fs_file_stat(g_fs, channel, "testfile", &stat);
CU_ASSERT(rc == 0);
CU_ASSERT(buf_length == stat.size);
g_file = NULL;
rc = spdk_fs_open_file(g_fs, channel, "testfile", 0, &g_file);
CU_ASSERT(rc == 0);
SPDK_CU_ASSERT_FATAL(g_file != NULL);
spdk_file_close(g_file, channel);
rc = spdk_fs_delete_file(g_fs, channel, "testfile");
CU_ASSERT(rc == 0);
spdk_fs_free_thread_ctx(channel);
ut_send_request(_fs_unload, NULL);
}
static void
cache_write_null_buffer(void)
{
@ -424,6 +517,7 @@ int main(int argc, char **argv)
if (
CU_add_test(suite, "cache read after write", cache_read_after_write) == NULL ||
CU_add_test(suite, "file length", file_length) == NULL ||
CU_add_test(suite, "write_null_buffer", cache_write_null_buffer) == NULL ||
CU_add_test(suite, "create_sync", fs_create_sync) == NULL ||
CU_add_test(suite, "rename_sync", fs_rename_sync) == NULL ||