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authorAri Sundholm <ari@tuxera.com>2018-07-04 17:59:35 +0300
committerKevin Wolf <kwolf@redhat.com>2018-07-05 10:50:20 +0200
commit0878b3c113145d4e01d65aadd4efaf097a3fda4b (patch)
treef1bdf1c9facbbae5d712b07c7c1add6678d60c76 /block/blklogwrites.c
parent2dacaf7c82c2771d507e5e59efcea78d933baca9 (diff)
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block/blklogwrites: Add an option for appending to an old log
Suggested by Kevin Wolf. May be useful when testing multiple batches of writes or doing long-term testing involving restarts of the VM. Signed-off-by: Ari Sundholm <ari@tuxera.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block/blklogwrites.c')
-rw-r--r--block/blklogwrites.c147
1 files changed, 133 insertions, 14 deletions
diff --git a/block/blklogwrites.c b/block/blklogwrites.c
index 272e11a..56154e7 100644
--- a/block/blklogwrites.c
+++ b/block/blklogwrites.c
@@ -24,6 +24,10 @@
#define LOG_FUA_FLAG (1 << 1)
#define LOG_DISCARD_FLAG (1 << 2)
#define LOG_MARK_FLAG (1 << 3)
+#define LOG_FLAG_MASK (LOG_FLUSH_FLAG \
+ | LOG_FUA_FLAG \
+ | LOG_DISCARD_FLAG \
+ | LOG_MARK_FLAG)
#define WRITE_LOG_VERSION 1ULL
#define WRITE_LOG_MAGIC 0x6a736677736872ULL
@@ -58,6 +62,11 @@ static QemuOptsList runtime_opts = {
.head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
.desc = {
{
+ .name = "log-append",
+ .type = QEMU_OPT_BOOL,
+ .help = "Append to an existing log",
+ },
+ {
.name = "log-sector-size",
.type = QEMU_OPT_SIZE,
.help = "Log sector size",
@@ -72,6 +81,53 @@ static inline uint32_t blk_log_writes_log2(uint32_t value)
return 31 - clz32(value);
}
+static inline bool blk_log_writes_sector_size_valid(uint32_t sector_size)
+{
+ return sector_size < (1ull << 24) && is_power_of_2(sector_size);
+}
+
+static uint64_t blk_log_writes_find_cur_log_sector(BdrvChild *log,
+ uint32_t sector_size,
+ uint64_t nr_entries,
+ Error **errp)
+{
+ uint64_t cur_sector = 1;
+ uint64_t cur_idx = 0;
+ uint32_t sector_bits = blk_log_writes_log2(sector_size);
+ struct log_write_entry cur_entry;
+
+ while (cur_idx < nr_entries) {
+ int read_ret = bdrv_pread(log, cur_sector << sector_bits, &cur_entry,
+ sizeof(cur_entry));
+ if (read_ret < 0) {
+ error_setg_errno(errp, -read_ret,
+ "Failed to read log entry %"PRIu64, cur_idx);
+ return (uint64_t)-1ull;
+ }
+
+ if (cur_entry.flags & ~cpu_to_le64(LOG_FLAG_MASK)) {
+ error_setg(errp, "Invalid flags 0x%"PRIx64" in log entry %"PRIu64,
+ le64_to_cpu(cur_entry.flags), cur_idx);
+ return (uint64_t)-1ull;
+ }
+
+ /* Account for the sector of the entry itself */
+ ++cur_sector;
+
+ /*
+ * Account for the data of the write.
+ * For discards, this data is not present.
+ */
+ if (!(cur_entry.flags & cpu_to_le64(LOG_DISCARD_FLAG))) {
+ cur_sector += le64_to_cpu(cur_entry.nr_sectors);
+ }
+
+ ++cur_idx;
+ }
+
+ return cur_sector;
+}
+
static int blk_log_writes_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
@@ -80,6 +136,7 @@ static int blk_log_writes_open(BlockDriverState *bs, QDict *options, int flags,
Error *local_err = NULL;
int ret;
uint64_t log_sector_size;
+ bool log_append;
opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
qemu_opts_absorb_qdict(opts, options, &local_err);
@@ -98,20 +155,6 @@ static int blk_log_writes_open(BlockDriverState *bs, QDict *options, int flags,
goto fail;
}
- log_sector_size = qemu_opt_get_size(opts, "log-sector-size",
- BDRV_SECTOR_SIZE);
-
- if (log_sector_size > (1ull << 23) || !is_power_of_2(log_sector_size)) {
- ret = -EINVAL;
- error_setg(errp, "Invalid log sector size %"PRIu64, log_sector_size);
- goto fail;
- }
-
- s->sectorsize = log_sector_size;
- s->sectorbits = blk_log_writes_log2(log_sector_size);
- s->cur_log_sector = 1;
- s->nr_entries = 0;
-
/* Open the log file */
s->log_file = bdrv_open_child(NULL, options, "log", bs, &child_file, false,
&local_err);
@@ -121,7 +164,83 @@ static int blk_log_writes_open(BlockDriverState *bs, QDict *options, int flags,
goto fail;
}
+ log_append = qemu_opt_get_bool(opts, "log-append", false);
+
+ if (log_append) {
+ struct log_write_super log_sb = { 0, 0, 0, 0 };
+
+ if (qemu_opt_find(opts, "log-sector-size")) {
+ ret = -EINVAL;
+ error_setg(errp, "log-append and log-sector-size are mutually "
+ "exclusive");
+ goto fail_log;
+ }
+
+ /* Read log superblock or fake one for an empty log */
+ if (!bdrv_getlength(s->log_file->bs)) {
+ log_sb.magic = cpu_to_le64(WRITE_LOG_MAGIC);
+ log_sb.version = cpu_to_le64(WRITE_LOG_VERSION);
+ log_sb.nr_entries = cpu_to_le64(0);
+ log_sb.sectorsize = cpu_to_le32(BDRV_SECTOR_SIZE);
+ } else {
+ ret = bdrv_pread(s->log_file, 0, &log_sb, sizeof(log_sb));
+ if (ret < 0) {
+ error_setg_errno(errp, -ret, "Could not read log superblock");
+ goto fail_log;
+ }
+ }
+
+ if (log_sb.magic != cpu_to_le64(WRITE_LOG_MAGIC)) {
+ ret = -EINVAL;
+ error_setg(errp, "Invalid log superblock magic");
+ goto fail_log;
+ }
+
+ if (log_sb.version != cpu_to_le64(WRITE_LOG_VERSION)) {
+ ret = -EINVAL;
+ error_setg(errp, "Unsupported log version %"PRIu64,
+ le64_to_cpu(log_sb.version));
+ goto fail_log;
+ }
+
+ log_sector_size = le32_to_cpu(log_sb.sectorsize);
+ s->cur_log_sector = 1;
+ s->nr_entries = 0;
+
+ if (blk_log_writes_sector_size_valid(log_sector_size)) {
+ s->cur_log_sector =
+ blk_log_writes_find_cur_log_sector(s->log_file, log_sector_size,
+ le64_to_cpu(log_sb.nr_entries), &local_err);
+ if (local_err) {
+ ret = -EINVAL;
+ error_propagate(errp, local_err);
+ goto fail_log;
+ }
+
+ s->nr_entries = le64_to_cpu(log_sb.nr_entries);
+ }
+ } else {
+ log_sector_size = qemu_opt_get_size(opts, "log-sector-size",
+ BDRV_SECTOR_SIZE);
+ s->cur_log_sector = 1;
+ s->nr_entries = 0;
+ }
+
+ if (!blk_log_writes_sector_size_valid(log_sector_size)) {
+ ret = -EINVAL;
+ error_setg(errp, "Invalid log sector size %"PRIu64, log_sector_size);
+ goto fail_log;
+ }
+
+ s->sectorsize = log_sector_size;
+ s->sectorbits = blk_log_writes_log2(log_sector_size);
+
ret = 0;
+fail_log:
+ if (ret < 0) {
+ bdrv_unref_child(bs, s->log_file);
+ s->log_file = NULL;
+ }
fail:
if (ret < 0) {
bdrv_unref_child(bs, bs->file);