A raid5/6 log can be loaded while mounting a btrfs (which already has
a disk set up as raid5/6 log) or setting up a disk as raid5/6 log for
the first time.
It gets %journal_tail from super_block where it can read the first 4K
block and goes through the sanity checks, if it's valid, then go check
if anything needs to be replayed, otherwise it creates a new empty
block at the beginning of the disk and new writes will append to it.
Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
---
fs/btrfs/disk-io.c | 16 +++++++
fs/btrfs/raid56.c | 128 +++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/btrfs/raid56.h | 1 +
3 files changed, 145 insertions(+)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 8685d67..c2d8697 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2987,6 +2987,22 @@ int open_ctree(struct super_block *sb,
fs_info->generation = generation;
fs_info->last_trans_committed = generation;
+ if (fs_info->r5log) {
+ u64 cp = btrfs_super_journal_tail(fs_info->super_copy);
+#ifdef BTRFS_DEBUG_R5LOG
+ trace_printk("%s: get journal_tail %llu\n", __func__, cp);
+#endif
+ /* if the data is not replayed, data and parity on
+ * disk are still consistent. So we can move on.
+ *
+ * About fsync, since fsync can make sure data is
+ * flushed onto disk and only metadata is kept into
+ * write-ahead log, the fsync'd data will never ends
+ * up with being replayed by raid56 log.
+ */
+ btrfs_r5l_load_log(fs_info, cp);
+ }
+
ret = btrfs_recover_balance(fs_info);
if (ret) {
btrfs_err(fs_info, "failed to recover balance: %d", ret);
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index 60010a6..5d7ea235 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -1477,6 +1477,134 @@ static bool btrfs_r5l_has_free_space(struct btrfs_r5l_log *log, u64 size)
return log->device_size > (used_size + size);
}
+static int btrfs_r5l_sync_page_io(struct btrfs_r5l_log *log,
+ struct btrfs_device *dev, sector_t sector,
+ int size, struct page *page, int op)
+{
+ struct bio *bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
+ int ret;
+
+ bio->bi_bdev = dev->bdev;
+ bio->bi_opf = op;
+ if (dev == log->dev)
+ bio->bi_iter.bi_sector = (log->data_offset >> 9) + sector;
+ else
+ bio->bi_iter.bi_sector = sector;
+
+#ifdef BTRFS_DEBUG_R5LOG
+ trace_printk("%s: op %d bi_sector 0x%llx\n", __func__, op, (bio->bi_iter.bi_sector << 9));
+#endif
+
+ bio_add_page(bio, page, size, 0);
+ submit_bio_wait(bio);
+ ret = !bio->bi_error;
+ bio_put(bio);
+ return ret;
+}
+
+static int btrfs_r5l_write_empty_meta_block(struct btrfs_r5l_log *log, u64 pos, u64 seq)
+{
+ struct page *page;
+ struct btrfs_r5l_meta_block *mb;
+ int ret = 0;
+
+#ifdef BTRFS_DEBUG_R5LOG
+ trace_printk("%s: pos %llu seq %llu\n", __func__, pos, seq);
+#endif
+
+ page = alloc_page(GFP_NOFS | __GFP_HIGHMEM | __GFP_ZERO);
+ ASSERT(page);
+
+ mb = kmap(page);
+ mb->magic = cpu_to_le32(BTRFS_R5LOG_MAGIC);
+ mb->meta_size = cpu_to_le32(sizeof(struct btrfs_r5l_meta_block));
+ mb->seq = cpu_to_le64(seq);
+ mb->position = cpu_to_le64(pos);
+ kunmap(page);
+
+ if (!btrfs_r5l_sync_page_io(log, log->dev, (pos >> 9), PAGE_SIZE, page, REQ_OP_WRITE | REQ_FUA)) {
+ ret = -EIO;
+ }
+
+ __free_page(page);
+ return ret;
+}
+
+static void btrfs_r5l_write_super(struct btrfs_fs_info *fs_info, u64 cp);
+
+static int btrfs_r5l_recover_log(struct btrfs_r5l_log *log)
+{
+ return 0;
+}
+
+/* return 0 if success, otherwise return errors */
+int btrfs_r5l_load_log(struct btrfs_fs_info *fs_info, u64 cp)
+{
+ struct btrfs_r5l_log *log = fs_info->r5log;
+ struct page *page;
+ struct btrfs_r5l_meta_block *mb;
+ bool create_new = false;
+
+ ASSERT(log);
+
+ page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+ ASSERT(page);
+
+ if (!btrfs_r5l_sync_page_io(log, log->dev, (cp >> 9), PAGE_SIZE, page,
+ REQ_OP_READ)) {
+ __free_page(page);
+ return -EIO;
+ }
+
+ mb = kmap(page);
+#ifdef BTRFS_DEBUG_R5LOG
+ trace_printk("r5l: mb->pos %llu cp %llu mb->seq %llu\n", le64_to_cpu(mb->position), cp, le64_to_cpu(mb->seq));
+#endif
+
+ if (le32_to_cpu(mb->magic) != BTRFS_R5LOG_MAGIC) {
+#ifdef BTRFS_DEBUG_R5LOG
+ trace_printk("magic not match: create new r5l\n");
+#endif
+ create_new = true;
+ goto create;
+ }
+
+ ASSERT(le64_to_cpu(mb->position) == cp);
+ if (le64_to_cpu(mb->position) != cp) {
+#ifdef BTRFS_DEBUG_R5LOG
+ trace_printk("mb->position not match: create new r5l\n");
+#endif
+ create_new = true;
+ goto create;
+ }
+create:
+ if (create_new) {
+ /* initial new r5log */
+ log->last_cp_seq = prandom_u32();
+ cp = 0;
+
+ btrfs_r5l_write_empty_meta_block(log, cp, log->last_cp_seq);
+ btrfs_r5l_write_super(fs_info, cp);
+ } else {
+ log->last_cp_seq = le64_to_cpu(mb->seq);
+ }
+
+ log->last_checkpoint = cp;
+
+ kunmap(page);
+ __free_page(page);
+
+ if (create_new) {
+ log->log_start = btrfs_r5l_ring_add(log, cp, PAGE_SIZE);
+ log->seq = log->last_cp_seq + 1;
+ log->next_checkpoint = cp;
+ } else {
+ btrfs_r5l_recover_log(log);
+ }
+
+ return 0;
+}
+
/*
* writing super with log->next_checkpoint
*
diff --git a/fs/btrfs/raid56.h b/fs/btrfs/raid56.h
index 76a20fa..314d299 100644
--- a/fs/btrfs/raid56.h
+++ b/fs/btrfs/raid56.h
@@ -131,4 +131,5 @@ void raid56_submit_missing_rbio(struct btrfs_raid_bio *rbio);
int btrfs_alloc_stripe_hash_table(struct btrfs_fs_info *info);
void btrfs_free_stripe_hash_table(struct btrfs_fs_info *info);
int btrfs_set_r5log(struct btrfs_fs_info *fs_info, struct btrfs_device *device);
+int btrfs_r5l_load_log(struct btrfs_fs_info *fs_info, u64 cp);
#endif
--
2.9.4
--
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