A typical write to the raid5/6 log needs three steps:
1) collect data/parity pages into the bio in io_unit;
2) submit the bio in io_unit;
3) writeback data/parity to raid array in end_io.
1) and 2) are protected within log->io_mutex, while 3) is not.
Since recovery needs to know the checkpoint offset where the highest
successful writeback is, we cannot allow IO to be reordered. This is
adding a list in which IO order is maintained properly.
Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
---
fs/btrfs/raid56.c | 42 ++++++++++++++++++++++++++++++++++--------
fs/btrfs/raid56.h | 5 +++++
2 files changed, 39 insertions(+), 8 deletions(-)
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index b771d7d..ceca415 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -183,6 +183,9 @@ struct btrfs_r5l_log {
/* protect this struct and log io */
struct mutex io_mutex;
+ spinlock_t io_list_lock;
+ struct list_head io_list;
+
/* r5log device */
struct btrfs_device *dev;
@@ -1205,6 +1208,7 @@ static struct btrfs_r5l_io_unit *btrfs_r5l_alloc_io_unit(struct btrfs_r5l_log *l
static void btrfs_r5l_free_io_unit(struct btrfs_r5l_log *log, struct btrfs_r5l_io_unit *io)
{
__free_page(io->meta_page);
+ ASSERT(list_empty(&io->list));
kfree(io);
}
@@ -1225,6 +1229,27 @@ static void btrfs_r5l_reserve_log_entry(struct btrfs_r5l_log *log, struct btrfs_
io->need_split_bio = true;
}
+/* the IO order is maintained in log->io_list. */
+static void btrfs_r5l_finish_io(struct btrfs_r5l_log *log)
+{
+ struct btrfs_r5l_io_unit *io, *next;
+
+ spin_lock(&log->io_list_lock);
+ list_for_each_entry_safe(io, next, &log->io_list, list) {
+ if (io->status != BTRFS_R5L_STRIPE_END)
+ break;
+
+#ifdef BTRFS_DEBUG_R5LOG
+ trace_printk("current log->next_checkpoint %llu (will be %llu after writing to RAID\n", log->next_checkpoint, io->log_start);
+#endif
+
+ list_del_init(&io->list);
+ log->next_checkpoint = io->log_start;
+ btrfs_r5l_free_io_unit(log, io);
+ }
+ spin_unlock(&log->io_list_lock);
+}
+
static void btrfs_write_rbio(struct btrfs_raid_bio *rbio);
static void btrfs_r5l_log_endio(struct bio *bio)
@@ -1234,18 +1259,12 @@ static void btrfs_r5l_log_endio(struct bio *bio)
bio_put(bio);
-#ifdef BTRFS_DEBUG_R5LOG
- trace_printk("move data to disk(current log->next_checkpoint %llu (will be %llu after writing to RAID\n", log->next_checkpoint, io->log_start);
-#endif
/* move data to RAID. */
btrfs_write_rbio(io->rbio);
+ io->status = BTRFS_R5L_STRIPE_END;
/* After stripe data has been flushed into raid, set ->next_checkpoint. */
- log->next_checkpoint = io->log_start;
-
- if (log->current_io == io)
- log->current_io = NULL;
- btrfs_r5l_free_io_unit(log, io);
+ btrfs_r5l_finish_io(log);
}
static struct bio *btrfs_r5l_bio_alloc(struct btrfs_r5l_log *log)
@@ -1299,6 +1318,11 @@ static struct btrfs_r5l_io_unit *btrfs_r5l_new_meta(struct btrfs_r5l_log *log)
bio_add_page(io->current_bio, io->meta_page, PAGE_SIZE, 0);
btrfs_r5l_reserve_log_entry(log, io);
+
+ INIT_LIST_HEAD(&io->list);
+ spin_lock(&log->io_list_lock);
+ list_add_tail(&io->list, &log->io_list);
+ spin_unlock(&log->io_list_lock);
return io;
}
@@ -3760,6 +3784,8 @@ struct btrfs_r5l_log * btrfs_r5l_init_log_prepare(struct btrfs_fs_info *fs_info,
ASSERT(sizeof(device->uuid) == BTRFS_UUID_SIZE);
log->uuid_csum = btrfs_crc32c(~0, device->uuid, sizeof(device->uuid));
mutex_init(&log->io_mutex);
+ spin_lock_init(&log->io_list_lock);
+ INIT_LIST_HEAD(&log->io_list);
return log;
}
diff --git a/fs/btrfs/raid56.h b/fs/btrfs/raid56.h
index 2cc64a3..fc4ff20 100644
--- a/fs/btrfs/raid56.h
+++ b/fs/btrfs/raid56.h
@@ -43,11 +43,16 @@ static inline int nr_data_stripes(struct map_lookup *map)
struct btrfs_r5l_log;
#define BTRFS_R5LOG_MAGIC 0x6433c509
+#define BTRFS_R5L_STRIPE_END 1
+
/* one meta block + several data + parity blocks */
struct btrfs_r5l_io_unit {
struct btrfs_r5l_log *log;
struct btrfs_raid_bio *rbio;
+ struct list_head list;
+ int status;
+
/* store meta block */
struct page *meta_page;
--
2.9.4
--
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