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Subject[PATCH] btrfs: convert data_seqcount to seqcount_mutex_t
Date
By doing so we can associate the sequence counter to the chunk_mutex
for lockdep purposes (compiled-out otherwise) and also avoid
explicitly disabling preemption around the write region as it will now
be done automatically by the seqcount machinery based on the lock type.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
---
fs/btrfs/volumes.c | 2 +-
fs/btrfs/volumes.h | 10 ++++------
2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 58b9c419a2b6..b6ee92ddc624 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -431,7 +431,7 @@ static struct btrfs_device *__alloc_device(struct btrfs_fs_info *fs_info)

atomic_set(&dev->reada_in_flight, 0);
atomic_set(&dev->dev_stats_ccnt, 0);
- btrfs_device_data_ordered_init(dev);
+ btrfs_device_data_ordered_init(dev, fs_info);
INIT_RADIX_TREE(&dev->reada_zones, GFP_NOFS & ~__GFP_DIRECT_RECLAIM);
INIT_RADIX_TREE(&dev->reada_extents, GFP_NOFS & ~__GFP_DIRECT_RECLAIM);
extent_io_tree_init(fs_info, &dev->alloc_state,
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index bf27ac07d315..ff3ec11bb9d2 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -39,10 +39,10 @@ struct btrfs_io_geometry {
#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
#include <linux/seqlock.h>
#define __BTRFS_NEED_DEVICE_DATA_ORDERED
-#define btrfs_device_data_ordered_init(device) \
- seqcount_init(&device->data_seqcount)
+#define btrfs_device_data_ordered_init(device, info) \
+ seqcount_mutex_init(&device->data_seqcount, &info->chunk_mutex)
#else
-#define btrfs_device_data_ordered_init(device) do { } while (0)
+#define btrfs_device_data_ordered_init(device, info) do { } while (0)
#endif

#define BTRFS_DEV_STATE_WRITEABLE (0)
@@ -71,7 +71,7 @@ struct btrfs_device {
blk_status_t last_flush_error;

#ifdef __BTRFS_NEED_DEVICE_DATA_ORDERED
- seqcount_t data_seqcount;
+ seqcount_mutex_t data_seqcount;
#endif

/* the internal btrfs device id */
@@ -162,11 +162,9 @@ btrfs_device_get_##name(const struct btrfs_device *dev) \
static inline void \
btrfs_device_set_##name(struct btrfs_device *dev, u64 size) \
{ \
- preempt_disable(); \
write_seqcount_begin(&dev->data_seqcount); \
dev->name = size; \
write_seqcount_end(&dev->data_seqcount); \
- preempt_enable(); \
}
#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION)
#define BTRFS_DEVICE_GETSET_FUNCS(name) \
--
2.26.2
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