[PATCH 1/5] btrfs: simplify ->flush_bio handling

From: Christoph Hellwig
Date: Wed Apr 06 2022 - 05:29:54 EST


Use and embedded bios that is initialized when used instead of
bio_kmalloc plus bio_reset.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
---
fs/btrfs/disk-io.c | 8 +++++---
fs/btrfs/volumes.c | 11 -----------
fs/btrfs/volumes.h | 4 ++--
3 files changed, 7 insertions(+), 16 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index b30309f187cf0..51f4cdf6bcaea 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -4225,6 +4225,7 @@ static int wait_dev_supers(struct btrfs_device *device, int max_mirrors)
*/
static void btrfs_end_empty_barrier(struct bio *bio)
{
+ bio_uninit(bio);
complete(bio->bi_private);
}

@@ -4234,7 +4235,7 @@ static void btrfs_end_empty_barrier(struct bio *bio)
*/
static void write_dev_flush(struct btrfs_device *device)
{
- struct bio *bio = device->flush_bio;
+ struct bio *bio = &device->flush_bio;

#ifndef CONFIG_BTRFS_FS_CHECK_INTEGRITY
/*
@@ -4252,7 +4253,8 @@ static void write_dev_flush(struct btrfs_device *device)
return;
#endif

- bio_reset(bio, device->bdev, REQ_OP_WRITE | REQ_SYNC | REQ_PREFLUSH);
+ bio_init(bio, device->bdev, NULL, 0,
+ REQ_OP_WRITE | REQ_SYNC | REQ_PREFLUSH);
bio->bi_end_io = btrfs_end_empty_barrier;
init_completion(&device->flush_wait);
bio->bi_private = &device->flush_wait;
@@ -4266,7 +4268,7 @@ static void write_dev_flush(struct btrfs_device *device)
*/
static blk_status_t wait_dev_flush(struct btrfs_device *device)
{
- struct bio *bio = device->flush_bio;
+ struct bio *bio = &device->flush_bio;

if (!test_bit(BTRFS_DEV_STATE_FLUSH_SENT, &device->dev_state))
return BLK_STS_OK;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 1be7cb2f955fc..00517239b5c01 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -405,7 +405,6 @@ void btrfs_free_device(struct btrfs_device *device)
WARN_ON(!list_empty(&device->post_commit_list));
rcu_string_free(device->name);
extent_io_tree_release(&device->alloc_state);
- bio_put(device->flush_bio);
btrfs_destroy_dev_zone_info(device);
kfree(device);
}
@@ -6956,16 +6955,6 @@ struct btrfs_device *btrfs_alloc_device(struct btrfs_fs_info *fs_info,
if (!dev)
return ERR_PTR(-ENOMEM);

- /*
- * Preallocate a bio that's always going to be used for flushing device
- * barriers and matches the device lifespan
- */
- dev->flush_bio = bio_kmalloc(GFP_KERNEL, 0);
- if (!dev->flush_bio) {
- kfree(dev);
- return ERR_PTR(-ENOMEM);
- }
-
INIT_LIST_HEAD(&dev->dev_list);
INIT_LIST_HEAD(&dev->dev_alloc_list);
INIT_LIST_HEAD(&dev->post_commit_list);
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index bd297f23d19e7..628c9af894749 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -121,8 +121,8 @@ struct btrfs_device {
/* bytes used on the current transaction */
u64 commit_bytes_used;

- /* for sending down flush barriers */
- struct bio *flush_bio;
+ /* Bio used for flushing device barriers */
+ struct bio flush_bio;
struct completion flush_wait;

/* per-device scrub information */
--
2.30.2