btrfs: simplify ->flush_bio handling

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

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220406061228.410163-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 126f244..cf9b5e2 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -4226,6 +4226,7 @@ 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);
 }
 
@@ -4235,7 +4236,7 @@ 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
        /*
@@ -4253,7 +4254,8 @@ 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;
@@ -4267,7 +4269,7 @@ 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 a8cc736..678504c 100644 (file)
--- 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);
 }
@@ -6949,16 +6948,6 @@ 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 bd297f2..628c9af 100644 (file)
--- 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 */