btrfs: introduce btrfs_bio::fs_info member

Currently we're doing a lot of work for btrfs_bio:

- Checksum verification for data read bios
- Bio splits if it crosses stripe boundary
- Read repair for data read bios

However for the incoming scrub patches, we don't want this extra
functionality at all, just plain logical + mirror -> physical mapping
ability.

Thus here we do the following changes:

- Introduce btrfs_bio::fs_info
  This is for the new scrub specific btrfs_bio, which would not populate
  btrfs_bio::inode.
  Thus we need such new member to grab a fs_info

  This new member will always be populated.

- Replace @inode argument with @fs_info for btrfs_bio_init() and its
  caller
  Since @inode is no longer a mandatory member, replace it with
  @fs_info, and let involved users populate @inode.

- Skip checksum verification and generation if @bbio->inode is NULL

- Add extra ASSERT()s
  To make sure:

  * bbio->inode is properly set for involved read repair path
  * if @file_offset is set, bbio->inode is also populated

- Grab @fs_info from @bbio directly
  We can no longer go @bbio->inode->root->fs_info, as bbio->inode can be
  NULL. This involves:

  * btrfs_simple_end_io()
  * should_async_write()
  * btrfs_wq_submit_bio()
  * btrfs_use_zone_append()

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 9 insertions, 4 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 93e16a408f43..57d070025c7a 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -7711,7 +7711,9 @@ static void btrfs_dio_submit_io(const struct iomap_iter *iter, struct bio *bio,
 		container_of(bbio, struct btrfs_dio_private, bbio);
 	struct btrfs_dio_data *dio_data = iter->private;
 
-	btrfs_bio_init(bbio, BTRFS_I(iter->inode), btrfs_dio_end_io, bio->bi_private);
+	btrfs_bio_init(bbio, BTRFS_I(iter->inode)->root->fs_info,
+		       btrfs_dio_end_io, bio->bi_private);
+	bbio->inode = BTRFS_I(iter->inode);
 	bbio->file_offset = file_offset;
 
 	dip->file_offset = file_offset;
@@ -9899,6 +9901,7 @@ int btrfs_encoded_read_regular_fill_pages(struct btrfs_inode *inode,
 					  u64 file_offset, u64 disk_bytenr,
 					  u64 disk_io_size, struct page **pages)
 {
+	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 	struct btrfs_encoded_read_private priv = {
 		.pending = ATOMIC_INIT(1),
 	};
@@ -9907,9 +9910,10 @@ int btrfs_encoded_read_regular_fill_pages(struct btrfs_inode *inode,
 
 	init_waitqueue_head(&priv.wait);
 
-	bbio = btrfs_bio_alloc(BIO_MAX_VECS, REQ_OP_READ, inode,
-			      btrfs_encoded_read_endio, &priv);
+	bbio = btrfs_bio_alloc(BIO_MAX_VECS, REQ_OP_READ, fs_info,
+			       btrfs_encoded_read_endio, &priv);
 	bbio->bio.bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT;
+	bbio->inode = inode;
 
 	do {
 		size_t bytes = min_t(u64, disk_io_size, PAGE_SIZE);
@@ -9918,9 +9922,10 @@ int btrfs_encoded_read_regular_fill_pages(struct btrfs_inode *inode,
 			atomic_inc(&priv.pending);
 			btrfs_submit_bio(bbio, 0);
 
-			bbio = btrfs_bio_alloc(BIO_MAX_VECS, REQ_OP_READ, inode,
+			bbio = btrfs_bio_alloc(BIO_MAX_VECS, REQ_OP_READ, fs_info,
 					       btrfs_encoded_read_endio, &priv);
 			bbio->bio.bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT;
+			bbio->inode = inode;
 			continue;
 		}