From: Goldwyn Rodrigues <rgoldwyn@suse.com>

Use btrfs_bioset so iomap allocates btrfs_bio for bios to be submitted
for btrfs.

Set the file_offset of the bbio from the first folio in the bio.

For compressed/encoded reads, call btrfs_submit_compressed_read()
else call btrfs_submit_bbio()

After the read is complete, call iomap_read_end_io() to finish reads on
the folios.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
---
 fs/btrfs/bio.c       |  2 +-
 fs/btrfs/bio.h       |  1 +
 fs/btrfs/extent_io.c | 29 +++++++++++++++++++++++++++++
 3 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c
index 056f8a171bba..9d448235b8bd 100644
--- a/fs/btrfs/bio.c
+++ b/fs/btrfs/bio.c
@@ -15,7 +15,7 @@
 #include "file-item.h"
 #include "raid-stripe-tree.h"
 
-static struct bio_set btrfs_bioset;
+struct bio_set btrfs_bioset;
 static struct bio_set btrfs_clone_bioset;
 static struct bio_set btrfs_repair_bioset;
 static mempool_t btrfs_failed_bio_pool;
diff --git a/fs/btrfs/bio.h b/fs/btrfs/bio.h
index e48612340745..687a8361202a 100644
--- a/fs/btrfs/bio.h
+++ b/fs/btrfs/bio.h
@@ -15,6 +15,7 @@
 struct btrfs_bio;
 struct btrfs_fs_info;
 struct btrfs_inode;
+extern struct bio_set btrfs_bioset;
 
 #define BTRFS_BIO_INLINE_CSUM_SIZE	64
 
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 6ef2fa802c30..43418b6d4824 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -985,10 +985,39 @@ static int btrfs_read_iomap_begin(struct inode *inode, loff_t pos,
 	return 0;
 }
 
+static void btrfs_read_endio(struct btrfs_bio *bbio)
+{
+       iomap_read_end_io(&bbio->bio);
+}
+
+static void btrfs_read_submit_io(struct inode *inode, struct bio *bio,
+				 const struct iomap *iomap)
+{
+	struct btrfs_bio *bbio = btrfs_bio(bio);
+	struct folio_iter fi;
+
+	btrfs_bio_init(bbio, btrfs_sb(inode->i_sb), btrfs_read_endio, NULL);
+	bbio->inode = BTRFS_I(inode);
+
+	bio_first_folio(&fi, bio, 0);
+	bbio->file_offset = folio_pos(fi.folio);
+
+	if (iomap->type & IOMAP_ENCODED) {
+		bbio->bio.bi_iter.bi_sector = iomap->addr >> SECTOR_SHIFT;
+		btrfs_submit_compressed_read(bbio);
+	} else {
+		btrfs_submit_bbio(bbio, 0);
+	}
+}
+
 static const struct iomap_ops btrfs_buffered_read_iomap_ops = {
 	.iomap_begin = btrfs_read_iomap_begin,
 };
 
+static const struct iomap_read_folio_ops btrfs_iomap_read_folio_ops = {
+	.submit_io      = btrfs_read_submit_io,
+	.bio_set        = &btrfs_bioset,
+};
 
 /*
  * basic readpage implementation.  Locked extent state structs are inserted
-- 
2.46.1