[PATCH 6/9] f2fs: implement iomap operations

[Eric Biggers <ebiggers@kernel.org>]

From: Eric Biggers <ebiggers@google.com>

Implement 'struct iomap_ops' and 'struct iomap_dio_ops' for f2fs, in
preparation for making f2fs use iomap for direct I/O.

Note that f2fs_iomap_ops may be used for other things besides direct I/O
in the future; however, for now I've only tested it for direct I/O.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/f2fs/Kconfig |  1 +
 fs/f2fs/data.c  | 95 +++++++++++++++++++++++++++++++++++++++++++++++--
 fs/f2fs/f2fs.h  |  2 ++
 3 files changed, 96 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/Kconfig b/fs/f2fs/Kconfig
index 7669de7b49ce..031fbb596450 100644
--- a/fs/f2fs/Kconfig
+++ b/fs/f2fs/Kconfig
@@ -7,6 +7,7 @@ config F2FS_FS
 	select CRYPTO_CRC32
 	select F2FS_FS_XATTR if FS_ENCRYPTION
 	select FS_ENCRYPTION_ALGS if FS_ENCRYPTION
+	select FS_IOMAP
 	select LZ4_COMPRESS if F2FS_FS_LZ4
 	select LZ4_DECOMPRESS if F2FS_FS_LZ4
 	select LZ4HC_COMPRESS if F2FS_FS_LZ4HC
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index cdadaa9daf55..9243159ee753 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -21,6 +21,7 @@
 #include <linux/cleancache.h>
 #include <linux/sched/signal.h>
 #include <linux/fiemap.h>
+#include <linux/iomap.h>
 
 #include "f2fs.h"
 #include "node.h"
@@ -3452,7 +3453,7 @@ static void f2fs_dio_end_io(struct bio *bio)
 	bio_endio(bio);
 }
 
-static void f2fs_dio_submit_bio(struct bio *bio, struct inode *inode,
+static void f2fs_dio_submit_bio_old(struct bio *bio, struct inode *inode,
 							loff_t file_offset)
 {
 	struct f2fs_private_dio *dio;
@@ -3481,6 +3482,35 @@ static void f2fs_dio_submit_bio(struct bio *bio, struct inode *inode,
 	bio_endio(bio);
 }
 
+static blk_qc_t f2fs_dio_submit_bio(struct inode *inode, struct iomap *iomap,
+				    struct bio *bio, loff_t file_offset)
+{
+	struct f2fs_private_dio *dio;
+	bool write = (bio_op(bio) == REQ_OP_WRITE);
+
+	dio = f2fs_kzalloc(F2FS_I_SB(inode),
+			sizeof(struct f2fs_private_dio), GFP_NOFS);
+	if (!dio)
+		goto out;
+
+	dio->inode = inode;
+	dio->orig_end_io = bio->bi_end_io;
+	dio->orig_private = bio->bi_private;
+	dio->write = write;
+
+	bio->bi_end_io = f2fs_dio_end_io;
+	bio->bi_private = dio;
+
+	inc_page_count(F2FS_I_SB(inode),
+			write ? F2FS_DIO_WRITE : F2FS_DIO_READ);
+
+	return submit_bio(bio);
+out:
+	bio->bi_status = BLK_STS_IOERR;
+	bio_endio(bio);
+	return BLK_QC_T_NONE;
+}
+
 static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 {
 	struct address_space *mapping = iocb->ki_filp->f_mapping;
@@ -3529,7 +3559,7 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 
 	err = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev,
 			iter, rw == WRITE ? get_data_block_dio_write :
-			get_data_block_dio, NULL, f2fs_dio_submit_bio,
+			get_data_block_dio, NULL, f2fs_dio_submit_bio_old,
 			rw == WRITE ? DIO_LOCKING | DIO_SKIP_HOLES :
 			DIO_SKIP_HOLES);
 
@@ -4101,3 +4131,64 @@ void f2fs_destroy_bio_entry_cache(void)
 {
 	kmem_cache_destroy(bio_entry_slab);
 }
+
+static int f2fs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
+			    unsigned int flags, struct iomap *iomap,
+			    struct iomap *srcmap)
+{
+	struct f2fs_map_blocks map = {};
+	pgoff_t next_pgofs = 0;
+	int err;
+
+	map.m_lblk = bytes_to_blks(inode, offset);
+	map.m_len = bytes_to_blks(inode, offset + length - 1) - map.m_lblk + 1;
+	map.m_next_pgofs = &next_pgofs;
+	map.m_seg_type = f2fs_rw_hint_to_seg_type(inode->i_write_hint);
+	if (flags & IOMAP_WRITE)
+		map.m_may_create = true;
+
+	err = f2fs_map_blocks(inode, &map, flags & IOMAP_WRITE,
+			      F2FS_GET_BLOCK_DIO);
+	if (err)
+		return err;
+
+	iomap->offset = blks_to_bytes(inode, map.m_lblk);
+
+	if (map.m_flags & (F2FS_MAP_MAPPED | F2FS_MAP_UNWRITTEN)) {
+		iomap->length = blks_to_bytes(inode, map.m_len);
+		if (map.m_flags & F2FS_MAP_MAPPED) {
+			iomap->type = IOMAP_MAPPED;
+			iomap->flags |= IOMAP_F_MERGED;
+		} else {
+			iomap->type = IOMAP_UNWRITTEN;
+		}
+		if (WARN_ON_ONCE(!__is_valid_data_blkaddr(map.m_pblk)))
+			return -EINVAL;
+		iomap->addr = blks_to_bytes(inode, map.m_pblk);
+
+		if (WARN_ON_ONCE(f2fs_is_multi_device(F2FS_I_SB(inode))))
+			return -EINVAL;
+		iomap->bdev = inode->i_sb->s_bdev;
+	} else {
+		iomap->length = blks_to_bytes(inode, next_pgofs) -
+				iomap->offset;
+		iomap->type = IOMAP_HOLE;
+		iomap->addr = IOMAP_NULL_ADDR;
+	}
+
+	if (map.m_flags & F2FS_MAP_NEW)
+		iomap->flags |= IOMAP_F_NEW;
+	if ((inode->i_state & I_DIRTY_DATASYNC) ||
+	    offset + length > i_size_read(inode))
+		iomap->flags |= IOMAP_F_DIRTY;
+
+	return 0;
+}
+
+const struct iomap_ops f2fs_iomap_ops = {
+	.iomap_begin	= f2fs_iomap_begin,
+};
+
+const struct iomap_dio_ops f2fs_iomap_dio_ops = {
+	.submit_io	= f2fs_dio_submit_bio,
+};
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index da1da3111f18..d2b1ef6976c4 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -3639,6 +3639,8 @@ int f2fs_init_post_read_processing(void);
 void f2fs_destroy_post_read_processing(void);
 int f2fs_init_post_read_wq(struct f2fs_sb_info *sbi);
 void f2fs_destroy_post_read_wq(struct f2fs_sb_info *sbi);
+extern const struct iomap_ops f2fs_iomap_ops;
+extern const struct iomap_dio_ops f2fs_iomap_dio_ops;
 
 /*
  * gc.c
-- 
2.32.0