Commit 925c86a1 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

fs: add CONFIG_BUFFER_HEAD 



Add a new config option that controls building the buffer_head code, and
select it from all file systems and stacking drivers that need it.

For the block device nodes and alternative iomap based buffered I/O path
is provided when buffer_head support is not enabled, and iomap needs a
a small tweak to define the IOMAP_F_BUFFER_HEAD flag to 0 to not call
into the buffer_head code when it doesn't exist.

Otherwise this is just Kconfig and ifdef changes.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
Reviewed-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20230801172201.1923299-7-hch@lst.de


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 487c607d

block/fops.c

+60 −10
Original line number Diff line number Diff line
@@ -24,15 +24,6 @@ static inline struct inode *bdev_file_inode(struct file *file) 
	return file->f_mapping->host;

}



static int blkdev_get_block(struct inode *inode, sector_t iblock,

		struct buffer_head *bh, int create)

{

	bh->b_bdev = I_BDEV(inode);

	bh->b_blocknr = iblock;

	set_buffer_mapped(bh);

	return 0;

}



static blk_opf_t dio_bio_write_op(struct kiocb *iocb)

{

	blk_opf_t opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
@@ -400,7 +391,7 @@ static int blkdev_iomap_begin(struct inode *inode, loff_t offset, loff_t length, 
	iomap->type = IOMAP_MAPPED;

	iomap->addr = iomap->offset;

	iomap->length = isize - iomap->offset;

	iomap->flags |= IOMAP_F_BUFFER_HEAD;

	iomap->flags |= IOMAP_F_BUFFER_HEAD; /* noop for !CONFIG_BUFFER_HEAD */

	return 0;

}
@@ -408,6 +399,16 @@ static const struct iomap_ops blkdev_iomap_ops = { 
	.iomap_begin		= blkdev_iomap_begin,

};



#ifdef CONFIG_BUFFER_HEAD

static int blkdev_get_block(struct inode *inode, sector_t iblock,

		struct buffer_head *bh, int create)

{

	bh->b_bdev = I_BDEV(inode);

	bh->b_blocknr = iblock;

	set_buffer_mapped(bh);

	return 0;

}



static int blkdev_writepage(struct page *page, struct writeback_control *wbc)

{

	return block_write_full_page(page, blkdev_get_block, wbc);
@@ -453,6 +454,55 @@ const struct address_space_operations def_blk_aops = { 
	.migrate_folio	= buffer_migrate_folio_norefs,

	.is_dirty_writeback = buffer_check_dirty_writeback,

};

#else /* CONFIG_BUFFER_HEAD */

static int blkdev_read_folio(struct file *file, struct folio *folio)

{

	return iomap_read_folio(folio, &blkdev_iomap_ops);

}



static void blkdev_readahead(struct readahead_control *rac)

{

	iomap_readahead(rac, &blkdev_iomap_ops);

}



static int blkdev_map_blocks(struct iomap_writepage_ctx *wpc,

		struct inode *inode, loff_t offset)

{

	loff_t isize = i_size_read(inode);



	if (WARN_ON_ONCE(offset >= isize))

		return -EIO;

	if (offset >= wpc->iomap.offset &&

	    offset < wpc->iomap.offset + wpc->iomap.length)

		return 0;

	return blkdev_iomap_begin(inode, offset, isize - offset,

				  IOMAP_WRITE, &wpc->iomap, NULL);

}



static const struct iomap_writeback_ops blkdev_writeback_ops = {

	.map_blocks		= blkdev_map_blocks,

};



static int blkdev_writepages(struct address_space *mapping,

		struct writeback_control *wbc)

{

	struct iomap_writepage_ctx wpc = { };



	return iomap_writepages(mapping, wbc, &wpc, &blkdev_writeback_ops);

}



const struct address_space_operations def_blk_aops = {

	.dirty_folio	= filemap_dirty_folio,

	.release_folio		= iomap_release_folio,

	.invalidate_folio	= iomap_invalidate_folio,

	.read_folio		= blkdev_read_folio,

	.readahead		= blkdev_readahead,

	.writepages		= blkdev_writepages,

	.is_partially_uptodate  = iomap_is_partially_uptodate,

	.error_remove_page	= generic_error_remove_page,

	.migrate_folio		= filemap_migrate_folio,

};

#endif /* CONFIG_BUFFER_HEAD */



/*

 * for a block special file file_inode(file)->i_size is zero

drivers/md/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ if MD 
config BLK_DEV_MD

	tristate "RAID support"

	select BLOCK_HOLDER_DEPRECATED if SYSFS

	select BUFFER_HEAD

	# BLOCK_LEGACY_AUTOLOAD requirement should be removed

	# after relevant mdadm enhancements - to make "names=yes"

	# the default - are widely available.

fs/Kconfig

+4 −0
Original line number Diff line number Diff line
@@ -18,8 +18,12 @@ config VALIDATE_FS_PARSER 
config FS_IOMAP

	bool



config BUFFER_HEAD

	bool



# old blockdev_direct_IO implementation.  Use iomap for new code instead

config LEGACY_DIRECT_IO

	depends on BUFFER_HEAD

	bool



if BLOCK

fs/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -17,7 +17,7 @@ obj-y := open.o read_write.o file_table.o super.o \ 
		fs_types.o fs_context.o fs_parser.o fsopen.o init.o \

		kernel_read_file.o mnt_idmapping.o remap_range.o



obj-$(CONFIG_BLOCK)		+= buffer.o mpage.o

obj-$(CONFIG_BUFFER_HEAD)	+= buffer.o mpage.o

obj-$(CONFIG_PROC_FS)		+= proc_namespace.o

obj-$(CONFIG_LEGACY_DIRECT_IO)	+= direct-io.o

obj-y				+= notify/

fs/adfs/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
config ADFS_FS

	tristate "ADFS file system support"

	depends on BLOCK

	select BUFFER_HEAD

	help

	  The Acorn Disc Filing System is the standard file system of the

	  RiscOS operating system which runs on Acorn's ARM-based Risc PC