Commit a08e67a0 authored by Huang Jianan's avatar Huang Jianan Committed by Gao Xiang
Browse files

erofs: iomap support for non-tailpacking DIO 

Add iomap support for non-tailpacking uncompressed data in order to
support DIO and DAX.

Direct I/O is useful in certain scenarios for uncompressed files.
For example, double pagecache can be avoid by direct I/O when
loop device is used for uncompressed files containing upper layer
compressed filesystem.

This adds iomap DIO support for non-tailpacking cases first and
tail-packing inline files are handled in the follow-up patch.

Link: https://lore.kernel.org/r/20210805003601.183063-2-hsiangkao@linux.alibaba.com


Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: default avatarChao Yu <chao@kernel.org>
Signed-off-by: default avatarHuang Jianan <huangjianan@oppo.com>
Signed-off-by: default avatarGao Xiang <hsiangkao@linux.alibaba.com>
parent c500bee1

fs/erofs/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -3,6 +3,7 @@ 
config EROFS_FS

	tristate "EROFS filesystem support"

	depends on BLOCK

	select FS_IOMAP

	select LIBCRC32C

	help

	  EROFS (Enhanced Read-Only File System) is a lightweight

fs/erofs/data.c

+94 −0
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
 */

#include "internal.h"

#include <linux/prefetch.h>

#include <linux/iomap.h>



#include <trace/events/erofs.h>
@@ -308,9 +309,102 @@ static sector_t erofs_bmap(struct address_space *mapping, sector_t block) 
	return 0;

}



static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,

		unsigned int flags, struct iomap *iomap, struct iomap *srcmap)

{

	int ret;

	struct erofs_map_blocks map;



	map.m_la = offset;

	map.m_llen = length;



	ret = erofs_map_blocks_flatmode(inode, &map, EROFS_GET_BLOCKS_RAW);

	if (ret < 0)

		return ret;



	iomap->bdev = inode->i_sb->s_bdev;

	iomap->offset = map.m_la;

	iomap->length = map.m_llen;

	iomap->flags = 0;



	if (!(map.m_flags & EROFS_MAP_MAPPED)) {

		iomap->type = IOMAP_HOLE;

		iomap->addr = IOMAP_NULL_ADDR;

		if (!iomap->length)

			iomap->length = length;

		return 0;

	}



	/* that shouldn't happen for now */

	if (map.m_flags & EROFS_MAP_META) {

		DBG_BUGON(1);

		return -ENOTBLK;

	}

	iomap->type = IOMAP_MAPPED;

	iomap->addr = map.m_pa;

	return 0;

}



static const struct iomap_ops erofs_iomap_ops = {

	.iomap_begin = erofs_iomap_begin,

};



static int erofs_prepare_dio(struct kiocb *iocb, struct iov_iter *to)

{

	struct inode *inode = file_inode(iocb->ki_filp);

	loff_t align = iocb->ki_pos | iov_iter_count(to) |

		iov_iter_alignment(to);

	struct block_device *bdev = inode->i_sb->s_bdev;

	unsigned int blksize_mask;



	if (bdev)

		blksize_mask = (1 << ilog2(bdev_logical_block_size(bdev))) - 1;

	else

		blksize_mask = (1 << inode->i_blkbits) - 1;



	if (align & blksize_mask)

		return -EINVAL;



	/*

	 * Temporarily fall back tail-packing inline to buffered I/O instead

	 * since tail-packing inline support relies on an iomap core update.

	 */

	if (EROFS_I(inode)->datalayout == EROFS_INODE_FLAT_INLINE &&

	    iocb->ki_pos + iov_iter_count(to) >

			rounddown(inode->i_size, EROFS_BLKSIZ))

		return 1;

	return 0;

}



static ssize_t erofs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)

{

	/* no need taking (shared) inode lock since it's a ro filesystem */

	if (!iov_iter_count(to))

		return 0;



	if (iocb->ki_flags & IOCB_DIRECT) {

		int err = erofs_prepare_dio(iocb, to);



		if (!err)

			return iomap_dio_rw(iocb, to, &erofs_iomap_ops,

					    NULL, 0);

		if (err < 0)

			return err;

	}

	return filemap_read(iocb, to, 0);

}



/* for uncompressed (aligned) files and raw access for other files */

const struct address_space_operations erofs_raw_access_aops = {

	.readpage = erofs_raw_access_readpage,

	.readahead = erofs_raw_access_readahead,

	.bmap = erofs_bmap,

	.direct_IO = noop_direct_IO,

};



const struct file_operations erofs_file_fops = {

	.llseek		= generic_file_llseek,

	.read_iter	= erofs_file_read_iter,

	.mmap		= generic_file_readonly_mmap,

	.splice_read	= generic_file_splice_read,

};

fs/erofs/inode.c

+4 −1
Original line number Diff line number Diff line
@@ -247,7 +247,10 @@ static int erofs_fill_inode(struct inode *inode, int isdir) 
	switch (inode->i_mode & S_IFMT) {

	case S_IFREG:

		inode->i_op = &erofs_generic_iops;

		if (erofs_inode_is_data_compressed(vi->datalayout))

			inode->i_fop = &generic_ro_fops;

		else

			inode->i_fop = &erofs_file_fops;

		break;

	case S_IFDIR:

		inode->i_op = &erofs_dir_iops;

fs/erofs/internal.h

+1 −0
Original line number Diff line number Diff line
@@ -371,6 +371,7 @@ static inline int z_erofs_map_blocks_iter(struct inode *inode, 
#endif	/* !CONFIG_EROFS_FS_ZIP */



/* data.c */

extern const struct file_operations erofs_file_fops;

struct page *erofs_get_meta_page(struct super_block *sb, erofs_blk_t blkaddr);



/* inode.c */