Commit 364443cb authored by Jan Kara's avatar Jan Kara Committed by Theodore Ts'o
Browse files

ext4: convert DAX reads to iomap infrastructure 



Implement basic iomap_begin function that handles reading and use it for
DAX reads.

Reviewed-by: default avatarRoss Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent a3caa24b

fs/ext4/ext4.h

+2 −0
Original line number Diff line number Diff line
@@ -3266,6 +3266,8 @@ static inline bool ext4_aligned_io(struct inode *inode, loff_t off, loff_t len) 
	return IS_ALIGNED(off, blksize) && IS_ALIGNED(len, blksize);

}



extern struct iomap_ops ext4_iomap_ops;



#endif	/* __KERNEL__ */



#define EFSBADCRC	EBADMSG		/* Bad CRC detected */

fs/ext4/file.c

+37 −1
Original line number Diff line number Diff line
@@ -31,6 +31,42 @@ 
#include "xattr.h"

#include "acl.h"



#ifdef CONFIG_FS_DAX

static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)

{

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

	ssize_t ret;



	inode_lock_shared(inode);

	/*

	 * Recheck under inode lock - at this point we are sure it cannot

	 * change anymore

	 */

	if (!IS_DAX(inode)) {

		inode_unlock_shared(inode);

		/* Fallback to buffered IO in case we cannot support DAX */

		return generic_file_read_iter(iocb, to);

	}

	ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);

	inode_unlock_shared(inode);



	file_accessed(iocb->ki_filp);

	return ret;

}

#endif



static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)

{

	if (!iov_iter_count(to))

		return 0; /* skip atime */



#ifdef CONFIG_FS_DAX

	if (IS_DAX(file_inode(iocb->ki_filp)))

		return ext4_dax_read_iter(iocb, to);

#endif

	return generic_file_read_iter(iocb, to);

}



/*

 * Called when an inode is released. Note that this is different

 * from ext4_file_open: open gets called at every open, but release
@@ -690,7 +726,7 @@ loff_t ext4_llseek(struct file *file, loff_t offset, int whence) 


const struct file_operations ext4_file_operations = {

	.llseek		= ext4_llseek,

	.read_iter	= generic_file_read_iter,

	.read_iter	= ext4_file_read_iter,

	.write_iter	= ext4_file_write_iter,

	.unlocked_ioctl = ext4_ioctl,

#ifdef CONFIG_COMPAT

fs/ext4/inode.c

+54 −0
Original line number Diff line number Diff line
@@ -37,6 +37,7 @@ 
#include <linux/printk.h>

#include <linux/slab.h>

#include <linux/bitops.h>

#include <linux/iomap.h>



#include "ext4_jbd2.h"

#include "xattr.h"
@@ -3318,6 +3319,59 @@ int ext4_dax_get_block(struct inode *inode, sector_t iblock, 
	clear_buffer_new(bh_result);

	return 0;

}



static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,

			    unsigned flags, struct iomap *iomap)

{

	unsigned int blkbits = inode->i_blkbits;

	unsigned long first_block = offset >> blkbits;

	unsigned long last_block = (offset + length - 1) >> blkbits;

	struct ext4_map_blocks map;

	int ret;



	if (flags & IOMAP_WRITE)

		return -EIO;



	if (WARN_ON_ONCE(ext4_has_inline_data(inode)))

		return -ERANGE;



	map.m_lblk = first_block;

	map.m_len = last_block - first_block + 1;



	ret = ext4_map_blocks(NULL, inode, &map, 0);

	if (ret < 0)

		return ret;



	iomap->flags = 0;

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

	iomap->offset = first_block << blkbits;



	if (ret == 0) {

		iomap->type = IOMAP_HOLE;

		iomap->blkno = IOMAP_NULL_BLOCK;

		iomap->length = (u64)map.m_len << blkbits;

	} else {

		if (map.m_flags & EXT4_MAP_MAPPED) {

			iomap->type = IOMAP_MAPPED;

		} else if (map.m_flags & EXT4_MAP_UNWRITTEN) {

			iomap->type = IOMAP_UNWRITTEN;

		} else {

			WARN_ON_ONCE(1);

			return -EIO;

		}

		iomap->blkno = (sector_t)map.m_pblk << (blkbits - 9);

		iomap->length = (u64)map.m_len << blkbits;

	}



	if (map.m_flags & EXT4_MAP_NEW)

		iomap->flags |= IOMAP_F_NEW;

	return 0;

}



struct iomap_ops ext4_iomap_ops = {

	.iomap_begin		= ext4_iomap_begin,

};



#else

/* Just define empty function, it will never get called. */

int ext4_dax_get_block(struct inode *inode, sector_t iblock,