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ext4: convert DAX reads to iomap infrastructure

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

Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Jan Kara 2016-11-20 17:36:06 -05:00 committed by Theodore Ts'o
parent a3caa24b70
commit 364443cbcf
3 changed files with 93 additions and 1 deletions
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2
fs/ext4/ext4.h
View File

@ -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 */

38
fs/ext4/file.c
View File

@ -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

54
fs/ext4/inode.c
View File

@ -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,