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: Chao Yu <chao@kernel.org>
Signed-off-by: Huang Jianan <huangjianan@oppo.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
This commit is contained in:
Huang Jianan 2021-08-05 08:35:59 +08:00 committed by Gao Xiang
parent c500bee1c5
commit a08e67a028
4 changed files with 100 additions and 1 deletions

View File

@ -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

View File

@ -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,
};

View File

@ -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;
inode->i_fop = &generic_ro_fops;
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;

View File

@ -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 */