From a08e67a0280215f74eccf14fda81dd7fed6596ba Mon Sep 17 00:00:00 2001 From: Huang Jianan Date: Thu, 5 Aug 2021 08:35:59 +0800 Subject: [PATCH] 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 Signed-off-by: Huang Jianan Signed-off-by: Gao Xiang --- fs/erofs/Kconfig | 1 + fs/erofs/data.c | 94 +++++++++++++++++++++++++++++++++++++++++++++ fs/erofs/inode.c | 5 ++- fs/erofs/internal.h | 1 + 4 files changed, 100 insertions(+), 1 deletion(-) diff --git a/fs/erofs/Kconfig b/fs/erofs/Kconfig index 906af0c1998c..14b747026742 100644 --- a/fs/erofs/Kconfig +++ b/fs/erofs/Kconfig @@ -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 diff --git a/fs/erofs/data.c b/fs/erofs/data.c index 3787a5fb0a42..4158572c9e1e 100644 --- a/fs/erofs/data.c +++ b/fs/erofs/data.c @@ -5,6 +5,7 @@ */ #include "internal.h" #include +#include #include @@ -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, }; diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c index aa8a0d770ba3..f296e1a2661e 100644 --- a/fs/erofs/inode.c +++ b/fs/erofs/inode.c @@ -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; diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h index 543c2ff97d30..2669c785d548 100644 --- a/fs/erofs/internal.h +++ b/fs/erofs/internal.h @@ -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 */