On Thu, Aug 29, 2024 at 8:29 PM Gao Xiang <hsiang...@linux.alibaba.com> wrote:
>
> Since EROFS only needs to handle read requests in simple contexts,
> Just directly use vfs_iocb_iter_read() for data I/Os.
>
> Signed-off-by: Gao Xiang <hsiang...@linux.alibaba.com>
> ---
> v2:
> - fix redundant refcount which cause hanging on chunked inodes.
>
> fs/erofs/Makefile | 1 +
> fs/erofs/data.c | 50 +++++++++++-
> fs/erofs/fileio.c | 181 ++++++++++++++++++++++++++++++++++++++++++++
> fs/erofs/inode.c | 17 +++--
> fs/erofs/internal.h | 7 +-
> fs/erofs/zdata.c | 46 ++---------
> 6 files changed, 251 insertions(+), 51 deletions(-)
> create mode 100644 fs/erofs/fileio.c
>
> diff --git a/fs/erofs/Makefile b/fs/erofs/Makefile
> index 097d672e6b14..4331d53c7109 100644
> --- a/fs/erofs/Makefile
> +++ b/fs/erofs/Makefile
> @@ -7,4 +7,5 @@ erofs-$(CONFIG_EROFS_FS_ZIP) += decompressor.o zmap.o zdata.o
> zutil.o
> erofs-$(CONFIG_EROFS_FS_ZIP_LZMA) += decompressor_lzma.o
> erofs-$(CONFIG_EROFS_FS_ZIP_DEFLATE) += decompressor_deflate.o
> erofs-$(CONFIG_EROFS_FS_ZIP_ZSTD) += decompressor_zstd.o
> +erofs-$(CONFIG_EROFS_FS_BACKED_BY_FILE) += fileio.o
> erofs-$(CONFIG_EROFS_FS_ONDEMAND) += fscache.o
> diff --git a/fs/erofs/data.c b/fs/erofs/data.c
> index 0fb31c588ae0..b4c07ce7a294 100644
> --- a/fs/erofs/data.c
> +++ b/fs/erofs/data.c
> @@ -132,7 +132,7 @@ int erofs_map_blocks(struct inode *inode, struct
> erofs_map_blocks *map)
> if (map->m_la >= inode->i_size) {
> /* leave out-of-bound access unmapped */
> map->m_flags = 0;
> - map->m_plen = 0;
> + map->m_plen = map->m_llen;
> goto out;
> }
>
> @@ -197,8 +197,13 @@ static void erofs_fill_from_devinfo(struct erofs_map_dev
> *map,
> struct erofs_device_info *dif)
> {
> map->m_bdev = NULL;
> - if (dif->file && S_ISBLK(file_inode(dif->file)->i_mode))
> - map->m_bdev = file_bdev(dif->file);
> + map->m_fp = NULL;
> + if (dif->file) {
> + if (S_ISBLK(file_inode(dif->file)->i_mode))
> + map->m_bdev = file_bdev(dif->file);
> + else
> + map->m_fp = dif->file;
> + }
> map->m_daxdev = dif->dax_dev;
> map->m_dax_part_off = dif->dax_part_off;
> map->m_fscache = dif->fscache;
> @@ -215,6 +220,7 @@ int erofs_map_dev(struct super_block *sb, struct
> erofs_map_dev *map)
> map->m_daxdev = EROFS_SB(sb)->dax_dev;
> map->m_dax_part_off = EROFS_SB(sb)->dax_part_off;
> map->m_fscache = EROFS_SB(sb)->s_fscache;
> + map->m_fp = EROFS_SB(sb)->fdev;
>
> if (map->m_deviceid) {
> down_read(&devs->rwsem);
> @@ -250,6 +256,42 @@ int erofs_map_dev(struct super_block *sb, struct
> erofs_map_dev *map)
> return 0;
> }
>
> +/*
> + * bit 30: I/O error occurred on this folio
> + * bit 0 - 29: remaining parts to complete this folio
> + */
> +#define EROFS_ONLINEFOLIO_EIO (1 << 30)
> +
> +void erofs_onlinefolio_init(struct folio *folio)
> +{
> + union {
> + atomic_t o;
> + void *v;
> + } u = { .o = ATOMIC_INIT(1) };
> +
> + folio->private = u.v; /* valid only if file-backed folio is locked
> */
> +}
> +
> +void erofs_onlinefolio_split(struct folio *folio)
> +{
> + atomic_inc((atomic_t *)&folio->private);
> +}
> +
> +void erofs_onlinefolio_end(struct folio *folio, int err)
> +{
> + int orig, v;
> +
> + do {
> + orig = atomic_read((atomic_t *)&folio->private);
> + v = (orig - 1) | (err ? EROFS_ONLINEFOLIO_EIO : 0);
> + } while (atomic_cmpxchg((atomic_t *)&folio->private, orig, v) !=
> orig);
> +
> + if (v & ~EROFS_ONLINEFOLIO_EIO)
> + return;
> + folio->private = 0;
> + folio_end_read(folio, !(v & EROFS_ONLINEFOLIO_EIO));
> +}
> +
> static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t
> length,
> unsigned int flags, struct iomap *iomap, struct iomap *srcmap)
> {
> @@ -399,7 +441,7 @@ static ssize_t erofs_file_read_iter(struct kiocb *iocb,
> struct iov_iter *to)
> }
>
> /* for uncompressed (aligned) files and raw access for other files */
> -const struct address_space_operations erofs_raw_access_aops = {
> +const struct address_space_operations erofs_aops = {
> .read_folio = erofs_read_folio,
> .readahead = erofs_readahead,
> .bmap = erofs_bmap,
> diff --git a/fs/erofs/fileio.c b/fs/erofs/fileio.c
> new file mode 100644
> index 000000000000..eab52b8abd0b
> --- /dev/null
> +++ b/fs/erofs/fileio.c
> @@ -0,0 +1,181 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (C) 2024, Alibaba Cloud
> + */
> +#include "internal.h"
> +#include <trace/events/erofs.h>
> +
> +struct erofs_fileio_rq {
> + struct bio_vec bvecs[BIO_MAX_VECS];
> + struct bio bio;
> + struct kiocb iocb;
> +};
> +
> +struct erofs_fileio {
> + struct erofs_map_blocks map;
> + struct erofs_map_dev dev;
> + struct erofs_fileio_rq *rq;
> +};
> +
> +static void erofs_fileio_ki_complete(struct kiocb *iocb, long ret)
> +{
> + struct erofs_fileio_rq *rq =
> + container_of(iocb, struct erofs_fileio_rq, iocb);
> + struct folio_iter fi;
> +
> + DBG_BUGON(rq->bio.bi_end_io);
> + if (ret > 0) {
> + if (ret != rq->bio.bi_iter.bi_size) {
> + bio_advance(&rq->bio, ret);
> + zero_fill_bio(&rq->bio);
> + }
> + ret = 0;
> + }
> + bio_for_each_folio_all(fi, &rq->bio) {
> + DBG_BUGON(folio_test_uptodate(fi.folio));
> + erofs_onlinefolio_end(fi.folio, ret);
> + }
> + kfree(rq);
> +}
> +
> +static void erofs_fileio_rq_submit(struct erofs_fileio_rq *rq)
> +{
> + struct iov_iter iter;
> + int ret;
> +
> + if (!rq)
> + return;
> + rq->iocb.ki_pos = rq->bio.bi_iter.bi_sector << 9;
> + rq->iocb.ki_ioprio = get_current_ioprio();
> + rq->iocb.ki_complete = erofs_fileio_ki_complete;
> + rq->iocb.ki_flags = (rq->iocb.ki_filp->f_mode & FMODE_CAN_ODIRECT) ?
> + IOCB_DIRECT : 0;
Hi Gao,
Does this mean, direct IO by default if the backing file supports it
(technically filesystem where image/backing file reside)?
Thanks,
Sandeep.
> + iov_iter_bvec(&iter, ITER_DEST, rq->bvecs, rq->bio.bi_vcnt,
> + rq->bio.bi_iter.bi_size);
> + ret = vfs_iocb_iter_read(rq->iocb.ki_filp, &rq->iocb, &iter);
> + if (ret != -EIOCBQUEUED)
> + erofs_fileio_ki_complete(&rq->iocb, ret);
> +}
> +
> +static struct erofs_fileio_rq *erofs_fileio_rq_alloc(struct erofs_map_dev
> *mdev)
> +{
> + struct erofs_fileio_rq *rq = kzalloc(sizeof(*rq), GFP_KERNEL);
> +
> + if (!rq)
> + return NULL;
> + bio_init(&rq->bio, NULL, rq->bvecs, BIO_MAX_VECS, REQ_OP_READ);
> + rq->iocb.ki_filp = mdev->m_fp;
> + return rq;
> +}
> +
> +static int erofs_fileio_scan_folio(struct erofs_fileio *io, struct folio
> *folio)
> +{
> + struct inode *inode = folio_inode(folio);
> + struct erofs_map_blocks *map = &io->map;
> + unsigned int cur = 0, end = folio_size(folio), len, attached = 0;
> + loff_t pos = folio_pos(folio), ofs;
> + struct iov_iter iter;
> + struct bio_vec bv;
> + int err = 0;
> +
> + erofs_onlinefolio_init(folio);
> + while (cur < end) {
> + if (!in_range(pos + cur, map->m_la, map->m_llen)) {
> + map->m_la = pos + cur;
> + map->m_llen = end - cur;
> + err = erofs_map_blocks(inode, map);
> + if (err)
> + break;
> + }
> +
> + ofs = folio_pos(folio) + cur - map->m_la;
> + len = min_t(loff_t, map->m_llen - ofs, end - cur);
> + if (map->m_flags & EROFS_MAP_META) {
> + struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
> + void *src;
> +
> + src = erofs_read_metabuf(&buf, inode->i_sb,
> + map->m_pa + ofs, EROFS_KMAP);
> + if (IS_ERR(src)) {
> + err = PTR_ERR(src);
> + break;
> + }
> + bvec_set_folio(&bv, folio, len, cur);
> + iov_iter_bvec(&iter, ITER_DEST, &bv, 1, len);
> + if (copy_to_iter(src, len, &iter) != len) {
> + erofs_put_metabuf(&buf);
> + err = -EIO;
> + break;
> + }
> + erofs_put_metabuf(&buf);
> + } else if (!(map->m_flags & EROFS_MAP_MAPPED)) {
> + folio_zero_segment(folio, cur, cur + len);
> + } else {
> + if (io->rq && (map->m_pa + ofs != io->dev.m_pa ||
> + map->m_deviceid !=
> io->dev.m_deviceid)) {
> +io_retry:
> + erofs_fileio_rq_submit(io->rq);
> + io->rq = NULL;
> + }
> +
> + if (!io->rq) {
> + io->dev = (struct erofs_map_dev) {
> + .m_pa = io->map.m_pa + ofs,
> + .m_deviceid = io->map.m_deviceid,
> + };
> + err = erofs_map_dev(inode->i_sb, &io->dev);
> + if (err)
> + break;
> + io->rq = erofs_fileio_rq_alloc(&io->dev);
> + if (!io->rq) {
> + err = -ENOMEM;
> + break;
> + }
> + io->rq->bio.bi_iter.bi_sector = io->dev.m_pa
> >> 9;
> + attached = 0;
> + }
> + if (!attached++)
> + erofs_onlinefolio_split(folio);
> + if (!bio_add_folio(&io->rq->bio, folio, len, cur))
> + goto io_retry;
> + io->dev.m_pa += len;
> + }
> + cur += len;
> + }
> + erofs_onlinefolio_end(folio, err);
> + return err;
> +}
> +
> +static int erofs_fileio_read_folio(struct file *file, struct folio *folio)
> +{
> + struct erofs_fileio io = {};
> + int err;
> +
> + trace_erofs_read_folio(folio, false);
> + err = erofs_fileio_scan_folio(&io, folio);
> + erofs_fileio_rq_submit(io.rq);
> + return err;
> +}
> +
> +static void erofs_fileio_readahead(struct readahead_control *rac)
> +{
> + struct inode *inode = rac->mapping->host;
> + struct erofs_fileio io = {};
> + struct folio *folio;
> + int err;
> +
> + trace_erofs_readpages(inode, readahead_index(rac),
> + readahead_count(rac), false);
> + while ((folio = readahead_folio(rac))) {
> + err = erofs_fileio_scan_folio(&io, folio);
> + if (err && err != -EINTR)
> + erofs_err(inode->i_sb, "readahead error at folio %lu
> @ nid %llu",
> + folio->index, EROFS_I(inode)->nid);
> + }
> + erofs_fileio_rq_submit(io.rq);
> +}
> +
> +const struct address_space_operations erofs_fileio_aops = {
> + .read_folio = erofs_fileio_read_folio,
> + .readahead = erofs_fileio_readahead,
> +};
> diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
> index d05b9e59f122..4a902e6e69a5 100644
> --- a/fs/erofs/inode.c
> +++ b/fs/erofs/inode.c
> @@ -258,11 +258,14 @@ static int erofs_fill_inode(struct inode *inode)
> }
>
> mapping_set_large_folios(inode->i_mapping);
> - if (erofs_is_fileio_mode(EROFS_SB(inode->i_sb))) {
> - /* XXX: data I/Os will be implemented in the following
> patches */
> - err = -EOPNOTSUPP;
> - } else if (erofs_inode_is_data_compressed(vi->datalayout)) {
> + if (erofs_inode_is_data_compressed(vi->datalayout)) {
> #ifdef CONFIG_EROFS_FS_ZIP
> +#ifdef CONFIG_EROFS_FS_BACKED_BY_FILE
> + if (erofs_is_fileio_mode(EROFS_SB(inode->i_sb))) {
> + err = -EOPNOTSUPP;
> + goto out_unlock;
> + }
> +#endif
> DO_ONCE_LITE_IF(inode->i_blkbits != PAGE_SHIFT,
> erofs_info, inode->i_sb,
> "EXPERIMENTAL EROFS subpage compressed block
> support in use. Use at your own risk!");
> @@ -271,10 +274,14 @@ static int erofs_fill_inode(struct inode *inode)
> err = -EOPNOTSUPP;
> #endif
> } else {
> - inode->i_mapping->a_ops = &erofs_raw_access_aops;
> + inode->i_mapping->a_ops = &erofs_aops;
> #ifdef CONFIG_EROFS_FS_ONDEMAND
> if (erofs_is_fscache_mode(inode->i_sb))
> inode->i_mapping->a_ops = &erofs_fscache_access_aops;
> +#endif
> +#ifdef CONFIG_EROFS_FS_BACKED_BY_FILE
> + if (erofs_is_fileio_mode(EROFS_SB(inode->i_sb)))
> + inode->i_mapping->a_ops = &erofs_fileio_aops;
> #endif
> }
> out_unlock:
> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> index 9bf4fb1cfa09..9bc4dcfd06d7 100644
> --- a/fs/erofs/internal.h
> +++ b/fs/erofs/internal.h
> @@ -372,6 +372,7 @@ struct erofs_map_dev {
> struct erofs_fscache *m_fscache;
> struct block_device *m_bdev;
> struct dax_device *m_daxdev;
> + struct file *m_fp;
> u64 m_dax_part_off;
>
> erofs_off_t m_pa;
> @@ -380,7 +381,8 @@ struct erofs_map_dev {
>
> extern const struct super_operations erofs_sops;
>
> -extern const struct address_space_operations erofs_raw_access_aops;
> +extern const struct address_space_operations erofs_aops;
> +extern const struct address_space_operations erofs_fileio_aops;
> extern const struct address_space_operations z_erofs_aops;
> extern const struct address_space_operations erofs_fscache_access_aops;
>
> @@ -411,6 +413,9 @@ int erofs_map_dev(struct super_block *sb, struct
> erofs_map_dev *dev);
> int erofs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
> u64 start, u64 len);
> int erofs_map_blocks(struct inode *inode, struct erofs_map_blocks *map);
> +void erofs_onlinefolio_init(struct folio *folio);
> +void erofs_onlinefolio_split(struct folio *folio);
> +void erofs_onlinefolio_end(struct folio *folio, int err);
> struct inode *erofs_iget(struct super_block *sb, erofs_nid_t nid);
> int erofs_getattr(struct mnt_idmap *idmap, const struct path *path,
> struct kstat *stat, u32 request_mask,
> diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
> index 424f656cd765..350612f32ac6 100644
> --- a/fs/erofs/zdata.c
> +++ b/fs/erofs/zdata.c
> @@ -122,42 +122,6 @@ static bool erofs_folio_is_managed(struct erofs_sb_info
> *sbi, struct folio *fo)
> return fo->mapping == MNGD_MAPPING(sbi);
> }
>
> -/*
> - * bit 30: I/O error occurred on this folio
> - * bit 0 - 29: remaining parts to complete this folio
> - */
> -#define Z_EROFS_FOLIO_EIO (1 << 30)
> -
> -static void z_erofs_onlinefolio_init(struct folio *folio)
> -{
> - union {
> - atomic_t o;
> - void *v;
> - } u = { .o = ATOMIC_INIT(1) };
> -
> - folio->private = u.v; /* valid only if file-backed folio is locked
> */
> -}
> -
> -static void z_erofs_onlinefolio_split(struct folio *folio)
> -{
> - atomic_inc((atomic_t *)&folio->private);
> -}
> -
> -static void z_erofs_onlinefolio_end(struct folio *folio, int err)
> -{
> - int orig, v;
> -
> - do {
> - orig = atomic_read((atomic_t *)&folio->private);
> - v = (orig - 1) | (err ? Z_EROFS_FOLIO_EIO : 0);
> - } while (atomic_cmpxchg((atomic_t *)&folio->private, orig, v) !=
> orig);
> -
> - if (v & ~Z_EROFS_FOLIO_EIO)
> - return;
> - folio->private = 0;
> - folio_end_read(folio, !(v & Z_EROFS_FOLIO_EIO));
> -}
> -
> #define Z_EROFS_ONSTACK_PAGES 32
>
> /*
> @@ -965,7 +929,7 @@ static int z_erofs_scan_folio(struct
> z_erofs_decompress_frontend *f,
> int err = 0;
>
> tight = (bs == PAGE_SIZE);
> - z_erofs_onlinefolio_init(folio);
> + erofs_onlinefolio_init(folio);
> do {
> if (offset + end - 1 < map->m_la ||
> offset + end - 1 >= map->m_la + map->m_llen) {
> @@ -1024,7 +988,7 @@ static int z_erofs_scan_folio(struct
> z_erofs_decompress_frontend *f,
> if (err)
> break;
>
> - z_erofs_onlinefolio_split(folio);
> + erofs_onlinefolio_split(folio);
> if (f->pcl->pageofs_out != (map->m_la & ~PAGE_MASK))
> f->pcl->multibases = true;
> if (f->pcl->length < offset + end - map->m_la) {
> @@ -1044,7 +1008,7 @@ static int z_erofs_scan_folio(struct
> z_erofs_decompress_frontend *f,
> tight = (bs == PAGE_SIZE);
> }
> } while ((end = cur) > 0);
> - z_erofs_onlinefolio_end(folio, err);
> + erofs_onlinefolio_end(folio, err);
> return err;
> }
>
> @@ -1147,7 +1111,7 @@ static void z_erofs_fill_other_copies(struct
> z_erofs_decompress_backend *be,
> cur += len;
> }
> kunmap_local(dst);
> - z_erofs_onlinefolio_end(page_folio(bvi->bvec.page), err);
> + erofs_onlinefolio_end(page_folio(bvi->bvec.page), err);
> list_del(p);
> kfree(bvi);
> }
> @@ -1302,7 +1266,7 @@ static int z_erofs_decompress_pcluster(struct
> z_erofs_decompress_backend *be,
>
> DBG_BUGON(z_erofs_page_is_invalidated(page));
> if (!z_erofs_is_shortlived_page(page)) {
> - z_erofs_onlinefolio_end(page_folio(page), err);
> + erofs_onlinefolio_end(page_folio(page), err);
> continue;
> }
> if (pcl->algorithmformat != Z_EROFS_COMPRESSION_LZ4) {
> --
> 2.43.5
>
