[PATCH v14 08/10] erofs: support unencoded inodes for page cache share
Gao Xiang
hsiangkao at linux.alibaba.com
Thu Jan 15 01:51:33 AEDT 2026
On 2026/1/9 18:28, Hongbo Li wrote:
> This patch adds inode page cache sharing functionality for unencoded
> files.
>
> I conducted experiments in the container environment. Below is the
> memory usage for reading all files in two different minor versions
> of container images:
>
> +-------------------+------------------+-------------+---------------+
> | Image | Page Cache Share | Memory (MB) | Memory |
> | | | | Reduction (%) |
> +-------------------+------------------+-------------+---------------+
> | | No | 241 | - |
> | redis +------------------+-------------+---------------+
> | 7.2.4 & 7.2.5 | Yes | 163 | 33% |
> +-------------------+------------------+-------------+---------------+
> | | No | 872 | - |
> | postgres +------------------+-------------+---------------+
> | 16.1 & 16.2 | Yes | 630 | 28% |
> +-------------------+------------------+-------------+---------------+
> | | No | 2771 | - |
> | tensorflow +------------------+-------------+---------------+
> | 2.11.0 & 2.11.1 | Yes | 2340 | 16% |
> +-------------------+------------------+-------------+---------------+
> | | No | 926 | - |
> | mysql +------------------+-------------+---------------+
> | 8.0.11 & 8.0.12 | Yes | 735 | 21% |
> +-------------------+------------------+-------------+---------------+
> | | No | 390 | - |
> | nginx +------------------+-------------+---------------+
> | 7.2.4 & 7.2.5 | Yes | 219 | 44% |
> +-------------------+------------------+-------------+---------------+
> | tomcat | No | 924 | - |
> | 10.1.25 & 10.1.26 +------------------+-------------+---------------+
> | | Yes | 474 | 49% |
> +-------------------+------------------+-------------+---------------+
>
> Additionally, the table below shows the runtime memory usage of the
> container:
>
> +-------------------+------------------+-------------+---------------+
> | Image | Page Cache Share | Memory (MB) | Memory |
> | | | | Reduction (%) |
> +-------------------+------------------+-------------+---------------+
> | | No | 35 | - |
> | redis +------------------+-------------+---------------+
> | 7.2.4 & 7.2.5 | Yes | 28 | 20% |
> +-------------------+------------------+-------------+---------------+
> | | No | 149 | - |
> | postgres +------------------+-------------+---------------+
> | 16.1 & 16.2 | Yes | 95 | 37% |
> +-------------------+------------------+-------------+---------------+
> | | No | 1028 | - |
> | tensorflow +------------------+-------------+---------------+
> | 2.11.0 & 2.11.1 | Yes | 930 | 10% |
> +-------------------+------------------+-------------+---------------+
> | | No | 155 | - |
> | mysql +------------------+-------------+---------------+
> | 8.0.11 & 8.0.12 | Yes | 132 | 15% |
> +-------------------+------------------+-------------+---------------+
> | | No | 25 | - |
> | nginx +------------------+-------------+---------------+
> | 7.2.4 & 7.2.5 | Yes | 20 | 20% |
> +-------------------+------------------+-------------+---------------+
> | tomcat | No | 186 | - |
> | 10.1.25 & 10.1.26 +------------------+-------------+---------------+
> | | Yes | 98 | 48% |
> +-------------------+------------------+-------------+---------------+
>
> Co-developed-by: Hongzhen Luo <hongzhen at linux.alibaba.com>
> Signed-off-by: Hongzhen Luo <hongzhen at linux.alibaba.com>
> Signed-off-by: Hongbo Li <lihongbo22 at huawei.com>
> ---
> fs/erofs/data.c | 32 +++++++++++++++++++++++---------
> fs/erofs/fileio.c | 25 ++++++++++++++++---------
> fs/erofs/inode.c | 2 ++
> fs/erofs/internal.h | 6 ++++++
> fs/erofs/ishare.c | 34 ++++++++++++++++++++++++++++++++++
> fs/erofs/zdata.c | 2 +-
> include/trace/events/erofs.h | 10 +++++-----
> 7 files changed, 87 insertions(+), 24 deletions(-)
>
> diff --git a/fs/erofs/data.c b/fs/erofs/data.c
> index 71e23d91123d..7bbd94781170 100644
> --- a/fs/erofs/data.c
> +++ b/fs/erofs/data.c
> @@ -269,6 +269,7 @@ void erofs_onlinefolio_end(struct folio *folio, int err, bool dirty)
> struct erofs_iomap_iter_ctx {
> struct page *page;
> void *base;
> + struct inode *realinode;
> };
>
> static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> @@ -276,14 +277,15 @@ static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> {
> struct iomap_iter *iter = container_of(iomap, struct iomap_iter, iomap);
> struct erofs_iomap_iter_ctx *ctx = iter->private;
> - struct super_block *sb = inode->i_sb;
> + struct inode *realinode = ctx ? ctx->realinode : inode;
> + struct super_block *sb = realinode->i_sb;
> struct erofs_map_blocks map;
> struct erofs_map_dev mdev;
> int ret;
>
> map.m_la = offset;
> map.m_llen = length;
> - ret = erofs_map_blocks(inode, &map);
> + ret = erofs_map_blocks(realinode, &map);
> if (ret < 0)
> return ret;
>
> @@ -296,7 +298,7 @@ static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> return 0;
> }
>
> - if (!(map.m_flags & EROFS_MAP_META) || !erofs_inode_in_metabox(inode)) {
> + if (!(map.m_flags & EROFS_MAP_META) || !erofs_inode_in_metabox(realinode)) {
> mdev = (struct erofs_map_dev) {
> .m_deviceid = map.m_deviceid,
> .m_pa = map.m_pa,
> @@ -322,7 +324,7 @@ static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> void *ptr;
>
> ptr = erofs_read_metabuf(&buf, sb, map.m_pa,
> - erofs_inode_in_metabox(inode));
> + erofs_inode_in_metabox(realinode));
> if (IS_ERR(ptr))
> return PTR_ERR(ptr);
> iomap->inline_data = ptr;
> @@ -383,11 +385,16 @@ static int erofs_read_folio(struct file *file, struct folio *folio)
> .ops = &iomap_bio_read_ops,
> .cur_folio = folio,
> };
> - struct erofs_iomap_iter_ctx iter_ctx = {};
> + bool need_iput;
> + struct erofs_iomap_iter_ctx iter_ctx = {
> + .realinode = erofs_real_inode(folio_inode(folio), &need_iput),
> + };
>
> - trace_erofs_read_folio(folio, true);
> + trace_erofs_read_folio(iter_ctx.realinode, folio, true);
>
> iomap_read_folio(&erofs_iomap_ops, &read_ctx, &iter_ctx);
> + if (need_iput)
> + iput(iter_ctx.realinode);
> return 0;
> }
>
> @@ -397,12 +404,17 @@ static void erofs_readahead(struct readahead_control *rac)
> .ops = &iomap_bio_read_ops,
> .rac = rac,
> };
> - struct erofs_iomap_iter_ctx iter_ctx = {};
> + bool need_iput;
> + struct erofs_iomap_iter_ctx iter_ctx = {
> + .realinode = erofs_real_inode(rac->mapping->host, &need_iput),
> + };
>
> - trace_erofs_readahead(rac->mapping->host, readahead_index(rac),
> + trace_erofs_readahead(iter_ctx.realinode, readahead_index(rac),
> readahead_count(rac), true);
Is it possible to add a commit to update the tracepoints
to add the new realinode first?
Also please fix the indentation in that commit together.
>
> iomap_readahead(&erofs_iomap_ops, &read_ctx, &iter_ctx);
> + if (need_iput)
> + iput(iter_ctx.realinode);
> }
>
> static sector_t erofs_bmap(struct address_space *mapping, sector_t block)
> @@ -423,7 +435,9 @@ static ssize_t erofs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
> return dax_iomap_rw(iocb, to, &erofs_iomap_ops);
> #endif
> if ((iocb->ki_flags & IOCB_DIRECT) && inode->i_sb->s_bdev) {
> - struct erofs_iomap_iter_ctx iter_ctx = {};
> + struct erofs_iomap_iter_ctx iter_ctx = {
> + .realinode = inode,
> + };
>
> return iomap_dio_rw(iocb, to, &erofs_iomap_ops,
> NULL, 0, &iter_ctx, 0);
> diff --git a/fs/erofs/fileio.c b/fs/erofs/fileio.c
> index 932e8b353ba1..c1d0081609dc 100644
> --- a/fs/erofs/fileio.c
> +++ b/fs/erofs/fileio.c
> @@ -88,9 +88,9 @@ void erofs_fileio_submit_bio(struct bio *bio)
> bio));
> }
>
> -static int erofs_fileio_scan_folio(struct erofs_fileio *io, struct folio *folio)
> +static int erofs_fileio_scan_folio(struct erofs_fileio *io,
> + struct inode *inode, 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;
> @@ -158,31 +158,38 @@ static int erofs_fileio_scan_folio(struct erofs_fileio *io, struct folio *folio)
>
> static int erofs_fileio_read_folio(struct file *file, struct folio *folio)
> {
> + bool need_iput;
> + struct inode *realinode = erofs_real_inode(folio_inode(folio), &need_iput);
> struct erofs_fileio io = {};
> int err;
>
> - trace_erofs_read_folio(folio, true);
> - err = erofs_fileio_scan_folio(&io, folio);
> + trace_erofs_read_folio(realinode, folio, true);
> + err = erofs_fileio_scan_folio(&io, realinode, folio);
> erofs_fileio_rq_submit(io.rq);
> + if (need_iput)
> + iput(realinode);
> return err;
> }
>
> static void erofs_fileio_readahead(struct readahead_control *rac)
> {
> - struct inode *inode = rac->mapping->host;
> + bool need_iput;
> + struct inode *realinode = erofs_real_inode(rac->mapping->host, &need_iput);
> struct erofs_fileio io = {};
> struct folio *folio;
> int err;
>
> - trace_erofs_readahead(inode, readahead_index(rac),
> + trace_erofs_readahead(realinode, readahead_index(rac),
> readahead_count(rac), true);
> while ((folio = readahead_folio(rac))) {
> - err = erofs_fileio_scan_folio(&io, folio);
> + err = erofs_fileio_scan_folio(&io, realinode, folio);
> if (err && err != -EINTR)
> - erofs_err(inode->i_sb, "readahead error at folio %lu @ nid %llu",
> - folio->index, EROFS_I(inode)->nid);
> + erofs_err(realinode->i_sb, "readahead error at folio %lu @ nid %llu",
> + folio->index, EROFS_I(realinode)->nid);
> }
> erofs_fileio_rq_submit(io.rq);
> + if (need_iput)
> + iput(realinode);
> }
>
> const struct address_space_operations erofs_fileio_aops = {
> diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
> index bce98c845a18..52179b706b5b 100644
> --- a/fs/erofs/inode.c
> +++ b/fs/erofs/inode.c
> @@ -215,6 +215,8 @@ static int erofs_fill_inode(struct inode *inode)
> case S_IFREG:
> inode->i_op = &erofs_generic_iops;
> inode->i_fop = &erofs_file_fops;
> + if (erofs_ishare_fill_inode(inode))
> + inode->i_fop = &erofs_ishare_fops;
inode->i_fop = erofs_ishare_fill_inode(inode) ?
&erofs_ishare_fops : &erofs_file_fops;
Otherwise it looks good to me.
Thanks,
Gao Xiang
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