Re: [PATCH v2 2/4] erofs: support unencoded inodes for fileio

[Gao Xiang]

On 2024/8/31 12:25, Sandeep Dhavale wrote:
> On Thu, Aug 29, 2024 at 8:29 PM Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> 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 <hsiangkao@xxxxxxxxxxxxxxxxx>
> > ---
> > 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;
> Hi Gao,
> Is this change intentional? At out label, we set this again as err is 0.

Yes, that is intentional, we will return the post-EOF extent as
m_plen == map->m_llen == passed in m_llen and an unmapped extent

so that the logic can be simplified and it's still compatible.

Thanks,
Gao Xiang