Hi Hongbo,
On Fri, Feb 13, 2026 at 07:33:45AM +0000, Hongbo Li wrote:
> Inode with identical data but different @aops cannot be mixed
> because the page cache is managed by different subsystems (e.g.,
> @aops for compressed on-disk inodes cannot handle plain on-disk
> inodes).
>
> In this patch, we never allow inodes to share the page cache
> among plain, compressed, and fileio cases. When a shared inode
> is created, we initialize @aops that is the same as the initial
> real inode, and subsequent inodes cannot share the page cache
> if the inferred @aops differ from the corresponding shared inode.
>
> This is reasonable as a first step because, in typical use cases,
> if an inode is compressible, it will fall into compressed
> inodes across different filesystem images unless users use plain
> filesystems. However, in that cases, users will use plain
> filesystems all the time.
>
> Fixes: 5ef3208e3be5 ("erofs: introduce the page cache share feature")
> Signed-off-by: Hongbo Li <[email protected]>
> ---
> fs/erofs/inode.c | 3 ++-
> fs/erofs/internal.h | 20 +++++++++-----------
> fs/erofs/ishare.c | 14 +++++++++-----
> 3 files changed, 20 insertions(+), 17 deletions(-)
>
> diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
> index 4f86169c23f1..5b05272fd9c4 100644
> --- a/fs/erofs/inode.c
> +++ b/fs/erofs/inode.c
> @@ -254,7 +254,8 @@ static int erofs_fill_inode(struct inode *inode)
> }
>
> mapping_set_large_folios(inode->i_mapping);
> - return erofs_inode_set_aops(inode, inode, false);
> + inode->i_mapping->a_ops = erofs_get_aops(inode, false);
> + return IS_ERR(inode->i_mapping->a_ops) ?
> PTR_ERR(inode->i_mapping->a_ops) : 0;
I hope there is an aops variable instead of assigning
inode->i_mapping->a_ops directly.
> }
>
> /*
> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> index d1634455e389..764e81b3bc08 100644
> --- a/fs/erofs/internal.h
> +++ b/fs/erofs/internal.h
> @@ -471,26 +471,24 @@ static inline void *erofs_vm_map_ram(struct page
> **pages, unsigned int count)
> return NULL;
> }
>
> -static inline int erofs_inode_set_aops(struct inode *inode,
> - struct inode *realinode, bool no_fscache)
> +static inline const struct address_space_operations *
> +erofs_get_aops(struct inode *realinode, bool no_fscache)
> {
> if (erofs_inode_is_data_compressed(EROFS_I(realinode)->datalayout)) {
> if (!IS_ENABLED(CONFIG_EROFS_FS_ZIP))
> - return -EOPNOTSUPP;
> + return ERR_PTR(-EOPNOTSUPP);
> DO_ONCE_LITE_IF(realinode->i_blkbits != PAGE_SHIFT,
> erofs_info, realinode->i_sb,
> "EXPERIMENTAL EROFS subpage compressed block support
> in use. Use at your own risk!");
> - inode->i_mapping->a_ops = &z_erofs_aops;
> - return 0;
> + return &z_erofs_aops;
> }
> - inode->i_mapping->a_ops = &erofs_aops;
> - if (IS_ENABLED(CONFIG_EROFS_FS_ONDEMAND) && !no_fscache &&
> - erofs_is_fscache_mode(realinode->i_sb))
> - inode->i_mapping->a_ops = &erofs_fscache_access_aops;
> if (IS_ENABLED(CONFIG_EROFS_FS_BACKED_BY_FILE) &&
> erofs_is_fileio_mode(EROFS_SB(realinode->i_sb)))
> - inode->i_mapping->a_ops = &erofs_fileio_aops;
> - return 0;
> + return &erofs_fileio_aops;
> + if (IS_ENABLED(CONFIG_EROFS_FS_ONDEMAND) && !no_fscache &&
> + erofs_is_fscache_mode(realinode->i_sb))
> + return &erofs_fscache_access_aops;
Can you rearrange it as
if (IS_ENABLED(CONFIG_EROFS_FS_ONDEMAND) && !no_fscache &&
erofs_is_fscache_mode(realinode->i_sb))
return &erofs_fscache_access_aops;
if (IS_ENABLED(CONFIG_EROFS_FS_BACKED_BY_FILE) &&
erofs_is_fileio_mode(EROFS_SB(realinode->i_sb)))
inode->i_mapping->a_ops = &erofs_fileio_aops;
return &erofs_aops;
?
Thanks,
Gao Xiang
