Re: [PATCH 2/3] ovl: Make ovl_dentry_weird() accept casefold dentries
From: Amir Goldstein
Date: Wed Apr 09 2025 - 13:12:01 EST
On Wed, Apr 9, 2025 at 5:01 PM André Almeida <andrealmeid@xxxxxxxxxx> wrote:
>
> ovl_dentry_weird() is used to avoid problems with filesystems that has
> their d_hash and d_compare implementations. Create an exception for this
> function, where only casefold filesystems are eligible to use their own
> d_hash and d_compare functions, allowing to support casefold
> filesystems.
What do you mean by this sentence?
Any casefold fs can be on any layer?
All layers on the same casefold sb? same casefold fstype?
>
> Signed-off-by: André Almeida <andrealmeid@xxxxxxxxxx>
> ---
> fs/overlayfs/namei.c | 11 ++++++-----
> fs/overlayfs/overlayfs.h | 2 +-
> fs/overlayfs/params.c | 3 ++-
> fs/overlayfs/util.c | 12 +++++++-----
> 4 files changed, 16 insertions(+), 12 deletions(-)
>
> diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
> index be5c65d6f8484b1fba6b3fee379ba1d034c0df8a..140bc609ffebe00151cbb446720f5106dbeb2ef2 100644
> --- a/fs/overlayfs/namei.c
> +++ b/fs/overlayfs/namei.c
> @@ -192,7 +192,7 @@ struct dentry *ovl_decode_real_fh(struct ovl_fs *ofs, struct ovl_fh *fh,
> return real;
> }
>
> - if (ovl_dentry_weird(real)) {
> + if (ovl_dentry_weird(real, ofs)) {
> dput(real);
> return NULL;
> }
> @@ -244,7 +244,7 @@ static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,
> goto out_err;
> }
>
> - if (ovl_dentry_weird(this)) {
> + if (ovl_dentry_weird(this, ofs)) {
> /* Don't support traversing automounts and other weirdness */
> err = -EREMOTE;
> goto out_err;
> @@ -365,6 +365,7 @@ static int ovl_lookup_data_layer(struct dentry *dentry, const char *redirect,
> struct path *datapath)
> {
> int err;
> + struct ovl_fs *ovl = OVL_FS(layer->fs->sb);
ofs please
>
> err = vfs_path_lookup(layer->mnt->mnt_root, layer->mnt, redirect,
> LOOKUP_BENEATH | LOOKUP_NO_SYMLINKS | LOOKUP_NO_XDEV,
> @@ -376,7 +377,7 @@ static int ovl_lookup_data_layer(struct dentry *dentry, const char *redirect,
> return err;
>
> err = -EREMOTE;
> - if (ovl_dentry_weird(datapath->dentry))
> + if (ovl_dentry_weird(datapath->dentry, ovl))
> goto out_path_put;
>
> err = -ENOENT;
> @@ -767,7 +768,7 @@ struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh)
>
> if (ovl_is_whiteout(index))
> err = -ESTALE;
> - else if (ovl_dentry_weird(index))
> + else if (ovl_dentry_weird(index, ofs))
> err = -EIO;
> else
> return index;
> @@ -815,7 +816,7 @@ struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
> dput(index);
> index = ERR_PTR(-ESTALE);
> goto out;
> - } else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) ||
> + } else if (ovl_dentry_weird(index, ofs) || ovl_is_whiteout(index) ||
> inode_wrong_type(inode, d_inode(origin)->i_mode)) {
> /*
> * Index should always be of the same file type as origin
> diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
> index 6f2f8f4cfbbc177fbd5441483395d7ff72efe332..f3de013517598c44c15ca9f950f6c2f0a5c2084b 100644
> --- a/fs/overlayfs/overlayfs.h
> +++ b/fs/overlayfs/overlayfs.h
> @@ -445,7 +445,7 @@ void ovl_dentry_init_reval(struct dentry *dentry, struct dentry *upperdentry,
> struct ovl_entry *oe);
> void ovl_dentry_init_flags(struct dentry *dentry, struct dentry *upperdentry,
> struct ovl_entry *oe, unsigned int mask);
> -bool ovl_dentry_weird(struct dentry *dentry);
> +bool ovl_dentry_weird(struct dentry *dentry, struct ovl_fs *ovl);
> enum ovl_path_type ovl_path_type(struct dentry *dentry);
> void ovl_path_upper(struct dentry *dentry, struct path *path);
> void ovl_path_lower(struct dentry *dentry, struct path *path);
> diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c
> index 6759f7d040c89d3b3c01572579c854a900411157..459e8bddf1777c12c9fa0bdfc150e2ea22eaafc3 100644
> --- a/fs/overlayfs/params.c
> +++ b/fs/overlayfs/params.c
> @@ -277,6 +277,7 @@ static int ovl_mount_dir_check(struct fs_context *fc, const struct path *path,
> enum ovl_opt layer, const char *name, bool upper)
> {
> struct ovl_fs_context *ctx = fc->fs_private;
> + struct ovl_fs *ovl = fc->s_fs_info;
ofs pls
>
> if (!d_is_dir(path->dentry))
> return invalfc(fc, "%s is not a directory", name);
> @@ -290,7 +291,7 @@ static int ovl_mount_dir_check(struct fs_context *fc, const struct path *path,
> if (sb_has_encoding(path->mnt->mnt_sb))
> return invalfc(fc, "case-insensitive capable filesystem on %s not supported", name);
>
> - if (ovl_dentry_weird(path->dentry))
> + if (ovl_dentry_weird(path->dentry, ovl))
> return invalfc(fc, "filesystem on %s not supported", name);
>
> /*
> diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
> index 0819c739cc2ffce0dfefa84d3ff8f9f103eec191..4dd523a1a13ab0a6cf51d967d0b712873e6d8580 100644
> --- a/fs/overlayfs/util.c
> +++ b/fs/overlayfs/util.c
> @@ -200,15 +200,17 @@ void ovl_dentry_init_flags(struct dentry *dentry, struct dentry *upperdentry,
> spin_unlock(&dentry->d_lock);
> }
>
> -bool ovl_dentry_weird(struct dentry *dentry)
> +bool ovl_dentry_weird(struct dentry *dentry, struct ovl_fs *ovl)
ovl_fs *ofs as first argument please
> {
> + int flags = DCACHE_NEED_AUTOMOUNT | DCACHE_MANAGE_TRANSIT;
> +
> + if (!ovl->casefold)
> + flags |= DCACHE_OP_HASH | DCACHE_OP_COMPARE;
> +
> if (!d_can_lookup(dentry) && !d_is_file(dentry) && !d_is_symlink(dentry))
> return true;
>
> - return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
> - DCACHE_MANAGE_TRANSIT |
> - DCACHE_OP_HASH |
> - DCACHE_OP_COMPARE);
> + return dentry->d_flags & flags;
> }
>
> enum ovl_path_type ovl_path_type(struct dentry *dentry)
>
> --
> 2.49.0
>