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charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, Aug 22, 2025 at 4:17=E2=80=AFPM Andr=C3=A9 Almeida wrote: > > To add overlayfs support casefold layers, create a new function > ovl_casefold(), to be able to do case-insensitive strncmp(). > > ovl_casefold() allocates a new buffer and stores the casefolded version > of the string on it. If the allocation or the casefold operation fails, > fallback to use the original string. > > The case-insentive name is then used in the rb-tree search/insertion > operation. If the name is found in the rb-tree, the name can be > discarded and the buffer is freed. If the name isn't found, it's then > stored at struct ovl_cache_entry to be used later. > > Reviewed-by: Amir Goldstein > Signed-off-by: Andr=C3=A9 Almeida > --- > Changes from v6: > - Last version was using `strncmp(... tmp->len)` which was causing > regressions. It should be `strncmp(... len)`. > - Rename cf_len to c_len > - Use c_len for tree operation: (cmp < 0 || len < tmp->c_len) > - Remove needless kfree(cf_name) > --- > fs/overlayfs/readdir.c | 113 ++++++++++++++++++++++++++++++++++++++++---= ------ > 1 file changed, 94 insertions(+), 19 deletions(-) > > diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c > index b65cdfce31ce27172d28d879559f1008b9c87320..dfc661b7bc3f87efbf14991e9= 7cee169400d823b 100644 > --- a/fs/overlayfs/readdir.c > +++ b/fs/overlayfs/readdir.c > @@ -27,6 +27,8 @@ struct ovl_cache_entry { > bool is_upper; > bool is_whiteout; > bool check_xwhiteout; > + const char *c_name; > + int c_len; > char name[]; > }; > > @@ -45,6 +47,7 @@ struct ovl_readdir_data { > struct list_head *list; > struct list_head middle; > struct ovl_cache_entry *first_maybe_whiteout; > + struct unicode_map *map; > int count; > int err; > bool is_upper; > @@ -66,6 +69,27 @@ static struct ovl_cache_entry *ovl_cache_entry_from_no= de(struct rb_node *n) > return rb_entry(n, struct ovl_cache_entry, node); > } > > +static int ovl_casefold(struct unicode_map *map, const char *str, int le= n, char **dst) > +{ > + const struct qstr qstr =3D { .name =3D str, .len =3D len }; > + int cf_len; > + > + if (!IS_ENABLED(CONFIG_UNICODE) || !map || is_dot_dotdot(str, len= )) > + return 0; > + > + *dst =3D kmalloc(NAME_MAX, GFP_KERNEL); > + > + if (dst) { > + cf_len =3D utf8_casefold(map, &qstr, *dst, NAME_MAX); > + > + if (cf_len > 0) > + return cf_len; > + } > + > + kfree(*dst); > + return 0; > +} > + > static bool ovl_cache_entry_find_link(const char *name, int len, > struct rb_node ***link, > struct rb_node **parent) > @@ -79,10 +103,10 @@ static bool ovl_cache_entry_find_link(const char *na= me, int len, > > *parent =3D *newp; > tmp =3D ovl_cache_entry_from_node(*newp); > - cmp =3D strncmp(name, tmp->name, len); > + cmp =3D strncmp(name, tmp->c_name, len); > if (cmp > 0) > newp =3D &tmp->node.rb_right; > - else if (cmp < 0 || len < tmp->len) > + else if (cmp < 0 || len < tmp->c_len) > newp =3D &tmp->node.rb_left; > else > found =3D true; > @@ -101,10 +125,10 @@ static struct ovl_cache_entry *ovl_cache_entry_find= (struct rb_root *root, > while (node) { > struct ovl_cache_entry *p =3D ovl_cache_entry_from_node(n= ode); > > - cmp =3D strncmp(name, p->name, len); > + cmp =3D strncmp(name, p->c_name, len); > if (cmp > 0) > node =3D p->node.rb_right; > - else if (cmp < 0 || len < p->len) > + else if (cmp < 0 || len < p->c_len) > node =3D p->node.rb_left; > else > return p; > @@ -145,6 +169,7 @@ static bool ovl_calc_d_ino(struct ovl_readdir_data *r= dd, > > static struct ovl_cache_entry *ovl_cache_entry_new(struct ovl_readdir_da= ta *rdd, > const char *name, int = len, > + const char *c_name, in= t c_len, > u64 ino, unsigned int = d_type) > { > struct ovl_cache_entry *p; > @@ -167,6 +192,14 @@ static struct ovl_cache_entry *ovl_cache_entry_new(s= truct ovl_readdir_data *rdd, > /* Defer check for overlay.whiteout to ovl_iterate() */ > p->check_xwhiteout =3D rdd->in_xwhiteouts_dir && d_type =3D=3D DT= _REG; > > + if (c_name && c_name !=3D name) { > + p->c_name =3D c_name; > + p->c_len =3D c_len; > + } else { > + p->c_name =3D p->name; > + p->c_len =3D len; > + } > + > if (d_type =3D=3D DT_CHR) { > p->next_maybe_whiteout =3D rdd->first_maybe_whiteout; > rdd->first_maybe_whiteout =3D p; > @@ -174,48 +207,55 @@ static struct ovl_cache_entry *ovl_cache_entry_new(= struct ovl_readdir_data *rdd, > return p; > } > > -static bool ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd, > - const char *name, int len, u64 ino, > +/* Return 0 for found, 1 for added, <0 for error */ > +static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd, > + const char *name, int len, > + const char *c_name, int c_len, > + u64 ino, > unsigned int d_type) > { > struct rb_node **newp =3D &rdd->root->rb_node; > struct rb_node *parent =3D NULL; > struct ovl_cache_entry *p; > > - if (ovl_cache_entry_find_link(name, len, &newp, &parent)) > - return true; > + if (ovl_cache_entry_find_link(c_name, c_len, &newp, &parent)) > + return 0; > > - p =3D ovl_cache_entry_new(rdd, name, len, ino, d_type); > + p =3D ovl_cache_entry_new(rdd, name, len, c_name, c_len, ino, d_t= ype); > if (p =3D=3D NULL) { > rdd->err =3D -ENOMEM; > - return false; > + return -ENOMEM; > } > > list_add_tail(&p->l_node, rdd->list); > rb_link_node(&p->node, parent, newp); > rb_insert_color(&p->node, rdd->root); > > - return true; > + return 1; > } > > -static bool ovl_fill_lowest(struct ovl_readdir_data *rdd, > +/* Return 0 for found, 1 for added, <0 for error */ > +static int ovl_fill_lowest(struct ovl_readdir_data *rdd, > const char *name, int namelen, > + const char *c_name, int c_len, > loff_t offset, u64 ino, unsigned int d_type) > { > struct ovl_cache_entry *p; > > - p =3D ovl_cache_entry_find(rdd->root, name, namelen); > + p =3D ovl_cache_entry_find(rdd->root, c_name, c_len); > if (p) { > list_move_tail(&p->l_node, &rdd->middle); > + return 0; > } else { > - p =3D ovl_cache_entry_new(rdd, name, namelen, ino, d_type= ); > + p =3D ovl_cache_entry_new(rdd, name, namelen, c_name, c_l= en, > + ino, d_type); > if (p =3D=3D NULL) > rdd->err =3D -ENOMEM; > else > list_add_tail(&p->l_node, &rdd->middle); > } > > - return rdd->err =3D=3D 0; > + return rdd->err ?: 1; > } > > void ovl_cache_free(struct list_head *list) > @@ -223,8 +263,11 @@ void ovl_cache_free(struct list_head *list) > struct ovl_cache_entry *p; > struct ovl_cache_entry *n; > > - list_for_each_entry_safe(p, n, list, l_node) > + list_for_each_entry_safe(p, n, list, l_node) { > + if (p->c_name !=3D p->name) > + kfree(p->c_name); > kfree(p); > + } > > INIT_LIST_HEAD(list); > } > @@ -260,12 +303,36 @@ static bool ovl_fill_merge(struct dir_context *ctx,= const char *name, > { > struct ovl_readdir_data *rdd =3D > container_of(ctx, struct ovl_readdir_data, ctx); > + struct ovl_fs *ofs =3D OVL_FS(rdd->dentry->d_sb); > + const char *c_name =3D NULL; > + char *cf_name =3D NULL; > + int c_len =3D 0, ret; > + > + if (ofs->casefold) > + c_len =3D ovl_casefold(rdd->map, name, namelen, &cf_name)= ; > + > + if (c_len <=3D 0) { > + c_name =3D name; > + c_len =3D namelen; > + } else { > + c_name =3D cf_name; > + } > > rdd->count++; > if (!rdd->is_lowest) > - return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_= type); > + ret =3D ovl_cache_entry_add_rb(rdd, name, namelen, c_name= , c_len, ino, d_type); > else > - return ovl_fill_lowest(rdd, name, namelen, offset, ino, d= _type); > + ret =3D ovl_fill_lowest(rdd, name, namelen, c_name, c_len= , offset, ino, d_type); > + > + /* > + * If ret =3D=3D 1, that means that c_name is being used as part = of struct > + * ovl_cache_entry and will be freed at ovl_cache_free(). Otherwi= se, > + * c_name was found in the rb-tree so we can free it here. > + */ > + if (ret !=3D 1 && c_name !=3D name) > + kfree(c_name); > + > + return ret >=3D 0; > } > > static int ovl_check_whiteouts(const struct path *path, struct ovl_readd= ir_data *rdd) > @@ -357,12 +424,18 @@ static int ovl_dir_read_merged(struct dentry *dentr= y, struct list_head *list, > .list =3D list, > .root =3D root, > .is_lowest =3D false, > + .map =3D NULL, > }; > int idx, next; > const struct ovl_layer *layer; > + struct ovl_fs *ofs =3D OVL_FS(dentry->d_sb); > > for (idx =3D 0; idx !=3D -1; idx =3D next) { > next =3D ovl_path_next(idx, dentry, &realpath, &layer); > + > + if (ofs->casefold) > + rdd.map =3D sb_encoding(realpath.dentry->d_sb); > + > rdd.is_upper =3D ovl_dentry_upper(dentry) =3D=3D realpath= .dentry; > rdd.in_xwhiteouts_dir =3D layer->has_xwhiteouts && > ovl_dentry_has_xwhiteouts(dentry)= ; > @@ -555,7 +628,7 @@ static bool ovl_fill_plain(struct dir_context *ctx, c= onst char *name, > container_of(ctx, struct ovl_readdir_data, ctx); > > rdd->count++; > - p =3D ovl_cache_entry_new(rdd, name, namelen, ino, d_type); > + p =3D ovl_cache_entry_new(rdd, name, namelen, NULL, 0, ino, d_typ= e); > if (p =3D=3D NULL) { > rdd->err =3D -ENOMEM; > return false; > @@ -1023,6 +1096,8 @@ int ovl_check_empty_dir(struct dentry *dentry, stru= ct list_head *list) > > del_entry: > list_del(&p->l_node); > + if (p->c_name !=3D p->name) > + kfree(p->c_name); > kfree(p); OK I thought this was contained in ovl_cache_free(). If we need to repeat this check, we need a helper ovl_cache_entry_free() to use instead of kfree(p) everywhere even in ovl_dir_read_impure() when it won't actually be needed. I can make this change on commit no need to repost. Thanks, Amir.