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AJvYcCUgDtKU0nkudQzLZAtQFEP1XYamkm/tyI65FvNQJxWv5pNXcQQjAizy6Mcb9WNscppIWzBSqXbsUU1y3uJT@vger.kernel.org, AJvYcCUwGH/aBvL0523ba8VLaR67oRClkGiYhfkF23vA75akPUStLmY9qJOZRMIHV9RJ82c8vayk+gNZQD60mT5A@vger.kernel.org, AJvYcCVAGiudtT6vzR+ZWIKWXuBjJmBiLk+0ehCVFUu2EZ7S9D0Xm1h5FbF7qS9TL7G0aGSnUOK3sirYyfw1Np63kg==@vger.kernel.org X-Gm-Message-State: AOJu0YybCR1bnhr8f/4DksF9qmJ6v6ZDKpcitVutgTQA5sLK+42UeLbU pg9WZpPAWBl6cQKbkhmtUSfMMSn8Jobuq6DWYKhJwFNm6jlA4Lq+3jpBnJqaQfWFnXW8sjv3vuG Nrdl6APdrxxYnRDuwFQStuU6cKxlRne4= X-Gm-Gg: ASbGncuGa71NcTZ4dSDxMLCUurir38WQ6MxzM52nsBHgKjltGuPVbiuShgHRTcMZ99d p4OUPJnxyvh4PmVW/CAwfrwhCxQTPi4VGeJyZshZXCkIJwozvZPebOKB9Ihhcf1isBVwm1VVJrO 6S8APwQ+JdVcfYlAYMaCtxXcH2Yq5Eu/9wut//rIM7dnARTuX3k8Mo7ULi/yvtCw5haFtyuOENE ixg308= X-Google-Smtp-Source: AGHT+IES/kdPcUbiRPAAbRz4Tp4WOFZqsbkPu8uIMfLyN/k4ZJO/cKJ4TooLegpUoe67jpwWijiAAfjMGXSOSEO0/+A= X-Received: by 2002:a05:6402:2694:b0:608:50ab:7e38 with SMTP id 4fb4d7f45d1cf-6188b9a6127mr3432232a12.14.1755197973139; Thu, 14 Aug 2025 11:59:33 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20250814-tonyk-overlayfs-v5-0-c5b80a909cbd@igalia.com> <20250814-tonyk-overlayfs-v5-4-c5b80a909cbd@igalia.com> In-Reply-To: <20250814-tonyk-overlayfs-v5-4-c5b80a909cbd@igalia.com> From: Amir Goldstein Date: Thu, 14 Aug 2025 20:59:21 +0200 X-Gm-Features: Ac12FXzEqpTy868WrZnYsgTzSINCWkuz4TbJK-lk8zLujrwkXc4ukyfSSKWFEKA Message-ID: Subject: Re: [PATCH v5 4/9] ovl: Create ovl_casefold() to support casefolded strncmp() To: =?UTF-8?Q?Andr=C3=A9_Almeida?= Cc: Miklos Szeredi , Theodore Tso , Gabriel Krisman Bertazi , linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Alexander Viro , Christian Brauner , Jan Kara , kernel-dev@igalia.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, Aug 14, 2025 at 7:22=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. > > Signed-off-by: Andr=C3=A9 Almeida > --- > Changes from v4: > - Move the consumer/free buffer logic out to the caller > - s/aux/c_name > > Changes from v3: > - Improve commit message text > - s/OVL_NAME_LEN/NAME_MAX > - drop #ifdef in favor of if(IS_ENABLED) > - use new helper sb_encoding > - merged patch "Store casefold name..." and "Create ovl_casefold()..." > - Guard all the casefolding inside of IS_ENABLED(UNICODE) > > Changes from v2: > - Refactor the patch to do a single kmalloc() per rb_tree operation > - Instead of casefolding the cache entry name everytime per strncmp(), > casefold it once and reuse it for every strncmp(). > --- > fs/overlayfs/readdir.c | 115 +++++++++++++++++++++++++++++++++++++++++--= ------ > 1 file changed, 97 insertions(+), 18 deletions(-) > > diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c > index b65cdfce31ce27172d28d879559f1008b9c87320..803ac6a7516d0156ae7793ee1= ff884dbbf2e20b0 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 *cf_name; > + int cf_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) > @@ -79,7 +103,7 @@ static bool ovl_cache_entry_find_link(const char *name= , 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->cf_name, tmp->cf_len); > if (cmp > 0) > newp =3D &tmp->node.rb_right; > else if (cmp < 0 || len < tmp->len) > @@ -101,7 +125,7 @@ static struct ovl_cache_entry *ovl_cache_entry_find(s= truct 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->cf_name, p->cf_len); > if (cmp > 0) > node =3D p->node.rb_right; > else if (cmp < 0 || len < p->len) > @@ -145,13 +169,16 @@ static bool ovl_calc_d_ino(struct ovl_readdir_data = *rdd, > > static struct ovl_cache_entry *ovl_cache_entry_new(struct ovl_readdir_da= ta *rdd, > const char *name, int = len, > + const char *cf_name, i= nt cf_len, > u64 ino, unsigned int = d_type) > { > struct ovl_cache_entry *p; > > p =3D kmalloc(struct_size(p, name, len + 1), GFP_KERNEL); > - if (!p) > + if (!p) { > + kfree(cf_name); Not needed. Caller will get -ENOMEM and will free c_name No need to repost just for this I can fix on commit. Reviewed-by: Amir Goldstein Thanks, Amir.