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[85.23.89.224]) by smtp.gmail.com with ESMTPSA id n18sm1313191ljg.40.2021.08.22.20.51.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 22 Aug 2021 20:51:52 -0700 (PDT) Date: Mon, 23 Aug 2021 06:51:50 +0300 From: Kari Argillander To: Pali =?utf-8?B?Um9ow6Fy?= Cc: linux-fsdevel@vger.kernel.org, linux-ntfs-dev@lists.sourceforge.net, linux-cifs@vger.kernel.org, jfs-discussion@lists.sourceforge.net, linux-kernel@vger.kernel.org, Alexander Viro , Jan Kara , OGAWA Hirofumi , "Theodore Y . Ts'o" , Luis de Bethencourt , Salah Triki , Andrew Morton , Dave Kleikamp , Anton Altaparmakov , Pavel Machek , Marek =?utf-8?B?QmVow7pu?= , Christoph Hellwig Subject: Re: [RFC PATCH 01/20] fat: Fix iocharset=utf8 mount option Message-ID: <20210823035150.h3dor7hanhzua7lh@kari-VirtualBox> References: <20210808162453.1653-1-pali@kernel.org> <20210808162453.1653-2-pali@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20210808162453.1653-2-pali@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org On Sun, Aug 08, 2021 at 06:24:34PM +0200, Pali Rohár wrote: > Currently iocharset=utf8 mount option is broken and error is printed to > dmesg when it is used. To use UTF-8 as iocharset, it is required to use > utf8=1 mount option. > > Fix iocharset=utf8 mount option to use be equivalent to the utf8=1 mount > option and remove printing error from dmesg. > > FAT by definition is case-insensitive but current Linux implementation is > case-sensitive for non-ASCII characters when UTF-8 is used. This patch does > not change this UTF-8 behavior. Only more comments in fat_utf8_strnicmp() > function are added about it. > > After this patch iocharset=utf8 starts working, so there is no need to have > separate config option FAT_DEFAULT_UTF8 as FAT_DEFAULT_IOCHARSET for utf8 > also starts working. So remove redundant config option FAT_DEFAULT_UTF8. > > Signed-off-by: Pali Rohár > --- > fs/fat/Kconfig | 15 --------------- > fs/fat/dir.c | 17 +++++++---------- > fs/fat/fat.h | 22 ++++++++++++++++++++++ > fs/fat/inode.c | 28 +++++++++++----------------- > fs/fat/namei_vfat.c | 26 +++++++++++++++++++------- > 5 files changed, 59 insertions(+), 49 deletions(-) > > diff --git a/fs/fat/Kconfig b/fs/fat/Kconfig > index 66532a71e8fd..a31594137d5e 100644 > --- a/fs/fat/Kconfig > +++ b/fs/fat/Kconfig > @@ -100,18 +100,3 @@ config FAT_DEFAULT_IOCHARSET > > Enable any character sets you need in File Systems/Native Language > Support. > - > -config FAT_DEFAULT_UTF8 > - bool "Enable FAT UTF-8 option by default" > - depends on VFAT_FS > - default n > - help > - Set this if you would like to have "utf8" mount option set > - by default when mounting FAT filesystems. > - > - Even if you say Y here can always disable UTF-8 for > - particular mount by adding "utf8=0" to mount options. > - > - Say Y if you use UTF-8 encoding for file names, N otherwise. > - > - See for more information. > diff --git a/fs/fat/dir.c b/fs/fat/dir.c > index c4a274285858..49fe8dc6e5f0 100644 > --- a/fs/fat/dir.c > +++ b/fs/fat/dir.c > @@ -33,11 +33,6 @@ > #define FAT_MAX_UNI_CHARS ((MSDOS_SLOTS - 1) * 13 + 1) > #define FAT_MAX_UNI_SIZE (FAT_MAX_UNI_CHARS * sizeof(wchar_t)) > > -static inline unsigned char fat_tolower(unsigned char c) > -{ > - return ((c >= 'A') && (c <= 'Z')) ? c+32 : c; > -} > - > static inline loff_t fat_make_i_pos(struct super_block *sb, > struct buffer_head *bh, > struct msdos_dir_entry *de) > @@ -258,10 +253,12 @@ static inline int fat_name_match(struct msdos_sb_info *sbi, > if (a_len != b_len) > return 0; > > - if (sbi->options.name_check != 's') > - return !nls_strnicmp(sbi->nls_io, a, b, a_len); > - else > + if (sbi->options.name_check == 's') > return !memcmp(a, b, a_len); > + else if (sbi->options.utf8) > + return !fat_utf8_strnicmp(a, b, a_len); > + else > + return !nls_strnicmp(sbi->nls_io, a, b, a_len); > } > > enum { PARSE_INVALID = 1, PARSE_NOT_LONGNAME, PARSE_EOF, }; > @@ -384,7 +381,7 @@ static int fat_parse_short(struct super_block *sb, > de->lcase & CASE_LOWER_BASE); > if (chl <= 1) { > if (!isvfat) > - ptname[i] = nocase ? c : fat_tolower(c); > + ptname[i] = nocase ? c : fat_ascii_to_lower(c); > i++; > if (c != ' ') { > name_len = i; > @@ -421,7 +418,7 @@ static int fat_parse_short(struct super_block *sb, > if (chl <= 1) { > k++; > if (!isvfat) > - ptname[i] = nocase ? c : fat_tolower(c); > + ptname[i] = nocase ? c : fat_ascii_to_lower(c); > i++; > if (c != ' ') { > name_len = i; > diff --git a/fs/fat/fat.h b/fs/fat/fat.h > index 02d4d4234956..0cd15fb3b042 100644 > --- a/fs/fat/fat.h > +++ b/fs/fat/fat.h > @@ -310,6 +310,28 @@ static inline void fatwchar_to16(__u8 *dst, const wchar_t *src, size_t len) > #endif > } > > +static inline unsigned char fat_ascii_to_lower(unsigned char c) > +{ > + return ((c >= 'A') && (c <= 'Z')) ? c+32 : c; > +} > + > +static inline int fat_utf8_strnicmp(const unsigned char *a, > + const unsigned char *b, > + int len) > +{ > + int i; > + > + /* > + * FIXME: UTF-8 doesn't provide FAT semantics > + * Case-insensitive support is only for 7-bit ASCII characters > + */ > + for (i = 0; i < len; i++) { > + if (fat_ascii_to_lower(a[i]) != fat_ascii_to_lower(b[i])) > + return 1; > + } > + return 0; > +} > + > /* fat/cache.c */ > extern void fat_cache_inval_inode(struct inode *inode); > extern int fat_get_cluster(struct inode *inode, int cluster, > diff --git a/fs/fat/inode.c b/fs/fat/inode.c > index de0c9b013a85..f8c8a739f8f0 100644 > --- a/fs/fat/inode.c > +++ b/fs/fat/inode.c > @@ -957,7 +957,9 @@ static int fat_show_options(struct seq_file *m, struct dentry *root) > /* strip "cp" prefix from displayed option */ > seq_printf(m, ",codepage=%s", &sbi->nls_disk->charset[2]); > if (isvfat) { > - if (sbi->nls_io) > + if (opts->utf8) > + seq_printf(m, ",iocharset=utf8"); checkpatch will probably warn you about this. WARNING: Prefer seq_puts to seq_printf > + else if (sbi->nls_io) > seq_printf(m, ",iocharset=%s", sbi->nls_io->charset); > > switch (opts->shortname) { > @@ -994,8 +996,6 @@ static int fat_show_options(struct seq_file *m, struct dentry *root) > if (opts->nocase) > seq_puts(m, ",nocase"); > } else { > - if (opts->utf8) > - seq_puts(m, ",utf8"); > if (opts->unicode_xlate) > seq_puts(m, ",uni_xlate"); > if (!opts->numtail) > @@ -1157,8 +1157,6 @@ static int parse_options(struct super_block *sb, char *options, int is_vfat, > opts->errors = FAT_ERRORS_RO; > *debug = 0; > > - opts->utf8 = IS_ENABLED(CONFIG_FAT_DEFAULT_UTF8) && is_vfat; > - > if (!options) > goto out; > > @@ -1319,10 +1317,14 @@ static int parse_options(struct super_block *sb, char *options, int is_vfat, > | VFAT_SFN_CREATE_WIN95; > break; > case Opt_utf8_no: /* 0 or no or false */ > - opts->utf8 = 0; > + fat_reset_iocharset(opts); > break; > case Opt_utf8_yes: /* empty or 1 or yes or true */ > - opts->utf8 = 1; > + fat_reset_iocharset(opts); > + iocharset = kstrdup("utf8", GFP_KERNEL); > + if (!iocharset) > + return -ENOMEM; > + opts->iocharset = iocharset; > break; > case Opt_uni_xl_no: /* 0 or no or false */ > opts->unicode_xlate = 0; > @@ -1360,18 +1362,11 @@ static int parse_options(struct super_block *sb, char *options, int is_vfat, > } > > out: > - /* UTF-8 doesn't provide FAT semantics */ > - if (!strcmp(opts->iocharset, "utf8")) { > - fat_msg(sb, KERN_WARNING, "utf8 is not a recommended IO charset" > - " for FAT filesystems, filesystem will be " > - "case sensitive!"); > - } > + opts->utf8 = !strcmp(opts->iocharset, "utf8") && is_vfat; > > /* If user doesn't specify allow_utime, it's initialized from dmask. */ > if (opts->allow_utime == (unsigned short)-1) > opts->allow_utime = ~opts->fs_dmask & (S_IWGRP | S_IWOTH); > - if (opts->unicode_xlate) > - opts->utf8 = 0; > if (opts->nfs == FAT_NFS_NOSTALE_RO) { > sb->s_flags |= SB_RDONLY; > sb->s_export_op = &fat_export_ops_nostale; > @@ -1832,8 +1827,7 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat, > goto out_fail; > } > > - /* FIXME: utf8 is using iocharset for upper/lower conversion */ > - if (sbi->options.isvfat) { > + if (sbi->options.isvfat && !sbi->options.utf8) { > sbi->nls_io = load_nls(sbi->options.iocharset); > if (!sbi->nls_io) { > fat_msg(sb, KERN_ERR, "IO charset %s not found", > diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c > index 5369d82e0bfb..efb3cb9ea8a8 100644 > --- a/fs/fat/namei_vfat.c > +++ b/fs/fat/namei_vfat.c > @@ -134,6 +134,7 @@ static int vfat_hash(const struct dentry *dentry, struct qstr *qstr) > static int vfat_hashi(const struct dentry *dentry, struct qstr *qstr) > { > struct nls_table *t = MSDOS_SB(dentry->d_sb)->nls_io; > + int utf8 = MSDOS_SB(dentry->d_sb)->options.utf8; > const unsigned char *name; > unsigned int len; > unsigned long hash; > @@ -142,8 +143,17 @@ static int vfat_hashi(const struct dentry *dentry, struct qstr *qstr) > len = vfat_striptail_len(qstr); > > hash = init_name_hash(dentry); > - while (len--) > - hash = partial_name_hash(nls_tolower(t, *name++), hash); > + if (utf8) { > + /* > + * FIXME: UTF-8 doesn't provide FAT semantics > + * Case-insensitive support is only for 7-bit ASCII characters > + */ > + while (len--) > + hash = partial_name_hash(fat_ascii_to_lower(*name++), hash); > + } else { > + while (len--) > + hash = partial_name_hash(nls_tolower(t, *name++), hash); > + } > qstr->hash = end_name_hash(hash); > > return 0; > @@ -156,16 +166,18 @@ static int vfat_cmpi(const struct dentry *dentry, > unsigned int len, const char *str, const struct qstr *name) > { > struct nls_table *t = MSDOS_SB(dentry->d_sb)->nls_io; > + int utf8 = MSDOS_SB(dentry->d_sb)->options.utf8; > unsigned int alen, blen; > > /* A filename cannot end in '.' or we treat it like it has none */ > alen = vfat_striptail_len(name); > blen = __vfat_striptail_len(len, str); > - if (alen == blen) { > - if (nls_strnicmp(t, name->name, str, alen) == 0) > - return 0; > - } > - return 1; > + if (alen != blen) > + return 1; > + else if (utf8) > + return fat_utf8_strnicmp(name->name, str, alen); > + else > + return nls_strnicmp(t, name->name, str, alen); > } > > /* > -- > 2.20.1 >