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Date: Wed, 17 Jul 2019 17:39:07 +0800
From: Chao Yu <yuchao0@...wei.com>
To: Daniel Rosenberg <drosen@...gle.com>,
Jaegeuk Kim <jaegeuk@...nel.org>,
Jonathan Corbet <corbet@....net>,
<linux-f2fs-devel@...ts.sourceforge.net>
CC: <linux-kernel@...r.kernel.org>, <linux-doc@...r.kernel.org>,
<linux-fsdevel@...r.kernel.org>, <kernel-team@...roid.com>
Subject: Re: [PATCH v2 1/2] f2fs: include charset encoding information in the
superblock
On 2019/7/17 11:14, Daniel Rosenberg wrote:
> Add charset encoding to f2fs to support casefolding. It is modeled after
> the same feature introduced in commit c83ad55eaa91 ("ext4: include charset
> encoding information in the superblock")
>
> Currently this is not compatible with encryption, similar to the current
> ext4 imlpementation. This will change in the future.
>
>>>From the ext4 patch:
> """
> The s_encoding field stores a magic number indicating the encoding
> format and version used globally by file and directory names in the
> filesystem. The s_encoding_flags defines policies for using the charset
> encoding, like how to handle invalid sequences. The magic number is
> mapped to the exact charset table, but the mapping is specific to ext4.
> Since we don't have any commitment to support old encodings, the only
> encoding I am supporting right now is utf8-12.1.0.
>
> The current implementation prevents the user from enabling encoding and
> per-directory encryption on the same filesystem at the same time. The
> incompatibility between these features lies in how we do efficient
> directory searches when we cannot be sure the encryption of the user
> provided fname will match the actual hash stored in the disk without
> decrypting every directory entry, because of normalization cases. My
> quickest solution is to simply block the concurrent use of these
> features for now, and enable it later, once we have a better solution.
> """
>
> Signed-off-by: Daniel Rosenberg <drosen@...gle.com>
> ---
> fs/f2fs/f2fs.h | 6 +++
> fs/f2fs/super.c | 81 +++++++++++++++++++++++++++++++++++++++++
> include/linux/f2fs_fs.h | 9 ++++-
> 3 files changed, 95 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 17382da7f0bd9..c6c7904572d0d 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -153,6 +153,7 @@ struct f2fs_mount_info {
> #define F2FS_FEATURE_LOST_FOUND 0x0200
> #define F2FS_FEATURE_VERITY 0x0400 /* reserved */
> #define F2FS_FEATURE_SB_CHKSUM 0x0800
> +#define F2FS_FEATURE_CASEFOLD 0x1000
>
> #define __F2FS_HAS_FEATURE(raw_super, mask) \
> ((raw_super->feature & cpu_to_le32(mask)) != 0)
> @@ -1169,6 +1170,10 @@ struct f2fs_sb_info {
> int valid_super_block; /* valid super block no */
> unsigned long s_flag; /* flags for sbi */
> struct mutex writepages; /* mutex for writepages() */
> +#ifdef CONFIG_UNICODE
> + struct unicode_map *s_encoding;
> + __u16 s_encoding_flags;
> +#endif
>
> #ifdef CONFIG_BLK_DEV_ZONED
> unsigned int blocks_per_blkz; /* F2FS blocks per zone */
> @@ -3562,6 +3567,7 @@ F2FS_FEATURE_FUNCS(quota_ino, QUOTA_INO);
> F2FS_FEATURE_FUNCS(inode_crtime, INODE_CRTIME);
> F2FS_FEATURE_FUNCS(lost_found, LOST_FOUND);
> F2FS_FEATURE_FUNCS(sb_chksum, SB_CHKSUM);
> +F2FS_FEATURE_FUNCS(casefold, CASEFOLD);
It needs to change sysfs.c like we did for other features, you can refer to
d440c52d3151 ("f2fs: support superblock checksum").
>
> #ifdef CONFIG_BLK_DEV_ZONED
> static inline bool f2fs_blkz_is_seq(struct f2fs_sb_info *sbi, int devi,
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 6de6cda440315..7927071ef5e95 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -23,6 +23,7 @@
> #include <linux/f2fs_fs.h>
> #include <linux/sysfs.h>
> #include <linux/quota.h>
> +#include <linux/unicode.h>
>
> #include "f2fs.h"
> #include "node.h"
> @@ -222,6 +223,36 @@ void f2fs_printk(struct f2fs_sb_info *sbi, const char *fmt, ...)
> va_end(args);
> }
>
> +#ifdef CONFIG_UNICODE
> +static const struct f2fs_sb_encodings {
> + __u16 magic;
> + char *name;
> + char *version;
> +} f2fs_sb_encoding_map[] = {
> + {F2FS_ENC_UTF8_12_1, "utf8", "12.1.0"},
> +};
> +
> +static int f2fs_sb_read_encoding(const struct f2fs_super_block *sb,
> + const struct f2fs_sb_encodings **encoding,
> + __u16 *flags)
> +{
> + __u16 magic = le16_to_cpu(sb->s_encoding);
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(f2fs_sb_encoding_map); i++)
> + if (magic == f2fs_sb_encoding_map[i].magic)
> + break;
> +
> + if (i >= ARRAY_SIZE(f2fs_sb_encoding_map))
> + return -EINVAL;
> +
> + *encoding = &f2fs_sb_encoding_map[i];
> + *flags = le16_to_cpu(sb->s_encoding_flags);
> +
> + return 0;
> +}
> +#endif
> +
> static inline void limit_reserve_root(struct f2fs_sb_info *sbi)
> {
> block_t limit = min((sbi->user_block_count << 1) / 1000,
> @@ -798,6 +829,13 @@ static int parse_options(struct super_block *sb, char *options)
> return -EINVAL;
> }
> #endif
> +#ifndef CONFIG_UNICODE
> + if (f2fs_sb_has_casefold(sbi)) {
> + f2fs_err(sbi,
> + "Filesystem with casefold feature cannot be mounted without CONFIG_UNICODE");
> + return -EINVAL;
> + }
> +#endif
>
> if (F2FS_IO_SIZE_BITS(sbi) && !test_opt(sbi, LFS)) {
> f2fs_err(sbi, "Should set mode=lfs with %uKB-sized IO",
> @@ -1089,6 +1127,9 @@ static void f2fs_put_super(struct super_block *sb)
> destroy_percpu_info(sbi);
> for (i = 0; i < NR_PAGE_TYPE; i++)
> kvfree(sbi->write_io[i]);
> +#ifdef CONFIG_UNICODE
> + utf8_unload(sbi->s_encoding);
> +#endif
> kvfree(sbi);
> }
>
> @@ -3126,6 +3167,42 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
> sb->s_maxbytes = sbi->max_file_blocks <<
> le32_to_cpu(raw_super->log_blocksize);
> sb->s_max_links = F2FS_LINK_MAX;
> +#ifdef CONFIG_UNICODE
> + if (f2fs_sb_has_casefold(sbi) && !sbi->s_encoding) {
> + const struct f2fs_sb_encodings *encoding_info;
> + struct unicode_map *encoding;
> + __u16 encoding_flags;
> +
> + if (f2fs_sb_has_encrypt(sbi)) {
> + f2fs_err(sbi,
> + "Can't mount with encoding and encryption");
Should set error number.
> + goto free_options;
> + }
> +
> + if (f2fs_sb_read_encoding(raw_super, &encoding_info,
> + &encoding_flags)) {
> + f2fs_err(sbi,
> + "Encoding requested by superblock is unknown");
Ditto
> + goto free_options;
> + }
> +
> + encoding = utf8_load(encoding_info->version);
> + if (IS_ERR(encoding)) {
> + f2fs_err(sbi,
> + "can't mount with superblock charset: %s-%s "
> + "not supported by the kernel. flags: 0x%x.",
> + encoding_info->name, encoding_info->version,
> + encoding_flags);
Ditto
> + goto free_options;
> + }
> + f2fs_info(sbi, "Using encoding defined by superblock: "
> + "%s-%s with flags 0x%hx", encoding_info->name,
> + encoding_info->version?:"\b", encoding_flags);
> +
> + sbi->s_encoding = encoding;
> + sbi->s_encoding_flags = encoding_flags;
> + }
> +#endif
How about wrapping these codes into function?
Thanks,
>
> #ifdef CONFIG_QUOTA
> sb->dq_op = &f2fs_quota_operations;
> @@ -3477,6 +3554,10 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
> free_bio_info:
> for (i = 0; i < NR_PAGE_TYPE; i++)
> kvfree(sbi->write_io[i]);
> +
> +#ifdef CONFIG_UNICODE
> + utf8_unload(sbi->s_encoding);
> +#endif
> free_options:
> #ifdef CONFIG_QUOTA
> for (i = 0; i < MAXQUOTAS; i++)
> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> index 65559900d4d76..b7c9c7f721339 100644
> --- a/include/linux/f2fs_fs.h
> +++ b/include/linux/f2fs_fs.h
> @@ -36,6 +36,11 @@
>
> #define F2FS_MAX_QUOTAS 3
>
> +#define F2FS_ENC_UTF8_12_1 1
> +#define F2FS_ENC_STRICT_MODE_FL (1 << 0)
> +#define f2fs_has_strict_mode(sbi) \
> + (sbi->s_encoding_flags & F2FS_ENC_STRICT_MODE_FL)
> +
> #define F2FS_IO_SIZE(sbi) (1 << F2FS_OPTION(sbi).write_io_size_bits) /* Blocks */
> #define F2FS_IO_SIZE_KB(sbi) (1 << (F2FS_OPTION(sbi).write_io_size_bits + 2)) /* KB */
> #define F2FS_IO_SIZE_BYTES(sbi) (1 << (F2FS_OPTION(sbi).write_io_size_bits + 12)) /* B */
> @@ -109,7 +114,9 @@ struct f2fs_super_block {
> struct f2fs_device devs[MAX_DEVICES]; /* device list */
> __le32 qf_ino[F2FS_MAX_QUOTAS]; /* quota inode numbers */
> __u8 hot_ext_count; /* # of hot file extension */
> - __u8 reserved[310]; /* valid reserved region */
> + __le16 s_encoding; /* Filename charset encoding */
> + __le16 s_encoding_flags; /* Filename charset encoding flags */
> + __u8 reserved[306]; /* valid reserved region */
> __le32 crc; /* checksum of superblock */
> } __packed;
>
>
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