On 2025/8/26 10:09, Gao Xiang wrote:
>On 2025/8/25 20:06, Bo Liu wrote:
>> From: Bo Liu (OpenAnolis) <liub...@inspur.com>
>>
>> Add support for reading to the erofs volume label from the
>> FS_IOC_GETFSLABEL ioctls.
>>
>> Signed-off-by: Bo Liu (OpenAnolis) <liub...@inspur.com>
>> ---
>>   fs/erofs/Makefile   |  2 +-
>>   fs/erofs/data.c     |  4 ++++
>>   fs/erofs/dir.c      |  4 ++++
>>   fs/erofs/inode.c    |  2 +-
>>   fs/erofs/internal.h | 10 ++++++++++
>>   fs/erofs/ioctl.c    | 47
>+++++++++++++++++++++++++++++++++++++++++++++
>>   fs/erofs/super.c    |  2 ++
>>   fs/erofs/zdata.c    | 11 +++++++++++
>>   8 files changed, 80 insertions(+), 2 deletions(-)
>>   create mode 100644 fs/erofs/ioctl.c
>>
>> diff --git a/fs/erofs/Makefile b/fs/erofs/Makefile index
>> 549abc424763..5be6cc4acc1c 100644
>> --- a/fs/erofs/Makefile
>> +++ b/fs/erofs/Makefile
>> @@ -1,7 +1,7 @@
>>   # SPDX-License-Identifier: GPL-2.0-only
>>
>>   obj-$(CONFIG_EROFS_FS) += erofs.o
>> -erofs-objs := super.o inode.o data.o namei.o dir.o sysfs.o
>> +erofs-objs := super.o inode.o data.o namei.o dir.o sysfs.o ioctl.o
>>   erofs-$(CONFIG_EROFS_FS_XATTR) += xattr.o
>>   erofs-$(CONFIG_EROFS_FS_ZIP) += decompressor.o zmap.o zdata.o zutil.o
>>   erofs-$(CONFIG_EROFS_FS_ZIP_LZMA) += decompressor_lzma.o diff --git
>> a/fs/erofs/data.c b/fs/erofs/data.c index 3b1ba571c728..8ca29962a3dd
>> 100644
>> --- a/fs/erofs/data.c
>> +++ b/fs/erofs/data.c
>> @@ -475,6 +475,10 @@ static loff_t erofs_file_llseek(struct file *file, 
>> loff_t
>offset, int whence)
>>   const struct file_operations erofs_file_fops = {
>>      .llseek         = erofs_file_llseek,
>>      .read_iter      = erofs_file_read_iter,
>> +    .unlocked_ioctl = erofs_ioctl,
>> +#ifdef CONFIG_COMPAT
>> +    .compat_ioctl   = erofs_compat_ioctl,
>> +#endif
>>      .mmap_prepare   = erofs_file_mmap_prepare,
>>      .get_unmapped_area = thp_get_unmapped_area,
>>      .splice_read    = filemap_splice_read,
>> diff --git a/fs/erofs/dir.c b/fs/erofs/dir.c index
>> debf469ad6bd..32b4f5aa60c9 100644
>> --- a/fs/erofs/dir.c
>> +++ b/fs/erofs/dir.c
>> @@ -123,4 +123,8 @@ const struct file_operations erofs_dir_fops = {
>>      .llseek         = generic_file_llseek,
>>      .read           = generic_read_dir,
>>      .iterate_shared = erofs_readdir,
>> +    .unlocked_ioctl = erofs_ioctl,
>> +#ifdef CONFIG_COMPAT
>> +    .compat_ioctl   = erofs_compat_ioctl,
>> +#endif
>>   };
>> diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c index
>> 9a2f59721522..9248143e26df 100644
>> --- a/fs/erofs/inode.c
>> +++ b/fs/erofs/inode.c
>> @@ -214,7 +214,7 @@ static int erofs_fill_inode(struct inode *inode)
>>      case S_IFREG:
>>              inode->i_op = &erofs_generic_iops;
>>              if (erofs_inode_is_data_compressed(vi->datalayout))
>> -                    inode->i_fop = &generic_ro_fops;
>> +                    inode->i_fop = &z_erofs_file_fops;
>
>Please also just use erofs_file_fops instead and adjust
>erofs_file_read_iter() for example.
>
>>              else
>>                      inode->i_fop = &erofs_file_fops;
>>              break;
>> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h index
>> 4ccc5f0ee8df..2f874b920c8b 100644
>> --- a/fs/erofs/internal.h
>> +++ b/fs/erofs/internal.h
>> @@ -32,6 +32,8 @@ __printf(2, 3) void _erofs_printk(struct super_block *sb,
>const char *fmt, ...);
>>   #define DBG_BUGON(x)            ((void)(x))
>>   #endif     /* !CONFIG_EROFS_FS_DEBUG */
>>
>> +#define EROFS_VOLUME_LABEL_LEN      16
>> +
>>   /* EROFS_SUPER_MAGIC_V1 to represent the whole file system */
>>   #define EROFS_SUPER_MAGIC   EROFS_SUPER_MAGIC_V1
>>
>> @@ -166,6 +168,9 @@ struct erofs_sb_info {
>>      struct erofs_domain *domain;
>>      char *fsid;
>>      char *domain_id;
>> +
>> +    /* volume name */
>> +    u8 volume_label[EROFS_VOLUME_LABEL_LEN];
>
>       char *volume_name;
>
>>   };
>>
>>   #define EROFS_SB(sb) ((struct erofs_sb_info *)(sb)->s_fs_info) @@
>> -404,6 +409,7 @@ extern const struct inode_operations erofs_dir_iops;
>>
>>   extern const struct file_operations erofs_file_fops;
>>   extern const struct file_operations erofs_dir_fops;
>> +extern const struct file_operations z_erofs_file_fops;
>>
>>   extern const struct iomap_ops z_erofs_iomap_report_ops;
>>
>> @@ -535,6 +541,10 @@ static inline struct bio
>*erofs_fscache_bio_alloc(struct erofs_map_dev *mdev) {
>>   static inline void erofs_fscache_submit_bio(struct bio *bio) {}
>>   #endif
>>
>> +long erofs_ioctl(struct file *filp, unsigned int cmd, unsigned long
>> +arg); long erofs_compat_ioctl(struct file *filp, unsigned int cmd,
>> +                    unsigned long arg);
>> +
>>   #define EFSCORRUPTED    EUCLEAN         /* Filesystem is corrupted
>*/
>>
>>   #endif     /* __EROFS_INTERNAL_H */
>> diff --git a/fs/erofs/ioctl.c b/fs/erofs/ioctl.c new file mode 100644
>> index 000000000000..10bfd593225f
>> --- /dev/null
>> +++ b/fs/erofs/ioctl.c
>> @@ -0,0 +1,47 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later #include <linux/fs.h>
>> +#include <linux/compat.h> #include <linux/file.h>
>> +
>> +#include "erofs_fs.h"
>> +#include "internal.h"
>> +
>> +static int erofs_ioctl_get_volume_label(struct inode *inode, void
>> +__user *arg) {
>> +    struct erofs_sb_info *sbi = EROFS_I_SB(inode);
>> +    size_t len;
>> +    int ret;
>> +    char label[EROFS_VOLUME_LABEL_LEN];
>> +
>> +    memcpy(label, sbi->volume_label, EROFS_VOLUME_LABEL_LEN);
>> +
>> +    len = strnlen(label, EROFS_VOLUME_LABEL_LEN);
>> +    if (len == EROFS_VOLUME_LABEL_LEN)
>> +            erofs_err(inode->i_sb, "label is too long, return the first %zu 
>> bytes",
>> +                      --len);
>
>No needed.
>
>> +
>> +    ret = copy_to_user(arg, label, len);
>
>
>       if (!sbi->volume_name)
>               ret = clear_user(arg, 1);
>       else
>               ret = copy_to_user(arg, sbi->volume_name,
>                                  strlen(sbi->volume_name));
>       return ret ? -EFAULT : 0;
>
>...
>
>> +
>> +    return ret ? -EFAULT : 0;
>> +}
>> +
>> +long erofs_ioctl(struct file *filp, unsigned int cmd, unsigned long
>> +arg) {
>> +    struct inode *inode = file_inode(filp);
>> +    void __user *argp = (void __user *)arg;
>> +
>> +    switch (cmd) {
>> +    case FS_IOC_GETFSLABEL:
>> +            return erofs_ioctl_get_volume_label(inode, argp);
>> +    default:
>> +            return -ENOTTY;
>> +    }
>> +}
>> +
>> +#ifdef CONFIG_COMPAT
>> +long erofs_compat_ioctl(struct file *filp, unsigned int cmd,
>> +                    unsigned long arg)
>> +{
>> +    return erofs_ioctl(filp, cmd, (unsigned long)compat_ptr(arg)); }
>> +#endif
>> diff --git a/fs/erofs/super.c b/fs/erofs/super.c index
>> 1b529ace4db0..e6ad6cf4ba82 100644
>> --- a/fs/erofs/super.c
>> +++ b/fs/erofs/super.c
>> @@ -343,6 +343,8 @@ static int erofs_read_superblock(struct super_block
>*sb)
>>      sbi->fixed_nsec = le32_to_cpu(dsb->fixed_nsec);
>>      super_set_uuid(sb, (void *)dsb->uuid, sizeof(dsb->uuid));
>>
>> +    memcpy(sbi->volume_label, dsb->volume_name,
>EROFS_VOLUME_LABEL_LEN);
>
>       if (dsb->volume_name[0]) {
>               sbi->volume_name = kstrndup(dsb->volume_name,
>dsb->volume_name, GFP_KERNEL);
>               if (!sbi->volume_name) {
>                       ...
>               }
>       }
>
>Need to kfree(sbi->volume_name) properly too.
>
>Thanks,
>Gao Xiang
>
>> +
>>      /* parse on-disk compression configurations */
>>      ret = z_erofs_parse_cfgs(sb, dsb);
>>      if (ret < 0)
>> diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index
>> 2d73297003d2..b612bf7b2f08 100644
>> --- a/fs/erofs/zdata.c
>> +++ b/fs/erofs/zdata.c
>> @@ -1931,3 +1931,14 @@ const struct address_space_operations
>z_erofs_aops = {
>>      .read_folio = z_erofs_read_folio,
>>      .readahead = z_erofs_readahead,
>>   };
>> +
>> +const struct file_operations z_erofs_file_fops = {
>> +    .llseek         = generic_file_llseek,
>> +    .read_iter      = generic_file_read_iter,
>> +    .unlocked_ioctl = erofs_ioctl,
>> +#ifdef CONFIG_COMPAT
>> +    .compat_ioctl   = erofs_compat_ioctl,
>> +#endif
>> +    .mmap           = generic_file_readonly_mmap,
>> +    .splice_read    = filemap_splice_read,
>> +};

Thanks for your comments.
I will send the next version of the patch later.

Thanks,
Bo Liu

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