On 2025/9/23 15:01, Bo Liu wrote:
From: Bo Liu (OpenAnolis) <[email protected]>

Add support for reading to the erofs volume label from the
FS_IOC_GETFSLABEL ioctls.

Signed-off-by: Bo Liu (OpenAnolis) <[email protected]>
Reviewed-by: Gao Xiang <[email protected]>

Reviewed-by: Hongbo Li <[email protected]>

Thanks,
Hongbo

---

v1: 
https://lore.kernel.org/linux-erofs/[email protected]/
v2: 
https://lore.kernel.org/linux-erofs/[email protected]/
v3: 
https://lore.kernel.org/linux-erofs/[email protected]/
v4: 
https://lore.kernel.org/linux-erofs/[email protected]/

change since v4:
- fix 0day build errors.

  fs/erofs/data.c     |  4 ++++
  fs/erofs/dir.c      |  4 ++++
  fs/erofs/inode.c    | 41 +++++++++++++++++++++++++++++++++++++----
  fs/erofs/internal.h |  6 ++++++
  fs/erofs/super.c    |  8 ++++++++
  5 files changed, 59 insertions(+), 4 deletions(-)

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..a3c505e9425d 100644
--- a/fs/erofs/inode.c
+++ b/fs/erofs/inode.c
@@ -5,6 +5,7 @@
   * Copyright (C) 2021, Alibaba Cloud
   */
  #include "xattr.h"
+#include <linux/compat.h>
  #include <trace/events/erofs.h>
static int erofs_fill_symlink(struct inode *inode, void *kaddr,
@@ -213,10 +214,7 @@ static int erofs_fill_inode(struct inode *inode)
        switch (inode->i_mode & S_IFMT) {
        case S_IFREG:
                inode->i_op = &erofs_generic_iops;
-               if (erofs_inode_is_data_compressed(vi->datalayout))
-                       inode->i_fop = &generic_ro_fops;
-               else
-                       inode->i_fop = &erofs_file_fops;
+               inode->i_fop = &erofs_file_fops;
                break;
        case S_IFDIR:
                inode->i_op = &erofs_dir_iops;
@@ -341,6 +339,41 @@ int erofs_getattr(struct mnt_idmap *idmap, const struct 
path *path,
        return 0;
  }
+static int erofs_ioctl_get_volume_label(struct inode *inode, void __user *arg)
+{
+       struct erofs_sb_info *sbi = EROFS_I_SB(inode);
+       int ret;
+
+       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;
+}
+
+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
+
  const struct inode_operations erofs_generic_iops = {
        .getattr = erofs_getattr,
        .listxattr = erofs_listxattr,
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 4ccc5f0ee8df..b70902e00586 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -166,6 +166,8 @@ struct erofs_sb_info {
        struct erofs_domain *domain;
        char *fsid;
        char *domain_id;
+
+       char *volume_name;
  };
#define EROFS_SB(sb) ((struct erofs_sb_info *)(sb)->s_fs_info)
@@ -535,6 +537,10 @@ 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/super.c b/fs/erofs/super.c
index 1b529ace4db0..f1535ebe03ec 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -343,6 +343,13 @@ 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));
+ if (dsb->volume_name[0]) {
+               sbi->volume_name = kstrndup(dsb->volume_name,
+                                           sizeof(dsb->volume_name), 
GFP_KERNEL);
+               if (!sbi->volume_name)
+                       return -ENOMEM;
+       }
+
        /* parse on-disk compression configurations */
        ret = z_erofs_parse_cfgs(sb, dsb);
        if (ret < 0)
@@ -822,6 +829,7 @@ static void erofs_sb_free(struct erofs_sb_info *sbi)
        kfree(sbi->domain_id);
        if (sbi->dif0.file)
                fput(sbi->dif0.file);
+       kfree(sbi->volume_name);
        kfree(sbi);
  }

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