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[PATCH] erofs: Add support for FS_IOC_GETFSLABEL

Bo Liu posted 1 patch 1 month, 1 week ago
There is a newer version of this series
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
[PATCH] erofs: Add support for FS_IOC_GETFSLABEL
Posted by Bo Liu 1 month, 1 week ago 
From: Bo Liu (OpenAnolis) <liubo03@inspur.com>

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

Signed-off-by: Bo Liu (OpenAnolis) <liubo03@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;
 		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];
 };
 
 #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);
+
+	ret = copy_to_user(arg, label, len);
+
+	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);
+
 	/* 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,
+};
-- 
2.31.1
Re: [PATCH] erofs: Add support for FS_IOC_GETFSLABEL
Posted by Gao Xiang 1 month, 1 week ago 
Hi Bo,

On 2025/8/25 20:06, Bo Liu wrote:
> From: Bo Liu (OpenAnolis) <liubo03@inspur.com>
> 
> Add support for reading to the erofs volume label from the
> FS_IOC_GETFSLABEL ioctls.
> 
> Signed-off-by: Bo Liu (OpenAnolis) <liubo03@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,
> +};
Re: [PATCH] erofs: Add support for FS_IOC_GETFSLABEL
Posted by Bo Liu (刘波)-浪潮信息 1 month, 1 week ago 
On 2025/8/26 10:09, Gao Xiang wrote:
>On 2025/8/25 20:06, Bo Liu wrote:
>> From: Bo Liu (OpenAnolis) <liubo03@inspur.com>
>>
>> Add support for reading to the erofs volume label from the
>> FS_IOC_GETFSLABEL ioctls.
>>
>> Signed-off-by: Bo Liu (OpenAnolis) <liubo03@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

Patchew 2.1-devel-b67e4c2

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