[Deepin-Kernel-SIG] [linux 6.6-y] [Upstream] fs: backport VFS-related patches in preparation for EROFS file-backed mount #966
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Reviewer's GuideThis PR backports upstream VFS patches to introduce filesystem UUID and sysfs‐path support by extending super_block, adding new ioctls, and updating existing filesystems to use a unified super_set_uuid interface. Sequence diagram for FS_IOC_GETFSUUID ioctl handlingsequenceDiagram
actor User
participant Kernel as Kernel (do_vfs_ioctl)
participant File as file
participant SB as super_block
User->>Kernel: ioctl(fd, FS_IOC_GETFSUUID, ...)
Kernel->>File: get file_inode(file)
File->>SB: access s_uuid, s_uuid_len
Kernel-->>User: copy fsuuid2 struct to user
Sequence diagram for FS_IOC_GETFSSYSFSPATH ioctl handlingsequenceDiagram
actor User
participant Kernel as Kernel (do_vfs_ioctl)
participant File as file
participant SB as super_block
User->>Kernel: ioctl(fd, FS_IOC_GETFSSYSFSPATH, ...)
Kernel->>File: get file_inode(file)
File->>SB: access s_sysfs_name
Kernel-->>User: copy fs_sysfs_path struct to user
Class diagram for updated struct super_block and new helpersclassDiagram
class super_block {
char s_id[32]
uuid_t s_uuid
u8 s_uuid_len
char s_sysfs_name[UUID_STRING_LEN + 1]
...
}
class super_set_uuid {
+void super_set_uuid(super_block *sb, const u8 *uuid, unsigned len)
}
class super_set_sysfs_name_bdev {
+void super_set_sysfs_name_bdev(super_block *sb)
}
class super_set_sysfs_name_uuid {
+void super_set_sysfs_name_uuid(super_block *sb)
}
class super_set_sysfs_name_id {
+void super_set_sysfs_name_id(super_block *sb)
}
class super_set_sysfs_name_generic {
+void super_set_sysfs_name_generic(super_block *sb, const char *fmt, ...)
}
super_set_uuid --|> super_block : modifies
super_set_sysfs_name_bdev --|> super_block : modifies
super_set_sysfs_name_uuid --|> super_block : modifies
super_set_sysfs_name_id --|> super_block : modifies
super_set_sysfs_name_generic --|> super_block : modifies
Class diagram for new ioctl data structuresclassDiagram
class fsuuid2 {
__u8 len
__u8 uuid[16]
}
class fs_sysfs_path {
__u8 len
__u8 name[128]
}
File-Level Changes
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Pull Request Overview
This PR backports VFS-related patches from upstream to prepare for EROFS file-backed mount support. The changes introduce new filesystem ioctl operations and standardize UUID handling across filesystems.
- Adds new FS_IOC_GETFSUUID and FS_IOC_GETFSSYSFSPATH ioctl operations for filesystem introspection
- Introduces super_set_uuid() helper function and updates all filesystem drivers to use it consistently
- Extends super_block structure with s_uuid_len and s_sysfs_name fields for better filesystem identification
Reviewed Changes
Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| include/uapi/linux/fs.h | Defines new ioctl structures and command constants |
| include/linux/fs.h | Adds new super_block fields and UUID helper functions |
| fs/ioctl.c | Implements the new ioctl handlers |
| mm/shmem.c | Updates to use new super_set_uuid() helper |
| fs/kernfs/mount.c | Updates to use new super_set_uuid() helper |
| fs/xfs/xfs_mount.c | Updates to use new super_set_uuid() helper |
| fs/ubifs/super.c | Updates to use new super_set_uuid() helper |
| fs/ocfs2/super.c | Updates to use new super_set_uuid() helper |
| fs/gfs2/ops_fstype.c | Updates to use new super_set_uuid() helper |
| fs/f2fs/super.c | Updates to use new super_set_uuid() helper |
| fs/ext4/super.c | Updates to use new super_set_uuid() helper |
| Documentation/userspace-api/ioctl/ioctl-number.rst | Updates ioctl number documentation |
| * We include a length field because some filesystems (vfat) have an identifier | ||
| * that we do want to expose as a UUID, but doesn't have the standard length. | ||
| * | ||
| * We use a fixed size buffer beacuse this interface will, by fiat, never |
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Spelling error: 'beacuse' should be 'because'.
Suggested change
| * We use a fixed size buffer beacuse this interface will, by fiat, never | |
| * We use a fixed size buffer because this interface will, by fiat, never |
Copilot uses AI. Check for mistakes.
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| if (!strlen(sb->s_sysfs_name)) | ||
| return -ENOIOCTLCMD; | ||
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| struct fs_sysfs_path u = {}; | ||
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Variable declaration should be at the beginning of the function scope for C89 compatibility, not in the middle of the function after other statements.
Suggested change
| if (!strlen(sb->s_sysfs_name)) | |
| return -ENOIOCTLCMD; | |
| struct fs_sysfs_path u = {}; | |
| struct fs_sysfs_path u = {}; | |
| if (!strlen(sb->s_sysfs_name)) | |
| return -ENOIOCTLCMD; |
Copilot uses AI. Check for mistakes.
added 3 commits
July 22, 2025 11:17
commit a4af51c upstream. Some weird old filesytems have UUID-like things that we wish to expose as UUIDs, but are smaller; add a length field so that the new FS_IOC_(GET|SET)UUID ioctls can handle them in generic code. And add a helper super_set_uuid(), for setting nonstandard length uuids. Helper is now required for the new FS_IOC_GETUUID ioctl; if super_set_uuid() hasn't been called, the ioctl won't be supported. Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev> Link: https://lore.kernel.org/r/20240207025624.1019754-2-kent.overstreet@linux.dev Signed-off-by: Christian Brauner <brauner@kernel.org> [ Backport from v6.9 ] Signed-off-by: Hongzhen Luo <hongzhen@linux.alibaba.com> Signed-off-by: WangYuli <wangyuli@uniontech.com>
commit 41bcbe5 upstream. Add a new generic ioctls for querying the filesystem UUID. These are lifted versions of the ext4 ioctls, with one change: we're not using a flexible array member, because UUIDs will never be more than 16 bytes. This patch adds a generic implementation of FS_IOC_GETFSUUID, which reads from super_block->s_uuid. We're not lifting SETFSUUID from ext4 - that can be done on offline filesystems by the people who need it, trying to do it online is just asking for too much trouble. Cc: Christian Brauner <brauner@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Dave Chinner <dchinner@redhat.com> Cc: Darrick J. Wong <djwong@kernel.org> Cc: Theodore Ts'o <tytso@mit.edu> Cc: linux-fsdevel@vger.kernel.org Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev> Link: https://lore.kernel.org/r/20240207025624.1019754-4-kent.overstreet@linux.dev Signed-off-by: Christian Brauner <brauner@kernel.org> [ Backport from v6.9 ] Signed-off-by: Hongzhen Luo <hongzhen@linux.alibaba.com> Signed-off-by: WangYuli <wangyuli@uniontech.com>
commit ae8c511 upstream. Add a new ioctl for getting the sysfs name of a filesystem - the path under /sys/fs. This is going to let us standardize exporting data from sysfs across filesystems, e.g. time stats. The returned path will always be of the form "$FSTYP/$SYSFS_IDENTIFIER", where the sysfs identifier may be a UUID (for bcachefs) or a device name (xfs). Cc: Christian Brauner <brauner@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Dave Chinner <dchinner@redhat.com> Cc: Darrick J. Wong <djwong@kernel.org> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev> Link: https://lore.kernel.org/r/20240207025624.1019754-6-kent.overstreet@linux.dev Signed-off-by: Christian Brauner <brauner@kernel.org> [ Backport from v6.9 ] Signed-off-by: Hongzhen Luo <hongzhen@linux.alibaba.com> Signed-off-by: WangYuli <wangyuli@uniontech.com>
Avenger-285714
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deepin pr auto review代码审查意见：
总体来说，这些改动提高了代码的可读性、可维护性和功能性，但应进一步确保所有新增函数和结构体的正确性和一致性。 |
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Hey @Avenger-285714 - I've reviewed your changes - here's some feedback:
- The new IOCTL FS_IOC_GETFSSYSFSPATH exposes internal sysfs paths without any capability checks; consider adding a permission check (e.g. CAP_SYS_ADMIN) to avoid leaking kernel internals to unprivileged users.
- The Q/A style comment block added above the super_block fields deviates from kernel coding style—please convert it into a concise explanatory comment or remove the ‘q:/a:’ lines.
- In ioctl_get_fs_sysfs_path, replace strlen(sb->s_sysfs_name) with a simple sb->s_sysfs_name[0] check to avoid scanning the entire buffer for emptiness.
Prompt for AI Agents
Please address the comments from this code review:
## Overall Comments
- The new IOCTL FS_IOC_GETFSSYSFSPATH exposes internal sysfs paths without any capability checks; consider adding a permission check (e.g. CAP_SYS_ADMIN) to avoid leaking kernel internals to unprivileged users.
- The Q/A style comment block added above the super_block fields deviates from kernel coding style—please convert it into a concise explanatory comment or remove the ‘q:/a:’ lines.
- In ioctl_get_fs_sysfs_path, replace strlen(sb->s_sysfs_name) with a simple sb->s_sysfs_name[0] check to avoid scanning the entire buffer for emptiness.Help me be more useful! Please click 👍 or 👎 on each comment and I'll use the feedback to improve your reviews.
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This cherry picks the following VFS patches from upstream:
fs: add FS_IOC_GETFSSYSFSPATH
fs: FS_IOC_GETUUID
fs: super_set_uuid()
There are no conflicts.
Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=11101
Link: https://gitee.com/anolis/cloud-kernel/pulls/4230
Summary by Sourcery
Backport upstream VFS patches to expose filesystem UUID and sysfs path via new ioctls, extend super_block with metadata fields and helpers, update filesystem code to use the new helpers, and update the ioctl documentation
New Features:
Enhancements:
Documentation: