[PATCH v2 00/13] fs: Use device special nodes for devfs

[Sascha Hauer <s.hauer@pengutronix.de>]

Until now we have a devfs which is a filesystem of its own. This
comes with a few limitations:

- we cannot create directories under /dev/
- Links are implemented in the devfs filesystem. They do not show
  up as regular links

This series overcomes these limitations by implementing device special
nodes. These nodes are limited to ramfs, so we cannot mount arbitrary
filesystems and use the device special files found on them. Nevertheless
we can create and use device special files on ramfs which is enough
to drop the devfs filesystem implementation and just use ramfs on /dev/.

This will in future allow us to create /dev/disk/by-* structures under
/dev/.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
Changes in v2:
- Fix storage-by-uuid driver for devfs changes
- remove created device special files and links on devfs_remove()
- Link to v1: https://lore.barebox.org/20251127-devfs-v1-0-4aff12818757@pengutronix.de

---
Sascha Hauer (13):
      fs: devfs-core: add devfs_create_link_node()
      storage-by-alias: drop fake cdev
      fs: implement mknod
      commands: add mknod command
      fs: ramfs: add device file support
      cdev: add cdev_size() helper
      fs: fix st_size for device files
      fs: retire devfs as filesystem
      fs: include cdevname in struct stat
      fs: stat_print: get cdevname from stat
      common: cdev-alias: rename struct
      fs: replace cdev links with aliases
      ls: use ~0 for FILE_SIZE_STREAM

 commands/Kconfig                |   4 +
 commands/Makefile               |   1 +
 commands/devinfo.c              |   7 +-
 commands/ls.c                   |   8 +-
 commands/mknod.c                |  43 ++++++++
 common/cdev-alias.c             |  12 +--
 common/partitions.c             |   2 +-
 common/startup.c                |   2 +-
 drivers/block/dm/dm-core.c      |   1 -
 drivers/misc/storage-by-alias.c | 120 ++--------------------
 fs/devfs-core.c                 | 214 +++++++++++++++++++++++++---------------
 fs/devfs.c                      | 180 +++------------------------------
 fs/fs.c                         |  75 +++++++++-----
 fs/ramfs.c                      |  18 ++++
 include/block.h                 |   2 -
 include/driver.h                |  20 +++-
 include/fcntl.h                 |   6 ++
 include/linux/fs.h              |  13 +++
 include/linux/stat.h            |   1 +
 19 files changed, 327 insertions(+), 402 deletions(-)
---
base-commit: 500df27eb054f86ce232c5bb30c3a7ea8f771e61
change-id: 20251127-devfs-c138cff5482a

Best regards,
-- 
Sascha Hauer <s.hauer@pengutronix.de>