linux-mainline/arch
Mickaël Salaün 74ce793bcb
hostfs: Fix ephemeral inodes
hostfs creates a new inode for each opened or created file, which
created useless inode allocations and forbade identifying a host file
with a kernel inode.

Fix this uncommon filesystem behavior by tying kernel inodes to host
file's inode and device IDs.  Even if the host filesystem inodes may be
recycled, this cannot happen while a file referencing it is opened,
which is the case with hostfs.  It should be noted that hostfs inode IDs
may not be unique for the same hostfs superblock because multiple host's
(backed) superblocks may be used.

Delete inodes when dropping them to force backed host's file descriptors
closing.

This enables to entirely remove ARCH_EPHEMERAL_INODES, and then makes
Landlock fully supported by UML.  This is very useful for testing
changes.

These changes also factor out and simplify some helpers thanks to the
new hostfs_inode_update() and the hostfs_iget() revamp: read_name(),
hostfs_create(), hostfs_lookup(), hostfs_mknod(), and
hostfs_fill_sb_common().

A following commit with new Landlock tests check this new hostfs inode
consistency.

Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Richard Weinberger <richard@nod.at>
Link: https://lore.kernel.org/r/20230612191430.339153-2-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>
2023-06-12 21:26:19 +02:00
..
alpha
arc
arm
arm64 ARM: SoC fixes for 6.4, part 2 2023-06-10 13:01:09 -07:00
csky
hexagon
ia64
loongarch
m68k
microblaze
mips
nios2
openrisc
parisc
powerpc
riscv RISC-V Fixes for 6.4-rc6 2023-06-09 09:36:17 -07:00
s390 s390 updates for 6.4-rc6 2023-06-09 09:29:51 -07:00
sh
sparc
um hostfs: Fix ephemeral inodes 2023-06-12 21:26:19 +02:00
x86 - Set up the kernel CS earlier in the boot process in case EFI boots the 2023-06-11 10:14:02 -07:00
xtensa
.gitignore
Kconfig hostfs: Fix ephemeral inodes 2023-06-12 21:26:19 +02:00