OpenCloudOS-Kernel/fs/proc
Linus Torvalds 0a2c2baafa
proc: fix missing conversion to 'iterate_shared'
I'm looking at the directory handling due to the discussion about f_pos
locking (see commit 797964253d35: "file: reinstate f_pos locking
optimization for regular files"), and wanting to clean that up.

And one source of ugliness is how we were supposed to move filesystems
over to the '->iterate_shared()' function that only takes the inode lock
for reading many many years ago, but several filesystems still use the
bad old '->iterate()' that takes the inode lock for exclusive access.

See commit 6192269444 ("introduce a parallel variant of ->iterate()")
that also added some documentation stating

      Old method is only used if the new one is absent; eventually it will
      be removed.  Switch while you still can; the old one won't stay.

and that was back in April 2016.  Here we are, many years later, and the
old version is still clearly sadly alive and well.

Now, some of those old style iterators are probably just because the
filesystem may end up having per-inode mutable data that it uses for
iterating a directory, but at least one case is just a mistake.

Al switched over most filesystems to use '->iterate_shared()' back when
it was introduced.  In particular, the /proc filesystem was converted as
one of the first ones in commit f50752eaa0 ("switch all procfs
directories ->iterate_shared()").

But then later one new user of '->iterate()' was then re-introduced by
commit 6d9c939dbe ("procfs: add smack subdir to attrs").

And that's clearly not what we wanted, since that new case just uses the
same 'proc_pident_readdir()' and 'proc_pident_lookup()' helper functions
that other /proc pident directories use, and they are most definitely
safe to use with the inode lock held shared.

So just fix it.

This still leaves a fair number of oddball filesystems using the
old-style directory iterator (ceph, coda, exfat, jfs, ntfs, ocfs2,
overlayfs, and vboxsf), but at least we don't have any remaining in the
core filesystems.

I'm going to add a wrapper function that just drops the read-lock and
takes it as a write lock, so that we can clean up the core vfs layer and
make all the ugly 'this filesystem needs exclusive inode locking' be
just filesystem-internal warts.

I just didn't want to make that conversion when we still had a core user
left.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-08-06 15:08:35 +02:00
..
Kconfig proc: make config PROC_CHILDREN depend on PROC_FS 2022-10-03 14:21:43 -07:00
Makefile proc: bootconfig: Add /proc/bootconfig to show boot config list 2020-01-13 13:19:39 -05:00
array.c Add support for new Linear Address Masking CPU feature. This is similar 2023-04-28 09:43:49 -07:00
base.c proc: fix missing conversion to 'iterate_shared' 2023-08-06 15:08:35 +02:00
bootconfig.c proc: bootconfig: Add null pointer check 2022-04-02 08:40:09 -04:00
cmdline.c proc: mark /proc/cmdline as permanent 2023-02-02 22:50:02 -08:00
consoles.c proc: consoles: use console_list_lock for list iteration 2022-12-02 11:25:02 +01:00
cpuinfo.c x86/aperfmperf: Replace aperfmperf_get_khz() 2022-04-27 20:22:19 +02:00
devices.c proc: mark more files as permanent 2022-10-03 14:21:45 -07:00
fd.c fs.idmapped.v6.3 2023-02-20 11:53:11 -08:00
fd.h fs: port ->permission() to pass mnt_idmap 2023-01-19 09:24:28 +01:00
generic.c proc: remove mark_inode_dirty() in .setattr() 2023-04-08 13:45:36 -07:00
inode.c tty, proc, kernfs, random: Use copy_splice_read() 2023-05-24 08:42:16 -06:00
internal.h fs: port ->getattr() to pass mnt_idmap 2023-01-19 09:24:25 +01:00
interrupts.c
kcore.c asm-generic updates for 6.5 2023-07-06 10:06:04 -07:00
kmsg.c printk changes for 6.1 2022-10-10 11:24:19 -07:00
loadavg.c proc: mark more files as permanent 2022-10-03 14:21:45 -07:00
meminfo.c mm: Add support for unaccepted memory 2023-06-06 16:38:22 +02:00
namespaces.c Merge branch 'work.openat2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-01-29 11:20:24 -08:00
nommu.c proc: delete unused <linux/uaccess.h> includes 2022-07-17 17:31:39 -07:00
page.c mm, pagemap: remove SLOB and SLQB from comments and documentation 2023-03-29 10:32:11 +02:00
proc_net.c fs: port ->getattr() to pass mnt_idmap 2023-01-19 09:24:25 +01:00
proc_sysctl.c sysctl: set variable sysctl_mount_point storage-class-specifier to static 2023-06-30 16:19:47 -07:00
proc_tty.c proc: delete unused <linux/uaccess.h> includes 2022-07-17 17:31:39 -07:00
root.c fs: port ->getattr() to pass mnt_idmap 2023-01-19 09:24:25 +01:00
self.c Revert "proc: don't allow async path resolution of /proc/self components" 2021-02-23 20:32:11 -07:00
softirqs.c proc: mark more files as permanent 2022-10-03 14:21:45 -07:00
stat.c proc/stat: remove arch_idle_time() 2023-04-18 16:39:33 -07:00
task_mmu.c mm: ptep_get() conversion 2023-06-19 16:19:25 -07:00
task_nommu.c mm: nommu: correct the range of mmap_sem_read_lock in task_mem() 2023-06-23 16:59:32 -07:00
thread_self.c Revert "proc: don't allow async path resolution of /proc/thread-self components" 2021-02-23 20:32:11 -07:00
uptime.c proc: mark more files as permanent 2022-10-03 14:21:45 -07:00
util.c
version.c proc: mark more files as permanent 2022-10-03 14:21:45 -07:00
vmcore.c proc/vmcore: fix signedness bug in read_from_oldmem() 2023-07-27 13:07:05 -07:00