linux.git/fs/autofs, branch v5.9

autofs: use __kernel_write() for the autofs pipe writing

2020-09-30T00:18:34+00:00

autofs got broken in some configurations by commit 13c164b1a186
("autofs: switch to kernel_write") because there is now an extra LSM
permission check done by security_file_permission() in rw_verify_area().

autofs is one if the few places that really does want the much more
limited __kernel_write(), because the write is an internal kernel one
that shouldn't do any user permission checks (it also doesn't need the
file_start_write/file_end_write logic, since it's just a pipe).

There are a couple of other cases like that - accounting, core dumping,
and splice - but autofs stands out because it can be built as a module.

As a result, we need to export this internal __kernel_write() function
again.

We really don't want any other module to use this, but we don't have a
"EXPORT_SYMBOL_FOR_AUTOFS_ONLY()".  But we can mark it GPL-only to at
least approximate that "internal use only" for licensing.

While in this area, make autofs pass in NULL for the file position
pointer, since it's always a pipe, and we now use a NULL file pointer
for streaming file descriptors (see file_ppos() and commit 438ab720c675:
"vfs: pass ppos=NULL to .read()/.write() of FMODE_STREAM files")

This effectively reverts commits 9db977522449 ("fs: unexport
__kernel_write") and 13c164b1a186 ("autofs: switch to kernel_write").

Fixes: 13c164b1a186 ("autofs: switch to kernel_write")
Reported-by: Ondrej Mosnacek 
Acked-by: Christoph Hellwig 
Acked-by: Acked-by: Ian Kent 
Signed-off-by: Linus Torvalds

fs: autofs: delete repeated words in comments

2020-08-15T02:56:56+00:00

Drop duplicated words {the, at} in comments.

Signed-off-by: Randy Dunlap 
Signed-off-by: Andrew Morton 
Acked-by: Ian Kent 
Link: http://lkml.kernel.org/r/20200811021817.24982-1-rdunlap@infradead.org
Signed-off-by: Linus Torvalds

autofs: switch to kernel_write

2020-07-08T06:27:56+00:00

While pipes don't really need sb_writers projection, __kernel_write is an
interface better kept private, and the additional rw_verify_area does not
hurt here.

Signed-off-by: Christoph Hellwig 
Acked-by: Ian Kent

LOOKUP_MOUNTPOINT: fold path_mountpointat() into path_lookupat()

2020-03-14T01:08:17+00:00

New LOOKUP flag, telling path_lookupat() to act as path_mountpointat().
IOW, traverse mounts at the final point and skip revalidation of the
location where it ends up.

Signed-off-by: Al Viro

Merge branch 'next.autofs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2019-12-06T01:11:48+00:00

Pull autofs updates from Al Viro:
 "autofs misuses checks for ->d_subdirs emptiness; the cursors are in
  the same lists, resulting in false negatives. It's not needed anyway,
  since autofs maintains counter in struct autofs_info, containing 0 for
  removed ones, 1 for live symlinks and 1 + number of children for live
  directories, which is precisely what we need for those checks.

  This series switches to use of that counter and untangles the crap
  around its uses (it needs not be atomic and there's a bunch of
  completely pointless "defensive" checks).

  This fell out of dcache_readdir work; the main point is to get rid of
  ->d_subdirs abuses in there. I've more followup cleanups, but I hadn't
  run those by Ian yet, so they can go next cycle"

* 'next.autofs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  autofs: don't bother with atomics for ino->count
  autofs_dir_rmdir(): check ino->count for deciding whether it's empty...
  autofs: get rid of pointless checks around ->count handling
  autofs_clear_leaf_automount_flags(): use ino->count instead of ->d_subdirs

autofs: fix a leak in autofs_expire_indirect()

2019-10-25T04:03:11+00:00

if the second call of should_expire() in there ends up
grabbing and returning a new reference to dentry, we need
to drop it before continuing.

Signed-off-by: Al Viro

autofs: don't bother with atomics for ino->count

2019-09-18T03:31:27+00:00

All writers are serialized on inode->i_rwsem.  So are the readers
outside of expire.c.  And the readers in expire.c are in the
code that really doesn't care about narrow races - it's looking
for expiry candidates and its callers have to cope with the
possibility of a good candidate becoming busy right under them.

No point bothering with atomic operations - just use int and
mark the non-serialized readers with READ_ONCE().

Signed-off-by: Al Viro

autofs_dir_rmdir(): check ino->count for deciding whether it's empty...

2019-09-18T03:28:08+00:00

Signed-off-by: Al Viro

autofs: get rid of pointless checks around ->count handling

2019-09-18T03:23:08+00:00

* IS_ROOT can't be true for unlink or rmdir victim
* any positive autofs dentry has non-NULL autofs_dentry_ino()
* autofs symlink can't have ->count other than 1
* autofs empty directory can't have ->count other than 1

Signed-off-by: Al Viro

autofs_clear_leaf_automount_flags(): use ino->count instead of ->d_subdirs

2019-09-18T02:16:58+00:00

We want to find out if the parent will become empty after we remove
the victim of rmdir().  Checking if the victim is the only element
of parent's ->d_subdirs is completely wrong - e.g. opening the parent
will end up with a cursor added to its ->d_parent and fooling the
check.

We do maintain ino->count - 0 for anything removed, 1 + number of
children for anything live.  Which gives us precisely what we need
for that check...

Signed-off-by: Al Viro