The dentry info. field count is used to check if a dentry is in use
during expire. But, to be used for this the count field must account for
the presence of child dentries in a directory dentry.
Therefore it can also be used to check for an empty directory dentry which
can be done without having to to take an additional lock or account for
the presence of a readdir cursor dentry as is done by simple_empty().
Link: https://lkml.kernel.org/r/165724459238.30914.1504611159945950108.stgit@donald.themaw.net
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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
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 <viro@zeniv.linux.org.uk>
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 <viro@zeniv.linux.org.uk>
* new helper: positive_after(parent, child); parent->d_lock is
held by caller, grabs and returns the first thing after child
in the list of children that has simple_positive() true. NULL
if nothing's found; NULL child == search the entire list.
* get_next_positive_subdir() loses the redundant check for
d_count and switches to use of that helper. BTW, dput(NULL) is
a no-op for a good reason...
* get_next_positive_dentry() switched to the same helper. Logics:
look for positive child in prev; if not found, look for the
positive child of prev's parent following prev, etc. That way
we are guaranteed that we are only moving rootwards through the
ancestors of prev, which is pinned and thus not going anywhere.
Since ->d_parent on autofs never changes, the same goes for
the entire chain of ancestors and we don't need overlapping
->d_lock on them. Which avoids the trylock loops, in addition
to simplifying the logics in there...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Based on 1 normalized pattern(s):
this file is part of the linux kernel and is made available under
the terms of the gnu general public license version 2 or at your
option any later version incorporated herein by reference
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 18 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190520075211.321157221@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
autofs_expire_run() calls dput(dentry) to drop the reference count of
dentry. However, dentry is read via autofs_dentry_ino(dentry) after
that. This may result in a use-free-bug. The patch drops the reference
count of dentry only when it is never used.
Link: http://lkml.kernel.org/r/154725122396.11260.16053424107144453867.stgit@pluto-themaw-net
Signed-off-by: Pan Bian <bianpan2016@163.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The userspace automount(8) daemon is meant to perform a forced expire when
sent a SIGUSR2.
But since the expiration is routed through the kernel and the kernel
doesn't send an expire request if the mount is busy this hasn't worked at
least since autofs version 5.
Add an AUTOFS_EXP_FORCED flag to allow implemention of the feature and
bump the protocol version so user space can check if it's implemented if
needed.
Link: http://lkml.kernel.org/r/152937734715.21213.6594007182776598970.stgit@pluto.themaw.net
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make the usage of the expire flags consistent by naming the expire flags
the same as it is named in the version 5 miscelaneous ioctl parameters and
only check the bit flags when needed.
Link: http://lkml.kernel.org/r/152937734046.21213.9454131988766280028.stgit@pluto.themaw.net
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The expire flag AUTOFS_EXP_LEAVES is cleared before the second call to
should_expire() in autofs_expire_indirect() but the parameter passed in
the second call is incorrect.
Fortunately AUTOFS_EXP_LEAVES expire flag has not been used for a long
time but might be needed in the future so fix it rather than remove the
expire leaves functionality.
Link: http://lkml.kernel.org/r/152937732410.21213.7447294898147765076.stgit@pluto.themaw.net
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The global variable "now" in fs/autofs/expire.c is used in an inconsistent
way, sometimes using jiffies directly, and sometimes using the "now"
variable, and setting it isn't done consistently either.
But the autofs dentry info last_used field is only updated during path
walks or during expire so jiffies can be used directly and the global
variable "now" removed.
Link: http://lkml.kernel.org/r/152937731702.21213.7371321165189170865.stgit@pluto.themaw.net
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Copy source files from the autofs4 directory to the autofs directory.
Link: http://lkml.kernel.org/r/152626705013.28589.931913083997578251.stgit@pluto.themaw.net
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Ian Kent