Tejun Heo 45a140e587 kernfs: restructure removal path to fix possible premature return ... The recursive nature of kernfs_remove() means that, even if kernfs_remove() is not allowed to be called multiple times on the same node, there may be race conditions between removal of parent and its descendants. While we can claim that kernfs_remove() shouldn't be called on one of the descendants while the removal of an ancestor is in progress, such rule is unnecessarily restrictive and very difficult to enforce. It's better to simply allow invoking kernfs_remove() as the caller sees fit as long as the caller ensures that the node is accessible. The current behavior in such situations is broken. Whoever enters removal path first takes the node off the hierarchy and then deactivates. Following removers either return as soon as it notices that it's not the first one or can't even find the target node as it has already been removed from the hierarchy. In both cases, the following removers may finish prematurely while the nodes which should be removed and drained are still being processed by the first one. This patch restructures so that multiple removers, whether through recursion or direction invocation, always follow the following rules. * When there are multiple concurrent removers, only one puts the base ref. * Regardless of which one puts the base ref, all removers are blocked until the target node is fully deactivated and removed. To achieve the above, removal path now first deactivates the subtree, drains it and then unlinks one-by-one. __kernfs_deactivate() is called directly from __kernfs_removal() and drops and regrabs kernfs_mutex for each descendant to drain active refs. As this means that multiple removers can enter __kernfs_deactivate() for the same node, the function is updated so that it can handle multiple deactivators of the same node - only one actually deactivates but all wait till drain completion. The restructured removal path guarantees that a removed node gets unlinked only after the node is deactivated and drained. Combined with proper multiple deactivator handling, this guarantees that any invocation of kernfs_remove() returns only after the node itself and all its descendants are deactivated, drained and removed. v2: Draining separated into a separate loop (used to be in the same loop as unlink) and done from __kernfs_deactivate(). This is to allow exposing deactivation as a separate interface later. Root node removal was broken in v1 patch. Fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2014-01-10 13:48:08 -08:00
..
9p	consolidate simple ->d_delete() instances	2013-11-15 22:04:17 -05:00
adfs	adfs: delayed freeing of sbi	2013-10-24 23:43:27 -04:00
affs	remove obsolete references to powertweak	2013-11-27 20:34:32 -08:00
afs	Merge branch 'fscache' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs into linux-next	2013-10-28 19:36:46 -04:00
autofs4	autofs4: make freeing sbi rcu-delayed	2013-10-24 23:43:27 -04:00
befs	befs: split symlink iops in two - for short and long symlinks resp.	2013-10-24 23:34:50 -04:00
bfs	truncate: drop 'oldsize' truncate_pagecache() parameter	2013-09-12 15:38:02 -07:00
btrfs	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs	2013-12-12 15:25:10 -08:00
cachefiles	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2013-11-13 15:34:18 +09:00
ceph	ceph: Avoid data inconsistency due to d-cache aliasing in readpage()	2013-12-13 09:11:38 -08:00
cifs	[CIFS] Do not use btrfs refcopy ioctl for SMB2 copy offload	2013-11-25 09:50:31 -06:00
coda	coda_revalidate_inode(): switch to passing inode...	2013-11-09 00:16:21 -05:00
configfs	configfs: fix race between dentry put and lookup	2013-11-21 16:42:27 -08:00
cramfs	cramfs: mark as obsolete	2013-11-13 12:09:12 +09:00
debugfs	debugfs: use list_next_entry() in debugfs_remove_recursive()	2013-11-13 12:09:24 +09:00
devpts	devpts: plug the memory leak in kill_sb	2013-11-13 12:09:36 +09:00
dlm	genetlink: only pass array to genl_register_family_with_ops()	2013-11-19 16:39:05 -05:00
ecryptfs	Quiet static checkers by removing unneeded conditionals	2013-11-22 10:58:14 -08:00
efivarfs	consolidate simple ->d_delete() instances	2013-11-15 22:04:17 -05:00
efs	efs: iget_locked() doesn't return an ERR_PTR()	2013-08-24 12:10:22 -04:00
exofs	truncate: drop 'oldsize' truncate_pagecache() parameter	2013-09-12 15:38:02 -07:00
exportfs	exportfs: fix quadratic behavior in filehandle lookup	2013-11-09 00:16:38 -05:00
ext2	ext2: Fix fs corruption in ext2_get_xip_mem()	2013-11-05 11:26:47 +01:00
ext3	Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs	2013-11-13 15:25:47 +09:00
ext4	Ext4 updates for 3.13. Mostly bug fixes and cleanups.	2013-11-14 17:19:58 +09:00
f2fs	f2fs: issue more large discard command	2013-11-11 09:36:32 +09:00
fat	fat: rcu-delay unloading nls and freeing sbi	2013-10-24 23:43:28 -04:00
freevxfs	[readdir] convert freevxfs	2013-06-29 12:56:53 +04:00
fscache	Merge branch 'for-3.13/core' of git://git.kernel.dk/linux-block	2013-11-14 12:08:14 +09:00
fuse	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2013-11-13 15:34:18 +09:00
gfs2	GFS2: Fix ref count bug relating to atomic_open	2013-11-21 18:47:57 +00:00
hfs	fs/hfs/btree.h: remove duplicate defines	2013-11-13 12:09:32 +09:00
hfsplus	block: submit_bio_wait() conversions	2013-11-24 16:33:41 -07:00
hostfs	consolidate simple ->d_delete() instances	2013-11-15 22:04:17 -05:00
hpfs	locks: break delegations on any attribute modification	2013-11-09 00:16:44 -05:00
hppfs	clean up scary strncpy(dst, src, strlen(src)) uses	2013-07-03 16:07:41 -07:00
hugetlbfs	cope with potentially long ->d_dname() output for shmem/hugetlb	2013-08-24 12:10:17 -04:00
isofs	isofs: don't pass dentry to isofs_hash{i,}_common()	2013-10-24 23:34:59 -04:00
jbd	jbd: Revert "jbd: remove dependency on __GFP_NOFAIL"	2013-10-31 20:37:15 +01:00
jbd2	jbd2: Fix endian mixing problems in the checksumming code	2013-08-28 14:59:58 -04:00
jffs2	jffs2: do not support the MLC nand	2013-10-27 16:27:07 -07:00
jfs	Just a patch to fix an oops in an error path.	2013-10-22 09:01:11 +01:00
kernfs	kernfs: restructure removal path to fix possible premature return	2014-01-10 13:48:08 -08:00
lockd	LOCKD: Don't call utsname()->nodename from nlmclnt_setlockargs	2013-08-05 15:03:46 -04:00
logfs	block: submit_bio_wait() conversions	2013-11-24 16:33:41 -07:00
minix	fs/minix: Drop dependency on H8300	2013-09-16 18:20:25 -07:00
ncpfs	ncpfs: rcu-delay unload_nls() and freeing ncp_server	2013-10-24 23:43:28 -04:00
nfs	NFS client bugfixes	2013-12-05 13:05:48 -08:00
nfs_common
nfsd	nfsd: when reusing an existing repcache entry, unhash it first	2013-12-10 20:34:44 -05:00
nilfs2	nilfs2: fix issue with race condition of competition between segments for dirty blocks	2013-09-30 14:31:02 -07:00
nls
notify	fsnotify: update comments concerning locking scheme	2013-07-09 10:33:20 -07:00
ntfs	iget/iget5: don't bother with ->i_lock until we find a match	2013-11-09 00:16:31 -05:00
ocfs2	tree-wide: use reinit_completion instead of INIT_COMPLETION	2013-11-15 09:32:21 +09:00
omfs	truncate: drop 'oldsize' truncate_pagecache() parameter	2013-09-12 15:38:02 -07:00
openpromfs	[readdir] convert openpromfs	2013-06-29 12:56:32 +04:00
proc	procfs: also fix proc_reg_get_unmapped_area() for !MMU case	2013-12-12 18:19:26 -08:00
pstore	pstore: Don't allow high traffic options on fragile devices	2013-12-20 13:12:01 -08:00
qnx4	qnx4: i_sb is never NULL	2013-11-09 00:16:32 -05:00
qnx6	[readdir] convert qnx6	2013-06-29 12:56:39 +04:00
quota	genetlink: make multicast groups const, prevent abuse	2013-11-19 16:39:06 -05:00
ramfs	initmpfs: move rootfs code from fs/ramfs/ to init/	2013-09-11 15:59:37 -07:00
reiserfs	reiserfs: fix race with flush_used_journal_lists and flush_journal_list	2013-09-24 11:24:21 +02:00
romfs	[readdir] convert romfs	2013-06-29 12:56:29 +04:00
squashfs	Squashfs: fix failure to unlock pages on decompress error	2013-11-24 01:02:50 +00:00
sysfs	kernfs: add kernfs_dir_ops	2013-12-17 08:59:15 -08:00
sysv	sysv: Add forgotten superblock lock init for v7 fs	2013-09-29 22:02:02 -04:00
ubifs	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2013-11-13 15:34:18 +09:00
udf	udf: fix for pathetic mount times in case of invalid file system	2013-10-18 22:39:07 +02:00
ufs	truncate: drop 'oldsize' truncate_pagecache() parameter	2013-09-12 15:38:02 -07:00
xfs	xfs: abort metadata writeback on permanent errors	2013-12-17 09:40:23 -06:00
aio.c	Merge git://git.kvack.org/~bcrl/aio-next	2013-12-22 11:03:49 -08:00
anon_inodes.c	... and kill anon_inode_getfile_private()	2013-11-09 00:16:28 -05:00
attr.c	locks: break delegations on any attribute modification	2013-11-09 00:16:44 -05:00
bad_inode.c	[readdir] ->readdir() is gone	2013-06-29 12:57:04 +04:00
binfmt_aout.c	dump_skip(): dump_seek() replacement taking coredump_params	2013-11-09 00:16:26 -05:00
binfmt_elf_fdpic.c	elf{,_fdpic} coredump: get rid of pointless if (siginfo->si_signo)	2013-11-09 00:16:30 -05:00
binfmt_elf.c	elf{,_fdpic} coredump: get rid of pointless if (siginfo->si_signo)	2013-11-09 00:16:30 -05:00
binfmt_em86.c	file->f_op is never NULL...	2013-10-24 23:34:54 -04:00
binfmt_flat.c
binfmt_misc.c
binfmt_script.c
binfmt_som.c
bio-integrity.c	Merge branch 'for-3.12/core' of git://git.kernel.dk/linux-block	2013-09-22 15:00:11 -07:00
bio.c	bio: fix argument of __bio_add_page() for max_sectors > 0xffff	2013-11-18 12:31:27 -07:00
block_dev.c	a trivial writeback fix	2013-09-13 23:06:40 -04:00
buffer.c	fs: buffer: move allocation failure loop into the allocator	2013-10-16 21:35:53 -07:00
char_dev.c	Merge branch 'for-3.13/core' of git://git.kernel.dk/linux-block	2013-11-14 12:08:14 +09:00
compat_binfmt_elf.c
compat_ioctl.c	file->f_op is never NULL...	2013-10-24 23:34:54 -04:00
compat.c	[readdir] constify ->actor	2013-06-29 12:57:05 +04:00
coredump.c	dump_emit(): use __kernel_write(), not vfs_write()	2013-11-15 22:04:09 -05:00
coredump.h
dcache.c	dcache: allow word-at-a-time name hashing with big-endian CPUs	2013-12-12 10:39:01 -08:00
dcookies.c
direct-io.c	direct-io: Use return from cmpxchg to decide of assignment happened	2013-09-09 10:47:42 -07:00
drop_caches.c	shrinker: add node awareness	2013-09-10 18:56:31 -04:00
eventfd.c
eventpoll.c	epoll: drop EPOLLWAKEUP if PM_SLEEP is disabled	2013-12-03 15:35:52 +01:00
exec.c	Merge git://git.infradead.org/users/eparis/audit	2013-11-21 19:18:14 -08:00
fcntl.c	file->f_op is never NULL...	2013-10-24 23:34:54 -04:00
fhandle.c
file_table.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2013-11-13 15:34:18 +09:00
file.c
filesystems.c
fs_struct.c	seqcount: Add lockdep functionality to seqcount/seqlock structures	2013-11-06 12:40:26 +01:00
fs-writeback.c	Merge branch 'akpm' (patches from Andrew Morton)	2013-11-13 15:45:43 +09:00
generic_acl.c
inode.c	locks: break delegations on any attribute modification	2013-11-09 00:16:44 -05:00
internal.h	get rid of s_files and files_lock	2013-11-09 00:16:20 -05:00
ioctl.c	file->f_op is never NULL...	2013-10-24 23:34:54 -04:00
ioprio.c
Kconfig
Kconfig.binfmt
libfs.c	consolidate simple ->d_delete() instances	2013-11-15 22:04:17 -05:00
locks.c	locks: missing unlock on error in generic_add_lease()	2013-11-13 07:30:53 -05:00
Makefile	sysfs, kernfs: add skeletons for kernfs	2013-11-27 13:28:24 -08:00
mbcache.c	fs: convert fs shrinkers to new scan/count API	2013-09-10 18:56:31 -04:00
mount.h	RCU'd vfsmounts	2013-11-09 00:16:19 -05:00
mpage.c
namei.c	dcache: allow word-at-a-time name hashing with big-endian CPUs	2013-12-12 10:39:01 -08:00
namespace.c	sysfs, kernfs: prepare mount path for kernfs	2013-11-29 18:16:08 -08:00
no-block.c
open.c	locks: break delegations on any attribute modification	2013-11-09 00:16:44 -05:00
pipe.c	vfs: fix subtle use-after-free of pipe_inode_info	2013-12-02 09:44:51 -08:00
pnode.c	split __lookup_mnt() in two functions	2013-10-24 23:35:00 -04:00
pnode.h	vfs: Don't copy mount bind mounts of /proc/<pid>/ns/mnt between namespaces	2013-08-26 18:42:15 -07:00
posix_acl.c
proc_namespace.c	don't bother with vfsmount_lock in mounts_poll()	2013-10-24 23:34:59 -04:00
read_write.c	file->f_op is never NULL...	2013-10-24 23:34:54 -04:00
readdir.c	file->f_op is never NULL...	2013-10-24 23:34:54 -04:00
select.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2013-11-13 15:34:18 +09:00
seq_file.c	seq_file: always clear m->count when we free m->buf	2013-11-18 19:07:53 -08:00
signalfd.c
splice.c	file->f_op is never NULL...	2013-10-24 23:34:54 -04:00
stack.c
stat.c	vfs: split out vfs_getattr_nosec	2013-11-09 00:16:31 -05:00
statfs.c	vfs: allow O_PATH file descriptors for fstatfs()	2013-10-12 13:12:31 -07:00
super.c	get rid of s_files and files_lock	2013-11-09 00:16:20 -05:00
sync.c	Merge branch 'akpm' (patches from Andrew Morton)	2013-11-13 15:45:43 +09:00
timerfd.c
utimes.c	locks: break delegations on any attribute modification	2013-11-09 00:16:44 -05:00
xattr_acl.c
xattr.c