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3985b70a3e
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Amir Goldstein 3985b70a3e ovl: decode connected upper dir file handles 
Until this change, we decoded upper file handles by instantiating an
overlay dentry from the real upper dentry. This is sufficient to handle
pure upper files, but insufficient to handle merge/impure dirs.

To that end, if decoded real upper dir is connected and hashed, we
lookup an overlay dentry with the same path as the real upper dir.
If decoded real upper is non-dir, we instantiate a disconnected overlay
dentry as before this change.

Because ovl_fh_to_dentry() returns a connected overlay dir dentry,
exportfs never needs to call get_parent() and get_name() to reconnect an
upper overlay dir. Because connectable non-dir file handles are not
supported, exportfs will not be able to use fh_to_parent() and get_name()
methods to reconnect a disconnected non-dir to its parent. Therefore, the
methods get_parent() and get_name() are implemented just to print out a
sanity warning and the method fh_to_parent() is implemented to warn the
user that using the 'subtree_check' exportfs option is not supported.

An alternative approach could have been to implement instantiating of
an overlay directory inode from origin/index and implement get_parent()
and get_name() by calling into underlying fs operations and them
instantiating the overlay parent dir.

The reasons for not choosing the get_parent() approach were:
- Obtaining a disconnected overlay dir dentry would requires a
  delicate re-factoring of ovl_lookup() to get a dentry with overlay
  parent info. It was preferred to avoid doing that re-factoring unless
  it was proven worthy.
- Going down the path of disconnected dir would mean that the (non
  trivial) code path of d_splice_alias() could be traveled and that
  meant writing more tests and introduces race cases that are very hard
  to hit on purpose. Taking the path of connecting overlay dentry by
  forward lookup is therefore the safe and boring way to avoid surprises.

The culprits of the chosen "connected overlay dentry" approach:
- We need to take special care to rename of ancestors while connecting
  the overlay dentry by real dentry path. These subtleties are usually
  handled by generic exportfs and VFS code.
- In a hypothetical workload, we could end up in a loop trying to connect,
  interrupted by rename and restarting connect forever.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
2018-01-24 11:26:00 +01:00
..
9p Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
adfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
affs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
afs afs: Fix missing error handling in afs_write_end() 2018-01-02 10:02:19 +00:00
autofs4 autofs: fix careless error in recent commit 2017-12-14 16:00:48 -08:00
befs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
bfs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
btrfs for-4.15-rc7-tag 2018-01-05 13:02:46 -08:00
cachefiles mm: remove __GFP_COLD 2017-11-15 18:21:06 -08:00
ceph ceph: drop negative child dentries before try pruning inode's alias 2017-12-08 11:07:12 +01:00
cifs CIFS: don't log STATUS_NOT_FOUND errors for DFS 2017-12-06 12:48:01 -06:00
coda Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
configfs configfs: make ci_type field, some pointers and function arguments const 2017-10-19 16:15:16 +02:00
cramfs cramfs: fix MTD dependency 2017-12-17 12:20:58 -08:00
crypto fscrypt: lots of cleanups, mostly courtesy by Eric Biggers 2017-11-14 11:35:15 -08:00
debugfs debugfs: Remove redundant license text 2017-11-07 20:25:03 +01:00
devpts pty: Repair TIOCGPTPEER 2017-08-24 13:23:03 -07:00
dlm A couple of configfs cleanups: 2017-11-14 14:44:04 -08:00
ecryptfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
efivarfs VFS: Kill off s_options and helpers 2017-07-11 06:09:21 -04:00
efs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
exofs Merge branch 'for-4.14/block' of git://git.kernel.dk/linux-block 2017-09-07 11:59:42 -07:00
exportfs
ext2 Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
ext4 ext4: fix crash when a directory's i_size is too small 2017-12-11 15:00:57 -05:00
f2fs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
fat fs/fat/inode.c: fix sb_rdonly() change 2017-11-29 18:40:43 -08:00
freevxfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
fscache AFS development 2017-11-16 11:41:22 -08:00
fuse Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
gfs2 Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
hfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
hfsplus Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
hostfs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
hpfs hpfs: don't bother with the i_version counter or f_version 2017-12-10 12:58:18 -08:00
hugetlbfs fs/hugetlbfs/inode.c: change put_page/unlock_page order in hugetlbfs_fallocate() 2017-11-29 18:40:43 -08:00
isofs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
jbd2 libnvdimm for 4.15 2017-11-17 09:51:57 -08:00
jffs2 Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
jfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
kernfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
lockd nlm_shutdown_hosts_net() cleanup 2017-11-27 16:45:11 -05:00
minix Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
ncpfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
nfs NFS client fixes for Linux 4.15-rc4 2017-12-16 13:12:53 -08:00
nfs_common lockd: fix "list_add double add" caused by legacy signal interface 2017-11-27 16:45:11 -05:00
nfsd kernel: make groups_sort calling a responsibility group_info allocators 2017-12-14 16:00:49 -08:00
nilfs2 Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
nls License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
notify Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
ntfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
ocfs2 Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
omfs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
openpromfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
orangefs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
overlayfs ovl: decode connected upper dir file handles 2018-01-24 11:26:00 +01:00
proc proc: show si_ptr in /proc/<pid>/timers without hashing 2017-12-06 18:23:27 -08:00
pstore treewide: Switch DEFINE_TIMER callbacks to struct timer_list * 2017-11-21 15:57:05 -08:00
qnx4 Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
qnx6 Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
quota quota: Check for register_shrinker() failure. 2017-11-29 16:46:48 +01:00
ramfs mm: make pagevec_lookup() update index 2017-09-06 17:27:26 -07:00
reiserfs Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs 2017-11-30 18:38:47 -05:00
romfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
squashfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
sysfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
sysv Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
tracefs VFS: Don't use save/replace_mount_options if not using generic_show_options 2017-07-06 03:31:46 -04:00
ubifs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
udf Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
ufs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
xfs Changes since last update: 2018-01-05 12:59:32 -08:00
aio.c Merge branch 'misc.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-11-17 11:54:55 -08:00
anon_inodes.c
attr.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
bad_inode.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
binfmt_aout.c fs: fix kernel_read prototype 2017-09-04 19:05:15 -04:00
binfmt_elf_fdpic.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-11-17 12:54:01 -08:00
binfmt_elf.c Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm 2017-11-16 12:50:35 -08:00
binfmt_em86.c
binfmt_flat.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
binfmt_misc.c fs/binfmt_misc.c: node could be NULL when evicting inode 2017-10-13 16:18:33 -07:00
binfmt_script.c exec: load_script: kill the onstack interp[BINPRM_BUF_SIZE] array 2017-10-03 17:54:25 -07:00
block_dev.c Merge branch 'for-4.15/block' of git://git.kernel.dk/linux-block 2017-11-14 15:32:19 -08:00
buffer.c mm, pagevec: remove cold parameter for pagevecs 2017-11-15 18:21:06 -08:00
char_dev.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
compat_binfmt_elf.c
compat_ioctl.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-11-17 12:54:01 -08:00
compat.c
coredump.c Merge branch 'misc.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-11-17 11:54:55 -08:00
dax.c Revert "mm: replace p??_write with pte_access_permitted in fault + gup paths" 2017-12-15 18:53:22 -08:00
dcache.c vfs: factor out helpers d_instantiate_anon() and d_alloc_anon() 2018-01-24 11:25:59 +01:00
dcookies.c
direct-io.c Merge branch 'for-4.15/block' of git://git.kernel.dk/linux-block 2017-11-14 15:32:19 -08:00
drop_caches.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
eventfd.c There has been a fair amount of activity in the docs tree this time 2017-07-03 21:13:25 -07:00
eventpoll.c Merge branch 'akpm' (patches from Andrew) 2017-11-17 16:56:17 -08:00
exec.c exec: Weaken dumpability for secureexec 2018-01-03 10:13:36 -08:00
fcntl.c fcntl: don't cap l_start and l_end values for F_GETLK64 in compat syscall 2017-11-15 08:08:36 -05:00
fhandle.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-11-17 12:54:01 -08:00
file_table.c fs, mm: account filp cache to kmemcg 2017-11-15 18:21:04 -08:00
file.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-11-17 12:54:01 -08:00
filesystems.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs_pin.c Merge branch 'linus' into locking/core, to resolve conflicts 2017-11-07 10:32:44 +01:00
fs_struct.c
fs-writeback.c Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
inode.c Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
internal.h fs: expose do_unlinkat for built-in callers 2017-11-10 08:48:46 -05:00
ioctl.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
iomap.c Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-11-17 12:08:18 -08:00
Kconfig fs/Kconfig: kill CONFIG_PERCPU_RWSEM some more 2017-07-12 16:26:00 -07:00
Kconfig.binfmt ARM: enable elf_fdpic on systems with an MMU 2017-09-10 19:31:46 -04:00
libfs.c Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
locks.c Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mbcache.c fs/mbcache.c: make count_objects() more robust 2017-11-29 18:40:43 -08:00
mount.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mpage.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
namei.c autofs: revert "autofs: fix AT_NO_AUTOMOUNT not being honored" 2017-11-29 18:40:43 -08:00
namespace.c VFS: Handle lazytime in do_mount() 2017-12-09 20:16:33 -05:00
no-block.c
nsfs.c Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
open.c ovl: don't allow writing ioctl on lower layer 2017-09-05 12:53:12 +02:00
pipe.c pipe: add proc_dopipe_max_size() to safely assign pipe_max_size 2017-11-17 16:10:03 -08:00
pnode.c
pnode.h
posix_acl.c
proc_namespace.c Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
read_write.c Merge branch 'work.iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-11-17 12:08:18 -08:00
readdir.c Merge branch 'linus' into locking/core, to resolve conflicts 2017-11-07 10:32:44 +01:00
select.c Merge branch 'misc.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-11-17 11:54:55 -08:00
seq_file.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
signalfd.c Merge branch 'misc.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-11-17 11:54:55 -08:00
splice.c locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE() 2017-10-25 11:01:08 +02:00
stack.c
stat.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
statfs.c Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
super.c sget(): handle failures of register_shrinker() 2017-12-18 15:05:07 -05:00
sync.c Merge branch 'for-4.15/block' of git://git.kernel.dk/linux-block 2017-11-14 15:32:19 -08:00
timerfd.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
userfaultfd.c userfaultfd: clear the vma->vm_userfaultfd_ctx if UFFD_EVENT_FORK fails 2018-01-04 16:45:09 -08:00
utimes.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
xattr.c lsm: fix smack_inode_removexattr and xattr_getsecurity memleak 2017-10-04 18:03:15 +11:00