linux.git/fs/overlayfs, branch v4.5

ovl: copy new uid/gid into overlayfs runtime inode

2016-03-03T16:17:46+00:00

Overlayfs must update uid/gid after chown, otherwise functions
like inode_owner_or_capable() will check user against stale uid.
Catched by xfstests generic/087, it chowns file and calls utimes.

Signed-off-by: Konstantin Khlebnikov 
Signed-off-by: Miklos Szeredi 
Cc:

ovl: ignore lower entries when checking purity of non-directory entries

2016-03-03T16:17:45+00:00

After rename file dentry still holds reference to lower dentry from
previous location. This doesn't matter for data access because data comes
from upper dentry. But this stale lower dentry taints dentry at new
location and turns it into non-pure upper. Such file leaves visible
whiteout entry after remove in directory which shouldn't have whiteouts at
all.

Overlayfs already tracks pureness of file location in oe->opaque.  This
patch just uses that for detecting actual path type.

Comment from Vivek Goyal's patch:

Here are the details of the problem. Do following.

$ mkdir upper lower work merged upper/dir/
$ touch lower/test
$ sudo mount -t overlay overlay -olowerdir=lower,upperdir=upper,workdir=
work merged
$ mv merged/test merged/dir/
$ rm merged/dir/test
$ ls -l merged/dir/
/usr/bin/ls: cannot access merged/dir/test: No such file or directory
total 0
c????????? ? ? ? ?            ? test

Basic problem seems to be that once a file has been unlinked, a whiteout
has been left behind which was not needed and hence it becomes visible.

Whiteout is visible because parent dir is of not type MERGE, hence
od->is_real is set during ovl_dir_open(). And that means ovl_iterate()
passes on iterate handling directly to underlying fs. Underlying fs does
not know/filter whiteouts so it becomes visible to user.

Why did we leave a whiteout to begin with when we should not have.
ovl_do_remove() checks for OVL_TYPE_PURE_UPPER() and does not leave
whiteout if file is pure upper. In this case file is not found to be pure
upper hence whiteout is left.

So why file was not PURE_UPPER in this case? I think because dentry is
still carrying some leftover state which was valid before rename. For
example, od->numlower was set to 1 as it was a lower file. After rename,
this state is not valid anymore as there is no such file in lower.

Signed-off-by: Konstantin Khlebnikov 
Reported-by: Viktor Stanchev 
Suggested-by: Vivek Goyal 
Link: https://bugzilla.kernel.org/show_bug.cgi?id=109611
Acked-by: Vivek Goyal 
Signed-off-by: Miklos Szeredi 
Cc:

ovl: fix getcwd() failure after unsuccessful rmdir

2016-03-03T16:17:45+00:00

ovl_remove_upper() should do d_drop() only after it successfully
removes the dir, otherwise a subsequent getcwd() system call will
fail, breaking userspace programs.

This is to fix: https://bugzilla.kernel.org/show_bug.cgi?id=110491

Signed-off-by: Rui Wang 
Reviewed-by: Konstantin Khlebnikov 
Signed-off-by: Miklos Szeredi 
Cc:

ovl: fix working on distributed fs as lower layer

2016-03-03T16:17:45+00:00

This adds missing .d_select_inode into alternative dentry_operations.

Signed-off-by: Konstantin Khlebnikov 
Fixes: 7c03b5d45b8e ("ovl: allow distributed fs as lower layer")
Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
Reviewed-by: Nikolay Borisov 
Tested-by: Nikolay Borisov 
Signed-off-by: Miklos Szeredi 
Cc:  # 4.2+

wrappers for ->i_mutex access

2016-01-22T23:04:28+00:00

parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.

Signed-off-by: Al Viro

Merge branch 'akpm' (patches from Andrew)

2016-01-21T20:32:08+00:00

Merge third patch-bomb from Andrew Morton:
 "I'm pretty much done for -rc1 now:

   - the rest of MM, basically

   - lib/ updates

   - checkpatch, epoll, hfs, fatfs, ptrace, coredump, exit

   - cpu_mask simplifications

   - kexec, rapidio, MAINTAINERS etc, etc.

   - more dma-mapping cleanups/simplifications from hch"

* emailed patches from Andrew Morton : (109 commits)
  MAINTAINERS: add/fix git URLs for various subsystems
  mm: memcontrol: add "sock" to cgroup2 memory.stat
  mm: memcontrol: basic memory statistics in cgroup2 memory controller
  mm: memcontrol: do not uncharge old page in page cache replacement
  Documentation: cgroup: add memory.swap.{current,max} description
  mm: free swap cache aggressively if memcg swap is full
  mm: vmscan: do not scan anon pages if memcg swap limit is hit
  swap.h: move memcg related stuff to the end of the file
  mm: memcontrol: replace mem_cgroup_lruvec_online with mem_cgroup_online
  mm: vmscan: pass memcg to get_scan_count()
  mm: memcontrol: charge swap to cgroup2
  mm: memcontrol: clean up alloc, online, offline, free functions
  mm: memcontrol: flatten struct cg_proto
  mm: memcontrol: rein in the CONFIG space madness
  net: drop tcp_memcontrol.c
  mm: memcontrol: introduce CONFIG_MEMCG_LEGACY_KMEM
  mm: memcontrol: allow to disable kmem accounting for cgroup2
  mm: memcontrol: account "kmem" consumers in cgroup2 memory controller
  mm: memcontrol: move kmem accounting code to CONFIG_MEMCG
  mm: memcontrol: separate kmem code from legacy tcp accounting code
  ...

Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

2016-01-21T20:20:46+00:00

Pull overlayfs updates from Miklos Szeredi:
 "This contains several bug fixes and a new mount option
  'default_permissions' that allows read-only exported NFS
  filesystems to be used as lower layer"

* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: check dentry positiveness in ovl_cleanup_whiteouts()
  ovl: setattr: check permissions before copy-up
  ovl: root: copy attr
  ovl: move super block magic number to magic.h
  ovl: use a minimal buffer in ovl_copy_xattr
  ovl: allow zero size xattr
  ovl: default permissions

fs/overlayfs/super.c needs pagemap.h

2016-01-21T01:09:18+00:00

i386 allmodconfig:

  In file included from fs/overlayfs/super.c:10:0:
  fs/overlayfs/super.c: In function 'ovl_fill_super':
  include/linux/fs.h:898:36: error: 'PAGE_CACHE_SIZE' undeclared (first use in this function)
   #define MAX_LFS_FILESIZE (((loff_t)PAGE_CACHE_SIZE << (BITS_PER_LONG-1))-1)
                                      ^
  fs/overlayfs/super.c:939:19: note: in expansion of macro 'MAX_LFS_FILESIZE'
    sb->s_maxbytes = MAX_LFS_FILESIZE;
                     ^
  include/linux/fs.h:898:36: note: each undeclared identifier is reported only once for each function it appears in
   #define MAX_LFS_FILESIZE (((loff_t)PAGE_CACHE_SIZE << (BITS_PER_LONG-1))-1)
                                      ^
  fs/overlayfs/super.c:939:19: note: in expansion of macro 'MAX_LFS_FILESIZE'
    sb->s_maxbytes = MAX_LFS_FILESIZE;
                     ^

Cc: Miklos Szeredi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

switch ->get_link() to delayed_call, kill ->put_link()

2015-12-30T18:01:03+00:00

Signed-off-by: Al Viro

ovl: check dentry positiveness in ovl_cleanup_whiteouts()

2015-12-11T15:30:49+00:00

This patch fixes kernel crash at removing directory which contains
whiteouts from lower layers.

Cache of directory content passed as "list" contains entries from all
layers, including whiteouts from lower layers. So, lookup in upper dir
(moved into work at this stage) will return negative entry. Plus this
cache is filled long before and we can race with external removal.

Example:
 mkdir -p lower0/dir lower1/dir upper work overlay
 touch lower0/dir/a lower0/dir/b
 mknod lower1/dir/a c 0 0
 mount -t overlay none overlay -o lowerdir=lower1:lower0,upperdir=upper,workdir=work
 rm -fr overlay/dir

Signed-off-by: Konstantin Khlebnikov 
Signed-off-by: Miklos Szeredi 
Cc:  # 3.18+