linux-toradex.git/fs/overlayfs/readdir.c, branch v4.4.26

ovl: check dentry positiveness in ovl_cleanup_whiteouts()

2016-02-25T20:01:24+00:00

commit 84889d49335627bc770b32787c1ef9ebad1da232 upstream.

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 
Signed-off-by: Greg Kroah-Hartman

ovl: lookup whiteouts outside iterate_dir()

2015-06-22T11:53:48+00:00

If jffs2 can deadlock on overlayfs readdir because it takes the same lock
on ->iterate() as in ->lookup().

Fix by moving whiteout checking outside iterate_dir().  Optimized by
collecting potential whiteouts (DT_CHR) in a temporary list and if
non-empty iterating throug these and checking for a 0/0 chardev.

Signed-off-by: Miklos Szeredi 
Fixes: 49c21e1cacd7 ("ovl: check whiteout while reading directory")
Reported-by: Roman Yeryomin

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

2015-02-20T09:58:52+00:00

ovl: discard independent cursor in readdir()

2015-01-09T13:55:57+00:00

Since the ovl_dir_cache is stable during a directory reading, the cursor
of struct ovl_dir_file don't need to be an independent entry in the list
of a merged directory.

This patch changes *cursor* to a pointer which points to the entry in the
ovl_dir_cache. After this, we don't need to check *is_cursor* either.

Signed-off-by: hujianyang 
Signed-off-by: Miklos Szeredi

ovl: check whiteout on lowest layer as well

2014-12-12T23:59:45+00:00

Not checking whiteouts on lowest layer was an optimization (there's nothing
to white out there), but it could result in inconsitent behavior when a
layer previously used as upper/middle is later used as lowest. 

Signed-off-by: Miklos Szeredi

ovl: multi-layer readdir

2014-12-12T23:59:44+00:00

If multiple lower layers exist, merge them as well in readdir according to
the same rules as merging upper with lower.  I.e. take whiteouts and opaque
directories into account on all but the lowers layer.

Signed-off-by: Miklos Szeredi

ovl: make path-type a bitmap

2014-12-12T23:59:42+00:00

OVL_PATH_PURE_UPPER -> __OVL_PATH_UPPER | __OVL_PATH_PURE
OVL_PATH_UPPER      -> __OVL_PATH_UPPER
OVL_PATH_MERGE      -> __OVL_PATH_UPPER | __OVL_PATH_MERGE
OVL_PATH_LOWER      -> 0

Multiple R/O layers will allow __OVL_PATH_MERGE without __OVL_PATH_UPPER.

Signed-off-by: Miklos Szeredi

ovl: check whiteout while reading directory

2014-12-12T23:59:42+00:00

Don't make a separate pass for checking whiteouts, since we can do it while
reading the upper directory.

This will make it easier to handle multiple layers.

Signed-off-by: Miklos Szeredi

Merge branch 'iov_iter' into for-next

2014-12-09T01:39:29+00:00

ovl: ovl_dir_fsync() cleanup

2014-11-20T15:40:02+00:00

Check against !OVL_PATH_LOWER instead of OVL_PATH_MERGE.  For a copied up
directory the two are currently equivalent.

Signed-off-by: Miklos Szeredi