Seprate on-disk encoding from in-memory and on-wire resresentation
of overlay file handle.
In-memory and on-wire we only ever pass around pointers to struct
ovl_fh, which encapsulates at offset 3 the on-disk format struct
ovl_fb. struct ovl_fb encapsulates at offset 21 the real file handle.
That makes sure that the real file handle is always 32bit aligned
in-memory when passed down to the underlying filesystem.
On-disk format remains the same and store/load are done into
correctly aligned buffer.
New nfs exported file handles are exported with aligned real fid.
Old nfs file handles are copied to an aligned buffer before being
decoded.
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Based on 2 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 4122 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Overlapping overlay layers are not supported and can cause unexpected
behavior, but overlayfs does not currently check or warn about these
configurations.
User is not supposed to specify the same directory for upper and
lower dirs or for different lower layers and user is not supposed to
specify directories that are descendants of each other for overlay
layers, but that is exactly what this zysbot repro did:
https://syzkaller.appspot.com/x/repro.syz?x=12c7a94f400000
Moving layer root directories into other layers while overlayfs
is mounted could also result in unexpected behavior.
This commit places "traps" in the overlay inode hash table.
Those traps are dummy overlay inodes that are hashed by the layers
root inodes.
On mount, the hash table trap entries are used to verify that overlay
layers are not overlapping. While at it, we also verify that overlay
layers are not overlapping with directories "in-use" by other overlay
instances as upperdir/workdir.
On lookup, the trap entries are used to verify that overlay layers
root inodes have not been moved into other layers after mount.
Some examples:
$ ./run --ov --samefs -s
...
( mkdir -p base/upper/0/u base/upper/0/w base/lower lower upper mnt
mount -o bind base/lower lower
mount -o bind base/upper upper
mount -t overlay none mnt ...
-o lowerdir=lower,upperdir=upper/0/u,workdir=upper/0/w)
$ umount mnt
$ mount -t overlay none mnt ...
-o lowerdir=base,upperdir=upper/0/u,workdir=upper/0/w
[ 94.434900] overlayfs: overlapping upperdir path
mount: mount overlay on mnt failed: Too many levels of symbolic links
$ mount -t overlay none mnt ...
-o lowerdir=upper/0/u,upperdir=upper/0/u,workdir=upper/0/w
[ 151.350132] overlayfs: conflicting lowerdir path
mount: none is already mounted or mnt busy
$ mount -t overlay none mnt ...
-o lowerdir=lower:lower/a,upperdir=upper/0/u,workdir=upper/0/w
[ 201.205045] overlayfs: overlapping lowerdir path
mount: mount overlay on mnt failed: Too many levels of symbolic links
$ mount -t overlay none mnt ...
-o lowerdir=lower,upperdir=upper/0/u,workdir=upper/0/w
$ mv base/upper/0/ base/lower/
$ find mnt/0
mnt/0
mnt/0/w
find: 'mnt/0/w/work': Too many levels of symbolic links
find: 'mnt/0/u': Too many levels of symbolic links
Reported-by: syzbot+9c69c282adc4edd2b540@syzkaller.appspotmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Generalize the helper ovl_open_maybe_copy_up() and use it to copy up file
with data before FS_IOC_SETFLAGS ioctl.
The FS_IOC_SETFLAGS ioctl is a bit of an odd ball in vfs, which probably
caused the confusion. File may be open O_RDONLY, but ioctl modifies the
file. VFS does not call mnt_want_write_file() nor lock inode mutex, but
fs-specific code for FS_IOC_SETFLAGS does. So ovl_ioctl() calls
mnt_want_write_file() for the overlay file, and fs-specific code calls
mnt_want_write_file() for upper fs file, but there was no call for
ovl_want_write() for copy up duration which prevents overlayfs from copying
up on a frozen upper fs.
Fixes: dab5ca8fd9 ("ovl: add lsattr/chattr support")
Cc: <stable@vger.kernel.org> # v4.19
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
If a file has been copied up metadata only, and later data is copied up,
upper loses any security.capability xattr it has (underlying filesystem
clears it as upon file write).
From a user's point of view, this is just a file copy-up and that should
not result in losing security.capability xattr. Hence, before data copy
up, save security.capability xattr (if any) and restore it on upper after
data copy up is complete.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Fixes: 0c28887493 ("ovl: A new xattr OVL_XATTR_METACOPY for file on upper")
Cc: <stable@vger.kernel.org> # v4.19+
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
It just makes the interface strange without adding any significant value.
The only case where locked is false and return value is 0 is in
ovl_rename() when new is negative, so handle that case explicitly in
ovl_rename().
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Format has a typo: it was meant to be "%.*s", not "%*s". But at some point
callers grew nonprintable values as well, so use "%*pE" instead with a
maximized length.
Reported-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 3a1e819b4e ("ovl: store file handle of lower inode on copy up")
Cc: <stable@vger.kernel.org> # v4.12
Right now we seem to check redirect only if upperdentry is found. But it
is possible that there is no upperdentry but later we found an index.
We need to check redirect on index as well and set it in
ovl_inode->redirect. Otherwise link code can assume that dentry does not
have redirect and place a new one which breaks things. In my testing
overlay/033 test started failing in xfstests. Following are the details.
For example do following.
$ mkdir lower upper work merged
- Make lower dir with 4 links.
$ echo "foo" > lower/l0.txt
$ ln lower/l0.txt lower/l1.txt
$ ln lower/l0.txt lower/l2.txt
$ ln lower/l0.txt lower/l3.txt
- Mount with index on and metacopy on.
$ mount -t overlay -o lowerdir=lower,upperdir=upper,workdir=work,\
index=on,metacopy=on none merged
- Link lower
$ ln merged/l0.txt merged/l4.txt
(This will metadata copy up of l0.txt and put an absolute redirect
/l0.txt)
$ echo 2 > /proc/sys/vm/drop/caches
$ ls merged/l1.txt
(Now l1.txt will be looked up. There is no upper dentry but there is
lower dentry and index will be found. We don't check for redirect on
index, hence ovl_inode->redirect will be NULL.)
- Link Upper
$ ln merged/l4.txt merged/l5.txt
(Lookup of l4.txt will use inode from l1.txt lookup which is still in
cache. It has ovl_inode->redirect NULL, hence link will put a new
redirect and replace /l0.txt with /l4.txt
- Drop caches.
echo 2 > /proc/sys/vm/drop_caches
- List l1.txt and it returns -ESTALE
$ ls merged/l0.txt
(It returns stale because, we found a metacopy of l0.txt in upper and it
has redirect l4.txt but there is no file named l4.txt in lower layer.
So lower data copy is not found and -ESTALE is returned.)
So problem here is that we did not process redirect on index. Check
redirect on index as well and then problem is fixed.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Add an ovl_inode flag OVL_CONST_INO. This flag signifies if inode number
will remain constant over copy up or not. This flag does not get updated
over copy up and remains unmodifed after setting once.
Next patch in the series will make use of this flag. It will basically
figure out if dentry is of type ORIGIN or not. And this can be derived by
this flag.
ORIGIN = (upperdentry && ovl_test_flag(OVL_CONST_INO, inode)).
Suggested-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Add an helper to retrieve real data inode associated with overlay inode.
This helper will ignore all metacopy inodes and will return only the real
inode which has data.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Right now ovl_inode stores inode pointer for lower inode. This helps with
quickly getting lower inode given overlay inode (ovl_inode_lower()).
Now with metadata only copy-up, we can have metacopy inode in middle layer
as well and inode containing data can be different from ->lower. I need to
be able to open the real file in ovl_open_realfile() and for that I need to
quickly find the lower data inode.
Hence store lower data inode also in ovl_inode. Also provide an helper
ovl_inode_lowerdata() to access this field.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
If an inode has been copied up metadata only, then we need to query the
number of blocks from lower and fill up the stat->st_blocks.
We need to be careful about races where we are doing stat on one cpu and
data copy up is taking place on other cpu. We want to return
stat->st_blocks either from lower or stable upper and not something in
between. Hence, ovl_has_upperdata() is called first to figure out whether
block reporting will take place from lower or upper.
We now support metacopy dentries in middle layer. That means number of
blocks reporting needs to come from lowest data dentry and this could be
different from lower dentry. Hence we end up making a separate
vfs_getxattr() call for metacopy dentries to get number of blocks.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Now we have the notion of data dentry and metacopy dentry.
ovl_dentry_lower() will return uppermost lower dentry, but it could be
either data or metacopy dentry. Now we support metacopy dentries in lower
layers so it is possible that lowerstack[0] is metacopy dentry while
lowerstack[1] is actual data dentry.
So add an helper which returns lowest most dentry which is supposed to be
data dentry.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
So far lower could not be a meta inode. So whenever it was time to copy up
data of a meta inode, we could copy it up from top most lower dentry.
But now lower itself can be a metacopy inode. That means data copy up
needs to take place from a data inode in metacopy inode chain. Find lower
data inode in the chain and use that for data copy up.
Introduced a helper called ovl_path_lowerdata() to find the lower data
inode chain.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This patch modifies ovl_lookup() and friends to lookup metacopy dentries.
It also allows for presence of metacopy dentries in lower layer.
During lookup, check for presence of OVL_XATTR_METACOPY and if not present,
set OVL_UPPERDATA bit in flags.
We don't support metacopy feature with nfs_export. So in nfs_export code,
we set OVL_UPPERDATA flag set unconditionally if upper inode exists.
Do not follow metacopy origin if we find a metacopy only inode and metacopy
feature is not enabled for that mount. Like redirect, this can have
security implications where an attacker could hand craft upper and try to
gain access to file on lower which it should not have to begin with.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Now we will have the capability to have upper inodes which might be only
metadata copy up and data is still on lower inode. So add a new xattr
OVL_XATTR_METACOPY to distinguish between two cases.
Presence of OVL_XATTR_METACOPY reflects that file has been copied up
metadata only and and data will be copied up later from lower origin. So
this xattr is set when a metadata copy takes place and cleared when data
copy takes place.
We also use a bit in ovl_inode->flags to cache OVL_UPPERDATA which reflects
whether ovl inode has data or not (as opposed to metadata only copy up).
If a file is copied up metadata only and later when same file is opened for
WRITE, then data copy up takes place. We copy up data, remove METACOPY
xattr and then set the UPPERDATA flag in ovl_inode->flags. While all these
operations happen with oi->lock held, read side of oi->flags can be
lockless. That is another thread on another cpu can check if UPPERDATA
flag is set or not.
So this gives us an ordering requirement w.r.t UPPERDATA flag. That is, if
another cpu sees UPPERDATA flag set, then it should be guaranteed that
effects of data copy up and remove xattr operations are also visible.
For example.
CPU1 CPU2
ovl_open() acquire(oi->lock)
ovl_open_maybe_copy_up() ovl_copy_up_data()
open_open_need_copy_up() vfs_removexattr()
ovl_already_copied_up()
ovl_dentry_needs_data_copy_up() ovl_set_flag(OVL_UPPERDATA)
ovl_test_flag(OVL_UPPERDATA) release(oi->lock)
Say CPU2 is copying up data and in the end sets UPPERDATA flag. But if
CPU1 perceives the effects of setting UPPERDATA flag but not the effects of
preceding operations (ex. upper that is not fully copied up), it will be a
problem.
Hence this patch introduces smp_wmb() on setting UPPERDATA flag operation
and smp_rmb() on UPPERDATA flag test operation.
May be some other lock or barrier is already covering it. But I am not sure
what that is and is it obvious enough that we will not break it in future.
So hence trying to be safe here and introducing barriers explicitly for
UPPERDATA flag/bit.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
There are couple of places where we need to know if file is already copied
up (in lockless manner). Right now its open coded and there are only two
conditions to check. Soon this patch series will introduce another
condition to check and Amir wants to introduce one more. So introduce a
helper instead to check this so that code is easier to read.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Right now two copy up helpers are in inode.c. Amir suggested it might be
better to move these to copy_up.c.
There will one more related function which will come in later patch.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
ovl_inode->redirect is an inode property and should be initialized in
ovl_get_inode() only when we are adding a new inode to cache. If inode is
already in cache, it is already initialized and we should not be touching
ovl_inode->redirect field.
As of now this is not a problem as redirects are used only for directories
which don't share inode. But soon I want to use redirects for regular
files also and there it can become an issue.
Hence, move ->redirect initialization in ovl_get_inode().
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Implement file operations on a regular overlay file. The underlying file
is opened separately and cached in ->private_data.
It might be worth making an exception for such files when accounting in
nr_file to confirm to userspace expectations. We are only adding a small
overhead (248bytes for the struct file) since the real inode and dentry are
pinned by overlayfs anyway.
This patch doesn't have any effect, since the vfs will use d_real() to find
the real underlying file to open. The patch at the end of the series will
actually enable this functionality.
AV: make it use open_with_fake_path(), don't mess with override_creds
SzM: still need to mess with override_creds() until no fs uses
current_cred() in their open method.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Copy i_size of the underlying inode to the overlay inode in ovl_copyattr().
This is in preparation for stacking I/O operations on overlay files.
This patch shouldn't have any observable effect.
Remove stale comment from ovl_setattr() [spotted by Vivek Goyal].
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
On inode creation copy certain inode flags from the underlying real inode
to the overlay inode.
This is in preparation for moving overlay functionality out of the VFS.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Copy up mtime and ctime to overlay inode after times in real object are
modified. Be careful not to dirty cachelines when not necessary.
This is in preparation for moving overlay functionality out of the VFS.
This patch shouldn't have any observable effect.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This is a late set of changes from Deepa Dinamani doing an automated
treewide conversion of the inode and iattr structures from 'timespec'
to 'timespec64', to push the conversion from the VFS layer into the
individual file systems.
There were no conflicts between this and the contents of linux-next
until just before the merge window, when we saw multiple problems:
- A minor conflict with my own y2038 fixes, which I could address
by adding another patch on top here.
- One semantic conflict with late changes to the NFS tree. I addressed
this by merging Deepa's original branch on top of the changes that
now got merged into mainline and making sure the merge commit includes
the necessary changes as produced by coccinelle.
- A trivial conflict against the removal of staging/lustre.
- Multiple conflicts against the VFS changes in the overlayfs tree.
These are still part of linux-next, but apparently this is no longer
intended for 4.18 [1], so I am ignoring that part.
As Deepa writes:
The series aims to switch vfs timestamps to use struct timespec64.
Currently vfs uses struct timespec, which is not y2038 safe.
The series involves the following:
1. Add vfs helper functions for supporting struct timepec64 timestamps.
2. Cast prints of vfs timestamps to avoid warnings after the switch.
3. Simplify code using vfs timestamps so that the actual
replacement becomes easy.
4. Convert vfs timestamps to use struct timespec64 using a script.
This is a flag day patch.
Next steps:
1. Convert APIs that can handle timespec64, instead of converting
timestamps at the boundaries.
2. Update internal data structures to avoid timestamp conversions.
Thomas Gleixner adds:
I think there is no point to drag that out for the next merge window.
The whole thing needs to be done in one go for the core changes which
means that you're going to play that catchup game forever. Let's get
over with it towards the end of the merge window.
[1] https://www.spinics.net/lists/linux-fsdevel/msg128294.html
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Merge tag 'vfs-timespec64' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground
Pull inode timestamps conversion to timespec64 from Arnd Bergmann:
"This is a late set of changes from Deepa Dinamani doing an automated
treewide conversion of the inode and iattr structures from 'timespec'
to 'timespec64', to push the conversion from the VFS layer into the
individual file systems.
As Deepa writes:
'The series aims to switch vfs timestamps to use struct timespec64.
Currently vfs uses struct timespec, which is not y2038 safe.
The series involves the following:
1. Add vfs helper functions for supporting struct timepec64
timestamps.
2. Cast prints of vfs timestamps to avoid warnings after the switch.
3. Simplify code using vfs timestamps so that the actual replacement
becomes easy.
4. Convert vfs timestamps to use struct timespec64 using a script.
This is a flag day patch.
Next steps:
1. Convert APIs that can handle timespec64, instead of converting
timestamps at the boundaries.
2. Update internal data structures to avoid timestamp conversions'
Thomas Gleixner adds:
'I think there is no point to drag that out for the next merge
window. The whole thing needs to be done in one go for the core
changes which means that you're going to play that catchup game
forever. Let's get over with it towards the end of the merge window'"
* tag 'vfs-timespec64' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground:
pstore: Remove bogus format string definition
vfs: change inode times to use struct timespec64
pstore: Convert internal records to timespec64
udf: Simplify calls to udf_disk_stamp_to_time
fs: nfs: get rid of memcpys for inode times
ceph: make inode time prints to be long long
lustre: Use long long type to print inode time
fs: add timespec64_truncate()
Currently, there is a small window where ovl_obtain_alias() can
race with ovl_instantiate() and create two different overlay inodes
with the same underlying real non-dir non-hardlink inode.
The race requires an adversary to guess the file handle of the
yet to be created upper inode and decode the guessed file handle
after ovl_creat_real(), but before ovl_instantiate().
This race does not affect overlay directory inodes, because those
are decoded via ovl_lookup_real() and not with ovl_obtain_alias().
This patch fixes the race, by using inode_insert5() to add a newly
created inode to cache.
If the newly created inode apears to already exist in cache (hashed
by the same real upper inode), we instantiate the dentry with the old
inode and drop the new inode, instead of silently not hashing the new
inode.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
ovl_get_inode() right now has 5 parameters. Soon this patch series will
add 2 more and suddenly argument list starts looking too long.
Hence pass arguments to ovl_get_inode() in a structure and it looks
little cleaner.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Also used ovl_create_temp() in ovl_create_index() instead of calling
ovl_do_mkdir() directly, so now all callers of ovl_do_mkdir() are routed
through ovl_create_real(), which paves the way for Al's fix for non-hashed
result from vfs_mkdir().
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Al Viro suggested to simplify callers of ovl_create_real() by
returning the created dentry (or ERR_PTR) from ovl_create_real().
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
When overlay layers are not all on the same fs, but all inode numbers
of underlying fs do not use the high 'xino' bits, overlay st_ino values
are constant and persistent.
In that case, set i_ino value to the same value as st_ino for nfsd
readdirplus validator.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
On 64bit systems, when overlay layers are not all on the same fs, but
all inode numbers of underlying fs are not using the high bits, use the
high bits to partition the overlay st_ino address space. The high bits
hold the fsid (upper fsid is 0). This way overlay inode numbers are unique
and all inodes use overlay st_dev. Inode numbers are also persistent
for a given layer configuration.
Currently, our only indication for available high ino bits is from a
filesystem that supports file handles and uses the default encode_fh()
operation, which encodes a 32bit inode number.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
A helper for ovl_getattr() to map the values of st_dev and st_ino
according to constant st_ino rules.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
On lookup of non directory, we try to decode the origin file handle
stored in upper inode. The origin file handle is supposed to be decoded
to a disconnected non-dir dentry, which is fine, because we only need
the lower inode of a copy up origin.
However, if the origin file handle somehow turns out to be a directory
we pay the expensive cost of reconnecting the directory dentry, only to
get a mismatch file type and drop the dentry.
Optimize this case by explicitly opting out of reconnecting the dentry.
Opting-out of reconnect is done by passing a NULL acceptable callback
to exportfs_decode_fh().
While the case described above is a strange corner case that does not
really need to be optimized, the API added for this optimization will
be used by a following patch to optimize a more common case of decoding
an overlayfs file handle.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Rename ovl_encode_fh() to ovl_encode_real_fh() to differentiate from the
exportfs function ovl_encode_inode_fh() and change the latter to
ovl_encode_fh() to match the exportfs method name.
Rename ovl_decode_fh() to ovl_decode_real_fh() for consistency.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This change relaxes copy up on encode of merge dir with lower layer > 1
and handles the case of encoding a merge dir with lower layer 1, where an
ancestor is a non-indexed merge dir. In that case, decode of the lower
file handle will not have been possible if the non-indexed ancestor is
redirected before or after encode.
Before encoding a non-upper directory file handle from real layer N, we
need to check if it will be possible to reconnect an overlay dentry from
the real lower decoded dentry. This is done by following the overlay
ancestry up to a "layer N connected" ancestor and verifying that all
parents along the way are "layer N connectable". If an ancestor that is
NOT "layer N connectable" is found, we need to copy up an ancestor, which
is "layer N connectable", thus making that ancestor "layer N connected".
For example:
layer 1: /a
layer 2: /a/b/c
The overlay dentry /a is NOT "layer 2 connectable", because if dir /a is
copied up and renamed, upper dir /a will be indexed by lower dir /a from
layer 1. The dir /a from layer 2 will never be indexed, so the algorithm
in ovl_lookup_real_ancestor() (*) will not be able to lookup a connected
overlay dentry from the connected lower dentry /a/b/c.
To avoid this problem on decode time, we need to copy up an ancestor of
/a/b/c, which is "layer 2 connectable", on encode time. That ancestor is
/a/b. After copy up (and index) of /a/b, it will become "layer 2 connected"
and when the time comes to decode the file handle from lower dentry /a/b/c,
ovl_lookup_real_ancestor() will find the indexed ancestor /a/b and decoding
a connected overlay dentry will be accomplished.
(*) the algorithm in ovl_lookup_real_ancestor() can be improved to lookup
an entry /a in the lower layers above layer N and find the indexed dir /a
from layer 1. If that improvement is made, then the check for "layer N
connected" will need to verify there are no redirects in lower layers above
layer N. In the example above, /a will be "layer 2 connectable". However,
if layer 2 dir /a is a target of a layer 1 redirect, then /a will NOT be
"layer 2 connectable":
layer 1: /A (redirect = /a)
layer 2: /a/b/c
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
ovl_lookup_real() in lower layer walks back lower parents to find the
topmost indexed parent. If an indexed ancestor is found before reaching
lower layer root, ovl_lookup_real() is called recursively with upper
layer to walk back from indexed upper to the topmost connected/hashed
upper parent (or up to root).
ovl_lookup_real() in upper layer then walks forward to connect the topmost
upper overlay dir dentry and ovl_lookup_real() in lower layer continues to
walk forward to connect the decoded lower overlay dir dentry.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Decoding a dir file handle requires walking backward up to layer root and
for lower dir also checking the index to see if any of the parents have
been copied up.
Lookup overlay ancestor dentry in inode/dentry cache by decoded real
parents to shortcut looking up all the way back to layer root.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Decoding an indexed dir file handle is done by looking up the file handle
in index dir by name and then decoding the upper dir from the index origin
file handle. The decoded upper path is used to lookup an overlay dentry of
the same path.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Lookup overlay inode in cache by origin inode, so we can decode a file
handle of an open file even if the index has a whiteout index entry to
mark this overlay inode was unlinked.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Decoding a lower non-dir file handle is done by decoding the lower dentry
from underlying lower fs, finding or allocating an overlay inode that is
hashed by the real lower inode and instantiating an overlay dentry with
that inode.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Decoding an upper file handle is done by decoding the upper dentry from
underlying upper fs, finding or allocating an overlay inode that is
hashed by the real upper inode and instantiating an overlay dentry with
that inode.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Encode overlay file handles as struct ovl_fh containing the file handle
encoding of the real upper inode.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
We need to make some room in struct ovl_entry to store information
about redirected ancestors for NFS export, so cram two booleans as
bit flags.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This is needed for using ovl_get_inode() for decoding file handles
for NFS export.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
The helper is needed to lookup an index by file handle for NFS export.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
With NFS export feature enabled, when overlay inode nlink drops to
zero, instead of removing the index entry, replace it with a whiteout
index entry.
This is needed for NFS export in order to prevent future open by handle
from opening the lower file directly.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
The helper determines which lower file needs to be indexed
on copy up and before nlink changes.
For index=on, the helper evaluates to true for lower hardlinks.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
A directory index is a directory type entry in index dir with a
"trusted.overlay.upper" xattr containing an encoded ovl_fh of the merge
directory upper dir inode.
On lookup of non-dir files, lower file is followed by origin file handle.
On lookup of dir entries, lower dir is found by name and then compared
to origin file handle. We only trust dir index if we verified that lower
dir matches origin file handle, otherwise index may be inconsistent and
we ignore it.
If we find an indexed non-upper dir or an indexed merged dir, whose
index 'upper' xattr points to a different upper dir, that means that the
lower directory may be also referenced by another upper dir via redirect,
so we fail the lookup on inconsistency error.
To be consistent with directory index entries format, the association of
index dir to upper root dir, that was stored by older kernels in
"trusted.overlay.origin" xattr is now stored in "trusted.overlay.upper"
xattr. This also serves as an indication that overlay was mounted with a
kernel that support index directory entries. For backward compatibility,
if an 'origin' xattr exists on the index dir we also verify it on mount.
Directory index entries are going to be used for NFS export.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Introduce the "nfs_export" config, module and mount options.
The NFS export feature depends on the "index" feature and enables two
implicit overlayfs features: "index_all" and "verify_lower".
The "index_all" feature creates an index on copy up of every file and
directory. The "verify_lower" feature uses the full index to detect
overlay filesystems inconsistencies on lookup, like redirect from
multiple upper dirs to the same lower dir.
NFS export can be enabled for non-upper mount with no index. However,
because lower layer redirects cannot be verified with the index, enabling
NFS export support on an overlay with no upper layer requires turning off
redirect follow (e.g. "redirect_dir=nofollow").
The full index may incur some overhead on mount time, especially when
verifying that lower directory file handles are not stale.
NFS export support, full index and consistency verification will be
implemented by following patches.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Remove the "origin" language from the functions that handle set, get
and verify of "origin" xattr and pass the xattr name as an argument.
The same helpers are going to be used for NFS export to get, get and
verify the "upper" xattr for directory index entries.
ovl_verify_origin() is now a helper used only to verify non upper
file handle stored in "origin" xattr of upper inode.
The upper root dir file handle is still stored in "origin" xattr on
the index dir for backward compatibility. This is going to be changed
by the patch that adds directory index entries support.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Pass the fs instance with lower_layers array instead of the dentry
lowerstack array to ovl_check_origin_fh(), because the dentry members
of lowerstack play no role in this helper.
This change simplifies the argument list of ovl_check_origin(),
ovl_cleanup_index() and ovl_verify_index().
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
For a merge dir that was copied up before v4.12 or that was hand crafted
offline (e.g. mkdir {upper/lower}/dir), upper dir does not contain the
'trusted.overlay.origin' xattr. In that case, stat(2) on the merge dir
returns the lower dir st_ino, but getdents(2) returns the upper dir d_ino.
After this change, on merge dir lookup, missing origin xattr on upper
dir will be fixed and 'impure' xattr will be fixed on parent of the legacy
merge dir.
Suggested-by: zhangyi (F) <yi.zhang@huawei.com>
Reviewed-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fix ptr_ret.cocci warnings:
fs/overlayfs/overlayfs.h:179:11-17: WARNING: PTR_ERR_OR_ZERO can be used
Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR
Generated by: scripts/coccinelle/api/ptr_ret.cocci
Signed-off-by: Vasyl Gomonovych <gomonovych@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Define new structures to represent overlay instance lower layers and
overlay merge dir lower layers to make room for storing more per layer
information in-memory.
Instead of keeping the fs instance lower layers in an array of struct
vfsmount, keep them in an array of new struct ovl_layer, that has a
pointer to struct vfsmount.
Instead of keeping the dentry lower layers in an array of struct path,
keep them in an array of new struct ovl_path, that has a pointer to
struct dentry and to struct ovl_layer.
Add a small helper to find the fs layer id that correspopnds to a lower
struct ovl_path and use it in ovl_lookup().
[amir: split re-structure from anonymous bdev patch]
Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Most overlayfs c files already explicitly include ovl_entry.h
to use overlay entry struct definitions and upcoming changes
are going to require even more c files to include this header.
All overlayfs c files include overlayfs.h and overlayfs.h itself
refers to some structs defined in ovl_entry.h, so it seems more
logic to include ovl_entry.h from overlayfs.h than from c files.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
If a non-merge dir in an overlay mount has an overlay.origin xattr, it
means it was once an upper merge dir, which may contain whiteouts and
then the lower dir was removed under it.
Do not iterate real dir directly in this case to avoid exposing whiteouts.
[SzM] Set OVL_WHITEOUT for all merge directories as well.
[amir] A directory that was just copied up does not have the OVL_WHITEOUTS
flag. We need to set it to fix merge dir iteration.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Commit fbaf94ee3c ("ovl: don't set origin on broken lower hardlink")
attempt to avoid the condition of non-indexed upper inode with lower
hardlink as origin. If this condition is found, lookup returns EIO.
The protection of commit mentioned above does not cover the case of lower
that is not a hardlink when it is copied up (with either index=off/on)
and then lower is hardlinked while overlay is offline.
Changes to lower layer while overlayfs is offline should not result in
unexpected behavior, so a permanent EIO error after creating a link in
lower layer should not be considered as correct behavior.
This fix replaces EIO error with success in cases where upper has origin
but no index is found, or index is found that does not match upper
inode. In those cases, lookup will not fail and the returned overlay inode
will be hashed by upper inode instead of by lower origin inode.
Fixes: 359f392ca5 ("ovl: lookup index entry for copy up origin")
Cc: <stable@vger.kernel.org> # v4.13
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Use the ovl_lock_rename_workdir() helper which requires
unlock_rename() only on lock success.
Fixes: ("fd210b7d67ee ovl: move copy up lock out")
Cc: <stable@vger.kernel.org> # v4.13
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Impure directories are ones which contain objects with origins (i.e. those
that have been copied up). These are relevant to readdir operation only
because of the d_ino field, no other transformation is necessary. Also a
directory can become impure between two getdents(2) calls.
This patch creates a cache for impure directories. Unlike the cache for
merged directories, this one only contains entries with origin and is not
refcounted but has a its lifetime tied to that of the dentry.
Similarly to the merged cache, the impure cache is invalidated based on a
version number. This version number is incremented when an entry with
origin is added or removed from the directory.
If the cache is empty, then the impure xattr is removed from the directory.
This patch also fixes up handling of d_ino for the ".." entry if the parent
directory is merged.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
inode_doinit_with_dentry() in SELinux wants to read the upper inode's xattr
to get security label, and ovl_xattr_get() calls ovl_dentry_real(), which
depends on dentry->d_inode, but d_inode is null and not initialized yet at
this point resulting in an Oops.
Fix by getting the upperdentry info from the inode directly in this case.
Reported-by: Eryu Guan <eguan@redhat.com>
Fixes: 09d8b58673 ("ovl: move __upperdentry to ovl_inode")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Commit 54fb347e83 ("ovl: verify index dir matches upper dir")
introduced a new ovl_fh flag OVL_FH_FLAG_PATH_UPPER to indicate
an upper file handle, but forgot to add the flag to the mask of
valid flags, so index dir origin verification always discards
existing origin and stores a new one.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
index entry should live only as long as there are upper or lower
hardlinks.
Cleanup orphan index entries on mount and when dropping the last
overlay inode nlink.
When about to cleanup or link up to orphan index and the index inode
nlink > 1, admit that something went wrong and adjust overlay nlink
to index inode nlink - 1 to prevent it from dropping below zero.
This could happen when adding lower hardlinks underneath a mounted
overlay and then trying to unlink them.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
With inodes index enabled, an overlay inode nlink counts the union of upper
and non-covered lower hardlinks. During the lifetime of a non-pure upper
inode, the following nlink modifying operations can happen:
1. Lower hardlink copy up
2. Upper hardlink created, unlinked or renamed over
3. Lower hardlink whiteout or renamed over
For the first, copy up case, the union nlink does not change, whether the
operation succeeds or fails, but the upper inode nlink may change.
Therefore, before copy up, we store the union nlink value relative to the
lower inode nlink in the index inode xattr trusted.overlay.nlink.
For the second, upper hardlink case, the union nlink should be incremented
or decremented IFF the operation succeeds, aligned with nlink change of the
upper inode. Therefore, before link/unlink/rename, we store the union nlink
value relative to the upper inode nlink in the index inode.
For the last, lower cover up case, we simplify things by preceding the
whiteout or cover up with copy up. This makes sure that there is an index
upper inode where the nlink xattr can be stored before the copied up upper
entry is unlink.
Return the overlay inode nlinks for indexed upper inodes on stat(2).
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
For rename, we need to ensure that an upper alias exists for hard links
before attempting the operation. Introduce a flag in ovl_entry to track
the state of the upper alias.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Bad index entries are entries whose name does not match the
origin file handle stored in trusted.overlay.origin xattr.
Bad index entries could be a result of a system power off in
the middle of copy up.
Stale index entries are entries whose origin file handle is
stale. Stale index entries could be a result of copying layers
or removing lower entries while the overlay is not mounted.
The case of copying layers should be detected earlier by the
verification of upper root dir origin and index dir origin.
Both bad and stale index entries are detected and removed
on mount.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
When inodes index feature is enabled, lookup in indexdir for the index
entry of lower real inode or copy up origin inode. The index entry name
is the hex representation of the lower inode file handle.
If the index dentry in negative, then either no lower aliases have been
copied up yet, or aliases have been copied up in older kernels and are
not indexed.
If the index dentry for a copy up origin inode is positive, but points
to an inode different than the upper inode, then either the upper inode
has been copied up and not indexed or it was indexed, but since then
index dir was cleared. Either way, that index cannot be used to indentify
the overlay inode.
If a positive dentry that matches the upper inode was found, then it is
safe to use the copy up origin st_ino for upper hardlinks, because all
indexed upper hardlinks are represented by the same overlay inode as the
copy up origin.
Set the INDEX type flag on an indexed upper dentry. A non-upper dentry
may also have a positive index from copy up of another lower hardlink.
This situation will be handled by following patches.
Index lookup is going to be used to prevent breaking hardlinks on copy up.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
An index dir contains persistent hardlinks to files in upper dir.
Therefore, we must never mount an existing index dir with a differnt
upper dir.
Store the upper root dir file handle in index dir inode when index
dir is created and verify the file handle before using an existing
index dir on mount.
Add an 'is_upper' flag to the overlay file handle encoding and set it
when encoding the upper root file handle. This is not critical for index
dir verification, but it is good practice towards a standard overlayfs
file handle format for NFS export.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
When inodes index feature is enabled, verify that the file handle stored
in upper root dir matches the lower root dir or fail to mount.
If upper root dir has no stored file handle, encode and store the lower
root dir file handle in overlay.origin xattr.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Create the index dir on mount. The index dir will contain hardlinks to
upper inodes, named after the hex representation of their origin lower
inodes.
The index dir is going to be used to prevent breaking lower hardlinks
on copy up and to implement overlayfs NFS export.
Because the feature is not fully backward compat, enabling the feature
is opt-in by config/module/mount option.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Added an i_state flag I_INUSE and helpers to set/clear/test the bit.
The 'inuse' lock is an 'advisory' inode lock, that can be used to extend
exclusive create protection beyond parent->i_mutex lock among cooperating
users.
This is going to be used by overlayfs to get exclusive ownership on upper
and work dirs among overlayfs mounts.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
An upper dir is marked "impure" to let ovl_iterate() know that this
directory may contain non pure upper entries whose d_ino may need to be
read from the origin inode.
We already mark a non-merge dir "impure" when moving a non-pure child
entry inside it, to let ovl_iterate() know not to iterate the non-merge
dir directly.
Mark also a merge dir "impure" when moving a non-pure child entry inside
it and when copying up a child entry inside it.
This can be used to optimize ovl_iterate() to perform a "pure merge" of
upper and lower directories, merging the content of the directories,
without having to read d_ino from origin inodes.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
When moving a merge dir or non-dir with copy up origin into a non-merge
upper dir (a.k.a pure upper dir), we are marking the target parent dir
"impure". ovl_iterate() iterates pure upper dirs directly, because there is
no need to filter out whiteouts and merge dir content with lower dir. But
for the case of an "impure" upper dir, ovl_iterate() will not be able to
iterate the real upper dir directly, because it will need to lookup the
origin inode and use it to fill d_ino.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
On failure to set opaque/redirect xattr on rename, skip setting xattr and
return -EXDEV.
On failure to set opaque xattr when creating a new directory, -EIO is
returned instead of -EOPNOTSUPP.
Any failure to set those xattr will be recorded in super block and
then setting any xattr on upper won't be attempted again.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
xattr are needed by overlayfs for setting opaque dir, redirect dir
and copy up origin.
Check at mount time by trying to set the overlay.opaque xattr on the
workdir and if that fails issue a warning message.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
For directory entries, non zero oe->numlower implies OVL_TYPE_MERGE.
Define a new type flag OVL_TYPE_ORIGIN to indicate that an entry holds a
reference to its lower copy up origin.
For directory entries ORIGIN := MERGE && UPPER. For non-dir entries ORIGIN
means that a lower type dentry has been recently copied up or that we were
able to find the copy up origin from overlay.origin xattr.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Sometimes it is interesting to know if an upper file is pure upper or a
copy up target, and if it is a copy up target, it may be interesting to
find the copy up origin.
This will be used to preserve lower inode numbers across copy up.
Store the lower inode file handle in upper inode extended attribute
overlay.origin on copy up to use it later for these cases. Store the lower
filesystem uuid along side the file handle, so we can validate that we are
looking for the origin file in the original fs.
If lower fs does not support NFS export ops store a zero sized xattr so we
can always use the overlay.origin xattr to distinguish between a copy up
and a pure upper inode.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Some features can only work when all layers are on the same fs. Test this
condition during mount time, so features can check them later.
Add helper ovl_same_sb() to return the common super block in case all
layers are on the same fs.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
The overlay sb 'copyup_wq' and overlay inode 'copying' condition
variable are about to replace the upper sb rename_lock, as finer
grained synchronization objects for concurrent copy up.
Suggested-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This is needed for choosing between concurrent copyup
using O_TMPFILE and legacy copyup using workdir+rename.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
FWIW, there's a bit of abuse of struct kstat in overlayfs object
creation paths - for one thing, it ends up with a very small subset
of struct kstat (mode + rdev), for another it also needs link in
case of symlinks and ends up passing it separately.
IMO it would be better to introduce a separate object for that.
In principle, we might even lift that thing into general API and switch
->mkdir()/->mknod()/->symlink() to identical calling conventions. Hell
knows, perhaps ->create() as well...
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
oe->opaque is set for
a) whiteouts
b) directories having the "trusted.overlay.opaque" xattr
Case b can be simplified, since setting the xattr always implies setting
oe->opaque. Also once set, the opaque flag is never cleared.
Don't need to set opaque flag for non-directories.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Current code returns EXDEV when a directory would need to be copied up to
move. We could copy up the directory tree in this case, but there's
another, simpler solution: point to old lower directory from moved upper
directory.
This is achieved with a "trusted.overlay.redirect" xattr storing the path
relative to the root of the overlay. After such attribute has been set,
the directory can be moved without further actions required.
This is a backward incompatible feature, old kernels won't be able to
correctly mount an overlay containing redirected directories.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
If a directory has the "trusted.overlay.redirect" xattr, it means that the
value of the xattr should be used to find the underlying directory on the
next lower layer.
The redirect may be relative or absolute. Absolute redirects begin with a
slash.
A relative redirect means: instead of the current dentry's name use the
value of the redirect to find the directory in the next lower
layer. Relative redirects must not contain a slash.
An absolute redirect means: look up the directory relative to the root of
the overlay using the value of the redirect in the next lower layer.
Redirects work on lower layers as well.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
fs/overlayfs/super.c is the biggest of the overlayfs source files and it
contains various utility functions as well as the rather complicated lookup
code. Split these parts out to separate files.
Before:
1446 fs/overlayfs/super.c
After:
919 fs/overlayfs/super.c
267 fs/overlayfs/namei.c
235 fs/overlayfs/util.c
51 fs/overlayfs/ovl_entry.h
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
d_is_dir() is safe to call on a negative dentry. Use this fact to simplify
handling of the lower or merged directories.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Currently ovl_lookup() checks existence of lower file even if there's a
non-directory on upper (which is always opaque). This is done so that
remove can decide whether a whiteout is needed or not.
It would be better to defer this check to unlink, since most of the time
the gathered information about opaqueness will be unused.
This adds a helper ovl_lower_positive() that checks if there's anything on
the lower layer(s).
The following patches also introduce changes to how the "opaque" attribute
is updated on directories: this attribute is added when the directory is
creted or moved over a whiteout or object covering something on the lower
layer. However following changes will allow the attribute to remain on the
directory after being moved, even if the new location doesn't cover
anything. Because of this, we need to check lower layers even for opaque
directories, so that whiteout is only created when necessary.
This function will later be also used to decide about marking a directory
opaque, so deal with negative dentries as well. When dealing with
negative, it's enough to check for being a whiteout
If the dentry is positive but not upper then it also obviously needs
whiteout/opaque.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Amir Goldstein