linux.git/fs/overlayfs, branch v5.6

ovl: fix lockdep warning for async write

2020-03-13T14:53:06+00:00

Lockdep reports "WARNING: lock held when returning to user space!" due to
async write holding freeze lock over the write.  Apparently aio.c already
deals with this by lying to lockdep about the state of the lock.

Do the same here.  No need to check for S_IFREG() here since these file ops
are regular-only.

Reported-by: syzbot+9331a354f4f624a52a55@syzkaller.appspotmail.com
Fixes: 2406a307ac7d ("ovl: implement async IO routines")
Signed-off-by: Miklos Szeredi

ovl: fix some xino configurations

2020-03-13T14:53:06+00:00

Fix up two bugs in the coversion to xino_mode:
1. xino=off does not always end up in disabled mode
2. xino=auto on 32bit arch should end up in disabled mode

Take a proactive approach to disabling xino on 32bit kernel:
1. Disable XINO_AUTO config during build time
2. Disable xino with a warning on mount time

As a by product, xino=on on 32bit arch also ends up in disabled mode.
We never intended to enable xino on 32bit arch and this will make the
rest of the logic simpler.

Fixes: 0f831ec85eda ("ovl: simplify ovl_same_sb() helper")
Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: fix lock in ovl_llseek()

2020-03-12T15:38:10+00:00

ovl_inode_lock() is interruptible. When inode_lock() in ovl_llseek()
was replaced with ovl_inode_lock(), we did not add a check for error.

Fix this by making ovl_inode_lock() uninterruptible and change the
existing call sites to use an _interruptible variant.

Reported-by: syzbot+66a9752fa927f745385e@syzkaller.appspotmail.com
Fixes: b1f9d3858f72 ("ovl: use ovl_inode_lock in ovl_llseek()")
Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: fix lseek overflow on 32bit

2020-02-03T10:41:53+00:00

ovl_lseek() is using ssize_t to return the value from vfs_llseek().  On a
32-bit kernel ssize_t is a 32-bit signed int, which overflows above 2 GB.

Assign the return value of vfs_llseek() to loff_t to fix this.

Reported-by: Boris Gjenero 
Fixes: 9e46b840c705 ("ovl: support stacked SEEK_HOLE/SEEK_DATA")
Cc:  # v4.19
Signed-off-by: Miklos Szeredi

ovl: add splice file read write helper

2020-01-24T15:28:15+00:00

Now overlayfs falls back to use default file splice read
and write, which is not compatiple with overlayfs, returning
EFAULT. xfstests generic/591 can reproduce part of this.

Tested this patch with xfstests auto group tests.

Signed-off-by: Murphy Zhou 
Signed-off-by: Miklos Szeredi

ovl: implement async IO routines

2020-01-24T08:46:46+00:00

A performance regression was observed since linux v4.19 with aio test using
fio with iodepth 128 on overlayfs.  The queue depth of the device was
always 1 which is unexpected.

After investigation, it was found that commit 16914e6fc7e1 ("ovl: add
ovl_read_iter()") and commit 2a92e07edc5e ("ovl: add ovl_write_iter()")
resulted in vfs_iter_{read,write} being called on underlying filesystem,
which always results in syncronous IO.

Implement async IO for stacked reading and writing.  This resolves the
performance regresion.

This is implemented by allocating a new kiocb for submitting the AIO
request on the underlying filesystem.  When the request is completed, the
new kiocb is freed and the completion callback is called on the original
iocb.

Signed-off-by: Jiufei Xue 
Signed-off-by: Miklos Szeredi

ovl: layer is const

2020-01-24T08:46:45+00:00

The ovl_layer struct is never modified except at initialization.

Signed-off-by: Miklos Szeredi

ovl: fix corner case of non-constant st_dev;st_ino

2020-01-24T08:46:45+00:00

On non-samefs overlay without xino, non pure upper inodes should use a
pseudo_dev assigned to each unique lower fs, but if lower layer is on the
same fs and upper layer, it has no pseudo_dev assigned.

In this overlay layers setup:
 - two filesystems, A and B
 - upper layer is on A
 - lower layer 1 is also on A
 - lower layer 2 is on B

Non pure upper overlay inode, whose origin is in layer 1 will have the
st_dev;st_ino values of the real lower inode before copy up and the
st_dev;st_ino values of the real upper inode after copy up.

Fix this inconsitency by assigning a unique pseudo_dev also for upper fs,
that will be used as st_dev value along with the lower inode st_dev for
overlay inodes in the case above.

Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: fix corner case of conflicting lower layer uuid

2020-01-24T08:46:45+00:00

This fixes ovl_lower_uuid_ok() to correctly detect the corner case:
 - two filesystems, A and B, both have null uuid
 - upper layer is on A
 - lower layer 1 is also on A
 - lower layer 2 is on B

In this case, bad_uuid would not have been set for B, because the check
only involved the list of lower fs.  Hence we'll try to decode a layer 2
origin on layer 1 and fail.

We check for conflicting (and null) uuid among all lower layers, including
those layers that are on the same fs as the upper layer.

Reported-by: Miklos Szeredi 
Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: generalize the lower_fs[] array

2020-01-24T08:46:45+00:00

Rename lower_fs[] array to fs[], extend its size by one and use index fsid
(instead of fsid-1) to access the fs[] array.

Initialize fs[0] with upper fs values. fsid 0 is reserved even with lower
only overlay, so fs[0] remains null in this case.

Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi