linux

iv/linux

History

Chengguang Xu b71759ef1e ovl: skip checking lower file's i_writecount on truncate

It is possible that a directory tree is shared between multiple overlay
instances as a lower layer.  In this case when one instance executes a file
residing on the lower layer, the other instance denies a truncate(2) call
on this file.

This only happens for truncate(2) and not for open(2) with the O_TRUNC
flag.

Fix this interference and inconsistency by removing the preliminary
i_writecount check before copy-up.

This means that unlike on normal filesystems truncate(argv[0]) will now
succeed.  If this ever causes a regression in a real world use case this
needs to be revisited.

One way to fix this properly would be to keep a correct i_writecount in the
overlay inode, but that is difficult due to memory mapping code only
dealing with the real file/inode.

Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

2021-08-17 11:47:44 +02:00

copy_up.c

ovl: consistent behavior for immutable/append-only inodes

2021-08-17 11:47:43 +02:00

dir.c

ovl: do not set overlay.opaque for new directories

2021-08-17 11:47:44 +02:00

export.c

ovl: fix uninitialized pointer read in ovl_lookup_real_one()

2021-08-10 10:21:30 +02:00

file.c

ovl: fix deadlock in splice write