From: Miklos Szeredi <mszeredi@redhat.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: [PATCH 0/9] overlay: fix inconsistency of ro file after copy-up
Date: Fri, 17 Feb 2017 17:09:29 +0100 [thread overview]
Message-ID: <1487347778-18596-1-git-send-email-mszeredi@redhat.com> (raw)
A file is opened for read-only, opened read-write (resulting in a copy up)
and modified. The data read back from the the read-only fd will be stale
in this case (the read-only file descriptor still refers to the lower,
unmodified file).
This patchset fixes issues related to this corner case. This is a
requirement from various parties for accepting overlayfs as a "POSIX"
filesystem.
When an operation (read, mmap, fsync) is done on an overlay fd opened
read-only that is referring to a lower file, check if it has been copied up
in the mean time. If so, open the upper file and use that for the operation.
To make the performance impact minimal for non-overlay case, use a flag in
file->f_mode to indicate that this is an overlay file.
Git tree is here:
git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git #overlay-ro-rw-fix
Miklos Szeredi (9):
vfs: extract common parts of {compat_,}do_readv_writev()
vfs: pass type instead of fn to do_{loop,iter}_readv_writev()
vfs: use helpers for calling f_op->{read,write}_iter()
vfs: intercept reads to overlay files
mm: ovl: copy-up on MAP_SHARED
mm: use helper for calling f_op->mmap()
ovl: intercept mmap on overlay files
vfs: use helper for calling f_op->fsync()
vfs: intercept fsync on overlay files
drivers/block/loop.c | 4 +-
drivers/gpu/drm/i915/i915_gem_dmabuf.c | 2 +-
drivers/gpu/drm/vgem/vgem_drv.c | 2 +-
fs/Makefile | 2 +-
fs/aio.c | 4 +-
fs/coda/file.c | 2 +-
fs/open.c | 2 +
fs/overlay_util.c | 77 +++++++++++++++++++++
fs/read_write.c | 121 +++++++++++++--------------------
fs/splice.c | 2 +-
fs/sync.c | 2 +-
include/linux/fs.h | 42 ++++++++++++
include/linux/overlay_util.h | 17 +++++
ipc/shm.c | 4 +-
mm/mmap.c | 5 +-
mm/nommu.c | 4 +-
mm/util.c | 22 ++++++
17 files changed, 227 insertions(+), 87 deletions(-)
create mode 100644 fs/overlay_util.c
create mode 100644 include/linux/overlay_util.h
--
2.5.5
next reply other threads:[~2017-02-17 16:09 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-17 16:09 Miklos Szeredi [this message]
2017-02-17 16:09 ` [PATCH 1/9] vfs: extract common parts of {compat_,}do_readv_writev() Miklos Szeredi
2017-02-17 16:09 ` [PATCH 2/9] vfs: pass type instead of fn to do_{loop,iter}_readv_writev() Miklos Szeredi
2017-02-17 16:09 ` [PATCH 3/9] vfs: use helpers for calling f_op->{read,write}_iter() Miklos Szeredi
2017-02-17 16:09 ` [PATCH 4/9] vfs: intercept reads to overlay files Miklos Szeredi
2017-02-19 9:05 ` Al Viro
2017-02-19 9:24 ` Miklos Szeredi
[not found] ` <D39694FF47DA2A43B120BF3DF6163E7A10CD2335@DGGEMA504-MBX.china.huawei.com>
2017-02-20 7:47 ` zhangyi (F)
2017-02-20 8:52 ` Miklos Szeredi
2017-02-17 16:09 ` [PATCH 5/9] mm: ovl: copy-up on MAP_SHARED Miklos Szeredi
2017-02-17 16:09 ` [PATCH 6/9] mm: use helper for calling f_op->mmap() Miklos Szeredi
2017-02-17 16:09 ` [PATCH 7/9] ovl: intercept mmap on overlay files Miklos Szeredi
2017-02-17 16:09 ` [PATCH 8/9] vfs: use helper for calling f_op->fsync() Miklos Szeredi
2017-02-17 16:09 ` [PATCH 9/9] vfs: intercept fsync on overlay files Miklos Szeredi
2017-02-19 9:14 ` [PATCH 0/9] overlay: fix inconsistency of ro file after copy-up Al Viro
2017-02-20 15:16 ` Miklos Szeredi
2017-03-07 16:26 ` Miklos Szeredi
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