diff options
| author | OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> | 2019-09-23 15:32:53 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-10-07 18:55:12 +0200 |
| commit | 3554b8a172a24278ba00193be0268f3095dbed22 (patch) | |
| tree | fc0b0194955282b3ca65b6c0b6d6c63dfe93f4f9 /block | |
| parent | 735ad03318db1e1999eaba29244ce5f8428cd91a (diff) | |
fat: work around race with userspace's read via blockdev while mounting
[ Upstream commit 07bfa4415ab607e459b69bd86aa7e7602ce10b4f ]
If userspace reads the buffer via blockdev while mounting,
sb_getblk()+modify can race with buffer read via blockdev.
For example,
FS userspace
bh = sb_getblk()
modify bh->b_data
read
ll_rw_block(bh)
fill bh->b_data by on-disk data
/* lost modified data by FS */
set_buffer_uptodate(bh)
set_buffer_uptodate(bh)
Userspace should not use the blockdev while mounting though, the udev
seems to be already doing this. Although I think the udev should try to
avoid this, workaround the race by small overhead.
Link: http://lkml.kernel.org/r/87pnk7l3sw.fsf_-_@mail.parknet.co.jp
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Reported-by: Jan Stancek <jstancek@redhat.com>
Tested-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'block')
0 files changed, 0 insertions, 0 deletions