There are a lot of ways we could approach this, and I sat down and wrote
the simplest variant I could think of, so hopefully there are not silly
bugs that get overlooked.
The code move all cleanup from mntput that would do filesystem I/O into
work queues.
The code waits in mntput for that I/O to complete if we wait today.
The code has been tested and it works, and it succeeds in running
deactivate_super in a stack from with just short of 7500 bytes free.
7500 bytes should be enough for anybody!
I want to double check that I am using work queues correctly, they used
to be deadlock prone, and sleep on everything before I commit to a final
version but this version is probably good enough.
I may be going overboard in the case where we auto close BSD accounting
files, but at this point I figure better safe than sorry.
Eric W. Biederman (4):
vfs: Remove useless loop in mntput_no_expire
vfs: Move autoclose of BSD accounting into a work queue
vfs: In mntput run deactivate_super on a shallow stack.
vfs: Block intuitively in the case of BSD accounting files
fs/mount.h | 14 +++++++++++---
fs/namespace.c | 43 +++++++++++++++++++++++++++++++++++--------
kernel/acct.c | 25 ++++++++++++++++++++-----
3 files changed, 66 insertions(+), 16 deletions(-)
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