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[PATCH] r/o bind mounts: debugging for missed calls

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There have been a few oopses caused by 'struct file's with NULL f_vfsmnts.
There was also a set of potentially missed mnt_want_write()s from
dentry_open() calls.

This patch provides a very simple debugging framework to catch these kinds of
bugs.  It will WARN_ON() them, but should stop us from having any oopses or
mnt_writer count imbalances.

I'm quite convinced that this is a good thing because it found bugs in the
stuff I was working on as soon as I wrote it.

[hch: made it conditional on a debug option.
      But it's still a little bit too ugly]

[hch: merged forced remount r/o fix from Dave and akpm's fix for the fix]

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Dave Hansen
2008-02-15 14:38:01 -08:00
committed by Al Viro
parent 2e4b7fcd92
commit ad775f5a8f
5 changed files with 82 additions and 3 deletions
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3
fs/super.c
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@@ -579,6 +579,9 @@ retry:
if (!(f->f_mode & FMODE_WRITE))
continue;
f->f_mode &= ~FMODE_WRITE;
if (file_check_writeable(f) != 0)
continue;
file_release_write(f);
mnt = mntget(f->f_path.mnt);
file_list_unlock();
/*