autofs4: fix indirect mount pending expire race

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The selection of a dentry for expiration and the setting of the
AUTOFS_INF_EXPIRING flag isn't done atomically which can lead to lookups
walking into an expiring mount.

What happens is that an expire is initiated by the daemon and a dentry is
selected for expire but, since there is no lock held between the selection
and setting of the expiring flag, a process may find the flag clear and
continue walking into the mount tree at the same time the daemon attempts
the expire it.

Signed-off-by: Ian Kent <raven@themaw.net>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

...

This commit is contained in:

Ian Kent 2008-07-23 21:30:26 -07:00 • committed by Linus Torvalds

parent 26e81b3142

commit 97e7449a7a

3 changed files with 65 additions and 23 deletions

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10

fs/autofs4/autofs_i.h

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46

fs/autofs4/expire.c

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32

fs/autofs4/root.c

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