diff options
author | Miklos Szeredi <miklos@szeredi.hu> | 2012-09-17 22:23:30 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-09-29 17:41:40 -0700 |
commit | 8110e16d42d587997bcaee0c864179e6d93603fe (patch) | |
tree | 210b83419cc6464b1a1faff58c47d8316f6e5939 /fs/xfs/Kconfig | |
parent | 6a3e3dbee62a8fcf13c349b141b3cedf35a65c41 (diff) |
vfs: dcache: fix deadlock in tree traversal
IBM reported a deadlock in select_parent(). This was found to be caused
by taking rename_lock when already locked when restarting the tree
traversal.
There are two cases when the traversal needs to be restarted:
1) concurrent d_move(); this can only happen when not already locked,
since taking rename_lock protects against concurrent d_move().
2) racing with final d_put() on child just at the moment of ascending
to parent; rename_lock doesn't protect against this rare race, so it
can happen when already locked.
Because of case 2, we need to be able to handle restarting the traversal
when rename_lock is already held. This patch fixes all three callers of
try_to_ascend().
IBM reported that the deadlock is gone with this patch.
[ I rewrote the patch to be smaller and just do the "goto again" if the
lock was already held, but credit goes to Miklos for the real work.
- Linus ]
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/xfs/Kconfig')
0 files changed, 0 insertions, 0 deletions