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authorAl Viro <viro@ZenIV.linux.org.uk>2017-06-03 07:20:09 +0100
committerAl Viro <viro@zeniv.linux.org.uk>2017-06-15 06:52:09 -0400
commit81be24d263dbeddaba35827036d6f6787a59c2c3 (patch)
tree16b383d5c65293575d98ec44264800c0e02807cb
parent32c1431eea4881a6b17bd7c639315010aeefa452 (diff)
Hang/soft lockup in d_invalidate with simultaneous calls
It's not hard to trigger a bunch of d_invalidate() on the same dentry in parallel. They end up fighting each other - any dentry picked for removal by one will be skipped by the rest and we'll go for the next iteration through the entire subtree, even if everything is being skipped. Morevoer, we immediately go back to scanning the subtree. The only thing we really need is to dissolve all mounts in the subtree and as soon as we've nothing left to do, we can just unhash the dentry and bugger off. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/dcache.c10
1 files changed, 4 insertions, 6 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index cddf39777835..a9f995f6859e 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1494,7 +1494,7 @@ static void check_and_drop(void *_data)
{
struct detach_data *data = _data;
- if (!data->mountpoint && !data->select.found)
+ if (!data->mountpoint && list_empty(&data->select.dispose))
__d_drop(data->select.start);
}
@@ -1536,17 +1536,15 @@ void d_invalidate(struct dentry *dentry)
d_walk(dentry, &data, detach_and_collect, check_and_drop);
- if (data.select.found)
+ if (!list_empty(&data.select.dispose))
shrink_dentry_list(&data.select.dispose);
+ else if (!data.mountpoint)
+ return;
if (data.mountpoint) {
detach_mounts(data.mountpoint);
dput(data.mountpoint);
}
-
- if (!data.mountpoint && !data.select.found)
- break;
-
cond_resched();
}
}