deal with deadlock in d_walk()
... by not hitting rename_retry for reasons other than rename having happened. In other words, do _not_ restart when finding that between unlocking the child and locking the parent the former got into __dentry_kill(). Skip the killed siblings instead... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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946e51f2bf
Коммит
ca5358ef75
31
fs/dcache.c
31
fs/dcache.c
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@ -495,7 +495,7 @@ static void __dentry_kill(struct dentry *dentry)
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}
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/* if it was on the hash then remove it */
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__d_drop(dentry);
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list_del(&dentry->d_child);
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__list_del_entry(&dentry->d_child);
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/*
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* Inform d_walk() that we are no longer attached to the
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* dentry tree
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@ -1081,33 +1081,31 @@ resume:
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/*
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* All done at this level ... ascend and resume the search.
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*/
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rcu_read_lock();
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ascend:
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if (this_parent != parent) {
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struct dentry *child = this_parent;
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this_parent = child->d_parent;
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rcu_read_lock();
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spin_unlock(&child->d_lock);
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spin_lock(&this_parent->d_lock);
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/*
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* might go back up the wrong parent if we have had a rename
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* or deletion
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*/
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if (this_parent != child->d_parent ||
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(child->d_flags & DCACHE_DENTRY_KILLED) ||
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need_seqretry(&rename_lock, seq)) {
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spin_unlock(&this_parent->d_lock);
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rcu_read_unlock();
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/* might go back up the wrong parent if we have had a rename. */
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if (need_seqretry(&rename_lock, seq))
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goto rename_retry;
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next = child->d_child.next;
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while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED)) {
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if (next == &this_parent->d_subdirs)
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goto ascend;
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child = list_entry(next, struct dentry, d_child);
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next = next->next;
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}
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rcu_read_unlock();
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next = child->d_child.next;
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goto resume;
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}
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if (need_seqretry(&rename_lock, seq)) {
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spin_unlock(&this_parent->d_lock);
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if (need_seqretry(&rename_lock, seq))
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goto rename_retry;
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}
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rcu_read_unlock();
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if (finish)
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finish(data);
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@ -1117,6 +1115,9 @@ out_unlock:
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return;
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rename_retry:
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spin_unlock(&this_parent->d_lock);
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rcu_read_unlock();
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BUG_ON(seq & 1);
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if (!retry)
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return;
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seq = 1;
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