[PATCH] __wait_on_freeing_inode fix (168a9fd6) · Commits · 戴 / test

This patch fixes queer behavior in __wait_on_freeing_inode(). If I_LOCK was not set it called yield(), effectively busy waiting for the removal of the inode from the hash. This change was introduced within "[PATCH] eliminate inode waitqueue hashtable" Changeset 1.1938.166.16 last october by wli. The solution is to restore the old behavior, of unconditionally waiting on the waitqueue. It doesn't matter if I_LOCK is not set initally, the task will go to sleep, and wake up when wake_up_inode() is called from generic_delete_inode() after removing the inode from the hash chain. Comment is also updated to better reflect current behavior. This condition is very hard to trigger normally (simultaneous clear_inode() with iget()) so probably only heavy stress testing can reveal any change of behavior. Signed-off-by:

Miklos Szeredi <miklos@szeredi.hu> Acked-by:

Christoph Hellwig <hch@lst.de> Signed-off-by:

Andrew Morton <akpm@osdl.org> Signed-off-by:

Linus Torvalds <torvalds@osdl.org>

fs/inode.c

+9 −17

Original line number	Diff line number	Diff line
		@@ -1244,29 +1244,21 @@ int inode_wait(void *word)
		}

		/*
		* If we try to find an inode in the inode hash while it is being deleted, we
		* have to wait until the filesystem completes its deletion before reporting
		* that it isn't found. This is because iget will immediately call
		* ->read_inode, and we want to be sure that evidence of the deletion is found
		* by ->read_inode.
		* If we try to find an inode in the inode hash while it is being
		* deleted, we have to wait until the filesystem completes its
		* deletion before reporting that it isn't found. This function waits
		* until the deletion _might_ have completed. Callers are responsible
		* to recheck inode state.
		*
		* It doesn't matter if I_LOCK is not set initially, a call to
		* wake_up_inode() after removing from the hash list will DTRT.
		*
		* This is called with inode_lock held.
		*/
		static void __wait_on_freeing_inode(struct inode *inode)
		{
		wait_queue_head_t *wq;
		DEFINE_WAIT_BIT(wait, &inode->i_state, __I_LOCK);

		/*
		* I_FREEING and I_CLEAR are cleared in process context under
		* inode_lock, so we have to give the tasks who would clear them
		* a chance to run and acquire inode_lock.
		*/
		if (!(inode->i_state & I_LOCK)) {
		spin_unlock(&inode_lock);
		yield();
		spin_lock(&inode_lock);
		return;
		}
		wq = bit_waitqueue(&inode->i_state, __I_LOCK);
		prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
		spin_unlock(&inode_lock);

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