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Commit ad5e195a authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Al Viro
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fs: Stop abusing find_inode_fast in iunique 



Stop abusing find_inode_fast for iunique and opencode the inode hash walk.
Introduce a new iunique_lock to protect the iunique counters once inode_lock
is removed.

Based on a patch originally from Nick Piggin.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 4c51acbc

fs/inode.c

+25 −5
Original line number Diff line number Diff line
@@ -884,6 +884,27 @@ static struct inode *get_new_inode_fast(struct super_block *sb, 
	return inode;

}



/*

 * search the inode cache for a matching inode number.

 * If we find one, then the inode number we are trying to

 * allocate is not unique and so we should not use it.

 *

 * Returns 1 if the inode number is unique, 0 if it is not.

 */

static int test_inode_iunique(struct super_block *sb, unsigned long ino)

{

	struct hlist_head *b = inode_hashtable + hash(sb, ino);

	struct hlist_node *node;

	struct inode *inode;



	hlist_for_each_entry(inode, node, b, i_hash) {

		if (inode->i_ino == ino && inode->i_sb == sb)

			return 0;

	}



	return 1;

}



/**

 *	iunique - get a unique inode number

 *	@sb: superblock
@@ -905,19 +926,18 @@ ino_t iunique(struct super_block *sb, ino_t max_reserved) 
	 * error if st_ino won't fit in target struct field. Use 32bit counter

	 * here to attempt to avoid that.

	 */

	static DEFINE_SPINLOCK(iunique_lock);

	static unsigned int counter;

	struct inode *inode;

	struct hlist_head *head;

	ino_t res;



	spin_lock(&inode_lock);

	spin_lock(&iunique_lock);

	do {

		if (counter <= max_reserved)

			counter = max_reserved + 1;

		res = counter++;

		head = inode_hashtable + hash(sb, res);

		inode = find_inode_fast(sb, head, res);

	} while (inode != NULL);

	} while (!test_inode_iunique(sb, res));

	spin_unlock(&iunique_lock);

	spin_unlock(&inode_lock);



	return res;