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Commit fe032c42 authored by Theodore Ts'o's avatar Theodore Ts'o Committed by Al Viro
Browse files

vfs: add find_inode_nowait() function 



Add a new function find_inode_nowait() which is an even more general
version of ilookup5_nowait().  It is designed for callers which need
very fine grained control over when the function is allowed to block
or increment the inode's reference count.

Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 0ae45f63

fs/inode.c

+50 −0
Original line number Diff line number Diff line
@@ -1284,6 +1284,56 @@ struct inode *ilookup(struct super_block *sb, unsigned long ino) 
}

EXPORT_SYMBOL(ilookup);



/**

 * find_inode_nowait - find an inode in the inode cache

 * @sb:		super block of file system to search

 * @hashval:	hash value (usually inode number) to search for

 * @match:	callback used for comparisons between inodes

 * @data:	opaque data pointer to pass to @match

 *

 * Search for the inode specified by @hashval and @data in the inode

 * cache, where the helper function @match will return 0 if the inode

 * does not match, 1 if the inode does match, and -1 if the search

 * should be stopped.  The @match function must be responsible for

 * taking the i_lock spin_lock and checking i_state for an inode being

 * freed or being initialized, and incrementing the reference count

 * before returning 1.  It also must not sleep, since it is called with

 * the inode_hash_lock spinlock held.

 *

 * This is a even more generalized version of ilookup5() when the

 * function must never block --- find_inode() can block in

 * __wait_on_freeing_inode() --- or when the caller can not increment

 * the reference count because the resulting iput() might cause an

 * inode eviction.  The tradeoff is that the @match funtion must be

 * very carefully implemented.

 */

struct inode *find_inode_nowait(struct super_block *sb,

				unsigned long hashval,

				int (*match)(struct inode *, unsigned long,

					     void *),

				void *data)

{

	struct hlist_head *head = inode_hashtable + hash(sb, hashval);

	struct inode *inode, *ret_inode = NULL;

	int mval;



	spin_lock(&inode_hash_lock);

	hlist_for_each_entry(inode, head, i_hash) {

		if (inode->i_sb != sb)

			continue;

		mval = match(inode, hashval, data);

		if (mval == 0)

			continue;

		if (mval == 1)

			ret_inode = inode;

		goto out;

	}

out:

	spin_unlock(&inode_hash_lock);

	return ret_inode;

}

EXPORT_SYMBOL(find_inode_nowait);



int insert_inode_locked(struct inode *inode)

{

	struct super_block *sb = inode->i_sb;

include/linux/fs.h

+5 −0
Original line number Diff line number Diff line
@@ -2441,6 +2441,11 @@ extern struct inode *ilookup(struct super_block *sb, unsigned long ino); 


extern struct inode * iget5_locked(struct super_block *, unsigned long, int (*test)(struct inode *, void *), int (*set)(struct inode *, void *), void *);

extern struct inode * iget_locked(struct super_block *, unsigned long);

extern struct inode *find_inode_nowait(struct super_block *,

				       unsigned long,

				       int (*match)(struct inode *,

						    unsigned long, void *),

				       void *data);

extern int insert_inode_locked4(struct inode *, unsigned long, int (*test)(struct inode *, void *), void *);

extern int insert_inode_locked(struct inode *);

#ifdef CONFIG_DEBUG_LOCK_ALLOC