Commit c2b6d621 authored by Al Viro's avatar Al Viro
Browse files

new primitive: discard_new_inode() 



	We don't want open-by-handle picking half-set-up in-core
struct inode from e.g. mkdir() having failed halfway through.
In other words, we don't want such inodes returned by iget_locked()
on their way to extinction.  However, we can't just have them
unhashed - otherwise open-by-handle immediately *after* that would've
ended up creating a new in-core inode over the on-disk one that
is in process of being freed right under us.

	Solution: new flag (I_CREATING) set by insert_inode_locked() and
removed by unlock_new_inode() and a new primitive (discard_new_inode())
to be used by such halfway-through-setup failure exits instead of
unlock_new_inode() / iput() combinations.  That primitive unlocks new
inode, but leaves I_CREATING in place.

	iget_locked() treats finding an I_CREATING inode as failure
(-ESTALE, once we sort out the error propagation).
	insert_inode_locked() treats the same as instant -EBUSY.
	ilookup() treats those as icache miss.

[Fix by Dan Carpenter <dan.carpenter@oracle.com> folded in]

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent c971e6a0

fs/dcache.c

+1 −1
Original line number Diff line number Diff line
@@ -1892,7 +1892,7 @@ void d_instantiate_new(struct dentry *entry, struct inode *inode) 
	spin_lock(&inode->i_lock);

	__d_instantiate(entry, inode);

	WARN_ON(!(inode->i_state & I_NEW));

	inode->i_state &= ~I_NEW;

	inode->i_state &= ~I_NEW & ~I_CREATING;

	smp_mb();

	wake_up_bit(&inode->i_state, __I_NEW);

	spin_unlock(&inode->i_lock);

fs/inode.c

+41 −4
Original line number Diff line number Diff line
@@ -804,6 +804,10 @@ repeat: 
			__wait_on_freeing_inode(inode);

			goto repeat;

		}

		if (unlikely(inode->i_state & I_CREATING)) {

			spin_unlock(&inode->i_lock);

			return ERR_PTR(-ESTALE);

		}

		__iget(inode);

		spin_unlock(&inode->i_lock);

		return inode;
@@ -831,6 +835,10 @@ repeat: 
			__wait_on_freeing_inode(inode);

			goto repeat;

		}

		if (unlikely(inode->i_state & I_CREATING)) {

			spin_unlock(&inode->i_lock);

			return ERR_PTR(-ESTALE);

		}

		__iget(inode);

		spin_unlock(&inode->i_lock);

		return inode;
@@ -961,13 +969,26 @@ void unlock_new_inode(struct inode *inode) 
	lockdep_annotate_inode_mutex_key(inode);

	spin_lock(&inode->i_lock);

	WARN_ON(!(inode->i_state & I_NEW));

	inode->i_state &= ~I_NEW;

	inode->i_state &= ~I_NEW & ~I_CREATING;

	smp_mb();

	wake_up_bit(&inode->i_state, __I_NEW);

	spin_unlock(&inode->i_lock);

}

EXPORT_SYMBOL(unlock_new_inode);



void discard_new_inode(struct inode *inode)

{

	lockdep_annotate_inode_mutex_key(inode);

	spin_lock(&inode->i_lock);

	WARN_ON(!(inode->i_state & I_NEW));

	inode->i_state &= ~I_NEW;

	smp_mb();

	wake_up_bit(&inode->i_state, __I_NEW);

	spin_unlock(&inode->i_lock);

	iput(inode);

}

EXPORT_SYMBOL(discard_new_inode);



/**

 * lock_two_nondirectories - take two i_mutexes on non-directory objects

 *
@@ -1039,6 +1060,8 @@ again: 
		 * Use the old inode instead of the preallocated one.

		 */

		spin_unlock(&inode_hash_lock);

		if (IS_ERR(old))

			return NULL;

		wait_on_inode(old);

		if (unlikely(inode_unhashed(old))) {

			iput(old);
@@ -1128,6 +1151,8 @@ again: 
	inode = find_inode_fast(sb, head, ino);

	spin_unlock(&inode_hash_lock);

	if (inode) {

		if (IS_ERR(inode))

			return NULL;

		wait_on_inode(inode);

		if (unlikely(inode_unhashed(inode))) {

			iput(inode);
@@ -1165,6 +1190,8 @@ again: 
		 */

		spin_unlock(&inode_hash_lock);

		destroy_inode(inode);

		if (IS_ERR(old))

			return NULL;

		inode = old;

		wait_on_inode(inode);

		if (unlikely(inode_unhashed(inode))) {
@@ -1282,7 +1309,7 @@ struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval, 
	inode = find_inode(sb, head, test, data);

	spin_unlock(&inode_hash_lock);



	return inode;

	return IS_ERR(inode) ? NULL : inode;

}

EXPORT_SYMBOL(ilookup5_nowait);
@@ -1338,6 +1365,8 @@ again: 
	spin_unlock(&inode_hash_lock);



	if (inode) {

		if (IS_ERR(inode))

			return NULL;

		wait_on_inode(inode);

		if (unlikely(inode_unhashed(inode))) {

			iput(inode);
@@ -1421,12 +1450,17 @@ int insert_inode_locked(struct inode *inode) 
		}

		if (likely(!old)) {

			spin_lock(&inode->i_lock);

			inode->i_state |= I_NEW;

			inode->i_state |= I_NEW | I_CREATING;

			hlist_add_head(&inode->i_hash, head);

			spin_unlock(&inode->i_lock);

			spin_unlock(&inode_hash_lock);

			return 0;

		}

		if (unlikely(old->i_state & I_CREATING)) {

			spin_unlock(&old->i_lock);

			spin_unlock(&inode_hash_lock);

			return -EBUSY;

		}

		__iget(old);

		spin_unlock(&old->i_lock);

		spin_unlock(&inode_hash_lock);
@@ -1443,7 +1477,10 @@ EXPORT_SYMBOL(insert_inode_locked); 
int insert_inode_locked4(struct inode *inode, unsigned long hashval,

		int (*test)(struct inode *, void *), void *data)

{

	struct inode *old = inode_insert5(inode, hashval, test, NULL, data);

	struct inode *old;



	inode->i_state |= I_CREATING;

	old = inode_insert5(inode, hashval, test, NULL, data);



	if (old != inode) {

		iput(old);

include/linux/fs.h

+5 −1
Original line number Diff line number Diff line
@@ -2016,6 +2016,8 @@ static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp) 
 * I_OVL_INUSE		Used by overlayfs to get exclusive ownership on upper

 *			and work dirs among overlayfs mounts.

 *

 * I_CREATING		New object's inode in the middle of setting up.

 *

 * Q: What is the difference between I_WILL_FREE and I_FREEING?

 */

#define I_DIRTY_SYNC		(1 << 0)
@@ -2037,6 +2039,7 @@ static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp) 
#define I_DIRTY_TIME_EXPIRED	(1 << __I_DIRTY_TIME_EXPIRED)

#define I_WB_SWITCH		(1 << 13)

#define I_OVL_INUSE		(1 << 14)

#define I_CREATING		(1 << 15)



#define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC)

#define I_DIRTY (I_DIRTY_INODE | I_DIRTY_PAGES)
@@ -2919,6 +2922,7 @@ extern void lockdep_annotate_inode_mutex_key(struct inode *inode); 
static inline void lockdep_annotate_inode_mutex_key(struct inode *inode) { };

#endif

extern void unlock_new_inode(struct inode *);

extern void discard_new_inode(struct inode *);

extern unsigned int get_next_ino(void);

extern void evict_inodes(struct super_block *sb);

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