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Commit 1c0eeaf5 authored by Joern Engel's avatar Joern Engel Committed by Linus Torvalds
Browse files

introduce I_SYNC 



I_LOCK was used for several unrelated purposes, which caused deadlock
situations in certain filesystems as a side effect.  One of the purposes
now uses the new I_SYNC bit.

Also document the various bits and change their order from historical to
logical.

[bunk@stusta.de: make fs/inode.c:wake_up_inode() static]
Signed-off-by: default avatarJoern Engel <joern@wohnheim.fh-wedel.de>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: David Chinner <dgc@sgi.com>
Cc: Anton Altaparmakov <aia21@cam.ac.uk>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: default avatarAdrian Bunk <bunk@stusta.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2e6883bd

fs/fs-writeback.c

+24 −15
Original line number Diff line number Diff line
@@ -100,11 +100,11 @@ void __mark_inode_dirty(struct inode *inode, int flags) 
		inode->i_state |= flags;



		/*

		 * If the inode is locked, just update its dirty state. 

		 * If the inode is being synced, just update its dirty state.

		 * The unlocker will place the inode on the appropriate

		 * superblock list, based upon its state.

		 */

		if (inode->i_state & I_LOCK)

		if (inode->i_state & I_SYNC)

			goto out;



		/*
@@ -172,6 +172,15 @@ static void requeue_io(struct inode *inode) 
	list_move(&inode->i_list, &inode->i_sb->s_more_io);

}



static void inode_sync_complete(struct inode *inode)

{

	/*

	 * Prevent speculative execution through spin_unlock(&inode_lock);

	 */

	smp_mb();

	wake_up_bit(&inode->i_state, __I_SYNC);

}



/*

 * Move expired dirty inodes from @delaying_queue to @dispatch_queue.

 */
@@ -225,11 +234,11 @@ __sync_single_inode(struct inode *inode, struct writeback_control *wbc) 
	int wait = wbc->sync_mode == WB_SYNC_ALL;

	int ret;



	BUG_ON(inode->i_state & I_LOCK);

	BUG_ON(inode->i_state & I_SYNC);



	/* Set I_LOCK, reset I_DIRTY */

	/* Set I_SYNC, reset I_DIRTY */

	dirty = inode->i_state & I_DIRTY;

	inode->i_state |= I_LOCK;

	inode->i_state |= I_SYNC;

	inode->i_state &= ~I_DIRTY;



	spin_unlock(&inode_lock);
@@ -250,7 +259,7 @@ __sync_single_inode(struct inode *inode, struct writeback_control *wbc) 
	}



	spin_lock(&inode_lock);

	inode->i_state &= ~I_LOCK;

	inode->i_state &= ~I_SYNC;

	if (!(inode->i_state & I_FREEING)) {

		if (!(inode->i_state & I_DIRTY) &&

		    mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
@@ -305,7 +314,7 @@ __sync_single_inode(struct inode *inode, struct writeback_control *wbc) 
			list_move(&inode->i_list, &inode_unused);

		}

	}

	wake_up_inode(inode);

	inode_sync_complete(inode);

	return ret;

}
@@ -324,7 +333,7 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) 
	else

		WARN_ON(inode->i_state & I_WILL_FREE);



	if ((wbc->sync_mode != WB_SYNC_ALL) && (inode->i_state & I_LOCK)) {

	if ((wbc->sync_mode != WB_SYNC_ALL) && (inode->i_state & I_SYNC)) {

		struct address_space *mapping = inode->i_mapping;

		int ret;
@@ -350,16 +359,16 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) 
	/*

	 * It's a data-integrity sync.  We must wait.

	 */

	if (inode->i_state & I_LOCK) {

		DEFINE_WAIT_BIT(wq, &inode->i_state, __I_LOCK);

	if (inode->i_state & I_SYNC) {

		DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC);



		wqh = bit_waitqueue(&inode->i_state, __I_LOCK);

		wqh = bit_waitqueue(&inode->i_state, __I_SYNC);

		do {

			spin_unlock(&inode_lock);

			__wait_on_bit(wqh, &wq, inode_wait,

							TASK_UNINTERRUPTIBLE);

			spin_lock(&inode_lock);

		} while (inode->i_state & I_LOCK);

		} while (inode->i_state & I_SYNC);

	}

	return __sync_single_inode(inode, wbc);

}
@@ -392,7 +401,7 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) 
 * The inodes to be written are parked on sb->s_io.  They are moved back onto

 * sb->s_dirty as they are selected for writing.  This way, none can be missed

 * on the writer throttling path, and we get decent balancing between many

 * throttled threads: we don't want them all piling up on __wait_on_inode.

 * throttled threads: we don't want them all piling up on inode_sync_wait.

 */

static void

sync_sb_inodes(struct super_block *sb, struct writeback_control *wbc)
@@ -661,7 +670,7 @@ int write_inode_now(struct inode *inode, int sync) 
	ret = __writeback_single_inode(inode, &wbc);

	spin_unlock(&inode_lock);

	if (sync)

		wait_on_inode(inode);

		inode_sync_wait(inode);

	return ret;

}

EXPORT_SYMBOL(write_inode_now);
@@ -736,7 +745,7 @@ int generic_osync_inode(struct inode *inode, struct address_space *mapping, int 
			err = err2;

	}

	else

		wait_on_inode(inode);

		inode_sync_wait(inode);



	return err;

}

fs/hugetlbfs/inode.c

+1 −1
Original line number Diff line number Diff line
@@ -384,7 +384,7 @@ static void hugetlbfs_forget_inode(struct inode *inode) __releases(inode_lock) 
	struct super_block *sb = inode->i_sb;



	if (!hlist_unhashed(&inode->i_hash)) {

		if (!(inode->i_state & (I_DIRTY|I_LOCK)))

		if (!(inode->i_state & (I_DIRTY|I_SYNC)))

			list_move(&inode->i_list, &inode_unused);

		inodes_stat.nr_unused++;

		if (!sb || (sb->s_flags & MS_ACTIVE)) {

fs/inode.c

+12 −12
Original line number Diff line number Diff line
@@ -99,6 +99,15 @@ struct inodes_stat_t inodes_stat; 


static struct kmem_cache * inode_cachep __read_mostly;



static void wake_up_inode(struct inode *inode)

{

	/*

	 * Prevent speculative execution through spin_unlock(&inode_lock);

	 */

	smp_mb();

	wake_up_bit(&inode->i_state, __I_LOCK);

}



static struct inode *alloc_inode(struct super_block *sb)

{

	static const struct address_space_operations empty_aops;
@@ -232,7 +241,7 @@ void __iget(struct inode * inode) 
		return;

	}

	atomic_inc(&inode->i_count);

	if (!(inode->i_state & (I_DIRTY|I_LOCK)))

	if (!(inode->i_state & (I_DIRTY|I_SYNC)))

		list_move(&inode->i_list, &inode_in_use);

	inodes_stat.nr_unused--;

}
@@ -253,7 +262,7 @@ void clear_inode(struct inode *inode) 
	BUG_ON(inode->i_data.nrpages);

	BUG_ON(!(inode->i_state & I_FREEING));

	BUG_ON(inode->i_state & I_CLEAR);

	wait_on_inode(inode);

	inode_sync_wait(inode);

	DQUOT_DROP(inode);

	if (inode->i_sb->s_op->clear_inode)

		inode->i_sb->s_op->clear_inode(inode);
@@ -1071,7 +1080,7 @@ static void generic_forget_inode(struct inode *inode) 
	struct super_block *sb = inode->i_sb;



	if (!hlist_unhashed(&inode->i_hash)) {

		if (!(inode->i_state & (I_DIRTY|I_LOCK)))

		if (!(inode->i_state & (I_DIRTY|I_SYNC)))

			list_move(&inode->i_list, &inode_unused);

		inodes_stat.nr_unused++;

		if (sb->s_flags & MS_ACTIVE) {
@@ -1314,15 +1323,6 @@ static void __wait_on_freeing_inode(struct inode *inode) 
	spin_lock(&inode_lock);

}



void wake_up_inode(struct inode *inode)

{

	/*

	 * Prevent speculative execution through spin_unlock(&inode_lock);

	 */

	smp_mb();

	wake_up_bit(&inode->i_state, __I_LOCK);

}



/*

 * We rarely want to lock two inodes that do not have a parent/child

 * relationship (such as directory, child inode) simultaneously. The

fs/jfs/jfs_txnmgr.c

+8 −1
Original line number Diff line number Diff line
@@ -1289,7 +1289,14 @@ int txCommit(tid_t tid, /* transaction identifier */ 
		 * commit the transaction synchronously, so the last iput

		 * will be done by the calling thread (or later)

		 */

		if (tblk->u.ip->i_state & I_LOCK)

		/*

		 * I believe this code is no longer needed.  Splitting I_LOCK

		 * into two bits, I_LOCK and I_SYNC should prevent this

		 * deadlock as well.  But since I don't have a JFS testload

		 * to verify this, only a trivial s/I_LOCK/I_SYNC/ was done.

		 * Joern

		 */

		if (tblk->u.ip->i_state & I_SYNC)

			tblk->xflag &= ~COMMIT_LAZY;

	}

fs/xfs/linux-2.6/xfs_iops.c

+2 −2
Original line number Diff line number Diff line
@@ -133,7 +133,7 @@ xfs_ichgtime( 
	 */

	SYNCHRONIZE();

	ip->i_update_core = 1;

	if (!(inode->i_state & I_LOCK))

	if (!(inode->i_state & I_SYNC))

		mark_inode_dirty_sync(inode);

}
@@ -185,7 +185,7 @@ xfs_ichgtime_fast( 
	 */

	SYNCHRONIZE();

	ip->i_update_core = 1;

	if (!(inode->i_state & I_LOCK))

	if (!(inode->i_state & I_SYNC))

		mark_inode_dirty_sync(inode);

}