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Commit 8089fe62 authored by David Sterba's avatar David Sterba Committed by David Sterba
Browse files

btrfs: put delayed item hook into inode 



Inodes for delayed iput allocate a trivial helper structure, let's place
the list hook directly into the inode and save a kmalloc (killing a
__GFP_NOFAIL as a bonus) at the cost of increasing size of btrfs_inode.

The inode can be put into the delayed_iputs list more than once and we
have to keep the count. This means we can't use the list_splice to
process a bunch of inodes because we'd lost track of the count if the
inode is put into the delayed iputs again while it's processed.

Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent c5ca8781

fs/btrfs/btrfs_inode.h

+4 −0
Original line number Diff line number Diff line
@@ -192,6 +192,10 @@ struct btrfs_inode { 
	/* File creation time. */

	struct timespec i_otime;



	/* Hook into fs_info->delayed_iputs */

	struct list_head delayed_iput;

	long delayed_iput_count;



	struct inode vfs_inode;

};

fs/btrfs/inode.c

+25 −31
Original line number Diff line number Diff line
@@ -3106,55 +3106,47 @@ static int btrfs_readpage_end_io_hook(struct btrfs_io_bio *io_bio, 
				      start, (size_t)(end - start + 1));

}



struct delayed_iput {

	struct list_head list;

	struct inode *inode;

};



/* JDM: If this is fs-wide, why can't we add a pointer to

 * btrfs_inode instead and avoid the allocation? */

void btrfs_add_delayed_iput(struct inode *inode)

{

	struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;

	struct delayed_iput *delayed;

	struct btrfs_inode *binode = BTRFS_I(inode);



	if (atomic_add_unless(&inode->i_count, -1, 1))

		return;



	delayed = kmalloc(sizeof(*delayed), GFP_NOFS | __GFP_NOFAIL);

	delayed->inode = inode;



	spin_lock(&fs_info->delayed_iput_lock);

	list_add_tail(&delayed->list, &fs_info->delayed_iputs);

	if (binode->delayed_iput_count == 0) {

		ASSERT(list_empty(&binode->delayed_iput));

		list_add_tail(&binode->delayed_iput, &fs_info->delayed_iputs);

	} else {

		binode->delayed_iput_count++;

	}

	spin_unlock(&fs_info->delayed_iput_lock);

}



void btrfs_run_delayed_iputs(struct btrfs_root *root)

{

	LIST_HEAD(list);

	struct btrfs_fs_info *fs_info = root->fs_info;

	struct delayed_iput *delayed;

	int empty;



	spin_lock(&fs_info->delayed_iput_lock);

	empty = list_empty(&fs_info->delayed_iputs);

	spin_unlock(&fs_info->delayed_iput_lock);

	if (empty)

		return;



	down_read(&fs_info->delayed_iput_sem);



	spin_lock(&fs_info->delayed_iput_lock);

	list_splice_init(&fs_info->delayed_iputs, &list);

	while (!list_empty(&fs_info->delayed_iputs)) {

		struct btrfs_inode *inode;



		inode = list_first_entry(&fs_info->delayed_iputs,

				struct btrfs_inode, delayed_iput);

		if (inode->delayed_iput_count) {

			inode->delayed_iput_count--;

			list_move_tail(&inode->delayed_iput,

					&fs_info->delayed_iputs);

		} else {

			list_del_init(&inode->delayed_iput);

		}

		spin_unlock(&fs_info->delayed_iput_lock);



	while (!list_empty(&list)) {

		delayed = list_entry(list.next, struct delayed_iput, list);

		list_del(&delayed->list);

		iput(delayed->inode);

		kfree(delayed);

		iput(&inode->vfs_inode);

		spin_lock(&fs_info->delayed_iput_lock);

	}



	spin_unlock(&fs_info->delayed_iput_lock);

	up_read(&root->fs_info->delayed_iput_sem);

}
@@ -9037,6 +9029,7 @@ struct inode *btrfs_alloc_inode(struct super_block *sb) 
	ei->dir_index = 0;

	ei->last_unlink_trans = 0;

	ei->last_log_commit = 0;

	ei->delayed_iput_count = 0;



	spin_lock_init(&ei->lock);

	ei->outstanding_extents = 0;
@@ -9061,6 +9054,7 @@ struct inode *btrfs_alloc_inode(struct super_block *sb) 
	mutex_init(&ei->delalloc_mutex);

	btrfs_ordered_inode_tree_init(&ei->ordered_tree);

	INIT_LIST_HEAD(&ei->delalloc_inodes);

	INIT_LIST_HEAD(&ei->delayed_iput);

	RB_CLEAR_NODE(&ei->rb_node);



	return inode;