Commit 82d5902d authored by Li Zefan's avatar Li Zefan
Browse files

Btrfs: Support reading/writing on disk free ino cache 



This is similar to block group caching.

We dedicate a special inode in fs tree to save free ino cache.

At the very first time we create/delete a file after mount, the free ino
cache will be loaded from disk into memory. When the fs tree is commited,
the cache will be written back to disk.

To keep compatibility, we check the root generation against the generation
of the special inode when loading the cache, so the loading will fail
if the btrfs filesystem was mounted in an older kernel before.

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
parent 33345d01

fs/btrfs/ctree.h

+7 −0
Original line number Diff line number Diff line
@@ -105,6 +105,12 @@ struct btrfs_ordered_sum; 
/* For storing free space cache */

#define BTRFS_FREE_SPACE_OBJECTID -11ULL



/*

 * The inode number assigned to the special inode for sotring

 * free ino cache

 */

#define BTRFS_FREE_INO_OBJECTID -12ULL



/* dummy objectid represents multiple objectids */

#define BTRFS_MULTIPLE_OBJECTIDS -255ULL
@@ -1110,6 +1116,7 @@ struct btrfs_root { 
	wait_queue_head_t cache_wait;

	struct btrfs_free_space_ctl *free_ino_pinned;

	u64 cache_progress;

	struct inode *cache_inode;



	struct mutex log_mutex;

	wait_queue_head_t log_writer_wait;

fs/btrfs/disk-io.c

+1 −0
Original line number Diff line number Diff line
@@ -2505,6 +2505,7 @@ int btrfs_free_fs_root(struct btrfs_fs_info *fs_info, struct btrfs_root *root) 


static void free_fs_root(struct btrfs_root *root)

{

	iput(root->cache_inode);

	WARN_ON(!RB_EMPTY_ROOT(&root->inode_tree));

	if (root->anon_super.s_dev) {

		down_write(&root->anon_super.s_umount);

fs/btrfs/extent-tree.c

+2 −1
Original line number Diff line number Diff line
@@ -3145,7 +3145,8 @@ int btrfs_check_data_free_space(struct inode *inode, u64 bytes) 
	/* make sure bytes are sectorsize aligned */

	bytes = (bytes + root->sectorsize - 1) & ~((u64)root->sectorsize - 1);



	if (root == root->fs_info->tree_root) {

	if (root == root->fs_info->tree_root ||

	    BTRFS_I(inode)->location.objectid == BTRFS_FREE_INO_OBJECTID) {

		alloc_chunk = 0;

		committed = 1;

	}

fs/btrfs/free-space-cache.c

+96 −1
Original line number Diff line number Diff line
@@ -209,7 +209,8 @@ int btrfs_truncate_free_space_cache(struct btrfs_root *root, 
		return ret;

	}



	return btrfs_update_inode(trans, root, inode);

	ret = btrfs_update_inode(trans, root, inode);

	return ret;

}



static int readahead_cache(struct inode *inode)
@@ -525,6 +526,7 @@ out: 
		spin_lock(&block_group->lock);

		block_group->disk_cache_state = BTRFS_DC_CLEAR;

		spin_unlock(&block_group->lock);

		ret = 0;



		printk(KERN_ERR "btrfs: failed to load free space cache "

		       "for block group %llu\n", block_group->key.objectid);
@@ -893,6 +895,7 @@ int btrfs_write_out_cache(struct btrfs_root *root, 
		spin_lock(&block_group->lock);

		block_group->disk_cache_state = BTRFS_DC_ERROR;

		spin_unlock(&block_group->lock);

		ret = 0;



		printk(KERN_ERR "btrfs: failed to write free space cace "

		       "for block group %llu\n", block_group->key.objectid);
@@ -2458,3 +2461,95 @@ out: 


	return ino;

}



struct inode *lookup_free_ino_inode(struct btrfs_root *root,

				    struct btrfs_path *path)

{

	struct inode *inode = NULL;



	spin_lock(&root->cache_lock);

	if (root->cache_inode)

		inode = igrab(root->cache_inode);

	spin_unlock(&root->cache_lock);

	if (inode)

		return inode;



	inode = __lookup_free_space_inode(root, path, 0);

	if (IS_ERR(inode))

		return inode;



	spin_lock(&root->cache_lock);

	if (!root->fs_info->closing)

		root->cache_inode = igrab(inode);

	spin_unlock(&root->cache_lock);



	return inode;

}



int create_free_ino_inode(struct btrfs_root *root,

			  struct btrfs_trans_handle *trans,

			  struct btrfs_path *path)

{

	return __create_free_space_inode(root, trans, path,

					 BTRFS_FREE_INO_OBJECTID, 0);

}



int load_free_ino_cache(struct btrfs_fs_info *fs_info, struct btrfs_root *root)

{

	struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;

	struct btrfs_path *path;

	struct inode *inode;

	int ret = 0;

	u64 root_gen = btrfs_root_generation(&root->root_item);



	/*

	 * If we're unmounting then just return, since this does a search on the

	 * normal root and not the commit root and we could deadlock.

	 */

	smp_mb();

	if (fs_info->closing)

		return 0;



	path = btrfs_alloc_path();

	if (!path)

		return 0;



	inode = lookup_free_ino_inode(root, path);

	if (IS_ERR(inode))

		goto out;



	if (root_gen != BTRFS_I(inode)->generation)

		goto out_put;



	ret = __load_free_space_cache(root, inode, ctl, path, 0);



	if (ret < 0)

		printk(KERN_ERR "btrfs: failed to load free ino cache for "

		       "root %llu\n", root->root_key.objectid);

out_put:

	iput(inode);

out:

	btrfs_free_path(path);

	return ret;

}



int btrfs_write_out_ino_cache(struct btrfs_root *root,

			      struct btrfs_trans_handle *trans,

			      struct btrfs_path *path)

{

	struct btrfs_free_space_ctl *ctl = root->free_ino_ctl;

	struct inode *inode;

	int ret;



	inode = lookup_free_ino_inode(root, path);

	if (IS_ERR(inode))

		return 0;



	ret = __btrfs_write_out_cache(root, inode, ctl, NULL, trans, path, 0);

	if (ret < 0)

		printk(KERN_ERR "btrfs: failed to write free ino cache "

		       "for root %llu\n", root->root_key.objectid);



	iput(inode);

	return ret;

}

fs/btrfs/free-space-cache.h

+11 −0
Original line number Diff line number Diff line
@@ -65,6 +65,17 @@ int btrfs_write_out_cache(struct btrfs_root *root, 
			  struct btrfs_block_group_cache *block_group,

			  struct btrfs_path *path);



struct inode *lookup_free_ino_inode(struct btrfs_root *root,

				    struct btrfs_path *path);

int create_free_ino_inode(struct btrfs_root *root,

			  struct btrfs_trans_handle *trans,

			  struct btrfs_path *path);

int load_free_ino_cache(struct btrfs_fs_info *fs_info,

			struct btrfs_root *root);

int btrfs_write_out_ino_cache(struct btrfs_root *root,

			      struct btrfs_trans_handle *trans,

			      struct btrfs_path *path);



void btrfs_init_free_space_ctl(struct btrfs_block_group_cache *block_group);

int __btrfs_add_free_space(struct btrfs_free_space_ctl *ctl,

			   u64 bytenr, u64 size);

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