ext4: add new pending reservation mechanism (1dc0aa46) · Commits · EulixOS / Software / Kernel

fs/ext4/ext4.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -1030,6 +1030,9 @@ struct ext4_inode_info {
		ext4_lblk_t i_da_metadata_calc_last_lblock;
		int i_da_metadata_calc_len;

		/* pending cluster reservations for bigalloc file systems */
		struct ext4_pending_tree i_pending_tree;

		/* on-disk additional length */
		__u16 i_extra_isize;

fs/ext4/extents_status.c

+187 −0

Original line number	Diff line number	Diff line
		@@ -142,6 +142,7 @@
		*/

		static struct kmem_cache *ext4_es_cachep;
		static struct kmem_cache *ext4_pending_cachep;

		static int __es_insert_extent(struct inode inode, struct extent_status newes);
		static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
		@@ -1365,3 +1366,189 @@ static int es_reclaim_extents(struct ext4_inode_info ei, int nr_to_scan)
		ei->i_es_tree.cache_es = NULL;
		return nr_shrunk;
		}

		#ifdef ES_DEBUG__
		static void ext4_print_pending_tree(struct inode *inode)
		{
		struct ext4_pending_tree *tree;
		struct rb_node *node;
		struct pending_reservation *pr;

		printk(KERN_DEBUG "pending reservations for inode %lu:", inode->i_ino);
		tree = &EXT4_I(inode)->i_pending_tree;
		node = rb_first(&tree->root);
		while (node) {
		pr = rb_entry(node, struct pending_reservation, rb_node);
		printk(KERN_DEBUG " %u", pr->lclu);
		node = rb_next(node);
		}
		printk(KERN_DEBUG "\n");
		}
		#else
		#define ext4_print_pending_tree(inode)
		#endif

		int __init ext4_init_pending(void)
		{
		ext4_pending_cachep = kmem_cache_create("ext4_pending_reservation",
		sizeof(struct pending_reservation),
		0, (SLAB_RECLAIM_ACCOUNT), NULL);
		if (ext4_pending_cachep == NULL)
		return -ENOMEM;
		return 0;
		}

		void ext4_exit_pending(void)
		{
		kmem_cache_destroy(ext4_pending_cachep);
		}

		void ext4_init_pending_tree(struct ext4_pending_tree *tree)
		{
		tree->root = RB_ROOT;
		}

		/*
		* __get_pending - retrieve a pointer to a pending reservation
		*
		* @inode - file containing the pending cluster reservation
		* @lclu - logical cluster of interest
		*
		* Returns a pointer to a pending reservation if it's a member of
		* the set, and NULL if not. Must be called holding i_es_lock.
		*/
		static struct pending_reservation __get_pending(struct inode inode,
		ext4_lblk_t lclu)
		{
		struct ext4_pending_tree *tree;
		struct rb_node *node;
		struct pending_reservation *pr = NULL;

		tree = &EXT4_I(inode)->i_pending_tree;
		node = (&tree->root)->rb_node;

		while (node) {
		pr = rb_entry(node, struct pending_reservation, rb_node);
		if (lclu < pr->lclu)
		node = node->rb_left;
		else if (lclu > pr->lclu)
		node = node->rb_right;
		else if (lclu == pr->lclu)
		return pr;
		}
		return NULL;
		}

		/*
		* __insert_pending - adds a pending cluster reservation to the set of
		* pending reservations
		*
		* @inode - file containing the cluster
		* @lblk - logical block in the cluster to be added
		*
		* Returns 0 on successful insertion and -ENOMEM on failure. If the
		* pending reservation is already in the set, returns successfully.
		*/
		static int __insert_pending(struct inode *inode, ext4_lblk_t lblk)
		{
		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
		struct ext4_pending_tree *tree = &EXT4_I(inode)->i_pending_tree;
		struct rb_node **p = &tree->root.rb_node;
		struct rb_node *parent = NULL;
		struct pending_reservation *pr;
		ext4_lblk_t lclu;
		int ret = 0;

		lclu = EXT4_B2C(sbi, lblk);
		/* search to find parent for insertion */
		while (*p) {
		parent = *p;
		pr = rb_entry(parent, struct pending_reservation, rb_node);

		if (lclu < pr->lclu) {
		p = &(*p)->rb_left;
		} else if (lclu > pr->lclu) {
		p = &(*p)->rb_right;
		} else {
		/* pending reservation already inserted */
		goto out;
		}
		}

		pr = kmem_cache_alloc(ext4_pending_cachep, GFP_ATOMIC);
		if (pr == NULL) {
		ret = -ENOMEM;
		goto out;
		}
		pr->lclu = lclu;

		rb_link_node(&pr->rb_node, parent, p);
		rb_insert_color(&pr->rb_node, &tree->root);

		out:
		return ret;
		}

		/*
		* __remove_pending - removes a pending cluster reservation from the set
		* of pending reservations
		*
		* @inode - file containing the cluster
		* @lblk - logical block in the pending cluster reservation to be removed
		*
		* Returns successfully if pending reservation is not a member of the set.
		*/
		static void __remove_pending(struct inode *inode, ext4_lblk_t lblk)
		{
		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
		struct pending_reservation *pr;
		struct ext4_pending_tree *tree;

		pr = __get_pending(inode, EXT4_B2C(sbi, lblk));
		if (pr != NULL) {
		tree = &EXT4_I(inode)->i_pending_tree;
		rb_erase(&pr->rb_node, &tree->root);
		kmem_cache_free(ext4_pending_cachep, pr);
		}
		}

		/*
		* ext4_remove_pending - removes a pending cluster reservation from the set
		* of pending reservations
		*
		* @inode - file containing the cluster
		* @lblk - logical block in the pending cluster reservation to be removed
		*
		* Locking for external use of __remove_pending.
		*/
		void ext4_remove_pending(struct inode *inode, ext4_lblk_t lblk)
		{
		struct ext4_inode_info *ei = EXT4_I(inode);

		write_lock(&ei->i_es_lock);
		__remove_pending(inode, lblk);
		write_unlock(&ei->i_es_lock);
		}

		/*
		* ext4_is_pending - determine whether a cluster has a pending reservation
		* on it
		*
		* @inode - file containing the cluster
		* @lblk - logical block in the cluster
		*
		* Returns true if there's a pending reservation for the cluster in the
		* set of pending reservations, and false if not.
		*/
		bool ext4_is_pending(struct inode *inode, ext4_lblk_t lblk)
		{
		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
		struct ext4_inode_info *ei = EXT4_I(inode);
		bool ret;

		read_lock(&ei->i_es_lock);
		ret = (bool)(__get_pending(inode, EXT4_B2C(sbi, lblk)) != NULL);
		read_unlock(&ei->i_es_lock);

		return ret;
		}

fs/ext4/extents_status.h

+51 −0

Original line number	Diff line number	Diff line
		@@ -78,6 +78,51 @@ struct ext4_es_stats {
		struct percpu_counter es_stats_shk_cnt;
		};

		/*
		* Pending cluster reservations for bigalloc file systems
		*
		* A cluster with a pending reservation is a logical cluster shared by at
		* least one extent in the extents status tree with delayed and unwritten
		* status and at least one other written or unwritten extent. The
		* reservation is said to be pending because a cluster reservation would
		* have to be taken in the event all blocks in the cluster shared with
		* written or unwritten extents were deleted while the delayed and
		* unwritten blocks remained.
		*
		* The set of pending cluster reservations is an auxiliary data structure
		* used with the extents status tree to implement reserved cluster/block
		* accounting for bigalloc file systems. The set is kept in memory and
		* records all pending cluster reservations.
		*
		* Its primary function is to avoid the need to read extents from the
		* disk when invalidating pages as a result of a truncate, punch hole, or
		* collapse range operation. Page invalidation requires a decrease in the
		* reserved cluster count if it results in the removal of all delayed
		* and unwritten extents (blocks) from a cluster that is not shared with a
		* written or unwritten extent, and no decrease otherwise. Determining
		* whether the cluster is shared can be done by searching for a pending
		* reservation on it.
		*
		* Secondarily, it provides a potentially faster method for determining
		* whether the reserved cluster count should be increased when a physical
		* cluster is deallocated as a result of a truncate, punch hole, or
		* collapse range operation. The necessary information is also present
		* in the extents status tree, but might be more rapidly accessed in
		* the pending reservation set in many cases due to smaller size.
		*
		* The pending cluster reservation set is implemented as a red-black tree
		* with the goal of minimizing per page search time overhead.
		*/

		struct pending_reservation {
		struct rb_node rb_node;
		ext4_lblk_t lclu;
		};

		struct ext4_pending_tree {
		struct rb_root root;
		};

		extern int __init ext4_init_es(void);
		extern void ext4_exit_es(void);
		extern void ext4_es_init_tree(struct ext4_es_tree *tree);
		@@ -182,4 +227,10 @@ extern void ext4_es_unregister_shrinker(struct ext4_sb_info *sbi);

		extern int ext4_seq_es_shrinker_info_show(struct seq_file seq, void v);

		extern int __init ext4_init_pending(void);
		extern void ext4_exit_pending(void);
		extern void ext4_init_pending_tree(struct ext4_pending_tree *tree);
		extern void ext4_remove_pending(struct inode *inode, ext4_lblk_t lblk);
		extern bool ext4_is_pending(struct inode *inode, ext4_lblk_t lblk);

		#endif /* _EXT4_EXTENTS_STATUS_H */

fs/ext4/super.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -1040,6 +1040,7 @@ static struct inode ext4_alloc_inode(struct super_block sb)
		ei->i_da_metadata_calc_len = 0;
		ei->i_da_metadata_calc_last_lblock = 0;
		spin_lock_init(&(ei->i_block_reservation_lock));
		ext4_init_pending_tree(&ei->i_pending_tree);
		#ifdef CONFIG_QUOTA
		ei->i_reserved_quota = 0;
		memset(&ei->i_dquot, 0, sizeof(ei->i_dquot));
		@@ -5954,6 +5955,10 @@ static int __init ext4_init_fs(void)
		if (err)
		return err;

		err = ext4_init_pending();
		if (err)
		goto out6;

		err = ext4_init_pageio();
		if (err)
		goto out5;
		@@ -5992,6 +5997,8 @@ static int __init ext4_init_fs(void)
		out4:
		ext4_exit_pageio();
		out5:
		ext4_exit_pending();
		out6:
		ext4_exit_es();

		return err;
		@@ -6009,6 +6016,7 @@ static void __exit ext4_exit_fs(void)
		ext4_exit_system_zone();
		ext4_exit_pageio();
		ext4_exit_es();
		ext4_exit_pending();
		}

		MODULE_AUTHOR("Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others");