Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2309 insertions, 0 deletions

diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
new file mode 100644
index 000000000..f4b50652f
--- /dev/null
+++ b/fs/ext4/extents_status.c
@@ -0,0 +1,2309 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  fs/ext4/extents_status.c
+ *
+ * Written by Yongqiang Yang <xiaoqiangnk@gmail.com>
+ * Modified by
+ *	Allison Henderson <achender@linux.vnet.ibm.com>
+ *	Hugh Dickins <hughd@google.com>
+ *	Zheng Liu <wenqing.lz@taobao.com>
+ *
+ * Ext4 extents status tree core functions.
+ */
+#include <linux/list_sort.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include "ext4.h"
+
+#include <trace/events/ext4.h>
+
+/*
+ * According to previous discussion in Ext4 Developer Workshop, we
+ * will introduce a new structure called io tree to track all extent
+ * status in order to solve some problems that we have met
+ * (e.g. Reservation space warning), and provide extent-level locking.
+ * Delay extent tree is the first step to achieve this goal.  It is
+ * original built by Yongqiang Yang.  At that time it is called delay
+ * extent tree, whose goal is only track delayed extents in memory to
+ * simplify the implementation of fiemap and bigalloc, and introduce
+ * lseek SEEK_DATA/SEEK_HOLE support.  That is why it is still called
+ * delay extent tree at the first commit.  But for better understand
+ * what it does, it has been rename to extent status tree.
+ *
+ * Step1:
+ * Currently the first step has been done.  All delayed extents are
+ * tracked in the tree.  It maintains the delayed extent when a delayed
+ * allocation is issued, and the delayed extent is written out or
+ * invalidated.  Therefore the implementation of fiemap and bigalloc
+ * are simplified, and SEEK_DATA/SEEK_HOLE are introduced.
+ *
+ * The following comment describes the implemenmtation of extent
+ * status tree and future works.
+ *
+ * Step2:
+ * In this step all extent status are tracked by extent status tree.
+ * Thus, we can first try to lookup a block mapping in this tree before
+ * finding it in extent tree.  Hence, single extent cache can be removed
+ * because extent status tree can do a better job.  Extents in status
+ * tree are loaded on-demand.  Therefore, the extent status tree may not
+ * contain all of the extents in a file.  Meanwhile we define a shrinker
+ * to reclaim memory from extent status tree because fragmented extent
+ * tree will make status tree cost too much memory.  written/unwritten/-
+ * hole extents in the tree will be reclaimed by this shrinker when we
+ * are under high memory pressure.  Delayed extents will not be
+ * reclimed because fiemap, bigalloc, and seek_data/hole need it.
+ */
+
+/*
+ * Extent status tree implementation for ext4.
+ *
+ *
+ * ==========================================================================
+ * Extent status tree tracks all extent status.
+ *
+ * 1. Why we need to implement extent status tree?
+ *
+ * Without extent status tree, ext4 identifies a delayed extent by looking
+ * up page cache, this has several deficiencies - complicated, buggy,
+ * and inefficient code.
+ *
+ * FIEMAP, SEEK_HOLE/DATA, bigalloc, and writeout all need to know if a
+ * block or a range of blocks are belonged to a delayed extent.
+ *
+ * Let us have a look at how they do without extent status tree.
+ *   --	FIEMAP
+ *	FIEMAP looks up page cache to identify delayed allocations from holes.
+ *
+ *   --	SEEK_HOLE/DATA
+ *	SEEK_HOLE/DATA has the same problem as FIEMAP.
+ *
+ *   --	bigalloc
+ *	bigalloc looks up page cache to figure out if a block is
+ *	already under delayed allocation or not to determine whether
+ *	quota reserving is needed for the cluster.
+ *
+ *   --	writeout
+ *	Writeout looks up whole page cache to see if a buffer is
+ *	mapped, If there are not very many delayed buffers, then it is
+ *	time consuming.
+ *
+ * With extent status tree implementation, FIEMAP, SEEK_HOLE/DATA,
+ * bigalloc and writeout can figure out if a block or a range of
+ * blocks is under delayed allocation(belonged to a delayed extent) or
+ * not by searching the extent tree.
+ *
+ *
+ * ==========================================================================
+ * 2. Ext4 extent status tree impelmentation
+ *
+ *   --	extent
+ *	A extent is a range of blocks which are contiguous logically and
+ *	physically.  Unlike extent in extent tree, this extent in ext4 is
+ *	a in-memory struct, there is no corresponding on-disk data.  There
+ *	is no limit on length of extent, so an extent can contain as many
+ *	blocks as they are contiguous logically and physically.
+ *
+ *   --	extent status tree
+ *	Every inode has an extent status tree and all allocation blocks
+ *	are added to the tree with different status.  The extent in the
+ *	tree are ordered by logical block no.
+ *
+ *   --	operations on a extent status tree
+ *	There are three important operations on a delayed extent tree: find
+ *	next extent, adding a extent(a range of blocks) and removing a extent.
+ *
+ *   --	race on a extent status tree
+ *	Extent status tree is protected by inode->i_es_lock.
+ *
+ *   --	memory consumption
+ *      Fragmented extent tree will make extent status tree cost too much
+ *      memory.  Hence, we will reclaim written/unwritten/hole extents from
+ *      the tree under a heavy memory pressure.
+ *
+ *
+ * ==========================================================================
+ * 3. Performance analysis
+ *
+ *   --	overhead
+ *	1. There is a cache extent for write access, so if writes are
+ *	not very random, adding space operaions are in O(1) time.
+ *
+ *   --	gain
+ *	2. Code is much simpler, more readable, more maintainable and
+ *	more efficient.
+ *
+ *
+ * ==========================================================================
+ * 4. TODO list
+ *
+ *   -- Refactor delayed space reservation
+ *
+ *   -- Extent-level locking
+ */
+
+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,
+			      struct extent_status *prealloc);
+static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
+			      ext4_lblk_t end, int *reserved,
+			      struct extent_status *prealloc);
+static int es_reclaim_extents(struct ext4_inode_info *ei, int *nr_to_scan);
+static int __es_shrink(struct ext4_sb_info *sbi, int nr_to_scan,
+		       struct ext4_inode_info *locked_ei);
+static int __revise_pending(struct inode *inode, ext4_lblk_t lblk,
+			    ext4_lblk_t len,
+			    struct pending_reservation **prealloc);
+
+int __init ext4_init_es(void)
+{
+	ext4_es_cachep = KMEM_CACHE(extent_status, SLAB_RECLAIM_ACCOUNT);
+	if (ext4_es_cachep == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+void ext4_exit_es(void)
+{
+	kmem_cache_destroy(ext4_es_cachep);
+}
+
+void ext4_es_init_tree(struct ext4_es_tree *tree)
+{
+	tree->root = RB_ROOT;
+	tree->cache_es = NULL;
+}
+
+#ifdef ES_DEBUG__
+static void ext4_es_print_tree(struct inode *inode)
+{
+	struct ext4_es_tree *tree;
+	struct rb_node *node;
+
+	printk(KERN_DEBUG "status extents for inode %lu:", inode->i_ino);
+	tree = &EXT4_I(inode)->i_es_tree;
+	node = rb_first(&tree->root);
+	while (node) {
+		struct extent_status *es;
+		es = rb_entry(node, struct extent_status, rb_node);
+		printk(KERN_DEBUG " [%u/%u) %llu %x",
+		       es->es_lblk, es->es_len,
+		       ext4_es_pblock(es), ext4_es_status(es));
+		node = rb_next(node);
+	}
+	printk(KERN_DEBUG "\n");
+}
+#else
+#define ext4_es_print_tree(inode)
+#endif
+
+static inline ext4_lblk_t ext4_es_end(struct extent_status *es)
+{
+	BUG_ON(es->es_lblk + es->es_len < es->es_lblk);
+	return es->es_lblk + es->es_len - 1;
+}
+
+/*
+ * search through the tree for an delayed extent with a given offset.  If
+ * it can't be found, try to find next extent.
+ */
+static struct extent_status *__es_tree_search(struct rb_root *root,
+					      ext4_lblk_t lblk)
+{
+	struct rb_node *node = root->rb_node;
+	struct extent_status *es = NULL;
+
+	while (node) {
+		es = rb_entry(node, struct extent_status, rb_node);
+		if (lblk < es->es_lblk)
+			node = node->rb_left;
+		else if (lblk > ext4_es_end(es))
+			node = node->rb_right;
+		else
+			return es;
+	}
+
+	if (es && lblk < es->es_lblk)
+		return es;
+
+	if (es && lblk > ext4_es_end(es)) {
+		node = rb_next(&es->rb_node);
+		return node ? rb_entry(node, struct extent_status, rb_node) :
+			      NULL;
+	}
+
+	return NULL;
+}
+
+/*
+ * ext4_es_find_extent_range - find extent with specified status within block
+ *                             range or next extent following block range in
+ *                             extents status tree
+ *
+ * @inode - file containing the range
+ * @matching_fn - pointer to function that matches extents with desired status
+ * @lblk - logical block defining start of range
+ * @end - logical block defining end of range
+ * @es - extent found, if any
+ *
+ * Find the first extent within the block range specified by @lblk and @end
+ * in the extents status tree that satisfies @matching_fn.  If a match
+ * is found, it's returned in @es.  If not, and a matching extent is found
+ * beyond the block range, it's returned in @es.  If no match is found, an
+ * extent is returned in @es whose es_lblk, es_len, and es_pblk components
+ * are 0.
+ */
+static void __es_find_extent_range(struct inode *inode,
+				   int (*matching_fn)(struct extent_status *es),
+				   ext4_lblk_t lblk, ext4_lblk_t end,
+				   struct extent_status *es)
+{
+	struct ext4_es_tree *tree = NULL;
+	struct extent_status *es1 = NULL;
+	struct rb_node *node;
+
+	WARN_ON(es == NULL);
+	WARN_ON(end < lblk);
+
+	tree = &EXT4_I(inode)->i_es_tree;
+
+	/* see if the extent has been cached */
+	es->es_lblk = es->es_len = es->es_pblk = 0;
+	es1 = READ_ONCE(tree->cache_es);
+	if (es1 && in_range(lblk, es1->es_lblk, es1->es_len)) {
+		es_debug("%u cached by [%u/%u) %llu %x\n",
+			 lblk, es1->es_lblk, es1->es_len,
+			 ext4_es_pblock(es1), ext4_es_status(es1));
+		goto out;
+	}
+
+	es1 = __es_tree_search(&tree->root, lblk);
+
+out:
+	if (es1 && !matching_fn(es1)) {
+		while ((node = rb_next(&es1->rb_node)) != NULL) {
+			es1 = rb_entry(node, struct extent_status, rb_node);
+			if (es1->es_lblk > end) {
+				es1 = NULL;
+				break;
+			}
+			if (matching_fn(es1))
+				break;
+		}
+	}
+
+	if (es1 && matching_fn(es1)) {
+		WRITE_ONCE(tree->cache_es, es1);
+		es->es_lblk = es1->es_lblk;
+		es->es_len = es1->es_len;
+		es->es_pblk = es1->es_pblk;
+	}
+
+}
+
+/*
+ * Locking for __es_find_extent_range() for external use
+ */
+void ext4_es_find_extent_range(struct inode *inode,
+			       int (*matching_fn)(struct extent_status *es),
+			       ext4_lblk_t lblk, ext4_lblk_t end,
+			       struct extent_status *es)
+{
+	if (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
+		return;
+
+	trace_ext4_es_find_extent_range_enter(inode, lblk);
+
+	read_lock(&EXT4_I(inode)->i_es_lock);
+	__es_find_extent_range(inode, matching_fn, lblk, end, es);
+	read_unlock(&EXT4_I(inode)->i_es_lock);
+
+	trace_ext4_es_find_extent_range_exit(inode, es);
+}
+
+/*
+ * __es_scan_range - search block range for block with specified status
+ *                   in extents status tree
+ *
+ * @inode - file containing the range
+ * @matching_fn - pointer to function that matches extents with desired status
+ * @lblk - logical block defining start of range
+ * @end - logical block defining end of range
+ *
+ * Returns true if at least one block in the specified block range satisfies
+ * the criterion specified by @matching_fn, and false if not.  If at least
+ * one extent has the specified status, then there is at least one block
+ * in the cluster with that status.  Should only be called by code that has
+ * taken i_es_lock.
+ */
+static bool __es_scan_range(struct inode *inode,
+			    int (*matching_fn)(struct extent_status *es),
+			    ext4_lblk_t start, ext4_lblk_t end)
+{
+	struct extent_status es;
+
+	__es_find_extent_range(inode, matching_fn, start, end, &es);
+	if (es.es_len == 0)
+		return false;   /* no matching extent in the tree */
+	else if (es.es_lblk <= start &&
+		 start < es.es_lblk + es.es_len)
+		return true;
+	else if (start <= es.es_lblk && es.es_lblk <= end)
+		return true;
+	else
+		return false;
+}
+/*
+ * Locking for __es_scan_range() for external use
+ */
+bool ext4_es_scan_range(struct inode *inode,
+			int (*matching_fn)(struct extent_status *es),
+			ext4_lblk_t lblk, ext4_lblk_t end)
+{
+	bool ret;
+
+	if (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
+		return false;
+
+	read_lock(&EXT4_I(inode)->i_es_lock);
+	ret = __es_scan_range(inode, matching_fn, lblk, end);
+	read_unlock(&EXT4_I(inode)->i_es_lock);
+
+	return ret;
+}
+
+/*
+ * __es_scan_clu - search cluster for block with specified status in
+ *                 extents status tree
+ *
+ * @inode - file containing the cluster
+ * @matching_fn - pointer to function that matches extents with desired status
+ * @lblk - logical block in cluster to be searched
+ *
+ * Returns true if at least one extent in the cluster containing @lblk
+ * satisfies the criterion specified by @matching_fn, and false if not.  If at
+ * least one extent has the specified status, then there is at least one block
+ * in the cluster with that status.  Should only be called by code that has
+ * taken i_es_lock.
+ */
+static bool __es_scan_clu(struct inode *inode,
+			  int (*matching_fn)(struct extent_status *es),
+			  ext4_lblk_t lblk)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	ext4_lblk_t lblk_start, lblk_end;
+
+	lblk_start = EXT4_LBLK_CMASK(sbi, lblk);
+	lblk_end = lblk_start + sbi->s_cluster_ratio - 1;
+
+	return __es_scan_range(inode, matching_fn, lblk_start, lblk_end);
+}
+
+/*
+ * Locking for __es_scan_clu() for external use
+ */
+bool ext4_es_scan_clu(struct inode *inode,
+		      int (*matching_fn)(struct extent_status *es),
+		      ext4_lblk_t lblk)
+{
+	bool ret;
+
+	if (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
+		return false;
+
+	read_lock(&EXT4_I(inode)->i_es_lock);
+	ret = __es_scan_clu(inode, matching_fn, lblk);
+	read_unlock(&EXT4_I(inode)->i_es_lock);
+
+	return ret;
+}
+
+static void ext4_es_list_add(struct inode *inode)
+{
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+
+	if (!list_empty(&ei->i_es_list))
+		return;
+
+	spin_lock(&sbi->s_es_lock);
+	if (list_empty(&ei->i_es_list)) {
+		list_add_tail(&ei->i_es_list, &sbi->s_es_list);
+		sbi->s_es_nr_inode++;
+	}
+	spin_unlock(&sbi->s_es_lock);
+}
+
+static void ext4_es_list_del(struct inode *inode)
+{
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+
+	spin_lock(&sbi->s_es_lock);
+	if (!list_empty(&ei->i_es_list)) {
+		list_del_init(&ei->i_es_list);
+		sbi->s_es_nr_inode--;
+		WARN_ON_ONCE(sbi->s_es_nr_inode < 0);
+	}
+	spin_unlock(&sbi->s_es_lock);
+}
+
+static inline struct pending_reservation *__alloc_pending(bool nofail)
+{
+	if (!nofail)
+		return kmem_cache_alloc(ext4_pending_cachep, GFP_ATOMIC);
+
+	return kmem_cache_zalloc(ext4_pending_cachep, GFP_KERNEL | __GFP_NOFAIL);
+}
+
+static inline void __free_pending(struct pending_reservation *pr)
+{
+	kmem_cache_free(ext4_pending_cachep, pr);
+}
+
+/*
+ * Returns true if we cannot fail to allocate memory for this extent_status
+ * entry and cannot reclaim it until its status changes.
+ */
+static inline bool ext4_es_must_keep(struct extent_status *es)
+{
+	/* fiemap, bigalloc, and seek_data/hole need to use it. */
+	if (ext4_es_is_delayed(es))
+		return true;
+
+	return false;
+}
+
+static inline struct extent_status *__es_alloc_extent(bool nofail)
+{
+	if (!nofail)
+		return kmem_cache_alloc(ext4_es_cachep, GFP_ATOMIC);
+
+	return kmem_cache_zalloc(ext4_es_cachep, GFP_KERNEL | __GFP_NOFAIL);
+}
+
+static void ext4_es_init_extent(struct inode *inode, struct extent_status *es,
+		ext4_lblk_t lblk, ext4_lblk_t len, ext4_fsblk_t pblk)
+{
+	es->es_lblk = lblk;
+	es->es_len = len;
+	es->es_pblk = pblk;
+
+	/* We never try to reclaim a must kept extent, so we don't count it. */
+	if (!ext4_es_must_keep(es)) {
+		if (!EXT4_I(inode)->i_es_shk_nr++)
+			ext4_es_list_add(inode);
+		percpu_counter_inc(&EXT4_SB(inode->i_sb)->
+					s_es_stats.es_stats_shk_cnt);
+	}
+
+	EXT4_I(inode)->i_es_all_nr++;
+	percpu_counter_inc(&EXT4_SB(inode->i_sb)->s_es_stats.es_stats_all_cnt);
+}
+
+static inline void __es_free_extent(struct extent_status *es)
+{
+	kmem_cache_free(ext4_es_cachep, es);
+}
+
+static void ext4_es_free_extent(struct inode *inode, struct extent_status *es)
+{
+	EXT4_I(inode)->i_es_all_nr--;
+	percpu_counter_dec(&EXT4_SB(inode->i_sb)->s_es_stats.es_stats_all_cnt);
+
+	/* Decrease the shrink counter when we can reclaim the extent. */
+	if (!ext4_es_must_keep(es)) {
+		BUG_ON(EXT4_I(inode)->i_es_shk_nr == 0);
+		if (!--EXT4_I(inode)->i_es_shk_nr)
+			ext4_es_list_del(inode);
+		percpu_counter_dec(&EXT4_SB(inode->i_sb)->
+					s_es_stats.es_stats_shk_cnt);
+	}
+
+	__es_free_extent(es);
+}
+
+/*
+ * Check whether or not two extents can be merged
+ * Condition:
+ *  - logical block number is contiguous
+ *  - physical block number is contiguous
+ *  - status is equal
+ */
+static int ext4_es_can_be_merged(struct extent_status *es1,
+				 struct extent_status *es2)
+{
+	if (ext4_es_type(es1) != ext4_es_type(es2))
+		return 0;
+
+	if (((__u64) es1->es_len) + es2->es_len > EXT_MAX_BLOCKS) {
+		pr_warn("ES assertion failed when merging extents. "
+			"The sum of lengths of es1 (%d) and es2 (%d) "
+			"is bigger than allowed file size (%d)\n",
+			es1->es_len, es2->es_len, EXT_MAX_BLOCKS);
+		WARN_ON(1);
+		return 0;
+	}
+
+	if (((__u64) es1->es_lblk) + es1->es_len != es2->es_lblk)
+		return 0;
+
+	if ((ext4_es_is_written(es1) || ext4_es_is_unwritten(es1)) &&
+	    (ext4_es_pblock(es1) + es1->es_len == ext4_es_pblock(es2)))
+		return 1;
+
+	if (ext4_es_is_hole(es1))
+		return 1;
+
+	/* we need to check delayed extent is without unwritten status */
+	if (ext4_es_is_delayed(es1) && !ext4_es_is_unwritten(es1))
+		return 1;
+
+	return 0;
+}
+
+static struct extent_status *
+ext4_es_try_to_merge_left(struct inode *inode, struct extent_status *es)
+{
+	struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
+	struct extent_status *es1;
+	struct rb_node *node;
+
+	node = rb_prev(&es->rb_node);
+	if (!node)
+		return es;
+
+	es1 = rb_entry(node, struct extent_status, rb_node);
+	if (ext4_es_can_be_merged(es1, es)) {
+		es1->es_len += es->es_len;
+		if (ext4_es_is_referenced(es))
+			ext4_es_set_referenced(es1);
+		rb_erase(&es->rb_node, &tree->root);
+		ext4_es_free_extent(inode, es);
+		es = es1;
+	}
+
+	return es;
+}
+
+static struct extent_status *
+ext4_es_try_to_merge_right(struct inode *inode, struct extent_status *es)
+{
+	struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
+	struct extent_status *es1;
+	struct rb_node *node;
+
+	node = rb_next(&es->rb_node);
+	if (!node)
+		return es;
+
+	es1 = rb_entry(node, struct extent_status, rb_node);
+	if (ext4_es_can_be_merged(es, es1)) {
+		es->es_len += es1->es_len;
+		if (ext4_es_is_referenced(es1))
+			ext4_es_set_referenced(es);
+		rb_erase(node, &tree->root);
+		ext4_es_free_extent(inode, es1);
+	}
+
+	return es;
+}
+
+#ifdef ES_AGGRESSIVE_TEST
+#include "ext4_extents.h"	/* Needed when ES_AGGRESSIVE_TEST is defined */
+
+static void ext4_es_insert_extent_ext_check(struct inode *inode,
+					    struct extent_status *es)
+{
+	struct ext4_ext_path *path = NULL;
+	struct ext4_extent *ex;
+	ext4_lblk_t ee_block;
+	ext4_fsblk_t ee_start;
+	unsigned short ee_len;
+	int depth, ee_status, es_status;
+
+	path = ext4_find_extent(inode, es->es_lblk, NULL, EXT4_EX_NOCACHE);
+	if (IS_ERR(path))
+		return;
+
+	depth = ext_depth(inode);
+	ex = path[depth].p_ext;
+
+	if (ex) {
+
+		ee_block = le32_to_cpu(ex->ee_block);
+		ee_start = ext4_ext_pblock(ex);
+		ee_len = ext4_ext_get_actual_len(ex);
+
+		ee_status = ext4_ext_is_unwritten(ex) ? 1 : 0;
+		es_status = ext4_es_is_unwritten(es) ? 1 : 0;
+
+		/*
+		 * Make sure ex and es are not overlap when we try to insert
+		 * a delayed/hole extent.
+		 */
+		if (!ext4_es_is_written(es) && !ext4_es_is_unwritten(es)) {
+			if (in_range(es->es_lblk, ee_block, ee_len)) {
+				pr_warn("ES insert assertion failed for "
+					"inode: %lu we can find an extent "
+					"at block [%d/%d/%llu/%c], but we "
+					"want to add a delayed/hole extent "
+					"[%d/%d/%llu/%x]\n",
+					inode->i_ino, ee_block, ee_len,
+					ee_start, ee_status ? 'u' : 'w',
+					es->es_lblk, es->es_len,
+					ext4_es_pblock(es), ext4_es_status(es));
+			}
+			goto out;
+		}
+
+		/*
+		 * We don't check ee_block == es->es_lblk, etc. because es
+		 * might be a part of whole extent, vice versa.
+		 */
+		if (es->es_lblk < ee_block ||
+		    ext4_es_pblock(es) != ee_start + es->es_lblk - ee_block) {
+			pr_warn("ES insert assertion failed for inode: %lu "
+				"ex_status [%d/%d/%llu/%c] != "
+				"es_status [%d/%d/%llu/%c]\n", inode->i_ino,
+				ee_block, ee_len, ee_start,
+				ee_status ? 'u' : 'w', es->es_lblk, es->es_len,
+				ext4_es_pblock(es), es_status ? 'u' : 'w');
+			goto out;
+		}
+
+		if (ee_status ^ es_status) {
+			pr_warn("ES insert assertion failed for inode: %lu "
+				"ex_status [%d/%d/%llu/%c] != "
+				"es_status [%d/%d/%llu/%c]\n", inode->i_ino,
+				ee_block, ee_len, ee_start,
+				ee_status ? 'u' : 'w', es->es_lblk, es->es_len,
+				ext4_es_pblock(es), es_status ? 'u' : 'w');
+		}
+	} else {
+		/*
+		 * We can't find an extent on disk.  So we need to make sure
+		 * that we don't want to add an written/unwritten extent.
+		 */
+		if (!ext4_es_is_delayed(es) && !ext4_es_is_hole(es)) {
+			pr_warn("ES insert assertion failed for inode: %lu "
+				"can't find an extent at block %d but we want "
+				"to add a written/unwritten extent "
+				"[%d/%d/%llu/%x]\n", inode->i_ino,
+				es->es_lblk, es->es_lblk, es->es_len,
+				ext4_es_pblock(es), ext4_es_status(es));
+		}
+	}
+out:
+	ext4_free_ext_path(path);
+}
+
+static void ext4_es_insert_extent_ind_check(struct inode *inode,
+					    struct extent_status *es)
+{
+	struct ext4_map_blocks map;
+	int retval;
+
+	/*
+	 * Here we call ext4_ind_map_blocks to lookup a block mapping because
+	 * 'Indirect' structure is defined in indirect.c.  So we couldn't
+	 * access direct/indirect tree from outside.  It is too dirty to define
+	 * this function in indirect.c file.
+	 */
+
+	map.m_lblk = es->es_lblk;
+	map.m_len = es->es_len;
+
+	retval = ext4_ind_map_blocks(NULL, inode, &map, 0);
+	if (retval > 0) {
+		if (ext4_es_is_delayed(es) || ext4_es_is_hole(es)) {
+			/*
+			 * We want to add a delayed/hole extent but this
+			 * block has been allocated.
+			 */
+			pr_warn("ES insert assertion failed for inode: %lu "
+				"We can find blocks but we want to add a "
+				"delayed/hole extent [%d/%d/%llu/%x]\n",
+				inode->i_ino, es->es_lblk, es->es_len,
+				ext4_es_pblock(es), ext4_es_status(es));
+			return;
+		} else if (ext4_es_is_written(es)) {
+			if (retval != es->es_len) {
+				pr_warn("ES insert assertion failed for "
+					"inode: %lu retval %d != es_len %d\n",
+					inode->i_ino, retval, es->es_len);
+				return;
+			}
+			if (map.m_pblk != ext4_es_pblock(es)) {
+				pr_warn("ES insert assertion failed for "
+					"inode: %lu m_pblk %llu != "
+					"es_pblk %llu\n",
+					inode->i_ino, map.m_pblk,
+					ext4_es_pblock(es));
+				return;
+			}
+		} else {
+			/*
+			 * We don't need to check unwritten extent because
+			 * indirect-based file doesn't have it.
+			 */
+			BUG();
+		}
+	} else if (retval == 0) {
+		if (ext4_es_is_written(es)) {
+			pr_warn("ES insert assertion failed for inode: %lu "
+				"We can't find the block but we want to add "
+				"a written extent [%d/%d/%llu/%x]\n",
+				inode->i_ino, es->es_lblk, es->es_len,
+				ext4_es_pblock(es), ext4_es_status(es));
+			return;
+		}
+	}
+}
+
+static inline void ext4_es_insert_extent_check(struct inode *inode,
+					       struct extent_status *es)
+{
+	/*
+	 * We don't need to worry about the race condition because
+	 * caller takes i_data_sem locking.
+	 */
+	BUG_ON(!rwsem_is_locked(&EXT4_I(inode)->i_data_sem));
+	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+		ext4_es_insert_extent_ext_check(inode, es);
+	else
+		ext4_es_insert_extent_ind_check(inode, es);
+}
+#else
+static inline void ext4_es_insert_extent_check(struct inode *inode,
+					       struct extent_status *es)
+{
+}
+#endif
+
+static int __es_insert_extent(struct inode *inode, struct extent_status *newes,
+			      struct extent_status *prealloc)
+{
+	struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
+	struct rb_node **p = &tree->root.rb_node;
+	struct rb_node *parent = NULL;
+	struct extent_status *es;
+
+	while (*p) {
+		parent = *p;
+		es = rb_entry(parent, struct extent_status, rb_node);
+
+		if (newes->es_lblk < es->es_lblk) {
+			if (ext4_es_can_be_merged(newes, es)) {
+				/*
+				 * Here we can modify es_lblk directly
+				 * because it isn't overlapped.
+				 */
+				es->es_lblk = newes->es_lblk;
+				es->es_len += newes->es_len;
+				if (ext4_es_is_written(es) ||
+				    ext4_es_is_unwritten(es))
+					ext4_es_store_pblock(es,
+							     newes->es_pblk);
+				es = ext4_es_try_to_merge_left(inode, es);
+				goto out;
+			}
+			p = &(*p)->rb_left;
+		} else if (newes->es_lblk > ext4_es_end(es)) {
+			if (ext4_es_can_be_merged(es, newes)) {
+				es->es_len += newes->es_len;
+				es = ext4_es_try_to_merge_right(inode, es);
+				goto out;
+			}
+			p = &(*p)->rb_right;
+		} else {
+			BUG();
+			return -EINVAL;
+		}
+	}
+
+	if (prealloc)
+		es = prealloc;
+	else
+		es = __es_alloc_extent(false);
+	if (!es)
+		return -ENOMEM;
+	ext4_es_init_extent(inode, es, newes->es_lblk, newes->es_len,
+			    newes->es_pblk);
+
+	rb_link_node(&es->rb_node, parent, p);
+	rb_insert_color(&es->rb_node, &tree->root);
+
+out:
+	tree->cache_es = es;
+	return 0;
+}
+
+/*
+ * ext4_es_insert_extent() adds information to an inode's extent
+ * status tree.
+ */
+void ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
+			   ext4_lblk_t len, ext4_fsblk_t pblk,
+			   unsigned int status)
+{
+	struct extent_status newes;
+	ext4_lblk_t end = lblk + len - 1;
+	int err1 = 0, err2 = 0, err3 = 0;
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	struct extent_status *es1 = NULL;
+	struct extent_status *es2 = NULL;
+	struct pending_reservation *pr = NULL;
+	bool revise_pending = false;
+
+	if (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
+		return;
+
+	es_debug("add [%u/%u) %llu %x to extent status tree of inode %lu\n",
+		 lblk, len, pblk, status, inode->i_ino);
+
+	if (!len)
+		return;
+
+	BUG_ON(end < lblk);
+
+	if ((status & EXTENT_STATUS_DELAYED) &&
+	    (status & EXTENT_STATUS_WRITTEN)) {
+		ext4_warning(inode->i_sb, "Inserting extent [%u/%u] as "
+				" delayed and written which can potentially "
+				" cause data loss.", lblk, len);
+		WARN_ON(1);
+	}
+
+	newes.es_lblk = lblk;
+	newes.es_len = len;
+	ext4_es_store_pblock_status(&newes, pblk, status);
+	trace_ext4_es_insert_extent(inode, &newes);
+
+	ext4_es_insert_extent_check(inode, &newes);
+
+	revise_pending = sbi->s_cluster_ratio > 1 &&
+			 test_opt(inode->i_sb, DELALLOC) &&
+			 (status & (EXTENT_STATUS_WRITTEN |
+				    EXTENT_STATUS_UNWRITTEN));
+retry:
+	if (err1 && !es1)
+		es1 = __es_alloc_extent(true);
+	if ((err1 || err2) && !es2)
+		es2 = __es_alloc_extent(true);
+	if ((err1 || err2 || err3) && revise_pending && !pr)
+		pr = __alloc_pending(true);
+	write_lock(&EXT4_I(inode)->i_es_lock);
+
+	err1 = __es_remove_extent(inode, lblk, end, NULL, es1);
+	if (err1 != 0)
+		goto error;
+	/* Free preallocated extent if it didn't get used. */
+	if (es1) {
+		if (!es1->es_len)
+			__es_free_extent(es1);
+		es1 = NULL;
+	}
+
+	err2 = __es_insert_extent(inode, &newes, es2);
+	if (err2 == -ENOMEM && !ext4_es_must_keep(&newes))
+		err2 = 0;
+	if (err2 != 0)
+		goto error;
+	/* Free preallocated extent if it didn't get used. */
+	if (es2) {
+		if (!es2->es_len)
+			__es_free_extent(es2);
+		es2 = NULL;
+	}
+
+	if (revise_pending) {
+		err3 = __revise_pending(inode, lblk, len, &pr);
+		if (err3 != 0)
+			goto error;
+		if (pr) {
+			__free_pending(pr);
+			pr = NULL;
+		}
+	}
+error:
+	write_unlock(&EXT4_I(inode)->i_es_lock);
+	if (err1 || err2 || err3)
+		goto retry;
+
+	ext4_es_print_tree(inode);
+	return;
+}
+
+/*
+ * ext4_es_cache_extent() inserts information into the extent status
+ * tree if and only if there isn't information about the range in
+ * question already.
+ */
+void ext4_es_cache_extent(struct inode *inode, ext4_lblk_t lblk,
+			  ext4_lblk_t len, ext4_fsblk_t pblk,
+			  unsigned int status)
+{
+	struct extent_status *es;
+	struct extent_status newes;
+	ext4_lblk_t end = lblk + len - 1;
+
+	if (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
+		return;
+
+	newes.es_lblk = lblk;
+	newes.es_len = len;
+	ext4_es_store_pblock_status(&newes, pblk, status);
+	trace_ext4_es_cache_extent(inode, &newes);
+
+	if (!len)
+		return;
+
+	BUG_ON(end < lblk);
+
+	write_lock(&EXT4_I(inode)->i_es_lock);
+
+	es = __es_tree_search(&EXT4_I(inode)->i_es_tree.root, lblk);
+	if (!es || es->es_lblk > end)
+		__es_insert_extent(inode, &newes, NULL);
+	write_unlock(&EXT4_I(inode)->i_es_lock);
+}
+
+/*
+ * ext4_es_lookup_extent() looks up an extent in extent status tree.
+ *
+ * ext4_es_lookup_extent is called by ext4_map_blocks/ext4_da_map_blocks.
+ *
+ * Return: 1 on found, 0 on not
+ */
+int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk,
+			  ext4_lblk_t *next_lblk,
+			  struct extent_status *es)
+{
+	struct ext4_es_tree *tree;
+	struct ext4_es_stats *stats;
+	struct extent_status *es1 = NULL;
+	struct rb_node *node;
+	int found = 0;
+
+	if (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
+		return 0;
+
+	trace_ext4_es_lookup_extent_enter(inode, lblk);
+	es_debug("lookup extent in block %u\n", lblk);
+
+	tree = &EXT4_I(inode)->i_es_tree;
+	read_lock(&EXT4_I(inode)->i_es_lock);
+
+	/* find extent in cache firstly */
+	es->es_lblk = es->es_len = es->es_pblk = 0;
+	es1 = READ_ONCE(tree->cache_es);
+	if (es1 && in_range(lblk, es1->es_lblk, es1->es_len)) {
+		es_debug("%u cached by [%u/%u)\n",
+			 lblk, es1->es_lblk, es1->es_len);
+		found = 1;
+		goto out;
+	}
+
+	node = tree->root.rb_node;
+	while (node) {
+		es1 = rb_entry(node, struct extent_status, rb_node);
+		if (lblk < es1->es_lblk)
+			node = node->rb_left;
+		else if (lblk > ext4_es_end(es1))
+			node = node->rb_right;
+		else {
+			found = 1;
+			break;
+		}
+	}
+
+out:
+	stats = &EXT4_SB(inode->i_sb)->s_es_stats;
+	if (found) {
+		BUG_ON(!es1);
+		es->es_lblk = es1->es_lblk;
+		es->es_len = es1->es_len;
+		es->es_pblk = es1->es_pblk;
+		if (!ext4_es_is_referenced(es1))
+			ext4_es_set_referenced(es1);
+		percpu_counter_inc(&stats->es_stats_cache_hits);
+		if (next_lblk) {
+			node = rb_next(&es1->rb_node);
+			if (node) {
+				es1 = rb_entry(node, struct extent_status,
+					       rb_node);
+				*next_lblk = es1->es_lblk;
+			} else
+				*next_lblk = 0;
+		}
+	} else {
+		percpu_counter_inc(&stats->es_stats_cache_misses);
+	}
+
+	read_unlock(&EXT4_I(inode)->i_es_lock);
+
+	trace_ext4_es_lookup_extent_exit(inode, es, found);
+	return found;
+}
+
+struct rsvd_count {
+	int ndelonly;
+	bool first_do_lblk_found;
+	ext4_lblk_t first_do_lblk;
+	ext4_lblk_t last_do_lblk;
+	struct extent_status *left_es;
+	bool partial;
+	ext4_lblk_t lclu;
+};
+
+/*
+ * init_rsvd - initialize reserved count data before removing block range
+ *	       in file from extent status tree
+ *
+ * @inode - file containing range
+ * @lblk - first block in range
+ * @es - pointer to first extent in range
+ * @rc - pointer to reserved count data
+ *
+ * Assumes es is not NULL
+ */
+static void init_rsvd(struct inode *inode, ext4_lblk_t lblk,
+		      struct extent_status *es, struct rsvd_count *rc)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	struct rb_node *node;
+
+	rc->ndelonly = 0;
+
+	/*
+	 * for bigalloc, note the first delonly block in the range has not
+	 * been found, record the extent containing the block to the left of
+	 * the region to be removed, if any, and note that there's no partial
+	 * cluster to track
+	 */
+	if (sbi->s_cluster_ratio > 1) {
+		rc->first_do_lblk_found = false;
+		if (lblk > es->es_lblk) {
+			rc->left_es = es;
+		} else {
+			node = rb_prev(&es->rb_node);
+			rc->left_es = node ? rb_entry(node,
+						      struct extent_status,
+						      rb_node) : NULL;
+		}
+		rc->partial = false;
+	}
+}
+
+/*
+ * count_rsvd - count the clusters containing delayed and not unwritten
+ *		(delonly) blocks in a range within an extent and add to
+ *	        the running tally in rsvd_count
+ *
+ * @inode - file containing extent
+ * @lblk - first block in range
+ * @len - length of range in blocks
+ * @es - pointer to extent containing clusters to be counted
+ * @rc - pointer to reserved count data
+ *
+ * Tracks partial clusters found at the beginning and end of extents so
+ * they aren't overcounted when they span adjacent extents
+ */
+static void count_rsvd(struct inode *inode, ext4_lblk_t lblk, long len,
+		       struct extent_status *es, struct rsvd_count *rc)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	ext4_lblk_t i, end, nclu;
+
+	if (!ext4_es_is_delonly(es))
+		return;
+
+	WARN_ON(len <= 0);
+
+	if (sbi->s_cluster_ratio == 1) {
+		rc->ndelonly += (int) len;
+		return;
+	}
+
+	/* bigalloc */
+
+	i = (lblk < es->es_lblk) ? es->es_lblk : lblk;
+	end = lblk + (ext4_lblk_t) len - 1;
+	end = (end > ext4_es_end(es)) ? ext4_es_end(es) : end;
+
+	/* record the first block of the first delonly extent seen */
+	if (!rc->first_do_lblk_found) {
+		rc->first_do_lblk = i;
+		rc->first_do_lblk_found = true;
+	}
+
+	/* update the last lblk in the region seen so far */
+	rc->last_do_lblk = end;
+
+	/*
+	 * if we're tracking a partial cluster and the current extent
+	 * doesn't start with it, count it and stop tracking
+	 */
+	if (rc->partial && (rc->lclu != EXT4_B2C(sbi, i))) {
+		rc->ndelonly++;
+		rc->partial = false;
+	}
+
+	/*
+	 * if the first cluster doesn't start on a cluster boundary but
+	 * ends on one, count it
+	 */
+	if (EXT4_LBLK_COFF(sbi, i) != 0) {
+		if (end >= EXT4_LBLK_CFILL(sbi, i)) {
+			rc->ndelonly++;
+			rc->partial = false;
+			i = EXT4_LBLK_CFILL(sbi, i) + 1;
+		}
+	}
+
+	/*
+	 * if the current cluster starts on a cluster boundary, count the
+	 * number of whole delonly clusters in the extent
+	 */
+	if ((i + sbi->s_cluster_ratio - 1) <= end) {
+		nclu = (end - i + 1) >> sbi->s_cluster_bits;
+		rc->ndelonly += nclu;
+		i += nclu << sbi->s_cluster_bits;
+	}
+
+	/*
+	 * start tracking a partial cluster if there's a partial at the end
+	 * of the current extent and we're not already tracking one
+	 */
+	if (!rc->partial && i <= end) {
+		rc->partial = true;
+		rc->lclu = EXT4_B2C(sbi, i);
+	}
+}
+
+/*
+ * __pr_tree_search - search for a pending cluster reservation
+ *
+ * @root - root of pending reservation tree
+ * @lclu - logical cluster to search for
+ *
+ * Returns the pending reservation for the cluster identified by @lclu
+ * if found.  If not, returns a reservation for the next cluster if any,
+ * and if not, returns NULL.
+ */
+static struct pending_reservation *__pr_tree_search(struct rb_root *root,
+						    ext4_lblk_t lclu)
+{
+	struct rb_node *node = root->rb_node;
+	struct pending_reservation *pr = NULL;
+
+	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
+			return pr;
+	}
+	if (pr && lclu < pr->lclu)
+		return pr;
+	if (pr && lclu > pr->lclu) {
+		node = rb_next(&pr->rb_node);
+		return node ? rb_entry(node, struct pending_reservation,
+				       rb_node) : NULL;
+	}
+	return NULL;
+}
+
+/*
+ * get_rsvd - calculates and returns the number of cluster reservations to be
+ *	      released when removing a block range from the extent status tree
+ *	      and releases any pending reservations within the range
+ *
+ * @inode - file containing block range
+ * @end - last block in range
+ * @right_es - pointer to extent containing next block beyond end or NULL
+ * @rc - pointer to reserved count data
+ *
+ * The number of reservations to be released is equal to the number of
+ * clusters containing delayed and not unwritten (delonly) blocks within
+ * the range, minus the number of clusters still containing delonly blocks
+ * at the ends of the range, and minus the number of pending reservations
+ * within the range.
+ */
+static unsigned int get_rsvd(struct inode *inode, ext4_lblk_t end,
+			     struct extent_status *right_es,
+			     struct rsvd_count *rc)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	struct pending_reservation *pr;
+	struct ext4_pending_tree *tree = &EXT4_I(inode)->i_pending_tree;
+	struct rb_node *node;
+	ext4_lblk_t first_lclu, last_lclu;
+	bool left_delonly, right_delonly, count_pending;
+	struct extent_status *es;
+
+	if (sbi->s_cluster_ratio > 1) {
+		/* count any remaining partial cluster */
+		if (rc->partial)
+			rc->ndelonly++;
+
+		if (rc->ndelonly == 0)
+			return 0;
+
+		first_lclu = EXT4_B2C(sbi, rc->first_do_lblk);
+		last_lclu = EXT4_B2C(sbi, rc->last_do_lblk);
+
+		/*
+		 * decrease the delonly count by the number of clusters at the
+		 * ends of the range that still contain delonly blocks -
+		 * these clusters still need to be reserved
+		 */
+		left_delonly = right_delonly = false;
+
+		es = rc->left_es;
+		while (es && ext4_es_end(es) >=
+		       EXT4_LBLK_CMASK(sbi, rc->first_do_lblk)) {
+			if (ext4_es_is_delonly(es)) {
+				rc->ndelonly--;
+				left_delonly = true;
+				break;
+			}
+			node = rb_prev(&es->rb_node);
+			if (!node)
+				break;
+			es = rb_entry(node, struct extent_status, rb_node);
+		}
+		if (right_es && (!left_delonly || first_lclu != last_lclu)) {
+			if (end < ext4_es_end(right_es)) {
+				es = right_es;
+			} else {
+				node = rb_next(&right_es->rb_node);
+				es = node ? rb_entry(node, struct extent_status,
+						     rb_node) : NULL;
+			}
+			while (es && es->es_lblk <=
+			       EXT4_LBLK_CFILL(sbi, rc->last_do_lblk)) {
+				if (ext4_es_is_delonly(es)) {
+					rc->ndelonly--;
+					right_delonly = true;
+					break;
+				}
+				node = rb_next(&es->rb_node);
+				if (!node)
+					break;
+				es = rb_entry(node, struct extent_status,
+					      rb_node);
+			}
+		}
+
+		/*
+		 * Determine the block range that should be searched for
+		 * pending reservations, if any.  Clusters on the ends of the
+		 * original removed range containing delonly blocks are
+		 * excluded.  They've already been accounted for and it's not
+		 * possible to determine if an associated pending reservation
+		 * should be released with the information available in the
+		 * extents status tree.
+		 */
+		if (first_lclu == last_lclu) {
+			if (left_delonly | right_delonly)
+				count_pending = false;
+			else
+				count_pending = true;
+		} else {
+			if (left_delonly)
+				first_lclu++;
+			if (right_delonly)
+				last_lclu--;
+			if (first_lclu <= last_lclu)
+				count_pending = true;
+			else
+				count_pending = false;
+		}
+
+		/*
+		 * a pending reservation found between first_lclu and last_lclu
+		 * represents an allocated cluster that contained at least one
+		 * delonly block, so the delonly total must be reduced by one
+		 * for each pending reservation found and released
+		 */
+		if (count_pending) {
+			pr = __pr_tree_search(&tree->root, first_lclu);
+			while (pr && pr->lclu <= last_lclu) {
+				rc->ndelonly--;
+				node = rb_next(&pr->rb_node);
+				rb_erase(&pr->rb_node, &tree->root);
+				__free_pending(pr);
+				if (!node)
+					break;
+				pr = rb_entry(node, struct pending_reservation,
+					      rb_node);
+			}
+		}
+	}
+	return rc->ndelonly;
+}
+
+
+/*
+ * __es_remove_extent - removes block range from extent status tree
+ *
+ * @inode - file containing range
+ * @lblk - first block in range
+ * @end - last block in range
+ * @reserved - number of cluster reservations released
+ * @prealloc - pre-allocated es to avoid memory allocation failures
+ *
+ * If @reserved is not NULL and delayed allocation is enabled, counts
+ * block/cluster reservations freed by removing range and if bigalloc
+ * enabled cancels pending reservations as needed. Returns 0 on success,
+ * error code on failure.
+ */
+static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
+			      ext4_lblk_t end, int *reserved,
+			      struct extent_status *prealloc)
+{
+	struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
+	struct rb_node *node;
+	struct extent_status *es;
+	struct extent_status orig_es;
+	ext4_lblk_t len1, len2;
+	ext4_fsblk_t block;
+	int err = 0;
+	bool count_reserved = true;
+	struct rsvd_count rc;
+
+	if (reserved == NULL || !test_opt(inode->i_sb, DELALLOC))
+		count_reserved = false;
+
+	es = __es_tree_search(&tree->root, lblk);
+	if (!es)
+		goto out;
+	if (es->es_lblk > end)
+		goto out;
+
+	/* Simply invalidate cache_es. */
+	tree->cache_es = NULL;
+	if (count_reserved)
+		init_rsvd(inode, lblk, es, &rc);
+
+	orig_es.es_lblk = es->es_lblk;
+	orig_es.es_len = es->es_len;
+	orig_es.es_pblk = es->es_pblk;
+
+	len1 = lblk > es->es_lblk ? lblk - es->es_lblk : 0;
+	len2 = ext4_es_end(es) > end ? ext4_es_end(es) - end : 0;
+	if (len1 > 0)
+		es->es_len = len1;
+	if (len2 > 0) {
+		if (len1 > 0) {
+			struct extent_status newes;
+
+			newes.es_lblk = end + 1;
+			newes.es_len = len2;
+			block = 0x7FDEADBEEFULL;
+			if (ext4_es_is_written(&orig_es) ||
+			    ext4_es_is_unwritten(&orig_es))
+				block = ext4_es_pblock(&orig_es) +
+					orig_es.es_len - len2;
+			ext4_es_store_pblock_status(&newes, block,
+						    ext4_es_status(&orig_es));
+			err = __es_insert_extent(inode, &newes, prealloc);
+			if (err) {
+				if (!ext4_es_must_keep(&newes))
+					return 0;
+
+				es->es_lblk = orig_es.es_lblk;
+				es->es_len = orig_es.es_len;
+				goto out;
+			}
+		} else {
+			es->es_lblk = end + 1;
+			es->es_len = len2;
+			if (ext4_es_is_written(es) ||
+			    ext4_es_is_unwritten(es)) {
+				block = orig_es.es_pblk + orig_es.es_len - len2;
+				ext4_es_store_pblock(es, block);
+			}
+		}
+		if (count_reserved)
+			count_rsvd(inode, orig_es.es_lblk + len1,
+				   orig_es.es_len - len1 - len2, &orig_es, &rc);
+		goto out_get_reserved;
+	}
+
+	if (len1 > 0) {
+		if (count_reserved)
+			count_rsvd(inode, lblk, orig_es.es_len - len1,
+				   &orig_es, &rc);
+		node = rb_next(&es->rb_node);
+		if (node)
+			es = rb_entry(node, struct extent_status, rb_node);
+		else
+			es = NULL;
+	}
+
+	while (es && ext4_es_end(es) <= end) {
+		if (count_reserved)
+			count_rsvd(inode, es->es_lblk, es->es_len, es, &rc);
+		node = rb_next(&es->rb_node);
+		rb_erase(&es->rb_node, &tree->root);
+		ext4_es_free_extent(inode, es);
+		if (!node) {
+			es = NULL;
+			break;
+		}
+		es = rb_entry(node, struct extent_status, rb_node);
+	}
+
+	if (es && es->es_lblk < end + 1) {
+		ext4_lblk_t orig_len = es->es_len;
+
+		len1 = ext4_es_end(es) - end;
+		if (count_reserved)
+			count_rsvd(inode, es->es_lblk, orig_len - len1,
+				   es, &rc);
+		es->es_lblk = end + 1;
+		es->es_len = len1;
+		if (ext4_es_is_written(es) || ext4_es_is_unwritten(es)) {
+			block = es->es_pblk + orig_len - len1;
+			ext4_es_store_pblock(es, block);
+		}
+	}
+
+out_get_reserved:
+	if (count_reserved)
+		*reserved = get_rsvd(inode, end, es, &rc);
+out:
+	return err;
+}
+
+/*
+ * ext4_es_remove_extent - removes block range from extent status tree
+ *
+ * @inode - file containing range
+ * @lblk - first block in range
+ * @len - number of blocks to remove
+ *
+ * Reduces block/cluster reservation count and for bigalloc cancels pending
+ * reservations as needed.
+ */
+void ext4_es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
+			   ext4_lblk_t len)
+{
+	ext4_lblk_t end;
+	int err = 0;
+	int reserved = 0;
+	struct extent_status *es = NULL;
+
+	if (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
+		return;
+
+	trace_ext4_es_remove_extent(inode, lblk, len);
+	es_debug("remove [%u/%u) from extent status tree of inode %lu\n",
+		 lblk, len, inode->i_ino);
+
+	if (!len)
+		return;
+
+	end = lblk + len - 1;
+	BUG_ON(end < lblk);
+
+retry:
+	if (err && !es)
+		es = __es_alloc_extent(true);
+	/*
+	 * ext4_clear_inode() depends on us taking i_es_lock unconditionally
+	 * so that we are sure __es_shrink() is done with the inode before it
+	 * is reclaimed.
+	 */
+	write_lock(&EXT4_I(inode)->i_es_lock);
+	err = __es_remove_extent(inode, lblk, end, &reserved, es);
+	/* Free preallocated extent if it didn't get used. */
+	if (es) {
+		if (!es->es_len)
+			__es_free_extent(es);
+		es = NULL;
+	}
+	write_unlock(&EXT4_I(inode)->i_es_lock);
+	if (err)
+		goto retry;
+
+	ext4_es_print_tree(inode);
+	ext4_da_release_space(inode, reserved);
+	return;
+}
+
+static int __es_shrink(struct ext4_sb_info *sbi, int nr_to_scan,
+		       struct ext4_inode_info *locked_ei)
+{
+	struct ext4_inode_info *ei;
+	struct ext4_es_stats *es_stats;
+	ktime_t start_time;
+	u64 scan_time;
+	int nr_to_walk;
+	int nr_shrunk = 0;
+	int retried = 0, nr_skipped = 0;
+
+	es_stats = &sbi->s_es_stats;
+	start_time = ktime_get();
+
+retry:
+	spin_lock(&sbi->s_es_lock);
+	nr_to_walk = sbi->s_es_nr_inode;
+	while (nr_to_walk-- > 0) {
+		if (list_empty(&sbi->s_es_list)) {
+			spin_unlock(&sbi->s_es_lock);
+			goto out;
+		}
+		ei = list_first_entry(&sbi->s_es_list, struct ext4_inode_info,
+				      i_es_list);
+		/* Move the inode to the tail */
+		list_move_tail(&ei->i_es_list, &sbi->s_es_list);
+
+		/*
+		 * Normally we try hard to avoid shrinking precached inodes,
+		 * but we will as a last resort.
+		 */
+		if (!retried && ext4_test_inode_state(&ei->vfs_inode,
+						EXT4_STATE_EXT_PRECACHED)) {
+			nr_skipped++;
+			continue;
+		}
+
+		if (ei == locked_ei || !write_trylock(&ei->i_es_lock)) {
+			nr_skipped++;
+			continue;
+		}
+		/*
+		 * Now we hold i_es_lock which protects us from inode reclaim
+		 * freeing inode under us
+		 */
+		spin_unlock(&sbi->s_es_lock);
+
+		nr_shrunk += es_reclaim_extents(ei, &nr_to_scan);
+		write_unlock(&ei->i_es_lock);
+
+		if (nr_to_scan <= 0)
+			goto out;
+		spin_lock(&sbi->s_es_lock);
+	}
+	spin_unlock(&sbi->s_es_lock);
+
+	/*
+	 * If we skipped any inodes, and we weren't able to make any
+	 * forward progress, try again to scan precached inodes.
+	 */
+	if ((nr_shrunk == 0) && nr_skipped && !retried) {
+		retried++;
+		goto retry;
+	}
+
+	if (locked_ei && nr_shrunk == 0)
+		nr_shrunk = es_reclaim_extents(locked_ei, &nr_to_scan);
+
+out:
+	scan_time = ktime_to_ns(ktime_sub(ktime_get(), start_time));
+	if (likely(es_stats->es_stats_scan_time))
+		es_stats->es_stats_scan_time = (scan_time +
+				es_stats->es_stats_scan_time*3) / 4;
+	else
+		es_stats->es_stats_scan_time = scan_time;
+	if (scan_time > es_stats->es_stats_max_scan_time)
+		es_stats->es_stats_max_scan_time = scan_time;
+	if (likely(es_stats->es_stats_shrunk))
+		es_stats->es_stats_shrunk = (nr_shrunk +
+				es_stats->es_stats_shrunk*3) / 4;
+	else
+		es_stats->es_stats_shrunk = nr_shrunk;
+
+	trace_ext4_es_shrink(sbi->s_sb, nr_shrunk, scan_time,
+			     nr_skipped, retried);
+	return nr_shrunk;
+}
+
+static unsigned long ext4_es_count(struct shrinker *shrink,
+				   struct shrink_control *sc)
+{
+	unsigned long nr;
+	struct ext4_sb_info *sbi;
+
+	sbi = container_of(shrink, struct ext4_sb_info, s_es_shrinker);
+	nr = percpu_counter_read_positive(&sbi->s_es_stats.es_stats_shk_cnt);
+	trace_ext4_es_shrink_count(sbi->s_sb, sc->nr_to_scan, nr);
+	return nr;
+}
+
+static unsigned long ext4_es_scan(struct shrinker *shrink,
+				  struct shrink_control *sc)
+{
+	struct ext4_sb_info *sbi = container_of(shrink,
+					struct ext4_sb_info, s_es_shrinker);
+	int nr_to_scan = sc->nr_to_scan;
+	int ret, nr_shrunk;
+
+	ret = percpu_counter_read_positive(&sbi->s_es_stats.es_stats_shk_cnt);
+	trace_ext4_es_shrink_scan_enter(sbi->s_sb, nr_to_scan, ret);
+
+	nr_shrunk = __es_shrink(sbi, nr_to_scan, NULL);
+
+	ret = percpu_counter_read_positive(&sbi->s_es_stats.es_stats_shk_cnt);
+	trace_ext4_es_shrink_scan_exit(sbi->s_sb, nr_shrunk, ret);
+	return nr_shrunk;
+}
+
+int ext4_seq_es_shrinker_info_show(struct seq_file *seq, void *v)
+{
+	struct ext4_sb_info *sbi = EXT4_SB((struct super_block *) seq->private);
+	struct ext4_es_stats *es_stats = &sbi->s_es_stats;
+	struct ext4_inode_info *ei, *max = NULL;
+	unsigned int inode_cnt = 0;
+
+	if (v != SEQ_START_TOKEN)
+		return 0;
+
+	/* here we just find an inode that has the max nr. of objects */
+	spin_lock(&sbi->s_es_lock);
+	list_for_each_entry(ei, &sbi->s_es_list, i_es_list) {
+		inode_cnt++;
+		if (max && max->i_es_all_nr < ei->i_es_all_nr)
+			max = ei;
+		else if (!max)
+			max = ei;
+	}
+	spin_unlock(&sbi->s_es_lock);
+
+	seq_printf(seq, "stats:\n  %lld objects\n  %lld reclaimable objects\n",
+		   percpu_counter_sum_positive(&es_stats->es_stats_all_cnt),
+		   percpu_counter_sum_positive(&es_stats->es_stats_shk_cnt));
+	seq_printf(seq, "  %lld/%lld cache hits/misses\n",
+		   percpu_counter_sum_positive(&es_stats->es_stats_cache_hits),
+		   percpu_counter_sum_positive(&es_stats->es_stats_cache_misses));
+	if (inode_cnt)
+		seq_printf(seq, "  %d inodes on list\n", inode_cnt);
+
+	seq_printf(seq, "average:\n  %llu us scan time\n",
+	    div_u64(es_stats->es_stats_scan_time, 1000));
+	seq_printf(seq, "  %lu shrunk objects\n", es_stats->es_stats_shrunk);
+	if (inode_cnt)
+		seq_printf(seq,
+		    "maximum:\n  %lu inode (%u objects, %u reclaimable)\n"
+		    "  %llu us max scan time\n",
+		    max->vfs_inode.i_ino, max->i_es_all_nr, max->i_es_shk_nr,
+		    div_u64(es_stats->es_stats_max_scan_time, 1000));
+
+	return 0;
+}
+
+int ext4_es_register_shrinker(struct ext4_sb_info *sbi)
+{
+	int err;
+
+	/* Make sure we have enough bits for physical block number */
+	BUILD_BUG_ON(ES_SHIFT < 48);
+	INIT_LIST_HEAD(&sbi->s_es_list);
+	sbi->s_es_nr_inode = 0;
+	spin_lock_init(&sbi->s_es_lock);
+	sbi->s_es_stats.es_stats_shrunk = 0;
+	err = percpu_counter_init(&sbi->s_es_stats.es_stats_cache_hits, 0,
+				  GFP_KERNEL);
+	if (err)
+		return err;
+	err = percpu_counter_init(&sbi->s_es_stats.es_stats_cache_misses, 0,
+				  GFP_KERNEL);
+	if (err)
+		goto err1;
+	sbi->s_es_stats.es_stats_scan_time = 0;
+	sbi->s_es_stats.es_stats_max_scan_time = 0;
+	err = percpu_counter_init(&sbi->s_es_stats.es_stats_all_cnt, 0, GFP_KERNEL);
+	if (err)
+		goto err2;
+	err = percpu_counter_init(&sbi->s_es_stats.es_stats_shk_cnt, 0, GFP_KERNEL);
+	if (err)
+		goto err3;
+
+	sbi->s_es_shrinker.scan_objects = ext4_es_scan;
+	sbi->s_es_shrinker.count_objects = ext4_es_count;
+	sbi->s_es_shrinker.seeks = DEFAULT_SEEKS;
+	err = register_shrinker(&sbi->s_es_shrinker, "ext4-es:%s",
+				sbi->s_sb->s_id);
+	if (err)
+		goto err4;
+
+	return 0;
+err4:
+	percpu_counter_destroy(&sbi->s_es_stats.es_stats_shk_cnt);
+err3:
+	percpu_counter_destroy(&sbi->s_es_stats.es_stats_all_cnt);
+err2:
+	percpu_counter_destroy(&sbi->s_es_stats.es_stats_cache_misses);
+err1:
+	percpu_counter_destroy(&sbi->s_es_stats.es_stats_cache_hits);
+	return err;
+}
+
+void ext4_es_unregister_shrinker(struct ext4_sb_info *sbi)
+{
+	percpu_counter_destroy(&sbi->s_es_stats.es_stats_cache_hits);
+	percpu_counter_destroy(&sbi->s_es_stats.es_stats_cache_misses);
+	percpu_counter_destroy(&sbi->s_es_stats.es_stats_all_cnt);
+	percpu_counter_destroy(&sbi->s_es_stats.es_stats_shk_cnt);
+	unregister_shrinker(&sbi->s_es_shrinker);
+}
+
+/*
+ * Shrink extents in given inode from ei->i_es_shrink_lblk till end. Scan at
+ * most *nr_to_scan extents, update *nr_to_scan accordingly.
+ *
+ * Return 0 if we hit end of tree / interval, 1 if we exhausted nr_to_scan.
+ * Increment *nr_shrunk by the number of reclaimed extents. Also update
+ * ei->i_es_shrink_lblk to where we should continue scanning.
+ */
+static int es_do_reclaim_extents(struct ext4_inode_info *ei, ext4_lblk_t end,
+				 int *nr_to_scan, int *nr_shrunk)
+{
+	struct inode *inode = &ei->vfs_inode;
+	struct ext4_es_tree *tree = &ei->i_es_tree;
+	struct extent_status *es;
+	struct rb_node *node;
+
+	es = __es_tree_search(&tree->root, ei->i_es_shrink_lblk);
+	if (!es)
+		goto out_wrap;
+
+	while (*nr_to_scan > 0) {
+		if (es->es_lblk > end) {
+			ei->i_es_shrink_lblk = end + 1;
+			return 0;
+		}
+
+		(*nr_to_scan)--;
+		node = rb_next(&es->rb_node);
+
+		if (ext4_es_must_keep(es))
+			goto next;
+		if (ext4_es_is_referenced(es)) {
+			ext4_es_clear_referenced(es);
+			goto next;
+		}
+
+		rb_erase(&es->rb_node, &tree->root);
+		ext4_es_free_extent(inode, es);
+		(*nr_shrunk)++;
+next:
+		if (!node)
+			goto out_wrap;
+		es = rb_entry(node, struct extent_status, rb_node);
+	}
+	ei->i_es_shrink_lblk = es->es_lblk;
+	return 1;
+out_wrap:
+	ei->i_es_shrink_lblk = 0;
+	return 0;
+}
+
+static int es_reclaim_extents(struct ext4_inode_info *ei, int *nr_to_scan)
+{
+	struct inode *inode = &ei->vfs_inode;
+	int nr_shrunk = 0;
+	ext4_lblk_t start = ei->i_es_shrink_lblk;
+	static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
+				      DEFAULT_RATELIMIT_BURST);
+
+	if (ei->i_es_shk_nr == 0)
+		return 0;
+
+	if (ext4_test_inode_state(inode, EXT4_STATE_EXT_PRECACHED) &&
+	    __ratelimit(&_rs))
+		ext4_warning(inode->i_sb, "forced shrink of precached extents");
+
+	if (!es_do_reclaim_extents(ei, EXT_MAX_BLOCKS, nr_to_scan, &nr_shrunk) &&
+	    start != 0)
+		es_do_reclaim_extents(ei, start - 1, nr_to_scan, &nr_shrunk);
+
+	ei->i_es_tree.cache_es = NULL;
+	return nr_shrunk;
+}
+
+/*
+ * Called to support EXT4_IOC_CLEAR_ES_CACHE.  We can only remove
+ * discretionary entries from the extent status cache.  (Some entries
+ * must be present for proper operations.)
+ */
+void ext4_clear_inode_es(struct inode *inode)
+{
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	struct extent_status *es;
+	struct ext4_es_tree *tree;
+	struct rb_node *node;
+
+	write_lock(&ei->i_es_lock);
+	tree = &EXT4_I(inode)->i_es_tree;
+	tree->cache_es = NULL;
+	node = rb_first(&tree->root);
+	while (node) {
+		es = rb_entry(node, struct extent_status, rb_node);
+		node = rb_next(node);
+		if (!ext4_es_must_keep(es)) {
+			rb_erase(&es->rb_node, &tree->root);
+			ext4_es_free_extent(inode, es);
+		}
+	}
+	ext4_clear_inode_state(inode, EXT4_STATE_EXT_PRECACHED);
+	write_unlock(&ei->i_es_lock);
+}
+
+#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(pending_reservation, SLAB_RECLAIM_ACCOUNT);
+	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
+ * @prealloc - preallocated pending entry
+ *
+ * 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 pending_reservation **prealloc)
+{
+	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;
+		}
+	}
+
+	if (likely(*prealloc == NULL)) {
+		pr = __alloc_pending(false);
+		if (!pr) {
+			ret = -ENOMEM;
+			goto out;
+		}
+	} else {
+		pr = *prealloc;
+		*prealloc = NULL;
+	}
+	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);
+		__free_pending(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;
+}
+
+/*
+ * ext4_es_insert_delayed_block - adds a delayed block to the extents status
+ *                                tree, adding a pending reservation where
+ *                                needed
+ *
+ * @inode - file containing the newly added block
+ * @lblk - logical block to be added
+ * @allocated - indicates whether a physical cluster has been allocated for
+ *              the logical cluster that contains the block
+ */
+void ext4_es_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk,
+				  bool allocated)
+{
+	struct extent_status newes;
+	int err1 = 0, err2 = 0, err3 = 0;
+	struct extent_status *es1 = NULL;
+	struct extent_status *es2 = NULL;
+	struct pending_reservation *pr = NULL;
+
+	if (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
+		return;
+
+	es_debug("add [%u/1) delayed to extent status tree of inode %lu\n",
+		 lblk, inode->i_ino);
+
+	newes.es_lblk = lblk;
+	newes.es_len = 1;
+	ext4_es_store_pblock_status(&newes, ~0, EXTENT_STATUS_DELAYED);
+	trace_ext4_es_insert_delayed_block(inode, &newes, allocated);
+
+	ext4_es_insert_extent_check(inode, &newes);
+
+retry:
+	if (err1 && !es1)
+		es1 = __es_alloc_extent(true);
+	if ((err1 || err2) && !es2)
+		es2 = __es_alloc_extent(true);
+	if ((err1 || err2 || err3) && allocated && !pr)
+		pr = __alloc_pending(true);
+	write_lock(&EXT4_I(inode)->i_es_lock);
+
+	err1 = __es_remove_extent(inode, lblk, lblk, NULL, es1);
+	if (err1 != 0)
+		goto error;
+	/* Free preallocated extent if it didn't get used. */
+	if (es1) {
+		if (!es1->es_len)
+			__es_free_extent(es1);
+		es1 = NULL;
+	}
+
+	err2 = __es_insert_extent(inode, &newes, es2);
+	if (err2 != 0)
+		goto error;
+	/* Free preallocated extent if it didn't get used. */
+	if (es2) {
+		if (!es2->es_len)
+			__es_free_extent(es2);
+		es2 = NULL;
+	}
+
+	if (allocated) {
+		err3 = __insert_pending(inode, lblk, &pr);
+		if (err3 != 0)
+			goto error;
+		if (pr) {
+			__free_pending(pr);
+			pr = NULL;
+		}
+	}
+error:
+	write_unlock(&EXT4_I(inode)->i_es_lock);
+	if (err1 || err2 || err3)
+		goto retry;
+
+	ext4_es_print_tree(inode);
+	ext4_print_pending_tree(inode);
+	return;
+}
+
+/*
+ * __es_delayed_clu - count number of clusters containing blocks that
+ *                    are delayed only
+ *
+ * @inode - file containing block range
+ * @start - logical block defining start of range
+ * @end - logical block defining end of range
+ *
+ * Returns the number of clusters containing only delayed (not delayed
+ * and unwritten) blocks in the range specified by @start and @end.  Any
+ * cluster or part of a cluster within the range and containing a delayed
+ * and not unwritten block within the range is counted as a whole cluster.
+ */
+static unsigned int __es_delayed_clu(struct inode *inode, ext4_lblk_t start,
+				     ext4_lblk_t end)
+{
+	struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
+	struct extent_status *es;
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	struct rb_node *node;
+	ext4_lblk_t first_lclu, last_lclu;
+	unsigned long long last_counted_lclu;
+	unsigned int n = 0;
+
+	/* guaranteed to be unequal to any ext4_lblk_t value */
+	last_counted_lclu = ~0ULL;
+
+	es = __es_tree_search(&tree->root, start);
+
+	while (es && (es->es_lblk <= end)) {
+		if (ext4_es_is_delonly(es)) {
+			if (es->es_lblk <= start)
+				first_lclu = EXT4_B2C(sbi, start);
+			else
+				first_lclu = EXT4_B2C(sbi, es->es_lblk);
+
+			if (ext4_es_end(es) >= end)
+				last_lclu = EXT4_B2C(sbi, end);
+			else
+				last_lclu = EXT4_B2C(sbi, ext4_es_end(es));
+
+			if (first_lclu == last_counted_lclu)
+				n += last_lclu - first_lclu;
+			else
+				n += last_lclu - first_lclu + 1;
+			last_counted_lclu = last_lclu;
+		}
+		node = rb_next(&es->rb_node);
+		if (!node)
+			break;
+		es = rb_entry(node, struct extent_status, rb_node);
+	}
+
+	return n;
+}
+
+/*
+ * ext4_es_delayed_clu - count number of clusters containing blocks that
+ *                       are both delayed and unwritten
+ *
+ * @inode - file containing block range
+ * @lblk - logical block defining start of range
+ * @len - number of blocks in range
+ *
+ * Locking for external use of __es_delayed_clu().
+ */
+unsigned int ext4_es_delayed_clu(struct inode *inode, ext4_lblk_t lblk,
+				 ext4_lblk_t len)
+{
+	struct ext4_inode_info *ei = EXT4_I(inode);
+	ext4_lblk_t end;
+	unsigned int n;
+
+	if (len == 0)
+		return 0;
+
+	end = lblk + len - 1;
+	WARN_ON(end < lblk);
+
+	read_lock(&ei->i_es_lock);
+
+	n = __es_delayed_clu(inode, lblk, end);
+
+	read_unlock(&ei->i_es_lock);
+
+	return n;
+}
+
+/*
+ * __revise_pending - makes, cancels, or leaves unchanged pending cluster
+ *                    reservations for a specified block range depending
+ *                    upon the presence or absence of delayed blocks
+ *                    outside the range within clusters at the ends of the
+ *                    range
+ *
+ * @inode - file containing the range
+ * @lblk - logical block defining the start of range
+ * @len  - length of range in blocks
+ * @prealloc - preallocated pending entry
+ *
+ * Used after a newly allocated extent is added to the extents status tree.
+ * Requires that the extents in the range have either written or unwritten
+ * status.  Must be called while holding i_es_lock.
+ */
+static int __revise_pending(struct inode *inode, ext4_lblk_t lblk,
+			    ext4_lblk_t len,
+			    struct pending_reservation **prealloc)
+{
+	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+	ext4_lblk_t end = lblk + len - 1;
+	ext4_lblk_t first, last;
+	bool f_del = false, l_del = false;
+	int ret = 0;
+
+	if (len == 0)
+		return 0;
+
+	/*
+	 * Two cases - block range within single cluster and block range
+	 * spanning two or more clusters.  Note that a cluster belonging
+	 * to a range starting and/or ending on a cluster boundary is treated
+	 * as if it does not contain a delayed extent.  The new range may
+	 * have allocated space for previously delayed blocks out to the
+	 * cluster boundary, requiring that any pre-existing pending
+	 * reservation be canceled.  Because this code only looks at blocks
+	 * outside the range, it should revise pending reservations
+	 * correctly even if the extent represented by the range can't be
+	 * inserted in the extents status tree due to ENOSPC.
+	 */
+
+	if (EXT4_B2C(sbi, lblk) == EXT4_B2C(sbi, end)) {
+		first = EXT4_LBLK_CMASK(sbi, lblk);
+		if (first != lblk)
+			f_del = __es_scan_range(inode, &ext4_es_is_delonly,
+						first, lblk - 1);
+		if (f_del) {
+			ret = __insert_pending(inode, first, prealloc);
+			if (ret < 0)
+				goto out;
+		} else {
+			last = EXT4_LBLK_CMASK(sbi, end) +
+			       sbi->s_cluster_ratio - 1;
+			if (last != end)
+				l_del = __es_scan_range(inode,
+							&ext4_es_is_delonly,
+							end + 1, last);
+			if (l_del) {
+				ret = __insert_pending(inode, last, prealloc);
+				if (ret < 0)
+					goto out;
+			} else
+				__remove_pending(inode, last);
+		}
+	} else {
+		first = EXT4_LBLK_CMASK(sbi, lblk);
+		if (first != lblk)
+			f_del = __es_scan_range(inode, &ext4_es_is_delonly,
+						first, lblk - 1);
+		if (f_del) {
+			ret = __insert_pending(inode, first, prealloc);
+			if (ret < 0)
+				goto out;
+		} else
+			__remove_pending(inode, first);
+
+		last = EXT4_LBLK_CMASK(sbi, end) + sbi->s_cluster_ratio - 1;
+		if (last != end)
+			l_del = __es_scan_range(inode, &ext4_es_is_delonly,
+						end + 1, last);
+		if (l_del) {
+			ret = __insert_pending(inode, last, prealloc);
+			if (ret < 0)
+				goto out;
+		} else
+			__remove_pending(inode, last);
+	}
+out:
+	return ret;
+}