Adding upstream version 6.1.76.upstream/6.1.76

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

1 files changed, 863 insertions, 0 deletions

diff --git a/fs/nilfs2/alloc.c b/fs/nilfs2/alloc.c
new file mode 100644
index 000000000..7342de296
--- /dev/null
+++ b/fs/nilfs2/alloc.c
@@ -0,0 +1,863 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * NILFS dat/inode allocator
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * Originally written by Koji Sato.
+ * Two allocators were unified by Ryusuke Konishi and Amagai Yoshiji.
+ */
+
+#include <linux/types.h>
+#include <linux/buffer_head.h>
+#include <linux/fs.h>
+#include <linux/bitops.h>
+#include <linux/slab.h>
+#include "mdt.h"
+#include "alloc.h"
+
+
+/**
+ * nilfs_palloc_groups_per_desc_block - get the number of groups that a group
+ *					descriptor block can maintain
+ * @inode: inode of metadata file using this allocator
+ */
+static inline unsigned long
+nilfs_palloc_groups_per_desc_block(const struct inode *inode)
+{
+	return i_blocksize(inode) /
+		sizeof(struct nilfs_palloc_group_desc);
+}
+
+/**
+ * nilfs_palloc_groups_count - get maximum number of groups
+ * @inode: inode of metadata file using this allocator
+ */
+static inline unsigned long
+nilfs_palloc_groups_count(const struct inode *inode)
+{
+	return 1UL << (BITS_PER_LONG - (inode->i_blkbits + 3 /* log2(8) */));
+}
+
+/**
+ * nilfs_palloc_init_blockgroup - initialize private variables for allocator
+ * @inode: inode of metadata file using this allocator
+ * @entry_size: size of the persistent object
+ */
+int nilfs_palloc_init_blockgroup(struct inode *inode, unsigned int entry_size)
+{
+	struct nilfs_mdt_info *mi = NILFS_MDT(inode);
+
+	mi->mi_bgl = kmalloc(sizeof(*mi->mi_bgl), GFP_NOFS);
+	if (!mi->mi_bgl)
+		return -ENOMEM;
+
+	bgl_lock_init(mi->mi_bgl);
+
+	nilfs_mdt_set_entry_size(inode, entry_size, 0);
+
+	mi->mi_blocks_per_group =
+		DIV_ROUND_UP(nilfs_palloc_entries_per_group(inode),
+			     mi->mi_entries_per_block) + 1;
+		/*
+		 * Number of blocks in a group including entry blocks
+		 * and a bitmap block
+		 */
+	mi->mi_blocks_per_desc_block =
+		nilfs_palloc_groups_per_desc_block(inode) *
+		mi->mi_blocks_per_group + 1;
+		/*
+		 * Number of blocks per descriptor including the
+		 * descriptor block
+		 */
+	return 0;
+}
+
+/**
+ * nilfs_palloc_group - get group number and offset from an entry number
+ * @inode: inode of metadata file using this allocator
+ * @nr: serial number of the entry (e.g. inode number)
+ * @offset: pointer to store offset number in the group
+ */
+static unsigned long nilfs_palloc_group(const struct inode *inode, __u64 nr,
+					unsigned long *offset)
+{
+	__u64 group = nr;
+
+	*offset = do_div(group, nilfs_palloc_entries_per_group(inode));
+	return group;
+}
+
+/**
+ * nilfs_palloc_desc_blkoff - get block offset of a group descriptor block
+ * @inode: inode of metadata file using this allocator
+ * @group: group number
+ *
+ * nilfs_palloc_desc_blkoff() returns block offset of the descriptor
+ * block which contains a descriptor of the specified group.
+ */
+static unsigned long
+nilfs_palloc_desc_blkoff(const struct inode *inode, unsigned long group)
+{
+	unsigned long desc_block =
+		group / nilfs_palloc_groups_per_desc_block(inode);
+	return desc_block * NILFS_MDT(inode)->mi_blocks_per_desc_block;
+}
+
+/**
+ * nilfs_palloc_bitmap_blkoff - get block offset of a bitmap block
+ * @inode: inode of metadata file using this allocator
+ * @group: group number
+ *
+ * nilfs_palloc_bitmap_blkoff() returns block offset of the bitmap
+ * block used to allocate/deallocate entries in the specified group.
+ */
+static unsigned long
+nilfs_palloc_bitmap_blkoff(const struct inode *inode, unsigned long group)
+{
+	unsigned long desc_offset =
+		group % nilfs_palloc_groups_per_desc_block(inode);
+	return nilfs_palloc_desc_blkoff(inode, group) + 1 +
+		desc_offset * NILFS_MDT(inode)->mi_blocks_per_group;
+}
+
+/**
+ * nilfs_palloc_group_desc_nfrees - get the number of free entries in a group
+ * @desc: pointer to descriptor structure for the group
+ * @lock: spin lock protecting @desc
+ */
+static unsigned long
+nilfs_palloc_group_desc_nfrees(const struct nilfs_palloc_group_desc *desc,
+			       spinlock_t *lock)
+{
+	unsigned long nfree;
+
+	spin_lock(lock);
+	nfree = le32_to_cpu(desc->pg_nfrees);
+	spin_unlock(lock);
+	return nfree;
+}
+
+/**
+ * nilfs_palloc_group_desc_add_entries - adjust count of free entries
+ * @desc: pointer to descriptor structure for the group
+ * @lock: spin lock protecting @desc
+ * @n: delta to be added
+ */
+static u32
+nilfs_palloc_group_desc_add_entries(struct nilfs_palloc_group_desc *desc,
+				    spinlock_t *lock, u32 n)
+{
+	u32 nfree;
+
+	spin_lock(lock);
+	le32_add_cpu(&desc->pg_nfrees, n);
+	nfree = le32_to_cpu(desc->pg_nfrees);
+	spin_unlock(lock);
+	return nfree;
+}
+
+/**
+ * nilfs_palloc_entry_blkoff - get block offset of an entry block
+ * @inode: inode of metadata file using this allocator
+ * @nr: serial number of the entry (e.g. inode number)
+ */
+static unsigned long
+nilfs_palloc_entry_blkoff(const struct inode *inode, __u64 nr)
+{
+	unsigned long group, group_offset;
+
+	group = nilfs_palloc_group(inode, nr, &group_offset);
+
+	return nilfs_palloc_bitmap_blkoff(inode, group) + 1 +
+		group_offset / NILFS_MDT(inode)->mi_entries_per_block;
+}
+
+/**
+ * nilfs_palloc_desc_block_init - initialize buffer of a group descriptor block
+ * @inode: inode of metadata file
+ * @bh: buffer head of the buffer to be initialized
+ * @kaddr: kernel address mapped for the page including the buffer
+ */
+static void nilfs_palloc_desc_block_init(struct inode *inode,
+					 struct buffer_head *bh, void *kaddr)
+{
+	struct nilfs_palloc_group_desc *desc = kaddr + bh_offset(bh);
+	unsigned long n = nilfs_palloc_groups_per_desc_block(inode);
+	__le32 nfrees;
+
+	nfrees = cpu_to_le32(nilfs_palloc_entries_per_group(inode));
+	while (n-- > 0) {
+		desc->pg_nfrees = nfrees;
+		desc++;
+	}
+}
+
+static int nilfs_palloc_get_block(struct inode *inode, unsigned long blkoff,
+				  int create,
+				  void (*init_block)(struct inode *,
+						     struct buffer_head *,
+						     void *),
+				  struct buffer_head **bhp,
+				  struct nilfs_bh_assoc *prev,
+				  spinlock_t *lock)
+{
+	int ret;
+
+	spin_lock(lock);
+	if (prev->bh && blkoff == prev->blkoff &&
+	    likely(buffer_uptodate(prev->bh))) {
+		get_bh(prev->bh);
+		*bhp = prev->bh;
+		spin_unlock(lock);
+		return 0;
+	}
+	spin_unlock(lock);
+
+	ret = nilfs_mdt_get_block(inode, blkoff, create, init_block, bhp);
+	if (!ret) {
+		spin_lock(lock);
+		/*
+		 * The following code must be safe for change of the
+		 * cache contents during the get block call.
+		 */
+		brelse(prev->bh);
+		get_bh(*bhp);
+		prev->bh = *bhp;
+		prev->blkoff = blkoff;
+		spin_unlock(lock);
+	}
+	return ret;
+}
+
+/**
+ * nilfs_palloc_delete_block - delete a block on the persistent allocator file
+ * @inode: inode of metadata file using this allocator
+ * @blkoff: block offset
+ * @prev: nilfs_bh_assoc struct of the last used buffer
+ * @lock: spin lock protecting @prev
+ */
+static int nilfs_palloc_delete_block(struct inode *inode, unsigned long blkoff,
+				     struct nilfs_bh_assoc *prev,
+				     spinlock_t *lock)
+{
+	spin_lock(lock);
+	if (prev->bh && blkoff == prev->blkoff) {
+		brelse(prev->bh);
+		prev->bh = NULL;
+	}
+	spin_unlock(lock);
+	return nilfs_mdt_delete_block(inode, blkoff);
+}
+
+/**
+ * nilfs_palloc_get_desc_block - get buffer head of a group descriptor block
+ * @inode: inode of metadata file using this allocator
+ * @group: group number
+ * @create: create flag
+ * @bhp: pointer to store the resultant buffer head
+ */
+static int nilfs_palloc_get_desc_block(struct inode *inode,
+				       unsigned long group,
+				       int create, struct buffer_head **bhp)
+{
+	struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;
+
+	return nilfs_palloc_get_block(inode,
+				      nilfs_palloc_desc_blkoff(inode, group),
+				      create, nilfs_palloc_desc_block_init,
+				      bhp, &cache->prev_desc, &cache->lock);
+}
+
+/**
+ * nilfs_palloc_get_bitmap_block - get buffer head of a bitmap block
+ * @inode: inode of metadata file using this allocator
+ * @group: group number
+ * @create: create flag
+ * @bhp: pointer to store the resultant buffer head
+ */
+static int nilfs_palloc_get_bitmap_block(struct inode *inode,
+					 unsigned long group,
+					 int create, struct buffer_head **bhp)
+{
+	struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;
+
+	return nilfs_palloc_get_block(inode,
+				      nilfs_palloc_bitmap_blkoff(inode, group),
+				      create, NULL, bhp,
+				      &cache->prev_bitmap, &cache->lock);
+}
+
+/**
+ * nilfs_palloc_delete_bitmap_block - delete a bitmap block
+ * @inode: inode of metadata file using this allocator
+ * @group: group number
+ */
+static int nilfs_palloc_delete_bitmap_block(struct inode *inode,
+					    unsigned long group)
+{
+	struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;
+
+	return nilfs_palloc_delete_block(inode,
+					 nilfs_palloc_bitmap_blkoff(inode,
+								    group),
+					 &cache->prev_bitmap, &cache->lock);
+}
+
+/**
+ * nilfs_palloc_get_entry_block - get buffer head of an entry block
+ * @inode: inode of metadata file using this allocator
+ * @nr: serial number of the entry (e.g. inode number)
+ * @create: create flag
+ * @bhp: pointer to store the resultant buffer head
+ */
+int nilfs_palloc_get_entry_block(struct inode *inode, __u64 nr,
+				 int create, struct buffer_head **bhp)
+{
+	struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;
+
+	return nilfs_palloc_get_block(inode,
+				      nilfs_palloc_entry_blkoff(inode, nr),
+				      create, NULL, bhp,
+				      &cache->prev_entry, &cache->lock);
+}
+
+/**
+ * nilfs_palloc_delete_entry_block - delete an entry block
+ * @inode: inode of metadata file using this allocator
+ * @nr: serial number of the entry
+ */
+static int nilfs_palloc_delete_entry_block(struct inode *inode, __u64 nr)
+{
+	struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;
+
+	return nilfs_palloc_delete_block(inode,
+					 nilfs_palloc_entry_blkoff(inode, nr),
+					 &cache->prev_entry, &cache->lock);
+}
+
+/**
+ * nilfs_palloc_block_get_group_desc - get kernel address of a group descriptor
+ * @inode: inode of metadata file using this allocator
+ * @group: group number
+ * @bh: buffer head of the buffer storing the group descriptor block
+ * @kaddr: kernel address mapped for the page including the buffer
+ */
+static struct nilfs_palloc_group_desc *
+nilfs_palloc_block_get_group_desc(const struct inode *inode,
+				  unsigned long group,
+				  const struct buffer_head *bh, void *kaddr)
+{
+	return (struct nilfs_palloc_group_desc *)(kaddr + bh_offset(bh)) +
+		group % nilfs_palloc_groups_per_desc_block(inode);
+}
+
+/**
+ * nilfs_palloc_block_get_entry - get kernel address of an entry
+ * @inode: inode of metadata file using this allocator
+ * @nr: serial number of the entry (e.g. inode number)
+ * @bh: buffer head of the buffer storing the entry block
+ * @kaddr: kernel address mapped for the page including the buffer
+ */
+void *nilfs_palloc_block_get_entry(const struct inode *inode, __u64 nr,
+				   const struct buffer_head *bh, void *kaddr)
+{
+	unsigned long entry_offset, group_offset;
+
+	nilfs_palloc_group(inode, nr, &group_offset);
+	entry_offset = group_offset % NILFS_MDT(inode)->mi_entries_per_block;
+
+	return kaddr + bh_offset(bh) +
+		entry_offset * NILFS_MDT(inode)->mi_entry_size;
+}
+
+/**
+ * nilfs_palloc_find_available_slot - find available slot in a group
+ * @bitmap: bitmap of the group
+ * @target: offset number of an entry in the group (start point)
+ * @bsize: size in bits
+ * @lock: spin lock protecting @bitmap
+ */
+static int nilfs_palloc_find_available_slot(unsigned char *bitmap,
+					    unsigned long target,
+					    unsigned int bsize,
+					    spinlock_t *lock)
+{
+	int pos, end = bsize;
+
+	if (likely(target < bsize)) {
+		pos = target;
+		do {
+			pos = nilfs_find_next_zero_bit(bitmap, end, pos);
+			if (pos >= end)
+				break;
+			if (!nilfs_set_bit_atomic(lock, pos, bitmap))
+				return pos;
+		} while (++pos < end);
+
+		end = target;
+	}
+
+	/* wrap around */
+	for (pos = 0; pos < end; pos++) {
+		pos = nilfs_find_next_zero_bit(bitmap, end, pos);
+		if (pos >= end)
+			break;
+		if (!nilfs_set_bit_atomic(lock, pos, bitmap))
+			return pos;
+	}
+
+	return -ENOSPC;
+}
+
+/**
+ * nilfs_palloc_rest_groups_in_desc_block - get the remaining number of groups
+ *					    in a group descriptor block
+ * @inode: inode of metadata file using this allocator
+ * @curr: current group number
+ * @max: maximum number of groups
+ */
+static unsigned long
+nilfs_palloc_rest_groups_in_desc_block(const struct inode *inode,
+				       unsigned long curr, unsigned long max)
+{
+	return min_t(unsigned long,
+		     nilfs_palloc_groups_per_desc_block(inode) -
+		     curr % nilfs_palloc_groups_per_desc_block(inode),
+		     max - curr + 1);
+}
+
+/**
+ * nilfs_palloc_count_desc_blocks - count descriptor blocks number
+ * @inode: inode of metadata file using this allocator
+ * @desc_blocks: descriptor blocks number [out]
+ */
+static int nilfs_palloc_count_desc_blocks(struct inode *inode,
+					    unsigned long *desc_blocks)
+{
+	__u64 blknum;
+	int ret;
+
+	ret = nilfs_bmap_last_key(NILFS_I(inode)->i_bmap, &blknum);
+	if (likely(!ret))
+		*desc_blocks = DIV_ROUND_UP(
+			(unsigned long)blknum,
+			NILFS_MDT(inode)->mi_blocks_per_desc_block);
+	return ret;
+}
+
+/**
+ * nilfs_palloc_mdt_file_can_grow - check potential opportunity for
+ *					MDT file growing
+ * @inode: inode of metadata file using this allocator
+ * @desc_blocks: known current descriptor blocks count
+ */
+static inline bool nilfs_palloc_mdt_file_can_grow(struct inode *inode,
+						    unsigned long desc_blocks)
+{
+	return (nilfs_palloc_groups_per_desc_block(inode) * desc_blocks) <
+			nilfs_palloc_groups_count(inode);
+}
+
+/**
+ * nilfs_palloc_count_max_entries - count max number of entries that can be
+ *					described by descriptor blocks count
+ * @inode: inode of metadata file using this allocator
+ * @nused: current number of used entries
+ * @nmaxp: max number of entries [out]
+ */
+int nilfs_palloc_count_max_entries(struct inode *inode, u64 nused, u64 *nmaxp)
+{
+	unsigned long desc_blocks = 0;
+	u64 entries_per_desc_block, nmax;
+	int err;
+
+	err = nilfs_palloc_count_desc_blocks(inode, &desc_blocks);
+	if (unlikely(err))
+		return err;
+
+	entries_per_desc_block = (u64)nilfs_palloc_entries_per_group(inode) *
+				nilfs_palloc_groups_per_desc_block(inode);
+	nmax = entries_per_desc_block * desc_blocks;
+
+	if (nused == nmax &&
+			nilfs_palloc_mdt_file_can_grow(inode, desc_blocks))
+		nmax += entries_per_desc_block;
+
+	if (nused > nmax)
+		return -ERANGE;
+
+	*nmaxp = nmax;
+	return 0;
+}
+
+/**
+ * nilfs_palloc_prepare_alloc_entry - prepare to allocate a persistent object
+ * @inode: inode of metadata file using this allocator
+ * @req: nilfs_palloc_req structure exchanged for the allocation
+ */
+int nilfs_palloc_prepare_alloc_entry(struct inode *inode,
+				     struct nilfs_palloc_req *req)
+{
+	struct buffer_head *desc_bh, *bitmap_bh;
+	struct nilfs_palloc_group_desc *desc;
+	unsigned char *bitmap;
+	void *desc_kaddr, *bitmap_kaddr;
+	unsigned long group, maxgroup, ngroups;
+	unsigned long group_offset, maxgroup_offset;
+	unsigned long n, entries_per_group;
+	unsigned long i, j;
+	spinlock_t *lock;
+	int pos, ret;
+
+	ngroups = nilfs_palloc_groups_count(inode);
+	maxgroup = ngroups - 1;
+	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
+	entries_per_group = nilfs_palloc_entries_per_group(inode);
+
+	for (i = 0; i < ngroups; i += n) {
+		if (group >= ngroups) {
+			/* wrap around */
+			group = 0;
+			maxgroup = nilfs_palloc_group(inode, req->pr_entry_nr,
+						      &maxgroup_offset) - 1;
+		}
+		ret = nilfs_palloc_get_desc_block(inode, group, 1, &desc_bh);
+		if (ret < 0)
+			return ret;
+		desc_kaddr = kmap(desc_bh->b_page);
+		desc = nilfs_palloc_block_get_group_desc(
+			inode, group, desc_bh, desc_kaddr);
+		n = nilfs_palloc_rest_groups_in_desc_block(inode, group,
+							   maxgroup);
+		for (j = 0; j < n; j++, desc++, group++) {
+			lock = nilfs_mdt_bgl_lock(inode, group);
+			if (nilfs_palloc_group_desc_nfrees(desc, lock) > 0) {
+				ret = nilfs_palloc_get_bitmap_block(
+					inode, group, 1, &bitmap_bh);
+				if (ret < 0)
+					goto out_desc;
+				bitmap_kaddr = kmap(bitmap_bh->b_page);
+				bitmap = bitmap_kaddr + bh_offset(bitmap_bh);
+				pos = nilfs_palloc_find_available_slot(
+					bitmap, group_offset,
+					entries_per_group, lock);
+				if (pos >= 0) {
+					/* found a free entry */
+					nilfs_palloc_group_desc_add_entries(
+						desc, lock, -1);
+					req->pr_entry_nr =
+						entries_per_group * group + pos;
+					kunmap(desc_bh->b_page);
+					kunmap(bitmap_bh->b_page);
+
+					req->pr_desc_bh = desc_bh;
+					req->pr_bitmap_bh = bitmap_bh;
+					return 0;
+				}
+				kunmap(bitmap_bh->b_page);
+				brelse(bitmap_bh);
+			}
+
+			group_offset = 0;
+		}
+
+		kunmap(desc_bh->b_page);
+		brelse(desc_bh);
+	}
+
+	/* no entries left */
+	return -ENOSPC;
+
+ out_desc:
+	kunmap(desc_bh->b_page);
+	brelse(desc_bh);
+	return ret;
+}
+
+/**
+ * nilfs_palloc_commit_alloc_entry - finish allocation of a persistent object
+ * @inode: inode of metadata file using this allocator
+ * @req: nilfs_palloc_req structure exchanged for the allocation
+ */
+void nilfs_palloc_commit_alloc_entry(struct inode *inode,
+				     struct nilfs_palloc_req *req)
+{
+	mark_buffer_dirty(req->pr_bitmap_bh);
+	mark_buffer_dirty(req->pr_desc_bh);
+	nilfs_mdt_mark_dirty(inode);
+
+	brelse(req->pr_bitmap_bh);
+	brelse(req->pr_desc_bh);
+}
+
+/**
+ * nilfs_palloc_commit_free_entry - finish deallocating a persistent object
+ * @inode: inode of metadata file using this allocator
+ * @req: nilfs_palloc_req structure exchanged for the removal
+ */
+void nilfs_palloc_commit_free_entry(struct inode *inode,
+				    struct nilfs_palloc_req *req)
+{
+	struct nilfs_palloc_group_desc *desc;
+	unsigned long group, group_offset;
+	unsigned char *bitmap;
+	void *desc_kaddr, *bitmap_kaddr;
+	spinlock_t *lock;
+
+	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
+	desc_kaddr = kmap(req->pr_desc_bh->b_page);
+	desc = nilfs_palloc_block_get_group_desc(inode, group,
+						 req->pr_desc_bh, desc_kaddr);
+	bitmap_kaddr = kmap(req->pr_bitmap_bh->b_page);
+	bitmap = bitmap_kaddr + bh_offset(req->pr_bitmap_bh);
+	lock = nilfs_mdt_bgl_lock(inode, group);
+
+	if (!nilfs_clear_bit_atomic(lock, group_offset, bitmap))
+		nilfs_warn(inode->i_sb,
+			   "%s (ino=%lu): entry number %llu already freed",
+			   __func__, inode->i_ino,
+			   (unsigned long long)req->pr_entry_nr);
+	else
+		nilfs_palloc_group_desc_add_entries(desc, lock, 1);
+
+	kunmap(req->pr_bitmap_bh->b_page);
+	kunmap(req->pr_desc_bh->b_page);
+
+	mark_buffer_dirty(req->pr_desc_bh);
+	mark_buffer_dirty(req->pr_bitmap_bh);
+	nilfs_mdt_mark_dirty(inode);
+
+	brelse(req->pr_bitmap_bh);
+	brelse(req->pr_desc_bh);
+}
+
+/**
+ * nilfs_palloc_abort_alloc_entry - cancel allocation of a persistent object
+ * @inode: inode of metadata file using this allocator
+ * @req: nilfs_palloc_req structure exchanged for the allocation
+ */
+void nilfs_palloc_abort_alloc_entry(struct inode *inode,
+				    struct nilfs_palloc_req *req)
+{
+	struct nilfs_palloc_group_desc *desc;
+	void *desc_kaddr, *bitmap_kaddr;
+	unsigned char *bitmap;
+	unsigned long group, group_offset;
+	spinlock_t *lock;
+
+	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
+	desc_kaddr = kmap(req->pr_desc_bh->b_page);
+	desc = nilfs_palloc_block_get_group_desc(inode, group,
+						 req->pr_desc_bh, desc_kaddr);
+	bitmap_kaddr = kmap(req->pr_bitmap_bh->b_page);
+	bitmap = bitmap_kaddr + bh_offset(req->pr_bitmap_bh);
+	lock = nilfs_mdt_bgl_lock(inode, group);
+
+	if (!nilfs_clear_bit_atomic(lock, group_offset, bitmap))
+		nilfs_warn(inode->i_sb,
+			   "%s (ino=%lu): entry number %llu already freed",
+			   __func__, inode->i_ino,
+			   (unsigned long long)req->pr_entry_nr);
+	else
+		nilfs_palloc_group_desc_add_entries(desc, lock, 1);
+
+	kunmap(req->pr_bitmap_bh->b_page);
+	kunmap(req->pr_desc_bh->b_page);
+
+	brelse(req->pr_bitmap_bh);
+	brelse(req->pr_desc_bh);
+
+	req->pr_entry_nr = 0;
+	req->pr_bitmap_bh = NULL;
+	req->pr_desc_bh = NULL;
+}
+
+/**
+ * nilfs_palloc_prepare_free_entry - prepare to deallocate a persistent object
+ * @inode: inode of metadata file using this allocator
+ * @req: nilfs_palloc_req structure exchanged for the removal
+ */
+int nilfs_palloc_prepare_free_entry(struct inode *inode,
+				    struct nilfs_palloc_req *req)
+{
+	struct buffer_head *desc_bh, *bitmap_bh;
+	unsigned long group, group_offset;
+	int ret;
+
+	group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
+	ret = nilfs_palloc_get_desc_block(inode, group, 1, &desc_bh);
+	if (ret < 0)
+		return ret;
+	ret = nilfs_palloc_get_bitmap_block(inode, group, 1, &bitmap_bh);
+	if (ret < 0) {
+		brelse(desc_bh);
+		return ret;
+	}
+
+	req->pr_desc_bh = desc_bh;
+	req->pr_bitmap_bh = bitmap_bh;
+	return 0;
+}
+
+/**
+ * nilfs_palloc_abort_free_entry - cancel deallocating a persistent object
+ * @inode: inode of metadata file using this allocator
+ * @req: nilfs_palloc_req structure exchanged for the removal
+ */
+void nilfs_palloc_abort_free_entry(struct inode *inode,
+				   struct nilfs_palloc_req *req)
+{
+	brelse(req->pr_bitmap_bh);
+	brelse(req->pr_desc_bh);
+
+	req->pr_entry_nr = 0;
+	req->pr_bitmap_bh = NULL;
+	req->pr_desc_bh = NULL;
+}
+
+/**
+ * nilfs_palloc_freev - deallocate a set of persistent objects
+ * @inode: inode of metadata file using this allocator
+ * @entry_nrs: array of entry numbers to be deallocated
+ * @nitems: number of entries stored in @entry_nrs
+ */
+int nilfs_palloc_freev(struct inode *inode, __u64 *entry_nrs, size_t nitems)
+{
+	struct buffer_head *desc_bh, *bitmap_bh;
+	struct nilfs_palloc_group_desc *desc;
+	unsigned char *bitmap;
+	void *desc_kaddr, *bitmap_kaddr;
+	unsigned long group, group_offset;
+	__u64 group_min_nr, last_nrs[8];
+	const unsigned long epg = nilfs_palloc_entries_per_group(inode);
+	const unsigned int epb = NILFS_MDT(inode)->mi_entries_per_block;
+	unsigned int entry_start, end, pos;
+	spinlock_t *lock;
+	int i, j, k, ret;
+	u32 nfree;
+
+	for (i = 0; i < nitems; i = j) {
+		int change_group = false;
+		int nempties = 0, n = 0;
+
+		group = nilfs_palloc_group(inode, entry_nrs[i], &group_offset);
+		ret = nilfs_palloc_get_desc_block(inode, group, 0, &desc_bh);
+		if (ret < 0)
+			return ret;
+		ret = nilfs_palloc_get_bitmap_block(inode, group, 0,
+						    &bitmap_bh);
+		if (ret < 0) {
+			brelse(desc_bh);
+			return ret;
+		}
+
+		/* Get the first entry number of the group */
+		group_min_nr = (__u64)group * epg;
+
+		bitmap_kaddr = kmap(bitmap_bh->b_page);
+		bitmap = bitmap_kaddr + bh_offset(bitmap_bh);
+		lock = nilfs_mdt_bgl_lock(inode, group);
+
+		j = i;
+		entry_start = rounddown(group_offset, epb);
+		do {
+			if (!nilfs_clear_bit_atomic(lock, group_offset,
+						    bitmap)) {
+				nilfs_warn(inode->i_sb,
+					   "%s (ino=%lu): entry number %llu already freed",
+					   __func__, inode->i_ino,
+					   (unsigned long long)entry_nrs[j]);
+			} else {
+				n++;
+			}
+
+			j++;
+			if (j >= nitems || entry_nrs[j] < group_min_nr ||
+			    entry_nrs[j] >= group_min_nr + epg) {
+				change_group = true;
+			} else {
+				group_offset = entry_nrs[j] - group_min_nr;
+				if (group_offset >= entry_start &&
+				    group_offset < entry_start + epb) {
+					/* This entry is in the same block */
+					continue;
+				}
+			}
+
+			/* Test if the entry block is empty or not */
+			end = entry_start + epb;
+			pos = nilfs_find_next_bit(bitmap, end, entry_start);
+			if (pos >= end) {
+				last_nrs[nempties++] = entry_nrs[j - 1];
+				if (nempties >= ARRAY_SIZE(last_nrs))
+					break;
+			}
+
+			if (change_group)
+				break;
+
+			/* Go on to the next entry block */
+			entry_start = rounddown(group_offset, epb);
+		} while (true);
+
+		kunmap(bitmap_bh->b_page);
+		mark_buffer_dirty(bitmap_bh);
+		brelse(bitmap_bh);
+
+		for (k = 0; k < nempties; k++) {
+			ret = nilfs_palloc_delete_entry_block(inode,
+							      last_nrs[k]);
+			if (ret && ret != -ENOENT)
+				nilfs_warn(inode->i_sb,
+					   "error %d deleting block that object (entry=%llu, ino=%lu) belongs to",
+					   ret, (unsigned long long)last_nrs[k],
+					   inode->i_ino);
+		}
+
+		desc_kaddr = kmap_atomic(desc_bh->b_page);
+		desc = nilfs_palloc_block_get_group_desc(
+			inode, group, desc_bh, desc_kaddr);
+		nfree = nilfs_palloc_group_desc_add_entries(desc, lock, n);
+		kunmap_atomic(desc_kaddr);
+		mark_buffer_dirty(desc_bh);
+		nilfs_mdt_mark_dirty(inode);
+		brelse(desc_bh);
+
+		if (nfree == nilfs_palloc_entries_per_group(inode)) {
+			ret = nilfs_palloc_delete_bitmap_block(inode, group);
+			if (ret && ret != -ENOENT)
+				nilfs_warn(inode->i_sb,
+					   "error %d deleting bitmap block of group=%lu, ino=%lu",
+					   ret, group, inode->i_ino);
+		}
+	}
+	return 0;
+}
+
+void nilfs_palloc_setup_cache(struct inode *inode,
+			      struct nilfs_palloc_cache *cache)
+{
+	NILFS_MDT(inode)->mi_palloc_cache = cache;
+	spin_lock_init(&cache->lock);
+}
+
+void nilfs_palloc_clear_cache(struct inode *inode)
+{
+	struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;
+
+	spin_lock(&cache->lock);
+	brelse(cache->prev_desc.bh);
+	brelse(cache->prev_bitmap.bh);
+	brelse(cache->prev_entry.bh);
+	cache->prev_desc.bh = NULL;
+	cache->prev_bitmap.bh = NULL;
+	cache->prev_entry.bh = NULL;
+	spin_unlock(&cache->lock);
+}
+
+void nilfs_palloc_destroy_cache(struct inode *inode)
+{
+	nilfs_palloc_clear_cache(inode);
+	NILFS_MDT(inode)->mi_palloc_cache = NULL;
+}