text: /*
   *  linux/fs/ext4/ialloc.c
   *
   * Copyright (C) 1992, 1993, 1994, 1995
   * Remy Card (card@masi.ibp.fr)
   * Laboratoire MASI - Institut Blaise Pascal
   * Universite Pierre et Marie Curie (Paris VI)
   *
   *  BSD ufs-inspired inode and directory allocation by
   *  Stephen Tweedie (sct@redhat.com), 1993
   *  Big-endian to little-endian byte-swapping/bitmaps by
   *        David S. Miller (davem@caip.rutgers.edu), 1995
   */
  
  #include <linux/time.h>
  #include <linux/fs.h>
  #include <linux/jbd2.h>
  #include <linux/stat.h>
  #include <linux/string.h>
  #include <linux/quotaops.h>
  #include <linux/buffer_head.h>
  #include <linux/random.h>
  #include <linux/bitops.h>
  #include <linux/blkdev.h>
  #include <asm/byteorder.h>
  #include <linux/ratelimit.h>
  
  #include "ext4.h"
  #include "ext4_jbd2.h"
  #include "xattr.h"
  #include "acl.h"
  
  #include <trace/events/ext4.h>
  
  /*
   * ialloc.c contains the inodes allocation and deallocation routines
   */
  
  /*
   * The free inodes are managed by bitmaps.  A file system contains several
   * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
   * block for inodes, N blocks for the inode table and data blocks.
   *
   * The file system contains group descriptors which are located after the
   * super block.  Each descriptor contains the number of the bitmap block and
   * the free blocks count in the block.
   */
  
  /*
   * To avoid calling the atomic setbit hundreds or thousands of times, we only
   * need to use it within a single byte (to ensure we get endianness right).
   * We can use memset for the rest of the bitmap as there are no other users.
   */
  void ext4_mark_bitmap_end(int start_bit, int end_bit, char *bitmap)
  {
  	int i;
  
  	if (start_bit >= end_bit)
  		return;
  
  	ext4_debug("mark end bits +%d through +%d used\n", start_bit, end_bit);
  	for (i = start_bit; i < ((start_bit + 7) & ~7UL); i++)
  		ext4_set_bit(i, bitmap);
  	if (i < end_bit)
  		memset(bitmap + (i >> 3), 0xff, (end_bit - i) >> 3);
  }
  
  void ext4_end_bitmap_read(struct buffer_head *bh, int uptodate)
  {
  	if (uptodate) {
  		set_buffer_uptodate(bh);
  		set_bitmap_uptodate(bh);
  	}
  	unlock_buffer(bh);
  	put_bh(bh);
  }
  
  /*
   * Read the inode allocation bitmap for a given block_group, reading
   * into the specified slot in the superblock's bitmap cache.
   *
   * Return buffer_head of bitmap on success or NULL.
   */
  static struct buffer_head *
  ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
  {
  	struct ext4_group_desc *desc;
  	struct ext4_sb_info *sbi = EXT4_SB(sb);
  	struct buffer_head *bh = NULL;
  	ext4_fsblk_t bitmap_blk;
  	struct ext4_group_info *grp;
  
  	desc = ext4_get_group_desc(sb, block_group, NULL);
  	if (!desc)
  		return NULL;
  
  	bitmap_blk = ext4_inode_bitmap(sb, desc);
  	if ((bitmap_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
  	    (bitmap_blk >= ext4_blocks_count(sbi->s_es))) {
  		ext4_error(sb, "Invalid inode bitmap blk %llu in "
  			   "block_group %u", bitmap_blk, block_group);
  		return ERR_PTR(-EUCLEAN);
  	}
  	bh = sb_getblk(sb, bitmap_blk);
  	if (unlikely(!bh)) {
  		ext4_error(sb, "Cannot read inode bitmap - "
  			    "block_group = %u, inode_bitmap = %llu",
  			    block_group, bitmap_blk);
  		return NULL;
  	}
  	if (bitmap_uptodate(bh))
  		goto verify;
  
  	lock_buffer(bh);
  	if (bitmap_uptodate(bh)) {
  		unlock_buffer(bh);
  		goto verify;
  	}
  
  	ext4_lock_group(sb, block_group);
  	if (ext4_has_group_desc_csum(sb) &&
  	    (desc->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT))) {
  		if (block_group == 0) {
  			ext4_unlock_group(sb, block_group);
  			unlock_buffer(bh);
  			ext4_error(sb, "Inode bitmap for bg 0 marked "
  				   "uninitialized");
  			put_bh(bh);
  			return NULL;
  		}
  		memset(bh->b_data, 0, (EXT4_INODES_PER_GROUP(sb) + 7) / 8);
  		ext4_mark_bitmap_end(EXT4_INODES_PER_GROUP(sb),
  				     sb->s_blocksize * 8, bh->b_data);
  		set_bitmap_uptodate(bh);
  		set_buffer_uptodate(bh);
  		set_buffer_verified(bh);
  		ext4_unlock_group(sb, block_group);
  		unlock_buffer(bh);
  		return bh;
  	}
  	ext4_unlock_group(sb, block_group);
  
  	if (buffer_uptodate(bh)) {
  		/*
  		 * if not uninit if bh is uptodate,
  		 * bitmap is also uptodate
  		 */
  		set_bitmap_uptodate(bh);
  		unlock_buffer(bh);
  		goto verify;
  	}
  	/*
  	 * submit the buffer_head for reading
  	 */
  	trace_ext4_load_inode_bitmap(sb, block_group);
  	bh->b_end_io = ext4_end_bitmap_read;
  	get_bh(bh);
  	submit_bh(READ | REQ_META | REQ_PRIO, bh);
  	wait_on_buffer(bh);
  	if (!buffer_uptodate(bh)) {
  		put_bh(bh);
  		ext4_error(sb, "Cannot read inode bitmap - "
  			   "block_group = %u, inode_bitmap = %llu",
  			   block_group, bitmap_blk);
  		return NULL;
  	}
  
  verify:
  	ext4_lock_group(sb, block_group);
  	if (!buffer_verified(bh) &&
  	    !ext4_inode_bitmap_csum_verify(sb, block_group, desc, bh,
  					   EXT4_INODES_PER_GROUP(sb) / 8)) {
  		ext4_unlock_group(sb, block_group);
  		put_bh(bh);
  		ext4_error(sb, "Corrupt inode bitmap - block_group = %u, "
  			   "inode_bitmap = %llu", block_group, bitmap_blk);
  		grp = ext4_get_group_info(sb, block_group);
  		if (!EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) {
  			int count;
  			count = ext4_free_inodes_count(sb, desc);
  			percpu_counter_sub(&sbi->s_freeinodes_counter,
  					   count);
  		}
  		set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
  		return NULL;
  	}
  	ext4_unlock_group(sb, block_group);
  	set_buffer_verified(bh);
  	return bh;
  }
  
  /*
   * NOTE! When we get the inode, we're the only people
   * that have access to it, and as such there are no
   * race conditions we have to worry about. The inode
   * is not on the hash-lists, and it cannot be reached
   * through the filesystem because the directory entry
   * has been deleted earlier.
   *
   * HOWEVER: we must make sure that we get no aliases,
   * which means that we have to call "clear_inode()"
   * _before_ we mark the inode not in use in the inode
   * bitmaps. Otherwise a newly created file might use
   * the same inode number (not actually the same pointer
   * though), and then we'd have two inodes sharing the
   * same inode number and space on the harddisk.
   */
  void ext4_free_inode(handle_t *handle, struct inode *inode)
  {
  	struct super_block *sb = inode->i_sb;
  	int is_directory;
  	unsigned long ino;
  	struct buffer_head *bitmap_bh = NULL;
  	struct buffer_head *bh2;
  	ext4_group_t block_group;
  	unsigned long bit;
  	struct ext4_group_desc *gdp;
  	struct ext4_super_block *es;
  	struct ext4_sb_info *sbi;
  	int fatal = 0, err, count, cleared;
  	struct ext4_group_info *grp;
  
  	if (!sb) {
  		printk(KERN_ERR "EXT4-fs: %s:%d: inode on "
  		       "nonexistent device\n", __func__, __LINE__);
  		return;
  	}
  	if (atomic_read(&inode->i_count) > 1) {
  		ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: count=%d",
  			 __func__, __LINE__, inode->i_ino,
  			 atomic_read(&inode->i_count));
  		return;
  	}
  	if (inode->i_nlink) {
  		ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: nlink=%d\n",
  			 __func__, __LINE__, inode->i_ino, inode->i_nlink);
  		return;
  	}
  	sbi = EXT4_SB(sb);
  
  	ino = inode->i_ino;
  	ext4_debug("freeing inode %lu\n", ino);
  	trace_ext4_free_inode(inode);
  
  	/*
  	 * Note: we must free any quota before locking the superblock,
  	 * as writing the quota to disk may need the lock as well.
  	 */
  	dquot_initialize(inode);
  	ext4_xattr_delete_inode(handle, inode);
  	dquot_free_inode(inode);
  	dquot_drop(inode);
  
  	is_directory = S_ISDIR(inode->i_mode);
  
  	/* Do this BEFORE marking the inode not in use or returning an error */
  	ext4_clear_inode(inode);
  
  	es = EXT4_SB(sb)->s_es;
  	if (ino < EXT4_FIRST_INO(sb) || ino > le32_to_cpu(es->s_inodes_count)) {
  		ext4_error(sb, "reserved or nonexistent inode %lu", ino);
  		goto error_return;
  	}
  	block_group = (ino - 1) / EXT4_INODES_PER_GROUP(sb);
  	bit = (ino - 1) % EXT4_INODES_PER_GROUP(sb);
  	bitmap_bh = ext4_read_inode_bitmap(sb, block_group);
  	/* Don't bother if the inode bitmap is corrupt. */
  	grp = ext4_get_group_info(sb, block_group);
  	if (unlikely(EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) || !bitmap_bh)
  		goto error_return;
  
  	BUFFER_TRACE(bitmap_bh, "get_write_access");
  	fatal = ext4_journal_get_write_access(handle, bitmap_bh);
  	if (fatal)
  		goto error_return;
  
  	fatal = -ESRCH;
  	gdp = ext4_get_group_desc(sb, block_group, &bh2);
  	if (gdp) {
  		BUFFER_TRACE(bh2, "get_write_access");
  		fatal = ext4_journal_get_write_access(handle, bh2);
  	}
  	ext4_lock_group(sb, block_group);
  	cleared = ext4_test_and_clear_bit(bit, bitmap_bh->b_data);
  	if (fatal || !cleared) {
  		ext4_unlock_group(sb, block_group);
  		goto out;
  	}
  
  	count = ext4_free_inodes_count(sb, gdp) + 1;
  	ext4_free_inodes_set(sb, gdp, count);
  	if (is_directory) {
  		count = ext4_used_dirs_count(sb, gdp) - 1;
  		ext4_used_dirs_set(sb, gdp, count);
  		percpu_counter_dec(&sbi->s_dirs_counter);
  	}
  	ext4_inode_bitmap_csum_set(sb, block_group, gdp, bitmap_bh,
  				   EXT4_INODES_PER_GROUP(sb) / 8);
  	ext4_group_desc_csum_set(sb, block_group, gdp);
  	ext4_unlock_group(sb, block_group);
  
  	percpu_counter_inc(&sbi->s_freeinodes_counter);
  	if (sbi->s_log_groups_per_flex) {
  		ext4_group_t f = ext4_flex_group(sbi, block_group);
  
  		atomic_inc(&sbi->s_flex_groups[f].free_inodes);
  		if (is_directory)
  			atomic_dec(&sbi->s_flex_groups[f].used_dirs);
  	}
  	BUFFER_TRACE(bh2, "call ext4_handle_dirty_metadata");
  	fatal = ext4_handle_dirty_metadata(handle, NULL, bh2);
  out:
  	if (cleared) {
  		BUFFER_TRACE(bitmap_bh, "call ext4_handle_dirty_metadata");
  		err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
  		if (!fatal)
  			fatal = err;
  	} else {
  		/* for debugging, sangwoo2.lee */
  		print_bh(sb, bitmap_bh, 0, EXT4_BLOCK_SIZE(sb));
  		/* for debugging */
  		ext4_error(sb, "bit already cleared for inode %lu", ino);
  		if (gdp && !EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) {
  			int count;
  			count = ext4_free_inodes_count(sb, gdp);
  			percpu_counter_sub(&sbi->s_freeinodes_counter,
  					   count);
  		}
  		set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
  	}
  
  error_return:
  	brelse(bitmap_bh);
  	ext4_std_error(sb, fatal);
  }
  
  struct orlov_stats {
  	__u64 free_clusters;
  	__u32 free_inodes;
  	__u32 used_dirs;
  };
  
  /*
   * Helper function for Orlov's allocator; returns critical information
   * for a particular block group or flex_bg.  If flex_size is 1, then g
   * is a block group number; otherwise it is flex_bg number.
   */
  static void get_orlov_stats(struct super_block *sb, ext4_group_t g,
  			    int flex_size, struct orlov_stats *stats)
  {
  	struct ext4_group_desc *desc;
  	struct flex_groups *flex_group = EXT4_SB(sb)->s_flex_groups;
  
  	if (flex_size > 1) {
  		stats->free_inodes = atomic_read(&flex_group[g].free_inodes);
  		stats->free_clusters = atomic64_read(&flex_group[g].free_clusters);
  		stats->used_dirs = atomic_read(&flex_group[g].used_dirs);
  		return;
  	}
  
  	desc = ext4_get_group_desc(sb, g, NULL);
  	if (desc) {
  		stats->free_inodes = ext4_free_inodes_count(sb, desc);
  		stats->free_clusters = ext4_free_group_clusters(sb, desc);
  		stats->used_dirs = ext4_used_dirs_count(sb, desc);
  	} else {
  		stats->free_inodes = 0;
  		stats->free_clusters = 0;
  		stats->used_dirs = 0;
  	}
  }
  
  /*
   * Orlov's allocator for directories.
   *
   * We always try to spread first-level directories.
   *
   * If there are blockgroups with both free inodes and free blocks counts
   * not worse than average we return one with smallest directory count.
   * Otherwise we simply return a random group.
   *
   * For the rest rules look so:
   *
   * It's OK to put directory into a group unless
   * it has too many directories already (max_dirs) or
   * it has too few free inodes left (min_inodes) or
   * it has too few free blocks left (min_blocks) or
   * Parent's group is preferred, if it doesn't satisfy these
   * conditions we search cyclically through the rest. If none
   * of the groups look good we just look for a group with more
   * free inodes than average (starting at parent's group).
   */
  
  static int find_group_orlov(struct super_block *sb, struct inode *parent,
  			    ext4_group_t *group, umode_t mode,
  			    const struct qstr *qstr)
  {
  	ext4_group_t parent_group = EXT4_I(parent)->i_block_group;
  	struct ext4_sb_info *sbi = EXT4_SB(sb);
  	ext4_group_t real_ngroups = ext4_get_groups_count(sb);
  	int inodes_per_group = EXT4_INODES_PER_GROUP(sb);
  	unsigned int freei, avefreei, grp_free;
  	ext4_fsblk_t freeb, avefreec;
  	unsigned int ndirs;
  	int max_dirs, min_inodes;
  	ext4_grpblk_t min_clusters;
  	ext4_group_t i, grp, g, ngroups;
  	struct ext4_group_desc *desc;
  	struct orlov_stats stats;
  	int flex_size = ext4_flex_bg_size(sbi);
  	struct dx_hash_info hinfo;
  
  	ngroups = real_ngroups;
  	if (flex_size > 1) {
  		ngroups = (real_ngroups + flex_size - 1) >>
  			sbi->s_log_groups_per_flex;
  		parent_group >>= sbi->s_log_groups_per_flex;
  	}
  
  	freei = percpu_counter_read_positive(&sbi->s_freeinodes_counter);
  	avefreei = freei / ngroups;
  	freeb = EXT4_C2B(sbi,
  		percpu_counter_read_positive(&sbi->s_freeclusters_counter));
  	avefreec = freeb;
  	do_div(avefreec, ngroups);
  	ndirs = percpu_counter_read_positive(&sbi->s_dirs_counter);
  
  	if (S_ISDIR(mode) &&
  	    ((parent == sb->s_root->d_inode) ||
  	     (ext4_test_inode_flag(parent, EXT4_INODE_TOPDIR)))) {
  		int best_ndir = inodes_per_group;
  		int ret = -1;
  
  		if (qstr) {
  			hinfo.hash_version = DX_HASH_HALF_MD4;
  			hinfo.seed = sbi->s_hash_seed;
  			ext4fs_dirhash(qstr->name, qstr->len, &hinfo);
  			grp = hinfo.hash;
  		} else
  			grp = prandom_u32();
  		parent_group = (unsigned)grp % ngroups;
  		for (i = 0; i < ngroups; i++) {
  			g = (parent_group + i) % ngroups;
  			get_orlov_stats(sb, g, flex_size, &stats);
  			if (!stats.free_inodes)
  				continue;
  			if (stats.used_dirs >= best_ndir)
  				continue;
  			if (stats.free_inodes < avefreei)
  				continue;
  			if (stats.free_clusters < avefreec)
  				continue;
  			grp = g;
  			ret = 0;
  			best_ndir = stats.used_dirs;
  		}
  		if (ret)
  			goto fallback;
  	found_flex_bg:
  		if (flex_size == 1) {
  			*group = grp;
  			return 0;
  		}
  
  		/*
  		 * We pack inodes at the beginning of the flexgroup's
  		 * inode tables.  Block allocation decisions will do
  		 * something similar, although regular files will
  		 * start at 2nd block group of the flexgroup.  See
  		 * ext4_ext_find_goal() and ext4_find_near().
  		 */
  		grp *= flex_size;
  		for (i = 0; i < flex_size; i++) {
  			if (grp+i >= real_ngroups)
  				break;
  			desc = ext4_get_group_desc(sb, grp+i, NULL);
  			if (desc && ext4_free_inodes_count(sb, desc)) {
  				*group = grp+i;
  				return 0;
  			}
  		}
  		goto fallback;
  	}
  
  	max_dirs = ndirs / ngroups + inodes_per_group / 16;
  	min_inodes = avefreei - inodes_per_group*flex_size / 4;
  	if (min_inodes < 1)
  		min_inodes = 1;
  	min_clusters = avefreec - EXT4_CLUSTERS_PER_GROUP(sb)*flex_size / 4;
  
  	/*
  	 * Start looking in the flex group where we last allocated an
  	 * inode for this parent directory
  	 */
  	if (EXT4_I(parent)->i_last_alloc_group != ~0) {
  		parent_group = EXT4_I(parent)->i_last_alloc_group;
  		if (flex_size > 1)
  			parent_group >>= sbi->s_log_groups_per_flex;
  	}
  
  	for (i = 0; i < ngroups; i++) {
  		grp = (parent_group + i) % ngroups;
  		get_orlov_stats(sb, grp, flex_size, &stats);
  		if (stats.used_dirs >= max_dirs)
  			continue;
  		if (stats.free_inodes < min_inodes)
  			continue;
  		if (stats.free_clusters < min_clusters)
  			continue;
  		goto found_flex_bg;
  	}
  
  fallback:
  	ngroups = real_ngroups;
  	avefreei = freei / ngroups;
  fallback_retry:
  	parent_group = EXT4_I(parent)->i_block_group;
  	for (i = 0; i < ngroups; i++) {
  		grp = (parent_group + i) % ngroups;
  		desc = ext4_get_group_desc(sb, grp, NULL);
  		if (desc) {
  			grp_free = ext4_free_inodes_count(sb, desc);
  			if (grp_free && grp_free >= avefreei) {
  				*group = grp;
  				return 0;
  			}
  		}
  	}
  
  	if (avefreei) {
  		/*
  		 * The free-inodes counter is approximate, and for really small
  		 * filesystems the above test can fail to find any blockgroups
  		 */
  		avefreei = 0;
  		goto fallback_retry;
  	}
  
  	return -1;
  }
  
  static int find_group_other(struct super_block *sb, struct inode *parent,
  			    ext4_group_t *group, umode_t mode)
  {
  	ext4_group_t parent_group = EXT4_I(parent)->i_block_group;
  	ext4_group_t i, last, ngroups = ext4_get_groups_count(sb);
  	struct ext4_group_desc *desc;
  	int flex_size = ext4_flex_bg_size(EXT4_SB(sb));
  
  	/*
  	 * Try to place the inode is the same flex group as its
  	 * parent.  If we can't find space, use the Orlov algorithm to
  	 * find another flex group, and store that information in the
  	 * parent directory's inode information so that use that flex
  	 * group for future allocations.
  	 */
  	if (flex_size > 1) {
  		int retry = 0;
  
  	try_again:
  		parent_group &= ~(flex_size-1);
  		last = parent_group + flex_size;
  		if (last > ngroups)
  			last = ngroups;
  		for  (i = parent_group; i < last; i++) {
  			desc = ext4_get_group_desc(sb, i, NULL);
  			if (desc && ext4_free_inodes_count(sb, desc)) {
  				*group = i;
  				return 0;
  			}
  		}
  		if (!retry && EXT4_I(parent)->i_last_alloc_group != ~0) {
  			retry = 1;
  			parent_group = EXT4_I(parent)->i_last_alloc_group;
  			goto try_again;
  		}
  		/*
  		 * If this didn't work, use the Orlov search algorithm
  		 * to find a new flex group; we pass in the mode to
  		 * avoid the topdir algorithms.
  		 */
  		*group = parent_group + flex_size;
  		if (*group > ngroups)
  			*group = 0;
  		return find_group_orlov(sb, parent, group, mode, NULL);
  	}
  
  	/*
  	 * Try to place the inode in its parent directory
  	 */
  	*group = parent_group;
  	desc = ext4_get_group_desc(sb, *group, NULL);
  	if (desc && ext4_free_inodes_count(sb, desc) &&
  	    ext4_free_group_clusters(sb, desc))
  		return 0;
  
  	/*
  	 * We're going to place this inode in a different blockgroup from its
  	 * parent.  We want to cause files in a common directory to all land in
  	 * the same blockgroup.  But we want files which are in a different
  	 * directory which shares a blockgroup with our parent to land in a
  	 * different blockgroup.
  	 *
  	 * So add our directory's i_ino into the starting point for the hash.
  	 */
  	*group = (*group + parent->i_ino) % ngroups;
  
  	/*
  	 * Use a quadratic hash to find a group with a free inode and some free
  	 * blocks.
  	 */
  	for (i = 1; i < ngroups; i <<= 1) {
  		*group += i;
  		if (*group >= ngroups)
  			*group -= ngroups;
  		desc = ext4_get_group_desc(sb, *group, NULL);
  		if (desc && ext4_free_inodes_count(sb, desc) &&
  		    ext4_free_group_clusters(sb, desc))
  			return 0;
  	}
  
  	/*
  	 * That failed: try linear search for a free inode, even if that group
  	 * has no free blocks.
  	 */
  	*group = parent_group;
  	for (i = 0; i < ngroups; i++) {
  		if (++*group >= ngroups)
  			*group = 0;
  		desc = ext4_get_group_desc(sb, *group, NULL);
  		if (desc && ext4_free_inodes_count(sb, desc))
  			return 0;
  	}
  
  	return -1;
  }
  
  /*
   * In no journal mode, if an inode has recently been deleted, we want
   * to avoid reusing it until we're reasonably sure the inode table
   * block has been written back to disk.  (Yes, these values are
   * somewhat arbitrary...)
   */
  #define RECENTCY_MIN	5
  #define RECENTCY_DIRTY	30
  
  static int recently_deleted(struct super_block *sb, ext4_group_t group, int ino)
  {
  	struct ext4_group_desc	*gdp;
  	struct ext4_inode	*raw_inode;
  	struct buffer_head	*bh;
  	unsigned long		dtime, now;
  	int	inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
  	int	offset, ret = 0, recentcy = RECENTCY_MIN;
  
  	gdp = ext4_get_group_desc(sb, group, NULL);
  	if (unlikely(!gdp))
  		return 0;
  
  	bh = sb_getblk(sb, ext4_inode_table(sb, gdp) +
  		       (ino / inodes_per_block));
  	if (unlikely(!bh) || !buffer_uptodate(bh))
  		/*
  		 * If the block is not in the buffer cache, then it
  		 * must have been written out.
  		 */
  		goto out;
  
  	offset = (ino % inodes_per_block) * EXT4_INODE_SIZE(sb);
  	raw_inode = (struct ext4_inode *) (bh->b_data + offset);
  	dtime = le32_to_cpu(raw_inode->i_dtime);
  	now = get_seconds();
  	if (buffer_dirty(bh))
  		recentcy += RECENTCY_DIRTY;
  
  	if (dtime && (dtime < now) && (now < dtime + recentcy))
  		ret = 1;
  out:
  	brelse(bh);
  	return ret;
  }
  
  /**
   * ext4_has_free_inodes()
   * @sbi: in-core super block structure.
   *
   * Check if filesystem has inodes available for allocation.
   * On success return 1, return 0 on failure.
   */
  static inline int ext4_has_free_inodes(struct ext4_sb_info *sbi)
  {
  	if (likely(percpu_counter_read_positive(&sbi->s_freeinodes_counter) >
  			sbi->s_r_inodes_count * 2))
  		return 1;
  
  #if ANDROID_VERSION < 90000
  	if (percpu_counter_read_positive(&sbi->s_freeinodes_counter) >
  			sbi->s_r_inodes_count &&
  			in_group_p(AID_USE_SEC_RESERVED))
  		return 1;
  #endif
  
  	/* Hm, nope.  Are (enough) root reserved inodes available? */
  	if (uid_eq(sbi->s_resuid, current_fsuid()) ||
  	    (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
  	    capable(CAP_SYS_RESOURCE) || ext4_android_claim_r_blocks(sbi))
  		return 1;
  	return 0;
  }
  
  /*
   * There are two policies for allocating an inode.  If the new inode is
   * a directory, then a forward search is made for a block group with both
   * free space and a low directory-to-inode ratio; if that fails, then of
   * the groups with above-average free space, that group with the fewest
   * directories already is chosen.
   *
   * For other inodes, search forward from the parent directory's block
   * group to find a free inode.
   */
  struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir,
  			       umode_t mode, const struct qstr *qstr,
  			       __u32 goal, uid_t *owner, int handle_type,
  			       unsigned int line_no, int nblocks)
  {
  	struct super_block *sb;
  	struct buffer_head *inode_bitmap_bh = NULL;
  	struct buffer_head *group_desc_bh;
  	ext4_group_t ngroups, group = 0;
  	unsigned long ino = 0;
  	struct inode *inode;
  	struct ext4_group_desc *gdp = NULL;
  	struct ext4_inode_info *ei;
  	struct ext4_sb_info *sbi;
  	int ret2, err = 0;
  	struct inode *ret;
  	ext4_group_t i;
  	ext4_group_t flex_group;
  	struct ext4_group_info *grp;
  	int encrypt = 0;
  
  	/* Cannot create files in a deleted directory */
  	if (!dir || !dir->i_nlink)
  		return ERR_PTR(-EPERM);
  
  	if ((ext4_encrypted_inode(dir) ||
  	     DUMMY_ENCRYPTION_ENABLED(EXT4_SB(dir->i_sb))) &&
  	    (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) {
  		err = ext4_get_encryption_info(dir);
  		if (err)
  			return ERR_PTR(err);
  		if (ext4_encryption_info(dir) == NULL)
  			return ERR_PTR(-EPERM);
  		if (!handle)
  			nblocks += EXT4_DATA_TRANS_BLOCKS(dir->i_sb);
  		encrypt = 1;
  	}
  
  	sb = dir->i_sb;
  	ngroups = ext4_get_groups_count(sb);
  	trace_ext4_request_inode(dir, mode);
  	inode = new_inode(sb);
  	if (!inode)
  		return ERR_PTR(-ENOMEM);
  	ei = EXT4_I(inode);
  	sbi = EXT4_SB(sb);
  
  	/*
  	 * Initalize owners and quota early so that we don't have to account
  	 * for quota initialization worst case in standard inode creating
  	 * transaction
  	 */
  	if (owner) {
  		inode->i_mode = mode;
  		i_uid_write(inode, owner[0]);
  		i_gid_write(inode, owner[1]);
  	} else if (test_opt(sb, GRPID)) {
  		inode->i_mode = mode;
  		inode->i_uid = current_fsuid();
  		inode->i_gid = dir->i_gid;
  	} else
  		inode_init_owner(inode, dir, mode);
  	dquot_initialize(inode);
  
  	if (!ext4_has_free_inodes(sbi)) {
  		err = -ENOSPC;
  		goto out;
  	}
  
  	if (!goal)
  		goal = sbi->s_inode_goal;
  
  	if (goal && goal <= le32_to_cpu(sbi->s_es->s_inodes_count)) {
  		group = (goal - 1) / EXT4_INODES_PER_GROUP(sb);
  		ino = (goal - 1) % EXT4_INODES_PER_GROUP(sb);
  		ret2 = 0;
  		goto got_group;
  	}
  
  	if (S_ISDIR(mode))
  		ret2 = find_group_orlov(sb, dir, &group, mode, qstr);
  	else
  		ret2 = find_group_other(sb, dir, &group, mode);
  
  got_group:
  	EXT4_I(dir)->i_last_alloc_group = group;
  	err = -ENOSPC;
  	if (ret2 == -1)
  		goto out;
  
  	/*
  	 * Normally we will only go through one pass of this loop,
  	 * unless we get unlucky and it turns out the group we selected
  	 * had its last inode grabbed by someone else.
  	 */
  	for (i = 0; i < ngroups; i++, ino = 0) {
  		err = -EIO;
  
  		gdp = ext4_get_group_desc(sb, group, &group_desc_bh);
  		if (!gdp)
  			goto out;
  
  		/*
  		 * Check free inodes count before loading bitmap.
  		 */
  		if (ext4_free_inodes_count(sb, gdp) == 0) {
  			if (++group == ngroups)
  				group = 0;
  			continue;
  		}
  
  		grp = ext4_get_group_info(sb, group);
  		/* Skip groups with already-known suspicious inode tables */
  		if (EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) {
  			if (++group == ngroups)
  				group = 0;
  			continue;
  		}
  
  		brelse(inode_bitmap_bh);
  		inode_bitmap_bh = ext4_read_inode_bitmap(sb, group);
  		/* Skip groups with suspicious inode tables */
  		if (EXT4_MB_GRP_IBITMAP_CORRUPT(grp) || !inode_bitmap_bh) {
  			if (++group == ngroups)
  				group = 0;
  			continue;
  		}
  
  repeat_in_this_group:
  		ino = ext4_find_next_zero_bit((unsigned long *)
  					      inode_bitmap_bh->b_data,
  					      EXT4_INODES_PER_GROUP(sb), ino);
  		if (ino >= EXT4_INODES_PER_GROUP(sb))
  			goto next_group;
  		if (group == 0 && (ino+1) < EXT4_FIRST_INO(sb)) {
  			ext4_error(sb, "reserved inode found cleared - "
  				   "inode=%lu", ino + 1);
  			continue;
  		}
  		if ((EXT4_SB(sb)->s_journal == NULL) &&
  		    recently_deleted(sb, group, ino)) {
  			ino++;
  			goto next_inode;
  		}
  		if (!handle) {
  			BUG_ON(nblocks <= 0);
  			handle = __ext4_journal_start_sb(dir->i_sb, line_no,
  							 handle_type, nblocks,
  							 0);
  			if (IS_ERR(handle)) {
  				err = PTR_ERR(handle);
  				ext4_std_error(sb, err);
  				goto out;
  			}
  		}
  		BUFFER_TRACE(inode_bitmap_bh, "get_write_access");
  		err = ext4_journal_get_write_access(handle, inode_bitmap_bh);
  		if (err) {
  			ext4_std_error(sb, err);
  			goto out;
  		}
  		ext4_lock_group(sb, group);
  		ret2 = ext4_test_and_set_bit(ino, inode_bitmap_bh->b_data);
  		ext4_unlock_group(sb, group);
  		ino++;		/* the inode bitmap is zero-based */
  		if (!ret2)
  			goto got; /* we grabbed the inode! */
  next_inode:
  		if (ino < EXT4_INODES_PER_GROUP(sb))
  			goto repeat_in_this_group;
  next_group:
  		if (++group == ngroups)
  			group = 0;
  	}
  	err = -ENOSPC;
  	goto out;
  
  got:
  	BUFFER_TRACE(inode_bitmap_bh, "call ext4_handle_dirty_metadata");
  	err = ext4_handle_dirty_metadata(handle, NULL, inode_bitmap_bh);
  	if (err) {
  		ext4_std_error(sb, err);
  		goto out;
  	}
  
  	BUFFER_TRACE(group_desc_bh, "get_write_access");
  	err = ext4_journal_get_write_access(handle, group_desc_bh);
  	if (err) {
  		ext4_std_error(sb, err);
  		goto out;
  	}
  
  	/* We may have to initialize the block bitmap if it isn't already */
  	if (ext4_has_group_desc_csum(sb) &&
  	    gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
  		struct buffer_head *block_bitmap_bh;
  
  		block_bitmap_bh = ext4_read_block_bitmap(sb, group);
  		if (!block_bitmap_bh) {
  			err = -EIO;
  			goto out;
  		}
  		BUFFER_TRACE(block_bitmap_bh, "get block bitmap access");
  		err = ext4_journal_get_write_access(handle, block_bitmap_bh);
  		if (err) {
  			brelse(block_bitmap_bh);
  			ext4_std_error(sb, err);
  			goto out;
  		}
  
  		BUFFER_TRACE(block_bitmap_bh, "dirty block bitmap");
  		err = ext4_handle_dirty_metadata(handle, NULL, block_bitmap_bh);
  
  		/* recheck and clear flag under lock if we still need to */
  		ext4_lock_group(sb, group);
  		if (ext4_has_group_desc_csum(sb) &&
  		    (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))) {
  			gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT);
  			ext4_free_group_clusters_set(sb, gdp,
  				ext4_free_clusters_after_init(sb, group, gdp));
  			ext4_block_bitmap_csum_set(sb, group, gdp,
  						   block_bitmap_bh);
  			ext4_group_desc_csum_set(sb, group, gdp);
  		}
  		ext4_unlock_group(sb, group);
  		brelse(block_bitmap_bh);
  
  		if (err) {
  			ext4_std_error(sb, err);
  			goto out;
  		}
  	}
  
  	/* Update the relevant bg descriptor fields */
  	if (ext4_has_group_desc_csum(sb)) {
  		int free;
  		struct ext4_group_info *grp = ext4_get_group_info(sb, group);
  
  		down_read(&grp->alloc_sem); /* protect vs itable lazyinit */
  		ext4_lock_group(sb, group); /* while we modify the bg desc */
  		free = EXT4_INODES_PER_GROUP(sb) -
  			ext4_itable_unused_count(sb, gdp);
  		if (gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)) {
  			gdp->bg_flags &= cpu_to_le16(~EXT4_BG_INODE_UNINIT);
  			free = 0;
  		}
  		/*
  		 * Check the relative inode number against the last used
  		 * relative inode number in this group. if it is greater
  		 * we need to update the bg_itable_unused count
  		 */
  		if (ino > free)
  			ext4_itable_unused_set(sb, gdp,
  					(EXT4_INODES_PER_GROUP(sb) - ino));
  		up_read(&grp->alloc_sem);
  	} else {
  		ext4_lock_group(sb, group);
  	}
  
  	ext4_free_inodes_set(sb, gdp, ext4_free_inodes_count(sb, gdp) - 1);
  	if (S_ISDIR(mode)) {
  		ext4_used_dirs_set(sb, gdp, ext4_used_dirs_count(sb, gdp) + 1);
  		if (sbi->s_log_groups_per_flex) {
  			ext4_group_t f = ext4_flex_group(sbi, group);
  
  			atomic_inc(&sbi->s_flex_groups[f].used_dirs);
  		}
  	}
  	if (ext4_has_group_desc_csum(sb)) {
  		ext4_inode_bitmap_csum_set(sb, group, gdp, inode_bitmap_bh,
  					   EXT4_INODES_PER_GROUP(sb) / 8);
  		ext4_group_desc_csum_set(sb, group, gdp);
  	}
  	ext4_unlock_group(sb, group);
  
  	BUFFER_TRACE(group_desc_bh, "call ext4_handle_dirty_metadata");
  	err = ext4_handle_dirty_metadata(handle, NULL, group_desc_bh);
  	if (err) {
  		ext4_std_error(sb, err);
  		goto out;
  	}
  
  	percpu_counter_dec(&sbi->s_freeinodes_counter);
  	if (S_ISDIR(mode))
  		percpu_counter_inc(&sbi->s_dirs_counter);
  
  	if (sbi->s_log_groups_per_flex) {
  		flex_group = ext4_flex_group(sbi, group);
  		atomic_dec(&sbi->s_flex_groups[flex_group].free_inodes);
  	}
  
  	inode->i_ino = ino + group * EXT4_INODES_PER_GROUP(sb);
  	/* This is the optimal IO size (for stat), not the fs block size */
  	inode->i_blocks = 0;
  	inode->i_mtime = inode->i_atime = inode->i_ctime = ei->i_crtime =
  						       ext4_current_time(inode);
  
  	memset(ei->i_data, 0, sizeof(ei->i_data));
  	ei->i_dir_start_lookup = 0;
  	ei->i_disksize = 0;
  
  	/* Don't inherit extent flag from directory, amongst others. */
  	ei->i_flags =
  		ext4_mask_flags(mode, EXT4_I(dir)->i_flags & EXT4_FL_INHERITED);
  	ei->i_file_acl = 0;
  	ei->i_dtime = 0;
  	ei->i_block_group = group;
  	ei->i_last_alloc_group = ~0;
  
  	ext4_set_inode_flags(inode);
  	if (IS_DIRSYNC(inode))
  		ext4_handle_sync(handle);
  	if (insert_inode_locked(inode) < 0) {
  		/*
  		 * Likely a bitmap corruption causing inode to be allocated
  		 * twice.
  		 */
  		err = -EIO;
  		ext4_error(sb, "failed to insert inode %lu: doubly allocated?",
  			   inode->i_ino);
  		goto out;
  	}
  	spin_lock(&sbi->s_next_gen_lock);
  	inode->i_generation = sbi->s_next_generation++;
  	spin_unlock(&sbi->s_next_gen_lock);
  
  	/* Precompute checksum seed for inode metadata */
  	if (ext4_has_metadata_csum(sb)) {
  		__u32 csum;
  		__le32 inum = cpu_to_le32(inode->i_ino);
  		__le32 gen = cpu_to_le32(inode->i_generation);
  		csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&inum,
  				   sizeof(inum));
  		ei->i_csum_seed = ext4_chksum(sbi, csum, (__u8 *)&gen,
  					      sizeof(gen));
  	}
  
  	ext4_clear_state_flags(ei); /* Only relevant on 32-bit archs */
  	ext4_set_inode_state(inode, EXT4_STATE_NEW);
  
  	ei->i_extra_isize = EXT4_SB(sb)->s_want_extra_isize;
  	ei->i_inline_off = 0;
  	if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_INLINE_DATA))
  		ext4_set_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
  	ret = inode;
  	err = dquot_alloc_inode(inode);
  	if (err)
  		goto fail_drop;
  
  	err = ext4_init_acl(handle, inode, dir);
  	if (err)
  		goto fail_free_drop;
  
  	err = ext4_init_security(handle, inode, dir, qstr);
  	if (err)
  		goto fail_free_drop;
  
  	if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)) {
  		/* set extent flag only for directory, file and normal symlink*/
  		if (S_ISDIR(mode) || S_ISREG(mode) || S_ISLNK(mode)) {
  			ext4_set_inode_flag(inode, EXT4_INODE_EXTENTS);
  			ext4_ext_tree_init(handle, inode);
  		}
  	}
  
  	if (ext4_handle_valid(handle)) {
  		ei->i_sync_tid = handle->h_transaction->t_tid;
  		ei->i_datasync_tid = handle->h_transaction->t_tid;
  	}
  
  	if (encrypt) {
  		err = ext4_inherit_context(dir, inode);
  		if (err)
  			goto fail_free_drop;
  	}
  
  	err = ext4_mark_inode_dirty(handle, inode);
  	if (err) {
  		ext4_std_error(sb, err);
  		goto fail_free_drop;
  	}
  
  	ext4_debug("allocating inode %lu\n", inode->i_ino);
  	trace_ext4_allocate_inode(inode, dir, mode);
  	brelse(inode_bitmap_bh);
  	return ret;
  
  fail_free_drop:
  	dquot_free_inode(inode);
  fail_drop:
  	clear_nlink(inode);
  	unlock_new_inode(inode);
  out:
  	if (err == -ENOSPC) {
  		printk_ratelimited(KERN_INFO "Return ENOSPC: ifree=%d, inodes=%u\n",
  			(int) percpu_counter_read_positive(&sbi->s_freeinodes_counter),
  			le32_to_cpu(sbi->s_es->s_inodes_count));
  	}
  	dquot_drop(inode);
  	inode->i_flags |= S_NOQUOTA;
  	iput(inode);
  	brelse(inode_bitmap_bh);
  	return ERR_PTR(err);
  }
  
  /* Verify that we are loading a valid orphan from disk */
  struct inode *ext4_orphan_get(struct super_block *sb, unsigned long ino)
  {
  	unsigned long max_ino = le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count);
  	ext4_group_t block_group;
  	int bit;
  	struct buffer_head *bitmap_bh = NULL;
  	struct inode *inode = NULL;
  	int err = -EIO;
  
  	if (ino < EXT4_FIRST_INO(sb) || ino > max_ino)
  		goto bad_orphan;
  
  	block_group = (ino - 1) / EXT4_INODES_PER_GROUP(sb);
  	bit = (ino - 1) % EXT4_INODES_PER_GROUP(sb);
  	bitmap_bh = ext4_read_inode_bitmap(sb, block_group);
  	if (!bitmap_bh) {
  		ext4_error(sb, "inode bitmap error %ld for orphan %lu",
  			   ino, PTR_ERR(bitmap_bh));
  		return (struct inode *) bitmap_bh;
  	}
  
  	/* Having the inode bit set should be a 100% indicator that this
  	 * is a valid orphan (no e2fsck run on fs).  Orphans also include
  	 * inodes that were being truncated, so we can't check i_nlink==0.
  	 */
  	if (!ext4_test_bit(bit, bitmap_bh->b_data))
  		goto bad_orphan;
  
  	inode = ext4_iget(sb, ino);
  	if (IS_ERR(inode)) {
  		err = PTR_ERR(inode);
  		ext4_error(sb, "couldn't read orphan inode %lu (err %d)",
  			   ino, err);
  		return inode;
  	}
  
  	/*
  	 * If the orphans has i_nlinks > 0 then it should be able to
  	 * be truncated, otherwise it won't be removed from the orphan
  	 * list during processing and an infinite loop will result.
  	 * Similarly, it must not be a bad inode.
  	 */
  	if ((inode->i_nlink && !ext4_can_truncate(inode)) ||
  	    is_bad_inode(inode))
  		goto bad_orphan;
  
  	if (NEXT_ORPHAN(inode) > max_ino)
  		goto bad_orphan;
  	brelse(bitmap_bh);
  	return inode;
  
  bad_orphan:
  	ext4_error(sb, "bad orphan inode %lu", ino);
  	if (bitmap_bh)
  		printk(KERN_ERR "ext4_test_bit(bit=%d, block=%llu) = %d\n",
  		       bit, (unsigned long long)bitmap_bh->b_blocknr,
  		       ext4_test_bit(bit, bitmap_bh->b_data));
  	if (inode) {
  		printk(KERN_ERR "is_bad_inode(inode)=%d\n",
  		       is_bad_inode(inode));
  		printk(KERN_ERR "NEXT_ORPHAN(inode)=%u\n",
  		       NEXT_ORPHAN(inode));
  		printk(KERN_ERR "max_ino=%lu\n", max_ino);
  		printk(KERN_ERR "i_nlink=%u\n", inode->i_nlink);
  		/* Avoid freeing blocks if we got a bad deleted inode */
  		if (inode->i_nlink == 0)
  			inode->i_blocks = 0;
  		iput(inode);
  	}
  	brelse(bitmap_bh);
  	return ERR_PTR(err);
  }
  
  unsigned long ext4_count_free_inodes(struct super_block *sb)
  {
  	unsigned long desc_count;
  	struct ext4_group_desc *gdp;
  	ext4_group_t i, ngroups = ext4_get_groups_count(sb);
  #ifdef EXT4FS_DEBUG
  	struct ext4_super_block *es;
  	unsigned long bitmap_count, x;
  	struct buffer_head *bitmap_bh = NULL;
  
  	es = EXT4_SB(sb)->s_es;
  	desc_count = 0;
  	bitmap_count = 0;
  	gdp = NULL;
  	for (i = 0; i < ngroups; i++) {
  		gdp = ext4_get_group_desc(sb, i, NULL);
  		if (!gdp)
  			continue;
  		desc_count += ext4_free_inodes_count(sb, gdp);
  		brelse(bitmap_bh);
  		bitmap_bh = ext4_read_inode_bitmap(sb, i);
  		if (!bitmap_bh)
  			continue;
  
  		x = ext4_count_free(bitmap_bh->b_data,
  				    EXT4_INODES_PER_GROUP(sb) / 8);
  		printk(KERN_DEBUG "group %lu: stored = %d, counted = %lu\n",
  			(unsigned long) i, ext4_free_inodes_count(sb, gdp), x);
  		bitmap_count += x;
  	}
  	brelse(bitmap_bh);
  	printk(KERN_DEBUG "ext4_count_free_inodes: "
  	       "stored = %u, computed = %lu, %lu\n",
  	       le32_to_cpu(es->s_free_inodes_count), desc_count, bitmap_count);
  	return desc_count;
  #else
  	desc_count = 0;
  	for (i = 0; i < ngroups; i++) {
  		gdp = ext4_get_group_desc(sb, i, NULL);
  		if (!gdp)
  			continue;
  		desc_count += ext4_free_inodes_count(sb, gdp);
  		cond_resched();
  	}
  	return desc_count;
  #endif
  }
  
  /* Called at mount-time, super-block is locked */
  unsigned long ext4_count_dirs(struct super_block * sb)
  {
  	unsigned long count = 0;
  	ext4_group_t i, ngroups = ext4_get_groups_count(sb);
  
  	for (i = 0; i < ngroups; i++) {
  		struct ext4_group_desc *gdp = ext4_get_group_desc(sb, i, NULL);
  		if (!gdp)
  			continue;
  		count += ext4_used_dirs_count(sb, gdp);
  	}
  	return count;
  }
  
  /*
   * Zeroes not yet zeroed inode table - just write zeroes through the whole
   * inode table. Must be called without any spinlock held. The only place
   * where it is called from on active part of filesystem is ext4lazyinit
   * thread, so we do not need any special locks, however we have to prevent
   * inode allocation from the current group, so we take alloc_sem lock, to
   * block ext4_new_inode() until we are finished.
   */
  int ext4_init_inode_table(struct super_block *sb, ext4_group_t group,
  				 int barrier)
  {
  	struct ext4_group_info *grp = ext4_get_group_info(sb, group);
  	struct ext4_sb_info *sbi = EXT4_SB(sb);
  	struct ext4_group_desc *gdp = NULL;
  	struct buffer_head *group_desc_bh;
  	handle_t *handle;
  	ext4_fsblk_t blk;
  	int num, ret = 0, used_blks = 0;
  
  	/* This should not happen, but just to be sure check this */
  	if (sb->s_flags & MS_RDONLY) {
  		ret = 1;
  		goto out;
  	}
  
  	gdp = ext4_get_group_desc(sb, group, &group_desc_bh);
  	if (!gdp)
  		goto out;
  
  	/*
  	 * We do not need to lock this, because we are the only one
  	 * handling this flag.
  	 */
  	if (gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_ZEROED))
  		goto out;
  
  	handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
  	if (IS_ERR(handle)) {
  		ret = PTR_ERR(handle);
  		goto out;
  	}
  
  	down_write(&grp->alloc_sem);
  	/*
  	 * If inode bitmap was already initialized there may be some
  	 * used inodes so we need to skip blocks with used inodes in
  	 * inode table.
  	 */
  	if (!(gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)))
  		used_blks = DIV_ROUND_UP((EXT4_INODES_PER_GROUP(sb) -
  			    ext4_itable_unused_count(sb, gdp)),
  			    sbi->s_inodes_per_block);
  
  	if ((used_blks < 0) || (used_blks > sbi->s_itb_per_group) ||
  	    ((group == 0) && ((EXT4_INODES_PER_GROUP(sb) -
  			       ext4_itable_unused_count(sb, gdp)) <
  			      EXT4_FIRST_INO(sb)))) {
  		ext4_error(sb, "Something is wrong with group %u: "
  			   "used itable blocks: %d; "
  			   "itable unused count: %u",
  			   group, used_blks,
  			   ext4_itable_unused_count(sb, gdp));
  		ret = 1;
  		goto err_out;
  	}
  
  	blk = ext4_inode_table(sb, gdp) + used_blks;
  	num = sbi->s_itb_per_group - used_blks;
  
  	BUFFER_TRACE(group_desc_bh, "get_write_access");
  	ret = ext4_journal_get_write_access(handle,
  					    group_desc_bh);
  	if (ret)
  		goto err_out;
  
  	/*
  	 * Skip zeroout if the inode table is full. But we set the ZEROED
  	 * flag anyway, because obviously, when it is full it does not need
  	 * further zeroing.
  	 */
  	if (unlikely(num == 0))
  		goto skip_zeroout;
  
  	ext4_debug("going to zero out inode table in group %d\n",
  		   group);
  	ret = sb_issue_zeroout(sb, blk, num, GFP_NOFS);
  	if (ret < 0)
  		goto err_out;
  	if (barrier)
  		blkdev_issue_flush(sb->s_bdev, GFP_NOFS, NULL);
  
  skip_zeroout:
  	ext4_lock_group(sb, group);
  	gdp->bg_flags |= cpu_to_le16(EXT4_BG_INODE_ZEROED);
  	ext4_group_desc_csum_set(sb, group, gdp);
  	ext4_unlock_group(sb, group);
  
  	BUFFER_TRACE(group_desc_bh,
  		     "call ext4_handle_dirty_metadata");
  	ret = ext4_handle_dirty_metadata(handle, NULL,
  					 group_desc_bh);
  
  err_out:
  	up_write(&grp->alloc_sem);
  	ext4_journal_stop(handle);
  out:
  	return ret;
  }
  