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inode.c

/*
 *  linux/fs/ext2/inode.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)
 *
 *  from
 *
 *  linux/fs/minix/inode.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Goal-directed block allocation by Stephen Tweedie
 *    (sct@dcs.ed.ac.uk), 1993, 1998
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 *  64-bit file support on 64-bit platforms by Jakub Jelinek
 *    (jj@sunsite.ms.mff.cuni.cz)
 *
 *  Assorted race fixes, rewrite of ext2_get_block() by Al Viro, 2000
 */

#include <linux/smp_lock.h>
#include <linux/time.h>
#include <linux/highuid.h>
#include <linux/pagemap.h>
#include <linux/quotaops.h>
#include <linux/module.h>
#include <linux/writeback.h>
#include <linux/buffer_head.h>
#include <linux/mpage.h>
#include "ext2.h"
#include "acl.h"
#include "xip.h"

MODULE_AUTHOR("Remy Card and others");
MODULE_DESCRIPTION("Second Extended Filesystem");
MODULE_LICENSE("GPL");

static int ext2_update_inode(struct inode * inode, int do_sync);

/*
 * Test whether an inode is a fast symlink.
 */
static inline int ext2_inode_is_fast_symlink(struct inode *inode)
{
      int ea_blocks = EXT2_I(inode)->i_file_acl ?
            (inode->i_sb->s_blocksize >> 9) : 0;

      return (S_ISLNK(inode->i_mode) &&
            inode->i_blocks - ea_blocks == 0);
}

/*
 * Called at the last iput() if i_nlink is zero.
 */
void ext2_delete_inode (struct inode * inode)
{
      truncate_inode_pages(&inode->i_data, 0);

      if (is_bad_inode(inode))
            goto no_delete;
      EXT2_I(inode)->i_dtime  = get_seconds();
      mark_inode_dirty(inode);
      ext2_update_inode(inode, inode_needs_sync(inode));

      inode->i_size = 0;
      if (inode->i_blocks)
            ext2_truncate (inode);
      ext2_free_inode (inode);

      return;
no_delete:
      clear_inode(inode);     /* We must guarantee clearing of inode... */
}

typedef struct {
      __le32      *p;
      __le32      key;
      struct buffer_head *bh;
} Indirect;

static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
{
      p->key = *(p->p = v);
      p->bh = bh;
}

static inline int verify_chain(Indirect *from, Indirect *to)
{
      while (from <= to && from->key == *from->p)
            from++;
      return (from > to);
}

/**
 *    ext2_block_to_path - parse the block number into array of offsets
 *    @inode: inode in question (we are only interested in its superblock)
 *    @i_block: block number to be parsed
 *    @offsets: array to store the offsets in
 *      @boundary: set this non-zero if the referred-to block is likely to be
 *             followed (on disk) by an indirect block.
 *    To store the locations of file's data ext2 uses a data structure common
 *    for UNIX filesystems - tree of pointers anchored in the inode, with
 *    data blocks at leaves and indirect blocks in intermediate nodes.
 *    This function translates the block number into path in that tree -
 *    return value is the path length and @offsets[n] is the offset of
 *    pointer to (n+1)th node in the nth one. If @block is out of range
 *    (negative or too large) warning is printed and zero returned.
 *
 *    Note: function doesn't find node addresses, so no IO is needed. All
 *    we need to know is the capacity of indirect blocks (taken from the
 *    inode->i_sb).
 */

/*
 * Portability note: the last comparison (check that we fit into triple
 * indirect block) is spelled differently, because otherwise on an
 * architecture with 32-bit longs and 8Kb pages we might get into trouble
 * if our filesystem had 8Kb blocks. We might use long long, but that would
 * kill us on x86. Oh, well, at least the sign propagation does not matter -
 * i_block would have to be negative in the very beginning, so we would not
 * get there at all.
 */

static int ext2_block_to_path(struct inode *inode,
                  long i_block, int offsets[4], int *boundary)
{
      int ptrs = EXT2_ADDR_PER_BLOCK(inode->i_sb);
      int ptrs_bits = EXT2_ADDR_PER_BLOCK_BITS(inode->i_sb);
      const long direct_blocks = EXT2_NDIR_BLOCKS,
            indirect_blocks = ptrs,
            double_blocks = (1 << (ptrs_bits * 2));
      int n = 0;
      int final = 0;

      if (i_block < 0) {
            ext2_warning (inode->i_sb, "ext2_block_to_path", "block < 0");
      } else if (i_block < direct_blocks) {
            offsets[n++] = i_block;
            final = direct_blocks;
      } else if ( (i_block -= direct_blocks) < indirect_blocks) {
            offsets[n++] = EXT2_IND_BLOCK;
            offsets[n++] = i_block;
            final = ptrs;
      } else if ((i_block -= indirect_blocks) < double_blocks) {
            offsets[n++] = EXT2_DIND_BLOCK;
            offsets[n++] = i_block >> ptrs_bits;
            offsets[n++] = i_block & (ptrs - 1);
            final = ptrs;
      } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
            offsets[n++] = EXT2_TIND_BLOCK;
            offsets[n++] = i_block >> (ptrs_bits * 2);
            offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
            offsets[n++] = i_block & (ptrs - 1);
            final = ptrs;
      } else {
            ext2_warning (inode->i_sb, "ext2_block_to_path", "block > big");
      }
      if (boundary)
            *boundary = final - 1 - (i_block & (ptrs - 1));

      return n;
}

/**
 *    ext2_get_branch - read the chain of indirect blocks leading to data
 *    @inode: inode in question
 *    @depth: depth of the chain (1 - direct pointer, etc.)
 *    @offsets: offsets of pointers in inode/indirect blocks
 *    @chain: place to store the result
 *    @err: here we store the error value
 *
 *    Function fills the array of triples <key, p, bh> and returns %NULL
 *    if everything went OK or the pointer to the last filled triple
 *    (incomplete one) otherwise. Upon the return chain[i].key contains
 *    the number of (i+1)-th block in the chain (as it is stored in memory,
 *    i.e. little-endian 32-bit), chain[i].p contains the address of that
 *    number (it points into struct inode for i==0 and into the bh->b_data
 *    for i>0) and chain[i].bh points to the buffer_head of i-th indirect
 *    block for i>0 and NULL for i==0. In other words, it holds the block
 *    numbers of the chain, addresses they were taken from (and where we can
 *    verify that chain did not change) and buffer_heads hosting these
 *    numbers.
 *
 *    Function stops when it stumbles upon zero pointer (absent block)
 *          (pointer to last triple returned, *@err == 0)
 *    or when it gets an IO error reading an indirect block
 *          (ditto, *@err == -EIO)
 *    or when it notices that chain had been changed while it was reading
 *          (ditto, *@err == -EAGAIN)
 *    or when it reads all @depth-1 indirect blocks successfully and finds
 *    the whole chain, all way to the data (returns %NULL, *err == 0).
 */
static Indirect *ext2_get_branch(struct inode *inode,
                         int depth,
                         int *offsets,
                         Indirect chain[4],
                         int *err)
{
      struct super_block *sb = inode->i_sb;
      Indirect *p = chain;
      struct buffer_head *bh;

      *err = 0;
      /* i_data is not going away, no lock needed */
      add_chain (chain, NULL, EXT2_I(inode)->i_data + *offsets);
      if (!p->key)
            goto no_block;
      while (--depth) {
            bh = sb_bread(sb, le32_to_cpu(p->key));
            if (!bh)
                  goto failure;
            read_lock(&EXT2_I(inode)->i_meta_lock);
            if (!verify_chain(chain, p))
                  goto changed;
            add_chain(++p, bh, (__le32*)bh->b_data + *++offsets);
            read_unlock(&EXT2_I(inode)->i_meta_lock);
            if (!p->key)
                  goto no_block;
      }
      return NULL;

changed:
      read_unlock(&EXT2_I(inode)->i_meta_lock);
      brelse(bh);
      *err = -EAGAIN;
      goto no_block;
failure:
      *err = -EIO;
no_block:
      return p;
}

/**
 *    ext2_find_near - find a place for allocation with sufficient locality
 *    @inode: owner
 *    @ind: descriptor of indirect block.
 *
 *    This function returns the prefered place for block allocation.
 *    It is used when heuristic for sequential allocation fails.
 *    Rules are:
 *      + if there is a block to the left of our position - allocate near it.
 *      + if pointer will live in indirect block - allocate near that block.
 *      + if pointer will live in inode - allocate in the same cylinder group.
 *
 * In the latter case we colour the starting block by the callers PID to
 * prevent it from clashing with concurrent allocations for a different inode
 * in the same block group.   The PID is used here so that functionally related
 * files will be close-by on-disk.
 *
 *    Caller must make sure that @ind is valid and will stay that way.
 */

static unsigned long ext2_find_near(struct inode *inode, Indirect *ind)
{
      struct ext2_inode_info *ei = EXT2_I(inode);
      __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
      __le32 *p;
      unsigned long bg_start;
      unsigned long colour;

      /* Try to find previous block */
      for (p = ind->p - 1; p >= start; p--)
            if (*p)
                  return le32_to_cpu(*p);

      /* No such thing, so let's try location of indirect block */
      if (ind->bh)
            return ind->bh->b_blocknr;

      /*
       * It is going to be refered from inode itself? OK, just put it into
       * the same cylinder group then.
       */
      bg_start = (ei->i_block_group * EXT2_BLOCKS_PER_GROUP(inode->i_sb)) +
            le32_to_cpu(EXT2_SB(inode->i_sb)->s_es->s_first_data_block);
      colour = (current->pid % 16) *
                  (EXT2_BLOCKS_PER_GROUP(inode->i_sb) / 16);
      return bg_start + colour;
}

/**
 *    ext2_find_goal - find a prefered place for allocation.
 *    @inode: owner
 *    @block:  block we want
 *    @chain:  chain of indirect blocks
 *    @partial: pointer to the last triple within a chain
 *
 *    Returns preferred place for a block (the goal).
 */

static inline int ext2_find_goal(struct inode *inode,
                         long block,
                         Indirect chain[4],
                         Indirect *partial)
{
      struct ext2_block_alloc_info *block_i;

      block_i = EXT2_I(inode)->i_block_alloc_info;

      /*
       * try the heuristic for sequential allocation,
       * failing that at least try to get decent locality.
       */
      if (block_i && (block == block_i->last_alloc_logical_block + 1)
            && (block_i->last_alloc_physical_block != 0)) {
            return block_i->last_alloc_physical_block + 1;
      }

      return ext2_find_near(inode, partial);
}

/**
 *    ext2_blks_to_allocate: Look up the block map and count the number
 *    of direct blocks need to be allocated for the given branch.
 *
 *    @branch: chain of indirect blocks
 *    @k: number of blocks need for indirect blocks
 *    @blks: number of data blocks to be mapped.
 *    @blocks_to_boundary:  the offset in the indirect block
 *
 *    return the total number of blocks to be allocate, including the
 *    direct and indirect blocks.
 */
static int
ext2_blks_to_allocate(Indirect * branch, int k, unsigned long blks,
            int blocks_to_boundary)
{
      unsigned long count = 0;

      /*
       * Simple case, [t,d]Indirect block(s) has not allocated yet
       * then it's clear blocks on that path have not allocated
       */
      if (k > 0) {
            /* right now don't hanel cross boundary allocation */
            if (blks < blocks_to_boundary + 1)
                  count += blks;
            else
                  count += blocks_to_boundary + 1;
            return count;
      }

      count++;
      while (count < blks && count <= blocks_to_boundary
            && le32_to_cpu(*(branch[0].p + count)) == 0) {
            count++;
      }
      return count;
}

/**
 *    ext2_alloc_blocks: multiple allocate blocks needed for a branch
 *    @indirect_blks: the number of blocks need to allocate for indirect
 *                blocks
 *
 *    @new_blocks: on return it will store the new block numbers for
 *    the indirect blocks(if needed) and the first direct block,
 *    @blks:      on return it will store the total number of allocated
 *          direct blocks
 */
static int ext2_alloc_blocks(struct inode *inode,
                  ext2_fsblk_t goal, int indirect_blks, int blks,
                  ext2_fsblk_t new_blocks[4], int *err)
{
      int target, i;
      unsigned long count = 0;
      int index = 0;
      ext2_fsblk_t current_block = 0;
      int ret = 0;

      /*
       * Here we try to allocate the requested multiple blocks at once,
       * on a best-effort basis.
       * To build a branch, we should allocate blocks for
       * the indirect blocks(if not allocated yet), and at least
       * the first direct block of this branch.  That's the
       * minimum number of blocks need to allocate(required)
       */
      target = blks + indirect_blks;

      while (1) {
            count = target;
            /* allocating blocks for indirect blocks and direct blocks */
            current_block = ext2_new_blocks(inode,goal,&count,err);
            if (*err)
                  goto failed_out;

            target -= count;
            /* allocate blocks for indirect blocks */
            while (index < indirect_blks && count) {
                  new_blocks[index++] = current_block++;
                  count--;
            }

            if (count > 0)
                  break;
      }

      /* save the new block number for the first direct block */
      new_blocks[index] = current_block;

      /* total number of blocks allocated for direct blocks */
      ret = count;
      *err = 0;
      return ret;
failed_out:
      for (i = 0; i <index; i++)
            ext2_free_blocks(inode, new_blocks[i], 1);
      return ret;
}

/**
 *    ext2_alloc_branch - allocate and set up a chain of blocks.
 *    @inode: owner
 *    @num: depth of the chain (number of blocks to allocate)
 *    @offsets: offsets (in the blocks) to store the pointers to next.
 *    @branch: place to store the chain in.
 *
 *    This function allocates @num blocks, zeroes out all but the last one,
 *    links them into chain and (if we are synchronous) writes them to disk.
 *    In other words, it prepares a branch that can be spliced onto the
 *    inode. It stores the information about that chain in the branch[], in
 *    the same format as ext2_get_branch() would do. We are calling it after
 *    we had read the existing part of chain and partial points to the last
 *    triple of that (one with zero ->key). Upon the exit we have the same
 *    picture as after the successful ext2_get_block(), excpet that in one
 *    place chain is disconnected - *branch->p is still zero (we did not
 *    set the last link), but branch->key contains the number that should
 *    be placed into *branch->p to fill that gap.
 *
 *    If allocation fails we free all blocks we've allocated (and forget
 *    their buffer_heads) and return the error value the from failed
 *    ext2_alloc_block() (normally -ENOSPC). Otherwise we set the chain
 *    as described above and return 0.
 */

static int ext2_alloc_branch(struct inode *inode,
                  int indirect_blks, int *blks, ext2_fsblk_t goal,
                  int *offsets, Indirect *branch)
{
      int blocksize = inode->i_sb->s_blocksize;
      int i, n = 0;
      int err = 0;
      struct buffer_head *bh;
      int num;
      ext2_fsblk_t new_blocks[4];
      ext2_fsblk_t current_block;

      num = ext2_alloc_blocks(inode, goal, indirect_blks,
                        *blks, new_blocks, &err);
      if (err)
            return err;

      branch[0].key = cpu_to_le32(new_blocks[0]);
      /*
       * metadata blocks and data blocks are allocated.
       */
      for (n = 1; n <= indirect_blks;  n++) {
            /*
             * Get buffer_head for parent block, zero it out
             * and set the pointer to new one, then send
             * parent to disk.
             */
            bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
            branch[n].bh = bh;
            lock_buffer(bh);
            memset(bh->b_data, 0, blocksize);
            branch[n].p = (__le32 *) bh->b_data + offsets[n];
            branch[n].key = cpu_to_le32(new_blocks[n]);
            *branch[n].p = branch[n].key;
            if ( n == indirect_blks) {
                  current_block = new_blocks[n];
                  /*
                   * End of chain, update the last new metablock of
                   * the chain to point to the new allocated
                   * data blocks numbers
                   */
                  for (i=1; i < num; i++)
                        *(branch[n].p + i) = cpu_to_le32(++current_block);
            }
            set_buffer_uptodate(bh);
            unlock_buffer(bh);
            mark_buffer_dirty_inode(bh, inode);
            /* We used to sync bh here if IS_SYNC(inode).
             * But we now rely upon generic_osync_inode()
             * and b_inode_buffers.  But not for directories.
             */
            if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
                  sync_dirty_buffer(bh);
      }
      *blks = num;
      return err;
}

/**
 * ext2_splice_branch - splice the allocated branch onto inode.
 * @inode: owner
 * @block: (logical) number of block we are adding
 * @chain: chain of indirect blocks (with a missing link - see
 *    ext2_alloc_branch)
 * @where: location of missing link
 * @num:   number of indirect blocks we are adding
 * @blks:  number of direct blocks we are adding
 *
 * This function fills the missing link and does all housekeeping needed in
 * inode (->i_blocks, etc.). In case of success we end up with the full
 * chain to new block and return 0.
 */
static void ext2_splice_branch(struct inode *inode,
                  long block, Indirect *where, int num, int blks)
{
      int i;
      struct ext2_block_alloc_info *block_i;
      ext2_fsblk_t current_block;

      block_i = EXT2_I(inode)->i_block_alloc_info;

      /* XXX LOCKING probably should have i_meta_lock ?*/
      /* That's it */

      *where->p = where->key;

      /*
       * Update the host buffer_head or inode to point to more just allocated
       * direct blocks blocks
       */
      if (num == 0 && blks > 1) {
            current_block = le32_to_cpu(where->key) + 1;
            for (i = 1; i < blks; i++)
                  *(where->p + i ) = cpu_to_le32(current_block++);
      }

      /*
       * update the most recently allocated logical & physical block
       * in i_block_alloc_info, to assist find the proper goal block for next
       * allocation
       */
      if (block_i) {
            block_i->last_alloc_logical_block = block + blks - 1;
            block_i->last_alloc_physical_block =
                        le32_to_cpu(where[num].key) + blks - 1;
      }

      /* We are done with atomic stuff, now do the rest of housekeeping */

      /* had we spliced it onto indirect block? */
      if (where->bh)
            mark_buffer_dirty_inode(where->bh, inode);

      inode->i_ctime = CURRENT_TIME_SEC;
      mark_inode_dirty(inode);
}

/*
 * Allocation strategy is simple: if we have to allocate something, we will
 * have to go the whole way to leaf. So let's do it before attaching anything
 * to tree, set linkage between the newborn blocks, write them if sync is
 * required, recheck the path, free and repeat if check fails, otherwise
 * set the last missing link (that will protect us from any truncate-generated
 * removals - all blocks on the path are immune now) and possibly force the
 * write on the parent block.
 * That has a nice additional property: no special recovery from the failed
 * allocations is needed - we simply release blocks and do not touch anything
 * reachable from inode.
 *
 * `handle' can be NULL if create == 0.
 *
 * The BKL may not be held on entry here.  Be sure to take it early.
 * return > 0, # of blocks mapped or allocated.
 * return = 0, if plain lookup failed.
 * return < 0, error case.
 */
static int ext2_get_blocks(struct inode *inode,
                     sector_t iblock, unsigned long maxblocks,
                     struct buffer_head *bh_result,
                     int create)
{
      int err = -EIO;
      int offsets[4];
      Indirect chain[4];
      Indirect *partial;
      ext2_fsblk_t goal;
      int indirect_blks;
      int blocks_to_boundary = 0;
      int depth;
      struct ext2_inode_info *ei = EXT2_I(inode);
      int count = 0;
      ext2_fsblk_t first_block = 0;

      depth = ext2_block_to_path(inode,iblock,offsets,&blocks_to_boundary);

      if (depth == 0)
            return (err);
reread:
      partial = ext2_get_branch(inode, depth, offsets, chain, &err);

      /* Simplest case - block found, no allocation needed */
      if (!partial) {
            first_block = le32_to_cpu(chain[depth - 1].key);
            clear_buffer_new(bh_result); /* What's this do? */
            count++;
            /*map more blocks*/
            while (count < maxblocks && count <= blocks_to_boundary) {
                  ext2_fsblk_t blk;

                  if (!verify_chain(chain, partial)) {
                        /*
                         * Indirect block might be removed by
                         * truncate while we were reading it.
                         * Handling of that case: forget what we've
                         * got now, go to reread.
                         */
                        count = 0;
                        goto changed;
                  }
                  blk = le32_to_cpu(*(chain[depth-1].p + count));
                  if (blk == first_block + count)
                        count++;
                  else
                        break;
            }
            goto got_it;
      }

      /* Next simple case - plain lookup or failed read of indirect block */
      if (!create || err == -EIO)
            goto cleanup;

      mutex_lock(&ei->truncate_mutex);

      /*
       * Okay, we need to do block allocation.  Lazily initialize the block
       * allocation info here if necessary
      */
      if (S_ISREG(inode->i_mode) && (!ei->i_block_alloc_info))
            ext2_init_block_alloc_info(inode);

      goal = ext2_find_goal(inode, iblock, chain, partial);

      /* the number of blocks need to allocate for [d,t]indirect blocks */
      indirect_blks = (chain + depth) - partial - 1;
      /*
       * Next look up the indirect map to count the totoal number of
       * direct blocks to allocate for this branch.
       */
      count = ext2_blks_to_allocate(partial, indirect_blks,
                              maxblocks, blocks_to_boundary);
      /*
       * XXX ???? Block out ext2_truncate while we alter the tree
       */
      err = ext2_alloc_branch(inode, indirect_blks, &count, goal,
                        offsets + (partial - chain), partial);

      if (err) {
            mutex_unlock(&ei->truncate_mutex);
            goto cleanup;
      }

      if (ext2_use_xip(inode->i_sb)) {
            /*
             * we need to clear the block
             */
            err = ext2_clear_xip_target (inode,
                  le32_to_cpu(chain[depth-1].key));
            if (err) {
                  mutex_unlock(&ei->truncate_mutex);
                  goto cleanup;
            }
      }

      ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
      mutex_unlock(&ei->truncate_mutex);
      set_buffer_new(bh_result);
got_it:
      map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
      if (count > blocks_to_boundary)
            set_buffer_boundary(bh_result);
      err = count;
      /* Clean up and exit */
      partial = chain + depth - 1;  /* the whole chain */
cleanup:
      while (partial > chain) {
            brelse(partial->bh);
            partial--;
      }
      return err;
changed:
      while (partial > chain) {
            brelse(partial->bh);
            partial--;
      }
      goto reread;
}

int ext2_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create)
{
      unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
      int ret = ext2_get_blocks(inode, iblock, max_blocks,
                        bh_result, create);
      if (ret > 0) {
            bh_result->b_size = (ret << inode->i_blkbits);
            ret = 0;
      }
      return ret;

}

static int ext2_writepage(struct page *page, struct writeback_control *wbc)
{
      return block_write_full_page(page, ext2_get_block, wbc);
}

static int ext2_readpage(struct file *file, struct page *page)
{
      return mpage_readpage(page, ext2_get_block);
}

static int
ext2_readpages(struct file *file, struct address_space *mapping,
            struct list_head *pages, unsigned nr_pages)
{
      return mpage_readpages(mapping, pages, nr_pages, ext2_get_block);
}

int __ext2_write_begin(struct file *file, struct address_space *mapping,
            loff_t pos, unsigned len, unsigned flags,
            struct page **pagep, void **fsdata)
{
      return block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
                                          ext2_get_block);
}

static int
ext2_write_begin(struct file *file, struct address_space *mapping,
            loff_t pos, unsigned len, unsigned flags,
            struct page **pagep, void **fsdata)
{
      *pagep = NULL;
      return __ext2_write_begin(file, mapping, pos, len, flags, pagep,fsdata);
}

static int
ext2_nobh_write_begin(struct file *file, struct address_space *mapping,
            loff_t pos, unsigned len, unsigned flags,
            struct page **pagep, void **fsdata)
{
      /*
       * Dir-in-pagecache still uses ext2_write_begin. Would have to rework
       * directory handling code to pass around offsets rather than struct
       * pages in order to make this work easily.
       */
      return nobh_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
                                          ext2_get_block);
}

static int ext2_nobh_writepage(struct page *page,
                  struct writeback_control *wbc)
{
      return nobh_writepage(page, ext2_get_block, wbc);
}

static sector_t ext2_bmap(struct address_space *mapping, sector_t block)
{
      return generic_block_bmap(mapping,block,ext2_get_block);
}

static ssize_t
ext2_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
                  loff_t offset, unsigned long nr_segs)
{
      struct file *file = iocb->ki_filp;
      struct inode *inode = file->f_mapping->host;

      return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
                        offset, nr_segs, ext2_get_block, NULL);
}

static int
ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
{
      return mpage_writepages(mapping, wbc, ext2_get_block);
}

const struct address_space_operations ext2_aops = {
      .readpage         = ext2_readpage,
      .readpages        = ext2_readpages,
      .writepage        = ext2_writepage,
      .sync_page        = block_sync_page,
      .write_begin            = ext2_write_begin,
      .write_end        = generic_write_end,
      .bmap             = ext2_bmap,
      .direct_IO        = ext2_direct_IO,
      .writepages       = ext2_writepages,
      .migratepage            = buffer_migrate_page,
};

const struct address_space_operations ext2_aops_xip = {
      .bmap             = ext2_bmap,
      .get_xip_page           = ext2_get_xip_page,
};

const struct address_space_operations ext2_nobh_aops = {
      .readpage         = ext2_readpage,
      .readpages        = ext2_readpages,
      .writepage        = ext2_nobh_writepage,
      .sync_page        = block_sync_page,
      .write_begin            = ext2_nobh_write_begin,
      .write_end        = nobh_write_end,
      .bmap             = ext2_bmap,
      .direct_IO        = ext2_direct_IO,
      .writepages       = ext2_writepages,
      .migratepage            = buffer_migrate_page,
};

/*
 * Probably it should be a library function... search for first non-zero word
 * or memcmp with zero_page, whatever is better for particular architecture.
 * Linus?
 */
static inline int all_zeroes(__le32 *p, __le32 *q)
{
      while (p < q)
            if (*p++)
                  return 0;
      return 1;
}

/**
 *    ext2_find_shared - find the indirect blocks for partial truncation.
 *    @inode:       inode in question
 *    @depth:       depth of the affected branch
 *    @offsets: offsets of pointers in that branch (see ext2_block_to_path)
 *    @chain:       place to store the pointers to partial indirect blocks
 *    @top:   place to the (detached) top of branch
 *
 *    This is a helper function used by ext2_truncate().
 *
 *    When we do truncate() we may have to clean the ends of several indirect
 *    blocks but leave the blocks themselves alive. Block is partially
 *    truncated if some data below the new i_size is refered from it (and
 *    it is on the path to the first completely truncated data block, indeed).
 *    We have to free the top of that path along with everything to the right
 *    of the path. Since no allocation past the truncation point is possible
 *    until ext2_truncate() finishes, we may safely do the latter, but top
 *    of branch may require special attention - pageout below the truncation
 *    point might try to populate it.
 *
 *    We atomically detach the top of branch from the tree, store the block
 *    number of its root in *@top, pointers to buffer_heads of partially
 *    truncated blocks - in @chain[].bh and pointers to their last elements
 *    that should not be removed - in @chain[].p. Return value is the pointer
 *    to last filled element of @chain.
 *
 *    The work left to caller to do the actual freeing of subtrees:
 *          a) free the subtree starting from *@top
 *          b) free the subtrees whose roots are stored in
 *                (@chain[i].p+1 .. end of @chain[i].bh->b_data)
 *          c) free the subtrees growing from the inode past the @chain[0].p
 *                (no partially truncated stuff there).
 */

static Indirect *ext2_find_shared(struct inode *inode,
                        int depth,
                        int offsets[4],
                        Indirect chain[4],
                        __le32 *top)
{
      Indirect *partial, *p;
      int k, err;

      *top = 0;
      for (k = depth; k > 1 && !offsets[k-1]; k--)
            ;
      partial = ext2_get_branch(inode, k, offsets, chain, &err);
      if (!partial)
            partial = chain + k-1;
      /*
       * If the branch acquired continuation since we've looked at it -
       * fine, it should all survive and (new) top doesn't belong to us.
       */
      write_lock(&EXT2_I(inode)->i_meta_lock);
      if (!partial->key && *partial->p) {
            write_unlock(&EXT2_I(inode)->i_meta_lock);
            goto no_top;
      }
      for (p=partial; p>chain && all_zeroes((__le32*)p->bh->b_data,p->p); p--)
            ;
      /*
       * OK, we've found the last block that must survive. The rest of our
       * branch should be detached before unlocking. However, if that rest
       * of branch is all ours and does not grow immediately from the inode
       * it's easier to cheat and just decrement partial->p.
       */
      if (p == chain + k - 1 && p > chain) {
            p->p--;
      } else {
            *top = *p->p;
            *p->p = 0;
      }
      write_unlock(&EXT2_I(inode)->i_meta_lock);

      while(partial > p)
      {
            brelse(partial->bh);
            partial--;
      }
no_top:
      return partial;
}

/**
 *    ext2_free_data - free a list of data blocks
 *    @inode:     inode we are dealing with
 *    @p:   array of block numbers
 *    @q:   points immediately past the end of array
 *
 *    We are freeing all blocks refered from that array (numbers are
 *    stored as little-endian 32-bit) and updating @inode->i_blocks
 *    appropriately.
 */
static inline void ext2_free_data(struct inode *inode, __le32 *p, __le32 *q)
{
      unsigned long block_to_free = 0, count = 0;
      unsigned long nr;

      for ( ; p < q ; p++) {
            nr = le32_to_cpu(*p);
            if (nr) {
                  *p = 0;
                  /* accumulate blocks to free if they're contiguous */
                  if (count == 0)
                        goto free_this;
                  else if (block_to_free == nr - count)
                        count++;
                  else {
                        mark_inode_dirty(inode);
                        ext2_free_blocks (inode, block_to_free, count);
                  free_this:
                        block_to_free = nr;
                        count = 1;
                  }
            }
      }
      if (count > 0) {
            mark_inode_dirty(inode);
            ext2_free_blocks (inode, block_to_free, count);
      }
}

/**
 *    ext2_free_branches - free an array of branches
 *    @inode:     inode we are dealing with
 *    @p:   array of block numbers
 *    @q:   pointer immediately past the end of array
 *    @depth:     depth of the branches to free
 *
 *    We are freeing all blocks refered from these branches (numbers are
 *    stored as little-endian 32-bit) and updating @inode->i_blocks
 *    appropriately.
 */
static void ext2_free_branches(struct inode *inode, __le32 *p, __le32 *q, int depth)
{
      struct buffer_head * bh;
      unsigned long nr;

      if (depth--) {
            int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
            for ( ; p < q ; p++) {
                  nr = le32_to_cpu(*p);
                  if (!nr)
                        continue;
                  *p = 0;
                  bh = sb_bread(inode->i_sb, nr);
                  /*
                   * A read failure? Report error and clear slot
                   * (should be rare).
                   */ 
                  if (!bh) {
                        ext2_error(inode->i_sb, "ext2_free_branches",
                              "Read failure, inode=%ld, block=%ld",
                              inode->i_ino, nr);
                        continue;
                  }
                  ext2_free_branches(inode,
                                 (__le32*)bh->b_data,
                                 (__le32*)bh->b_data + addr_per_block,
                                 depth);
                  bforget(bh);
                  ext2_free_blocks(inode, nr, 1);
                  mark_inode_dirty(inode);
            }
      } else
            ext2_free_data(inode, p, q);
}

void ext2_truncate(struct inode *inode)
{
      __le32 *i_data = EXT2_I(inode)->i_data;
      struct ext2_inode_info *ei = EXT2_I(inode);
      int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
      int offsets[4];
      Indirect chain[4];
      Indirect *partial;
      __le32 nr = 0;
      int n;
      long iblock;
      unsigned blocksize;

      if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
          S_ISLNK(inode->i_mode)))
            return;
      if (ext2_inode_is_fast_symlink(inode))
            return;
      if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
            return;

      blocksize = inode->i_sb->s_blocksize;
      iblock = (inode->i_size + blocksize-1)
                              >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);

      if (mapping_is_xip(inode->i_mapping))
            xip_truncate_page(inode->i_mapping, inode->i_size);
      else if (test_opt(inode->i_sb, NOBH))
            nobh_truncate_page(inode->i_mapping,
                        inode->i_size, ext2_get_block);
      else
            block_truncate_page(inode->i_mapping,
                        inode->i_size, ext2_get_block);

      n = ext2_block_to_path(inode, iblock, offsets, NULL);
      if (n == 0)
            return;

      /*
       * From here we block out all ext2_get_block() callers who want to
       * modify the block allocation tree.
       */
      mutex_lock(&ei->truncate_mutex);

      if (n == 1) {
            ext2_free_data(inode, i_data+offsets[0],
                              i_data + EXT2_NDIR_BLOCKS);
            goto do_indirects;
      }

      partial = ext2_find_shared(inode, n, offsets, chain, &nr);
      /* Kill the top of shared branch (already detached) */
      if (nr) {
            if (partial == chain)
                  mark_inode_dirty(inode);
            else
                  mark_buffer_dirty_inode(partial->bh, inode);
            ext2_free_branches(inode, &nr, &nr+1, (chain+n-1) - partial);
      }
      /* Clear the ends of indirect blocks on the shared branch */
      while (partial > chain) {
            ext2_free_branches(inode,
                           partial->p + 1,
                           (__le32*)partial->bh->b_data+addr_per_block,
                           (chain+n-1) - partial);
            mark_buffer_dirty_inode(partial->bh, inode);
            brelse (partial->bh);
            partial--;
      }
do_indirects:
      /* Kill the remaining (whole) subtrees */
      switch (offsets[0]) {
            default:
                  nr = i_data[EXT2_IND_BLOCK];
                  if (nr) {
                        i_data[EXT2_IND_BLOCK] = 0;
                        mark_inode_dirty(inode);
                        ext2_free_branches(inode, &nr, &nr+1, 1);
                  }
            case EXT2_IND_BLOCK:
                  nr = i_data[EXT2_DIND_BLOCK];
                  if (nr) {
                        i_data[EXT2_DIND_BLOCK] = 0;
                        mark_inode_dirty(inode);
                        ext2_free_branches(inode, &nr, &nr+1, 2);
                  }
            case EXT2_DIND_BLOCK:
                  nr = i_data[EXT2_TIND_BLOCK];
                  if (nr) {
                        i_data[EXT2_TIND_BLOCK] = 0;
                        mark_inode_dirty(inode);
                        ext2_free_branches(inode, &nr, &nr+1, 3);
                  }
            case EXT2_TIND_BLOCK:
                  ;
      }

      ext2_discard_reservation(inode);

      mutex_unlock(&ei->truncate_mutex);
      inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
      if (inode_needs_sync(inode)) {
            sync_mapping_buffers(inode->i_mapping);
            ext2_sync_inode (inode);
      } else {
            mark_inode_dirty(inode);
      }
}

static struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,
                              struct buffer_head **p)
{
      struct buffer_head * bh;
      unsigned long block_group;
      unsigned long block;
      unsigned long offset;
      struct ext2_group_desc * gdp;

      *p = NULL;
      if ((ino != EXT2_ROOT_INO && ino < EXT2_FIRST_INO(sb)) ||
          ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
            goto Einval;

      block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb);
      gdp = ext2_get_group_desc(sb, block_group, NULL);
      if (!gdp)
            goto Egdp;
      /*
       * Figure out the offset within the block group inode table
       */
      offset = ((ino - 1) % EXT2_INODES_PER_GROUP(sb)) * EXT2_INODE_SIZE(sb);
      block = le32_to_cpu(gdp->bg_inode_table) +
            (offset >> EXT2_BLOCK_SIZE_BITS(sb));
      if (!(bh = sb_bread(sb, block)))
            goto Eio;

      *p = bh;
      offset &= (EXT2_BLOCK_SIZE(sb) - 1);
      return (struct ext2_inode *) (bh->b_data + offset);

Einval:
      ext2_error(sb, "ext2_get_inode", "bad inode number: %lu",
               (unsigned long) ino);
      return ERR_PTR(-EINVAL);
Eio:
      ext2_error(sb, "ext2_get_inode",
               "unable to read inode block - inode=%lu, block=%lu",
               (unsigned long) ino, block);
Egdp:
      return ERR_PTR(-EIO);
}

void ext2_set_inode_flags(struct inode *inode)
{
      unsigned int flags = EXT2_I(inode)->i_flags;

      inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
      if (flags & EXT2_SYNC_FL)
            inode->i_flags |= S_SYNC;
      if (flags & EXT2_APPEND_FL)
            inode->i_flags |= S_APPEND;
      if (flags & EXT2_IMMUTABLE_FL)
            inode->i_flags |= S_IMMUTABLE;
      if (flags & EXT2_NOATIME_FL)
            inode->i_flags |= S_NOATIME;
      if (flags & EXT2_DIRSYNC_FL)
            inode->i_flags |= S_DIRSYNC;
}

/* Propagate flags from i_flags to EXT2_I(inode)->i_flags */
void ext2_get_inode_flags(struct ext2_inode_info *ei)
{
      unsigned int flags = ei->vfs_inode.i_flags;

      ei->i_flags &= ~(EXT2_SYNC_FL|EXT2_APPEND_FL|
                  EXT2_IMMUTABLE_FL|EXT2_NOATIME_FL|EXT2_DIRSYNC_FL);
      if (flags & S_SYNC)
            ei->i_flags |= EXT2_SYNC_FL;
      if (flags & S_APPEND)
            ei->i_flags |= EXT2_APPEND_FL;
      if (flags & S_IMMUTABLE)
            ei->i_flags |= EXT2_IMMUTABLE_FL;
      if (flags & S_NOATIME)
            ei->i_flags |= EXT2_NOATIME_FL;
      if (flags & S_DIRSYNC)
            ei->i_flags |= EXT2_DIRSYNC_FL;
}

void ext2_read_inode (struct inode * inode)
{
      struct ext2_inode_info *ei = EXT2_I(inode);
      ino_t ino = inode->i_ino;
      struct buffer_head * bh;
      struct ext2_inode * raw_inode = ext2_get_inode(inode->i_sb, ino, &bh);
      int n;

#ifdef CONFIG_EXT2_FS_POSIX_ACL
      ei->i_acl = EXT2_ACL_NOT_CACHED;
      ei->i_default_acl = EXT2_ACL_NOT_CACHED;
#endif
      ei->i_block_alloc_info = NULL;

      if (IS_ERR(raw_inode))
            goto bad_inode;

      inode->i_mode = le16_to_cpu(raw_inode->i_mode);
      inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
      inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
      if (!(test_opt (inode->i_sb, NO_UID32))) {
            inode->i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
            inode->i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
      }
      inode->i_nlink = le16_to_cpu(raw_inode->i_links_count);
      inode->i_size = le32_to_cpu(raw_inode->i_size);
      inode->i_atime.tv_sec = (signed)le32_to_cpu(raw_inode->i_atime);
      inode->i_ctime.tv_sec = (signed)le32_to_cpu(raw_inode->i_ctime);
      inode->i_mtime.tv_sec = (signed)le32_to_cpu(raw_inode->i_mtime);
      inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
      ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
      /* We now have enough fields to check if the inode was active or not.
       * This is needed because nfsd might try to access dead inodes
       * the test is that same one that e2fsck uses
       * NeilBrown 1999oct15
       */
      if (inode->i_nlink == 0 && (inode->i_mode == 0 || ei->i_dtime)) {
            /* this inode is deleted */
            brelse (bh);
            goto bad_inode;
      }
      inode->i_blocks = le32_to_cpu(raw_inode->i_blocks);
      ei->i_flags = le32_to_cpu(raw_inode->i_flags);
      ei->i_faddr = le32_to_cpu(raw_inode->i_faddr);
      ei->i_frag_no = raw_inode->i_frag;
      ei->i_frag_size = raw_inode->i_fsize;
      ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl);
      ei->i_dir_acl = 0;
      if (S_ISREG(inode->i_mode))
            inode->i_size |= ((__u64)le32_to_cpu(raw_inode->i_size_high)) << 32;
      else
            ei->i_dir_acl = le32_to_cpu(raw_inode->i_dir_acl);
      ei->i_dtime = 0;
      inode->i_generation = le32_to_cpu(raw_inode->i_generation);
      ei->i_state = 0;
      ei->i_block_group = (ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);
      ei->i_dir_start_lookup = 0;

      /*
       * NOTE! The in-memory inode i_data array is in little-endian order
       * even on big-endian machines: we do NOT byteswap the block numbers!
       */
      for (n = 0; n < EXT2_N_BLOCKS; n++)
            ei->i_data[n] = raw_inode->i_block[n];

      if (S_ISREG(inode->i_mode)) {
            inode->i_op = &ext2_file_inode_operations;
            if (ext2_use_xip(inode->i_sb)) {
                  inode->i_mapping->a_ops = &ext2_aops_xip;
                  inode->i_fop = &ext2_xip_file_operations;
            } else if (test_opt(inode->i_sb, NOBH)) {
                  inode->i_mapping->a_ops = &ext2_nobh_aops;
                  inode->i_fop = &ext2_file_operations;
            } else {
                  inode->i_mapping->a_ops = &ext2_aops;
                  inode->i_fop = &ext2_file_operations;
            }
      } else if (S_ISDIR(inode->i_mode)) {
            inode->i_op = &ext2_dir_inode_operations;
            inode->i_fop = &ext2_dir_operations;
            if (test_opt(inode->i_sb, NOBH))
                  inode->i_mapping->a_ops = &ext2_nobh_aops;
            else
                  inode->i_mapping->a_ops = &ext2_aops;
      } else if (S_ISLNK(inode->i_mode)) {
            if (ext2_inode_is_fast_symlink(inode))
                  inode->i_op = &ext2_fast_symlink_inode_operations;
            else {
                  inode->i_op = &ext2_symlink_inode_operations;
                  if (test_opt(inode->i_sb, NOBH))
                        inode->i_mapping->a_ops = &ext2_nobh_aops;
                  else
                        inode->i_mapping->a_ops = &ext2_aops;
            }
      } else {
            inode->i_op = &ext2_special_inode_operations;
            if (raw_inode->i_block[0])
                  init_special_inode(inode, inode->i_mode,
                     old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
            else 
                  init_special_inode(inode, inode->i_mode,
                     new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
      }
      brelse (bh);
      ext2_set_inode_flags(inode);
      return;
      
bad_inode:
      make_bad_inode(inode);
      return;
}

static int ext2_update_inode(struct inode * inode, int do_sync)
{
      struct ext2_inode_info *ei = EXT2_I(inode);
      struct super_block *sb = inode->i_sb;
      ino_t ino = inode->i_ino;
      uid_t uid = inode->i_uid;
      gid_t gid = inode->i_gid;
      struct buffer_head * bh;
      struct ext2_inode * raw_inode = ext2_get_inode(sb, ino, &bh);
      int n;
      int err = 0;

      if (IS_ERR(raw_inode))
            return -EIO;

      /* For fields not not tracking in the in-memory inode,
       * initialise them to zero for new inodes. */
      if (ei->i_state & EXT2_STATE_NEW)
            memset(raw_inode, 0, EXT2_SB(sb)->s_inode_size);

      ext2_get_inode_flags(ei);
      raw_inode->i_mode = cpu_to_le16(inode->i_mode);
      if (!(test_opt(sb, NO_UID32))) {
            raw_inode->i_uid_low = cpu_to_le16(low_16_bits(uid));
            raw_inode->i_gid_low = cpu_to_le16(low_16_bits(gid));
/*
 * Fix up interoperability with old kernels. Otherwise, old inodes get
 * re-used with the upper 16 bits of the uid/gid intact
 */
            if (!ei->i_dtime) {
                  raw_inode->i_uid_high = cpu_to_le16(high_16_bits(uid));
                  raw_inode->i_gid_high = cpu_to_le16(high_16_bits(gid));
            } else {
                  raw_inode->i_uid_high = 0;
                  raw_inode->i_gid_high = 0;
            }
      } else {
            raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(uid));
            raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(gid));
            raw_inode->i_uid_high = 0;
            raw_inode->i_gid_high = 0;
      }
      raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
      raw_inode->i_size = cpu_to_le32(inode->i_size);
      raw_inode->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
      raw_inode->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
      raw_inode->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);

      raw_inode->i_blocks = cpu_to_le32(inode->i_blocks);
      raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
      raw_inode->i_flags = cpu_to_le32(ei->i_flags);
      raw_inode->i_faddr = cpu_to_le32(ei->i_faddr);
      raw_inode->i_frag = ei->i_frag_no;
      raw_inode->i_fsize = ei->i_frag_size;
      raw_inode->i_file_acl = cpu_to_le32(ei->i_file_acl);
      if (!S_ISREG(inode->i_mode))
            raw_inode->i_dir_acl = cpu_to_le32(ei->i_dir_acl);
      else {
            raw_inode->i_size_high = cpu_to_le32(inode->i_size >> 32);
            if (inode->i_size > 0x7fffffffULL) {
                  if (!EXT2_HAS_RO_COMPAT_FEATURE(sb,
                              EXT2_FEATURE_RO_COMPAT_LARGE_FILE) ||
                      EXT2_SB(sb)->s_es->s_rev_level ==
                              cpu_to_le32(EXT2_GOOD_OLD_REV)) {
                         /* If this is the first large file
                        * created, add a flag to the superblock.
                        */
                        lock_kernel();
                        ext2_update_dynamic_rev(sb);
                        EXT2_SET_RO_COMPAT_FEATURE(sb,
                              EXT2_FEATURE_RO_COMPAT_LARGE_FILE);
                        unlock_kernel();
                        ext2_write_super(sb);
                  }
            }
      }
      
      raw_inode->i_generation = cpu_to_le32(inode->i_generation);
      if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
            if (old_valid_dev(inode->i_rdev)) {
                  raw_inode->i_block[0] =
                        cpu_to_le32(old_encode_dev(inode->i_rdev));
                  raw_inode->i_block[1] = 0;
            } else {
                  raw_inode->i_block[0] = 0;
                  raw_inode->i_block[1] =
                        cpu_to_le32(new_encode_dev(inode->i_rdev));
                  raw_inode->i_block[2] = 0;
            }
      } else for (n = 0; n < EXT2_N_BLOCKS; n++)
            raw_inode->i_block[n] = ei->i_data[n];
      mark_buffer_dirty(bh);
      if (do_sync) {
            sync_dirty_buffer(bh);
            if (buffer_req(bh) && !buffer_uptodate(bh)) {
                  printk ("IO error syncing ext2 inode [%s:%08lx]\n",
                        sb->s_id, (unsigned long) ino);
                  err = -EIO;
            }
      }
      ei->i_state &= ~EXT2_STATE_NEW;
      brelse (bh);
      return err;
}

int ext2_write_inode(struct inode *inode, int wait)
{
      return ext2_update_inode(inode, wait);
}

int ext2_sync_inode(struct inode *inode)
{
      struct writeback_control wbc = {
            .sync_mode = WB_SYNC_ALL,
            .nr_to_write = 0, /* sys_fsync did this */
      };
      return sync_inode(inode, &wbc);
}

int ext2_setattr(struct dentry *dentry, struct iattr *iattr)
{
      struct inode *inode = dentry->d_inode;
      int error;

      error = inode_change_ok(inode, iattr);
      if (error)
            return error;
      if ((iattr->ia_valid & ATTR_UID && iattr->ia_uid != inode->i_uid) ||
          (iattr->ia_valid & ATTR_GID && iattr->ia_gid != inode->i_gid)) {
            error = DQUOT_TRANSFER(inode, iattr) ? -EDQUOT : 0;
            if (error)
                  return error;
      }
      error = inode_setattr(inode, iattr);
      if (!error && (iattr->ia_valid & ATTR_MODE))
            error = ext2_acl_chmod(inode);
      return error;
}

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