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bmap.c

/******************************************************************************
*******************************************************************************
**
**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
**  Copyright (C) 2004 Red Hat, Inc.  All rights reserved.
**
**  This copyrighted material is made available to anyone wishing to use,
**  modify, copy, or redistribute it subject to the terms and conditions
**  of the GNU General Public License v.2.
**
*******************************************************************************
******************************************************************************/

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/spinlock.h>
#include <asm/semaphore.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>

#include "gfs.h"
#include "bmap.h"
#include "dio.h"
#include "glock.h"
#include "inode.h"
#include "quota.h"
#include "rgrp.h"
#include "trans.h"

struct metapath {
      unsigned int mp_list[GFS_MAX_META_HEIGHT];
};

typedef int (*block_call_t) (struct gfs_inode *ip, struct buffer_head *dibh,
                       struct buffer_head *bh, uint64_t *top,
                       uint64_t *bottom, unsigned int height,
                       void *data);

struct strip_mine {
      int sm_first;
      unsigned int sm_height;
};

/**
 * gfs_unstuffer_sync - unstuff a dinode synchronously
 * @ip: the inode
 * @dibh: the dinode buffer
 * @block: the block number that was allocated
 * @private: not used
 *
 * Returns: errno
 */

int
gfs_unstuffer_sync(struct gfs_inode *ip, struct buffer_head *dibh,
               uint64_t block, void *private)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      struct buffer_head *bh;
      int error;

      error = gfs_get_data_buffer(ip, block, TRUE, &bh);
      if (error)
            return error;

      gfs_buffer_copy_tail(bh, 0, dibh, sizeof(struct gfs_dinode));

      error = gfs_dwrite(sdp, bh, DIO_DIRTY | DIO_START | DIO_WAIT);

      brelse(bh);

      return error;
}

/**
 * gfs_unstuffer_async - unstuff a dinode asynchronously
 * @ip: the inode
 * @dibh: the dinode buffer
 * @block: the block number that was allocated
 * @private: not used
 *
 * Returns: errno
 */

int
gfs_unstuffer_async(struct gfs_inode *ip, struct buffer_head *dibh,
                uint64_t block, void *private)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      struct buffer_head *bh;
      int error;

      error = gfs_get_data_buffer(ip, block, TRUE, &bh);
      if (error)
            return error;

      gfs_buffer_copy_tail(bh, 0, dibh, sizeof(struct gfs_dinode));

      error = gfs_dwrite(sdp, bh, DIO_DIRTY);

      brelse(bh);

      return error;
}

/**
 * gfs_unstuff_dinode - Unstuff a dinode when the data has grown too big
 * @ip: The GFS inode to unstuff
 * @unstuffer: the routine that handles unstuffing a non-zero length file
 * @private: private data for the unstuffer
 *
 * This routine unstuffs a dinode and returns it to a "normal" state such 
 * that the height can be grown in the traditional way.
 *
 * Returns: errno
 */

int
gfs_unstuff_dinode(struct gfs_inode *ip, gfs_unstuffer_t unstuffer,
               void *private)
{
      struct buffer_head *bh, *dibh;
      uint64_t block = 0;
      int journaled = gfs_is_jdata(ip);
      int error;

      down_write(&ip->i_rw_mutex);
 
      error = gfs_get_inode_buffer(ip, &dibh);
      if (error)
            goto out;

      if (ip->i_di.di_size) {
            /* Get a free block, fill it with the stuffed data,
               and write it out to disk */

            if (journaled) {
                  error = gfs_metaalloc(ip, &block);
                  if (error)
                        goto out_brelse;

                  error = gfs_get_data_buffer(ip, block, TRUE, &bh);
                  if (error)
                        goto out_brelse;

                  gfs_buffer_copy_tail(bh, sizeof(struct gfs_meta_header),
                                   dibh, sizeof(struct gfs_dinode));

                  brelse(bh);
            } else {
                  gfs_blkalloc(ip, &block);

                  error = unstuffer(ip, dibh, block, private);
                  if (error)
                        goto out_brelse;
            }
      }

      /*  Set up the pointer to the new block  */

      gfs_trans_add_bh(ip->i_gl, dibh);

      gfs_buffer_clear_tail(dibh, sizeof(struct gfs_dinode));

      if (ip->i_di.di_size) {
            *(uint64_t *)(dibh->b_data + sizeof(struct gfs_dinode)) = cpu_to_gfs64(block);
            ip->i_di.di_blocks++;
      }

      ip->i_di.di_height = 1;

      gfs_dinode_out(&ip->i_di, dibh->b_data);

 out_brelse:
      brelse(dibh);

 out:
      up_write(&ip->i_rw_mutex);

      return error;
}

/**
 * calc_tree_height - Calculate the height of a metadata tree
 * @ip: The GFS inode
 * @size: The proposed size of the file
 *
 * Work out how tall a metadata tree needs to be in order to accommodate a
 * file of a particular size. If size is less than the current size of
 * the inode, then the current size of the inode is used instead of the
 * supplied one.
 *
 * Returns: the height the tree should be
 */

static unsigned int
calc_tree_height(struct gfs_inode *ip, uint64_t size)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      uint64_t *arr;
      unsigned int max, height;

      if (ip->i_di.di_size > size)
            size = ip->i_di.di_size;

      if (gfs_is_jdata(ip)) {
            arr = sdp->sd_jheightsize;
            max = sdp->sd_max_jheight;
      } else {
            arr = sdp->sd_heightsize;
            max = sdp->sd_max_height;
      }

      for (height = 0; height < max; height++)
            if (arr[height] >= size)
                  break;

      return height;
}

/**
 * build_height - Build a metadata tree of the requested height
 * @ip: The GFS inode
 * @height: The height to build to
 *
 * This routine makes sure that the metadata tree is tall enough to hold
 * "size" bytes of data.
 *
 * Returns: errno
 */

static int
build_height(struct gfs_inode *ip, int height)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      struct buffer_head *bh, *dibh;
      uint64_t block, *bp;
      unsigned int x;
      int new_block;
      int error;

      while (ip->i_di.di_height < height) {
            error = gfs_get_inode_buffer(ip, &dibh);
            if (error)
                  return error;

            new_block = FALSE;
            bp = (uint64_t *)(dibh->b_data + sizeof(struct gfs_dinode));
            for (x = 0; x < sdp->sd_diptrs; x++, bp++)
                  if (*bp) {
                        new_block = TRUE;
                        break;
                  }

            if (new_block) {
                  /*  Get a new block, fill it with the old direct pointers,
                      and write it out  */

                  error = gfs_metaalloc(ip, &block);
                  if (error)
                        goto fail;

                  error = gfs_dread(ip->i_gl, block,
                                DIO_NEW | DIO_START | DIO_WAIT, &bh);
                  if (error)
                        goto fail;

                  gfs_trans_add_bh(ip->i_gl, bh);
                  gfs_metatype_set(bh,
                               GFS_METATYPE_IN,
                               GFS_FORMAT_IN);
                  memset(bh->b_data + sizeof(struct gfs_meta_header),
                         0,
                         sizeof(struct gfs_indirect) -
                         sizeof(struct gfs_meta_header));
                  gfs_buffer_copy_tail(bh, sizeof(struct gfs_indirect),
                                   dibh, sizeof(struct gfs_dinode));

                  brelse(bh);
            }

            /*  Set up the new direct pointer and write it out to disk  */

            gfs_trans_add_bh(ip->i_gl, dibh);

            gfs_buffer_clear_tail(dibh, sizeof(struct gfs_dinode));

            if (new_block) {
                  *(uint64_t *)(dibh->b_data + sizeof(struct gfs_dinode)) = cpu_to_gfs64(block);
                  ip->i_di.di_blocks++;
            }

            ip->i_di.di_height++;

            gfs_dinode_out(&ip->i_di, dibh->b_data);
            brelse(dibh);
      }

      return 0;

 fail:
      brelse(dibh);

      return error;
}

/**
 * find_metapath - Find path through the metadata tree
 * @ip: The inode pointer
 * @mp: The metapath to return the result in
 * @block: The disk block to look up
 *
 *   This routine returns a struct metapath structure that defines a path through
 *   the metadata of inode "ip" to get to block "block".
 *
 *   Example:
 *   Given:  "ip" is a height 3 file, "offset" is 101342453, and this is a
 *   filesystem with a blocksize of 4096.
 *
 *   find_metapath() would return a struct metapath structure set to:
 *   mp_offset = 101342453, mp_height = 3, mp_list[0] = 0, mp_list[1] = 48,
 *   and mp_list[2] = 165.
 *
 *   That means that in order to get to the block containing the byte at
 *   offset 101342453, we would load the indirect block pointed to by pointer
 *   0 in the dinode.  We would then load the indirect block pointed to by
 *   pointer 48 in that indirect block.  We would then load the data block
 *   pointed to by pointer 165 in that indirect block.
 *
 *             ----------------------------------------
 *             | Dinode |                             |
 *             |        |                            4|
 *             |        |0 1 2 3 4 5                 9|
 *             |        |                            6|
 *             ----------------------------------------
 *                       |
 *                       |
 *                       V
 *             ----------------------------------------
 *             | Indirect Block                       |
 *             |                                     5|
 *             |            4 4 4 4 4 5 5            1|
 *             |0           5 6 7 8 9 0 1            2|
 *             ----------------------------------------
 *                                |
 *                                |
 *                                V
 *             ----------------------------------------
 *             | Indirect Block                       |
 *             |                         1 1 1 1 1   5|
 *             |                         6 6 6 6 6   1|
 *             |0                        3 4 5 6 7   2|
 *             ----------------------------------------
 *                                           |
 *                                           |
 *                                           V
 *             ----------------------------------------
 *             | Data block containing offset         |
 *             |            101342453                 |
 *             |                                      |
 *             |                                      |
 *             ----------------------------------------
 *
 */

static struct metapath *
find_metapath(struct gfs_inode *ip, uint64_t block)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      struct metapath *mp;
      uint64_t b = block;
      unsigned int i;

      mp = gmalloc(sizeof(struct metapath));
      memset(mp, 0, sizeof(struct metapath));

      for (i = ip->i_di.di_height; i--;)
            mp->mp_list[i] = do_div(b, sdp->sd_inptrs);

      return mp;
}

/**
 * metapointer - Return pointer to start of metadata in a buffer
 * @bh: The buffer
 * @height: The metadata height (0 = dinode)
 * @mp: The metapath 
 *
 * Return a pointer to the block number of the next height of the metadata
 * tree given a buffer containing the pointer to the current height of the
 * metadata tree.
 */

static __inline__ uint64_t *
metapointer(struct buffer_head *bh, unsigned int height, struct metapath *mp)
{
      unsigned int head_size = (height > 0) ?
            sizeof(struct gfs_indirect) : sizeof(struct gfs_dinode);

      return ((uint64_t *)(bh->b_data + head_size)) + mp->mp_list[height];
}

/**
 * get_metablock - Get the next metadata block in metadata tree
 * @ip: The GFS inode
 * @bh: Buffer containing the pointers to metadata blocks
 * @height: The height of the tree (0 = dinode)
 * @mp: The metapath
 * @create: Non-zero if we may create a new meatdata block
 * @new: Used to indicate if we did create a new metadata block
 * @block: the returned disk block number
 *
 * Given a metatree, complete to a particular height, checks to see if the next
 * height of the tree exists. If not the next height of the tree is created.
 * The block number of the next height of the metadata tree is returned.
 *
 * Returns: errno
 */

static int
get_metablock(struct gfs_inode *ip,
            struct buffer_head *bh, unsigned int height, struct metapath *mp,
            int create, int *new, uint64_t *block)
{
      uint64_t *ptr = metapointer(bh, height, mp);
      int error;

      if (*ptr) {
            *block = gfs64_to_cpu(*ptr);
            return 0;
      }

      *block = 0;

      if (!create)
            return 0;

      error = gfs_metaalloc(ip, block);
      if (error)
            return error;

      gfs_trans_add_bh(ip->i_gl, bh);

      *ptr = cpu_to_gfs64(*block);
      ip->i_di.di_blocks++;

      *new = 1;

      return 0;
}

/**
 * get_datablock - Get datablock number from metadata block
 * @ip: The GFS inode
 * @bh: The buffer containing pointers to datablocks
 * @mp: The metapath
 * @create: Non-zero if we may create a new data block
 * @new: Used to indicate if we created a new data block
 * @block: the returned disk block number
 *
 * Given a fully built metadata tree, checks to see if a particular data
 * block exists. It is created if it does not exist and the block number
 * on disk is returned.
 *
 * Returns: errno
 */

static int
get_datablock(struct gfs_inode *ip,
            struct buffer_head *bh, struct metapath *mp,
            int create, int *new, uint64_t *block)
{
      uint64_t *ptr = metapointer(bh, ip->i_di.di_height - 1, mp);

      if (*ptr) {
            *block = gfs64_to_cpu(*ptr);
            return 0;
      }

      *block = 0;

      if (!create)
            return 0;

      if (gfs_is_jdata(ip)) {
            int error;
            error = gfs_metaalloc(ip, block);
            if (error)
                  return error;
      } else
            gfs_blkalloc(ip, block);

      gfs_trans_add_bh(ip->i_gl, bh);

      *ptr = cpu_to_gfs64(*block);
      ip->i_di.di_blocks++;

      *new = 1;

      return 0;
}

/**
 * gfs_block_map - Map a block from an inode to a disk block
 * @ip: The GFS inode
 * @lblock: The logical block number
 * @new: Value/Result argument (1 = may create/did create new blocks)
 * @dblock: the disk block number of the start of an extent
 * @extlen: the size of the extent
 *
 * Find the block number on the current device which corresponds to an
 * inode's block. If the block had to be created, "new" will be set.
 *
 * Returns: errno
 */

int
gfs_block_map(struct gfs_inode *ip,
            uint64_t lblock, int *new,
            uint64_t *dblock, uint32_t *extlen)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      struct buffer_head *bh;
      struct metapath *mp;
      int create = *new;
      unsigned int bsize;
      unsigned int height;
      unsigned int end_of_metadata;
      unsigned int x;
      int error = 0;

      *new = 0;
      *dblock = 0;
      if (extlen)
            *extlen = 0;

      if (create)
            down_write(&ip->i_rw_mutex);
      else
            down_read(&ip->i_rw_mutex);

      if (gfs_assert_warn(sdp, !gfs_is_stuffed(ip)))
            goto out;

      bsize = (gfs_is_jdata(ip)) ? sdp->sd_jbsize : sdp->sd_sb.sb_bsize;

      height = calc_tree_height(ip, (lblock + 1) * bsize);
      if (ip->i_di.di_height < height) {
            if (!create)
                  goto out;

            error = build_height(ip, height);
            if (error)
                  goto out;
      }

      mp = find_metapath(ip, lblock);
      end_of_metadata = ip->i_di.di_height - 1;

      error = gfs_get_inode_buffer(ip, &bh);
      if (error)
            goto out_kfree;

      for (x = 0; x < end_of_metadata; x++) {
            error = get_metablock(ip, bh, x, mp, create, new, dblock);
            brelse(bh);
            if (error || !*dblock)
                  goto out_kfree;

            error = gfs_get_meta_buffer(ip, x + 1, *dblock, *new, &bh);
            if (error)
                  goto out_kfree;
      }

      error = get_datablock(ip, bh, mp, create, new, dblock);
      if (error) {
            brelse(bh);
            goto out_kfree;
      }

      if (extlen && *dblock) {
            *extlen = 1;

            if (!*new) {
                  uint64_t tmp_dblock;
                  int tmp_new;
                  unsigned int nptrs;

                  nptrs = (end_of_metadata) ? sdp->sd_inptrs : sdp->sd_diptrs;

                  while (++mp->mp_list[end_of_metadata] < nptrs) {
                        get_datablock(ip, bh, mp,
                                    FALSE, &tmp_new,
                                    &tmp_dblock);

                        if (*dblock + *extlen != tmp_dblock)
                              break;

                        (*extlen)++;
                  }
            }
      }

      brelse(bh);

      if (*new) {
            error = gfs_get_inode_buffer(ip, &bh);
            if (!error) {
                  gfs_trans_add_bh(ip->i_gl, bh);
                  gfs_dinode_out(&ip->i_di, bh->b_data);
                  brelse(bh);
            }
      }

 out_kfree:
      kfree(mp);

 out:
      if (create)
            up_write(&ip->i_rw_mutex);
      else
            up_read(&ip->i_rw_mutex);
 
      return error;
}

/**
 * do_grow - Make a file look bigger than it is
 * @ip: the inode
 * @size: the size to set the file to
 *
 * Called with an exclusive lock on @ip.
 *
 * Returns: errno
 */

static int
do_grow(struct gfs_inode *ip, uint64_t size)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      struct gfs_alloc *al;
      struct buffer_head *dibh;
      unsigned int h;
      int journaled = gfs_is_jdata(ip);
      int error;

      al = gfs_alloc_get(ip);

      error = gfs_quota_lock_m(ip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE);
      if (error)
            goto out;

      error = gfs_quota_check(ip, ip->i_di.di_uid, ip->i_di.di_gid);
      if (error)
            goto out_gunlock_q;

      if (journaled)
            al->al_requested_meta = sdp->sd_max_height + 1;
      else {
            al->al_requested_meta = sdp->sd_max_height;
            al->al_requested_data = 1;
      }

      error = gfs_inplace_reserve(ip);
      if (error)
            goto out_gunlock_q;

      /* Trans may require:
         Full extention of the metadata tree, block allocation,
         a dinode modification, and a quota change */

      error = gfs_trans_begin(sdp,
                        sdp->sd_max_height + al->al_rgd->rd_ri.ri_length +
                        1 + !!journaled,
                        1);
      if (error)
            goto out_ipres;

      if (size > sdp->sd_sb.sb_bsize - sizeof(struct gfs_dinode)) {
            if (gfs_is_stuffed(ip)) {
                  error = gfs_unstuff_dinode(ip, gfs_unstuffer_sync, NULL);
                  if (error)
                        goto out_end_trans;
            }

            h = calc_tree_height(ip, size);
            if (ip->i_di.di_height < h) {
                  down_write(&ip->i_rw_mutex);
                  error = build_height(ip, h);
                  up_write(&ip->i_rw_mutex);
                  if (error)
                        goto out_end_trans;
            }
      }

      ip->i_di.di_size = size;
      ip->i_di.di_mtime = ip->i_di.di_ctime = get_seconds();

      error = gfs_get_inode_buffer(ip, &dibh);
      if (error)
            goto out_end_trans;

      gfs_trans_add_bh(ip->i_gl, dibh);
      gfs_dinode_out(&ip->i_di, dibh->b_data);
      brelse(dibh);

 out_end_trans:
      gfs_trans_end(sdp);

 out_ipres:
      gfs_inplace_release(ip);

 out_gunlock_q:
      gfs_quota_unlock_m(ip);

 out:
      gfs_alloc_put(ip);

      return error;
}

/**
 * recursive_scan - recursively scan through the end of a file
 * @ip: the inode
 * @dibh: the dinode buffer
 * @mp: the path through the metadata to the point to start
 * @height: the height the recursion is at
 * @block: the indirect block to look at
 * @first: TRUE if this is the first block
 * @bc: the call to make for each piece of metadata
 * @data: data opaque to this function to pass to @bc
 *
 * When this is first called @height and @block should be zero and
 * @first should be TRUE.
 *
 * Returns: errno
 */

static int
recursive_scan(struct gfs_inode *ip, struct buffer_head *dibh,
             struct metapath *mp, unsigned int height, uint64_t block,
             int first, block_call_t bc, void *data)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      struct buffer_head *bh = NULL;
      uint64_t *top, *bottom;
      uint64_t bn;
      int error;

      if (!height) {
            error = gfs_get_inode_buffer(ip, &bh);
            if (error)
                  goto fail;
            dibh = bh;

            top = (uint64_t *)(bh->b_data + sizeof(struct gfs_dinode)) +
                  mp->mp_list[0];
            bottom = (uint64_t *)(bh->b_data + sizeof(struct gfs_dinode)) +
                  sdp->sd_diptrs;
      } else {
            error = gfs_get_meta_buffer(ip, height, block, FALSE, &bh);
            if (error)
                  goto fail;

            top = (uint64_t *)(bh->b_data + sizeof(struct gfs_indirect)) +
                  ((first) ? mp->mp_list[height] : 0);
            bottom = (uint64_t *)(bh->b_data + sizeof(struct gfs_indirect)) +
                  sdp->sd_inptrs;
      }

      error = bc(ip, dibh, bh, top, bottom, height, data);
      if (error)
            goto fail;

      if (height < ip->i_di.di_height - 1)
            for (; top < bottom; top++, first = FALSE) {
                  if (!*top)
                        continue;

                  bn = gfs64_to_cpu(*top);

                  error = recursive_scan(ip, dibh, mp,
                                     height + 1, bn, first,
                                     bc, data);
                  if (error)
                        goto fail;
            }

      brelse(bh);

      return 0;

 fail:
      if (bh)
            brelse(bh);

      return error;
}

/**
 * do_strip - Look for a layer a particular layer of the file and strip it off
 * @ip: the inode
 * @dibh: the dinode buffer
 * @bh: A buffer of pointers
 * @top: The first pointer in the buffer
 * @bottom: One more than the last pointer
 * @height: the height this buffer is at
 * @data: a pointer to a struct strip_mine
 *
 * Returns: errno
 */

static int
do_strip(struct gfs_inode *ip, struct buffer_head *dibh,
       struct buffer_head *bh, uint64_t *top, uint64_t *bottom,
       unsigned int height, void *data)
{
      struct strip_mine *sm = (struct strip_mine *)data;
      struct gfs_sbd *sdp = ip->i_sbd;
      struct gfs_rgrp_list rlist;
      uint64_t bn, bstart;
      uint32_t blen;
      uint64_t *p;
      unsigned int rg_blocks = 0;
      int metadata;
      int x;
      int error;

      if (!*top)
            sm->sm_first = FALSE;

      if (height != sm->sm_height)
            return 0;

      if (sm->sm_first) {
            top++;
            sm->sm_first = FALSE;
      }

      metadata = (height != ip->i_di.di_height - 1) || gfs_is_jdata(ip);

      error = gfs_rindex_hold(sdp, &ip->i_alloc->al_ri_gh);
      if (error)
            return error;

      memset(&rlist, 0, sizeof(struct gfs_rgrp_list));
      bstart = 0;
      blen = 0;

      for (p = top; p < bottom; p++) {
            if (!*p)
                  continue;

            bn = gfs64_to_cpu(*p);

            if (bstart + blen == bn)
                  blen++;
            else {
                  if (bstart)
                        gfs_rlist_add(sdp, &rlist, bstart);

                  bstart = bn;
                  blen = 1;
            }
      }

      if (bstart)
            gfs_rlist_add(sdp, &rlist, bstart);
      else
            goto out; /* Nothing to do */

      gfs_rlist_alloc(&rlist, LM_ST_EXCLUSIVE, 0);

      for (x = 0; x < rlist.rl_rgrps; x++) {
            struct gfs_rgrpd *rgd;
            rgd = get_gl2rgd(rlist.rl_ghs[x].gh_gl);
            rg_blocks += rgd->rd_ri.ri_length;
      }

      error = gfs_glock_nq_m(rlist.rl_rgrps, rlist.rl_ghs);
      if (error)
            goto out_rlist;

      /* Trans may require:
         All the bitmaps that were reserved. 
         One block for the dinode.
         One block for the indirect block being cleared.
         One block for a quota change. */

      error = gfs_trans_begin(sdp, rg_blocks + 2, 1);
      if (error)
            goto out_rg_gunlock;

      down_write(&ip->i_rw_mutex);

      gfs_trans_add_bh(ip->i_gl, dibh);
      gfs_trans_add_bh(ip->i_gl, bh);

      bstart = 0;
      blen = 0;

      for (p = top; p < bottom; p++) {
            if (!*p)
                  continue;

            bn = gfs64_to_cpu(*p);

            if (bstart + blen == bn)
                  blen++;
            else {
                  if (bstart) {
                        if (metadata)
                              gfs_metafree(ip, bstart, blen);
                        else
                              gfs_blkfree(ip, bstart, blen);
                  }

                  bstart = bn;
                  blen = 1;
            }

            *p = 0;
            if (!ip->i_di.di_blocks)
                  gfs_consist_inode(ip);
            ip->i_di.di_blocks--;
      }
      if (bstart) {
            if (metadata)
                  gfs_metafree(ip, bstart, blen);
            else
                  gfs_blkfree(ip, bstart, blen);
      }

      ip->i_di.di_mtime = ip->i_di.di_ctime = get_seconds();

      gfs_dinode_out(&ip->i_di, dibh->b_data);

      up_write(&ip->i_rw_mutex);

      gfs_trans_end(sdp);

 out_rg_gunlock:
      gfs_glock_dq_m(rlist.rl_rgrps, rlist.rl_ghs);

 out_rlist:
      gfs_rlist_free(&rlist);

 out:
      gfs_glock_dq_uninit(&ip->i_alloc->al_ri_gh);

      return error;
}

/**
 * gfs_truncator_default - truncate a partial data block
 * @ip: the inode
 * @size: the size the file should be
 *
 * Returns: errno
 */

int
gfs_truncator_default(struct gfs_inode *ip, uint64_t size)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      struct buffer_head *bh;
      uint64_t bn;
      int not_new = 0;
      int error;

      error = gfs_block_map(ip, size >> sdp->sd_sb.sb_bsize_shift, &not_new,
                        &bn, NULL);
      if (error)
            return error;
      if (!bn)
            return 0;

      error = gfs_get_data_buffer(ip, bn, FALSE, &bh);
      if (error)
            return error;

      gfs_buffer_clear_tail(bh, size & (sdp->sd_sb.sb_bsize - 1));

      error = gfs_dwrite(sdp, bh, DIO_DIRTY);

      brelse(bh);

      return error;
}

/**
 * truncator_journaled - truncate a partial data block
 * @ip: the inode
 * @size: the size the file should be
 *
 * Returns: errno
 */

static int
truncator_journaled(struct gfs_inode *ip, uint64_t size)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      struct buffer_head *bh;
      uint64_t lbn, dbn;
      uint32_t off;
      int not_new = 0;
      int error;

      lbn = size;
      off = do_div(lbn, sdp->sd_jbsize);

      error = gfs_block_map(ip, lbn, &not_new, &dbn, NULL);
      if (error)
            return error;
      if (!dbn)
            return 0;

      error = gfs_trans_begin(sdp, 1, 0);
      if (error)
            return error;

      error = gfs_get_data_buffer(ip, dbn, FALSE, &bh);
      if (!error) {
            gfs_trans_add_bh(ip->i_gl, bh);
            gfs_buffer_clear_tail(bh,
                              sizeof(struct gfs_meta_header) +
                              off);
            brelse(bh);
      }

      gfs_trans_end(sdp);

      return error;
}

/**
 * gfs_shrink - make a file smaller
 * @ip: the inode
 * @size: the size to make the file
 * @truncator: function to truncate the last partial block
 *
 * Called with an exclusive lock on @ip.
 *
 * Returns: errno
 */

int
gfs_shrink(struct gfs_inode *ip, uint64_t size, gfs_truncator_t truncator)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      struct gfs_holder ri_gh;
      struct gfs_rgrpd *rgd;
      struct buffer_head *dibh;
      uint64_t block;
      unsigned int height;
      int journaled = gfs_is_jdata(ip);
      int error;

      if (!size)
            block = 0;
      else if (journaled) {
            block = size - 1;
            do_div(block, sdp->sd_jbsize);
      }
      else
            block = (size - 1) >> sdp->sd_sb.sb_bsize_shift;

      /*  Get rid of all the data/metadata blocks  */

      height = ip->i_di.di_height;
      if (height) {
            struct metapath *mp = find_metapath(ip, block);
            gfs_alloc_get(ip);

            error = gfs_quota_hold_m(ip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE);
            if (error) {
                  gfs_alloc_put(ip);
                  kfree(mp);
                  return error;
            }

            while (height--) {
                  struct strip_mine sm;

                  sm.sm_first = (size) ? TRUE : FALSE;
                  sm.sm_height = height;

                  error = recursive_scan(ip, NULL, mp, 0, 0, TRUE,
                                     do_strip, &sm);
                  if (error) {
                        gfs_quota_unhold_m(ip);
                        gfs_alloc_put(ip);
                        kfree(mp);
                        return error;
                  }
            }

            gfs_quota_unhold_m(ip);
            gfs_alloc_put(ip);
            kfree(mp);
      }

      /*  If we truncated in the middle of a block, zero out the leftovers.  */

      if (gfs_is_stuffed(ip)) {
            /*  Do nothing  */
      } else if (journaled) {
            if (do_mod(size, sdp->sd_jbsize)) {
                  error = truncator_journaled(ip, size);
                  if (error)
                        return error;
            }
      } else if (size & (uint64_t)(sdp->sd_sb.sb_bsize - 1)) {
            error = truncator(ip, size);
            if (error)
                  return error;
      }

      /*  Set the new size (and possibly the height)  */

      if (!size) {
            error = gfs_rindex_hold(sdp, &ri_gh);
            if (error)
                  return error;
      }

      error = gfs_trans_begin(sdp, 1, 0);
      if (error)
            goto out;

      down_write(&ip->i_rw_mutex);

      error = gfs_get_inode_buffer(ip, &dibh);
      if (error)
            goto out_end_trans;

      if (!size) {
            ip->i_di.di_height = 0;

            rgd = gfs_blk2rgrpd(sdp, ip->i_num.no_addr);
            if (!rgd) {
                  gfs_consist_inode(ip);
                  error = -EIO;
                  goto out_end_trans;
            }

            ip->i_di.di_goal_rgrp = rgd->rd_ri.ri_addr;
            ip->i_di.di_goal_dblk =
                  ip->i_di.di_goal_mblk =
                  ip->i_num.no_addr - rgd->rd_ri.ri_data1;
      }

      ip->i_di.di_size = size;
      ip->i_di.di_mtime = ip->i_di.di_ctime = get_seconds();

      gfs_trans_add_bh(ip->i_gl, dibh);

      if (!ip->i_di.di_height &&
          size < sdp->sd_sb.sb_bsize - sizeof(struct gfs_dinode))
            gfs_buffer_clear_tail(dibh, sizeof(struct gfs_dinode) + size);

      gfs_dinode_out(&ip->i_di, dibh->b_data);
      brelse(dibh);

 out_end_trans:
      up_write(&ip->i_rw_mutex);

      gfs_trans_end(sdp);

 out:
      if (!size)
            gfs_glock_dq_uninit(&ri_gh);

      return error;
}

/**
 * do_same - truncate to same size (update time stamps)
 * @ip: 
 *
 * Returns: errno
 */

static int
do_same(struct gfs_inode *ip)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      struct buffer_head *dibh;
      int error;

      error = gfs_trans_begin(sdp, 1, 0);
      if (error)
            return error;

      error = gfs_get_inode_buffer(ip, &dibh);
      if (error)
            goto out;

      ip->i_di.di_mtime = ip->i_di.di_ctime = get_seconds();

      gfs_trans_add_bh(ip->i_gl, dibh);
      gfs_dinode_out(&ip->i_di, dibh->b_data);

      brelse(dibh);

 out:
      gfs_trans_end(sdp);

      return error;
}

/**
 * gfs_truncatei - make a file a give size
 * @ip: the inode
 * @size: the size to make the file
 * @truncator: function to truncate the last partial block
 *
 * The file size can grow, shrink, or stay the same size.
 *
 * Returns: errno
 */

int
gfs_truncatei(struct gfs_inode *ip, uint64_t size,
            gfs_truncator_t truncator)
{
      if (gfs_assert_warn(ip->i_sbd, ip->i_di.di_type == GFS_FILE_REG))
            return -EINVAL;

      if (size == ip->i_di.di_size)
            return do_same(ip);
      else if (size > ip->i_di.di_size)
            return do_grow(ip, size);
      else
            return gfs_shrink(ip, size, truncator);
}

/**
 * gfs_write_calc_reserv - calculate the number of blocks needed to write to a file
 * @ip: the file
 * @len: the number of bytes to be written to the file
 * @data_blocks: returns the number of data blocks required
 * @ind_blocks: returns the number of indirect blocks required
 *
 */

void
gfs_write_calc_reserv(struct gfs_inode *ip, unsigned int len,
                  unsigned int *data_blocks, unsigned int *ind_blocks)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      unsigned int tmp;

      if (gfs_is_jdata(ip)) {
            *data_blocks = DIV_RU(len, sdp->sd_jbsize) + 2;
            *ind_blocks = 3 * (sdp->sd_max_jheight - 1);
      } else {
            *data_blocks = (len >> sdp->sd_sb.sb_bsize_shift) + 3;
            *ind_blocks = 3 * (sdp->sd_max_height - 1);
      }

      for (tmp = *data_blocks; tmp > sdp->sd_diptrs;) {
            tmp = DIV_RU(tmp, sdp->sd_inptrs);
            *ind_blocks += tmp;
      }
}

/**
 * gfs_write_alloc_required - figure out if a write is going to require an allocation
 * @ip: the file being written to
 * @offset: the offset to write to
 * @len: the number of bytes being written
 * @alloc_required: the int is set to TRUE if an alloc is required, FALSE otherwise
 *
 * Returns: errno
 */

int
gfs_write_alloc_required(struct gfs_inode *ip,
                   uint64_t offset, unsigned int len,
                   int *alloc_required)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      uint64_t lblock, lblock_stop, dblock;
      uint32_t extlen;
      int not_new = FALSE;
      int error = 0;

      *alloc_required = FALSE;

      if (!len)
            return 0;

      if (gfs_is_stuffed(ip)) {
            if (offset + len > sdp->sd_sb.sb_bsize - sizeof(struct gfs_dinode))
                  *alloc_required = TRUE;
            return 0;
      }

      if (gfs_is_jdata(ip)) {
            unsigned int bsize = sdp->sd_jbsize;
            lblock = offset;
            do_div(lblock, bsize);
            lblock_stop = offset + len + bsize - 1;
            do_div(lblock_stop, bsize);
      } else {
            unsigned int shift = sdp->sd_sb.sb_bsize_shift;
            lblock = offset >> shift;
            lblock_stop = (offset + len + sdp->sd_sb.sb_bsize - 1) >> shift;
      }

      for (; lblock < lblock_stop; lblock += extlen) {
            error = gfs_block_map(ip, lblock, &not_new, &dblock, &extlen);
            if (error)
                  return error;

            if (!dblock) {
                  *alloc_required = TRUE;
                  return 0;
            }
      }

      return 0;
}

/**
 * do_gfm - Copy out the dinode/indirect blocks of a file
 * @ip: the file
 * @dibh: the dinode buffer
 * @bh: the indirect buffer we're looking at
 * @top: the first pointer in the block
 * @bottom: one more than the last pointer in the block
 * @height: the height the block is at
 * @data: a pointer to a struct gfs_user_buffer structure
 *
 * If this is a journaled file, copy out the data too.
 *
 * Returns: errno
 */

static int
do_gfm(struct gfs_inode *ip, struct buffer_head *dibh,
       struct buffer_head *bh, uint64_t *top, uint64_t *bottom,
       unsigned int height, void *data)
{
      struct gfs_user_buffer *ub = (struct gfs_user_buffer *)data;
      int error;

      error = gfs_add_bh_to_ub(ub, bh);
      if (error)
            return error;

      if (ip->i_di.di_type != GFS_FILE_DIR ||
          height + 1 != ip->i_di.di_height)
            return 0;

      for (; top < bottom; top++)
            if (*top) {
                  struct buffer_head *data_bh;

                  error = gfs_dread(ip->i_gl, gfs64_to_cpu(*top),
                                DIO_START | DIO_WAIT,
                                &data_bh);
                  if (error)
                        return error;

                  error = gfs_add_bh_to_ub(ub, data_bh);

                  brelse(data_bh);

                  if (error)
                        return error;
            }

      return 0;
}

/**
 * gfs_get_file_meta - return all the metadata for a file
 * @ip: the file
 * @ub: the structure representing the meta
 *
 * Returns: errno
 */

int
gfs_get_file_meta(struct gfs_inode *ip, struct gfs_user_buffer *ub)
{
      int error;

      if (gfs_is_stuffed(ip)) {
            struct buffer_head *dibh;
            error = gfs_get_inode_buffer(ip, &dibh);
            if (!error) {
                  error = gfs_add_bh_to_ub(ub, dibh);
                  brelse(dibh);
            }
      } else {
            struct metapath *mp = find_metapath(ip, 0);
            error = recursive_scan(ip, NULL, mp, 0, 0, TRUE, do_gfm, ub);
            kfree(mp);
      }

      return error;
}

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