static inline void truncate (struct inode * inode)
{
struct super_block *sb = inode->i_sb;
block_t *idata = i_data(inode);
int offsets[DEPTH];
Indirect chain[DEPTH];
Indirect *partial;
block_t nr = 0;
int n;
int first_whole;
long iblock;
iblock = (inode->i_size + sb->s_blocksize -1) >> sb->s_blocksize_bits;
block_truncate_page(inode->i_mapping, inode->i_size, get_block);
n = block_to_path(inode, iblock, offsets);
if (!n)
return;
if (n == 1) {
free_data(inode, idata+offsets[0], idata + DIRECT);
first_whole = 0;
goto do_indirects;
}
first_whole = offsets[0] + 1 - DIRECT;
partial = find_shared(inode, n, offsets, chain, &nr);
if (nr) {
if (partial == chain)
mark_inode_dirty(inode);
else
mark_buffer_dirty_inode(partial->bh, inode);
free_branches(inode, &nr, &nr+1, (chain+n-1) - partial);
}
/* Clear the ends of indirect blocks on the shared branch */
while (partial > chain) {
free_branches(inode, partial->p + 1, block_end(partial->bh),
(chain+n-1) - partial);
mark_buffer_dirty_inode(partial->bh, inode);
brelse (partial->bh);
partial--;
}
do_indirects:
/* Kill the remaining (whole) subtrees */
while (first_whole < DEPTH-1) {
nr = idata[DIRECT+first_whole];
if (nr) {
idata[DIRECT+first_whole] = 0;
mark_inode_dirty(inode);
free_branches(inode, &nr, &nr+1, first_whole+1);
}
first_whole++;
}
inode->i_mtime = inode->i_ctime = current_time(inode);
mark_inode_dirty(inode);
}
static inline Indirect *get_branch(struct inode *inode,
int depth,
int *offsets,
Indirect chain[DEPTH],
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, i_data(inode) + *offsets);
if (!p->key)
goto no_block;
while (--depth) {
bh = sb_bread(sb, block_to_cpu(p->key));
if (!bh)
goto failure;
read_lock(&pointers_lock);
if (!verify_chain(chain, p))
goto changed;
add_chain(++p, bh, (block_t *)bh->b_data + *++offsets);
read_unlock(&pointers_lock);
if (!p->key)
goto no_block;
}
return NULL;
changed:
read_unlock(&pointers_lock);
brelse(bh);
*err = -EAGAIN;
goto no_block;
failure:
*err = -EIO;
no_block:
return p;
}
static inline Indirect *get_branch(struct inode *inode,
int depth,
int *offsets,
Indirect chain[DEPTH],
int *err)
{
kdev_t dev = inode->i_dev;
Indirect *p = chain;
struct buffer_head *bh;
*err = 0;
/* i_data is not going away, no lock needed */
add_chain (chain, NULL, i_data(inode) + *offsets);
if (!p->key)
goto no_block;
while (--depth) {
bh = bread(dev, block_to_cpu(p->key), BLOCK_SIZE);
if (!bh)
goto failure;
/* Reader: pointers */
if (!verify_chain(chain, p))
goto changed;
add_chain(++p, bh, (block_t *)bh->b_data + *++offsets);
/* Reader: end */
if (!p->key)
goto no_block;
}
return NULL;
changed:
*err = -EAGAIN;
goto no_block;
failure:
*err = -EIO;
no_block:
return p;
}
