/* The function is NOT SCHEDULE-SAFE! */
int
search_for_position_by_key(struct reiserfs_sb_info *p_s_sbi,
const struct cpu_key *p_cpu_key, /* Key to search (cpu variable) */
struct path *p_s_search_path) /* Filled up by this function. */
{
int retval, n_blk_size;
off_t item_offset, offset;
struct item_head *p_le_ih; /* Pointer to on-disk structure */
struct reiserfs_dir_entry de;
/* If searching for directory entry. */
if (is_direntry_cpu_key(p_cpu_key))
return (search_by_entry_key(p_s_sbi, p_cpu_key,
p_s_search_path, &de));
/* If not searching for directory entry. */
/* If item is found. */
retval = search_item(p_s_sbi, p_cpu_key, p_s_search_path);
if (retval == IO_ERROR)
return (retval);
if (retval == ITEM_FOUND) {
if (ih_item_len(B_N_PITEM_HEAD(
PATH_PLAST_BUFFER(p_s_search_path),
PATH_LAST_POSITION(p_s_search_path))) == 0) {
reiserfs_log(LOG_WARNING, "item length equals zero\n");
}
pos_in_item(p_s_search_path) = 0;
return (POSITION_FOUND);
}
if (PATH_LAST_POSITION(p_s_search_path) == 0) {
reiserfs_log(LOG_WARNING, "position equals zero\n");
}
/* Item is not found. Set path to the previous item. */
p_le_ih = B_N_PITEM_HEAD(PATH_PLAST_BUFFER(p_s_search_path),
--PATH_LAST_POSITION(p_s_search_path));
n_blk_size = p_s_sbi->s_blocksize;
if (comp_short_keys(&(p_le_ih->ih_key), p_cpu_key)) {
return (FILE_NOT_FOUND);
}
item_offset = le_ih_k_offset(p_le_ih);
offset = cpu_key_k_offset(p_cpu_key);
/* Needed byte is contained in the item pointed to by the path.*/
if (item_offset <= offset &&
item_offset + op_bytes_number(p_le_ih, n_blk_size) > offset) {
pos_in_item(p_s_search_path) = offset - item_offset;
if (is_indirect_le_ih(p_le_ih)) {
pos_in_item(p_s_search_path) /= n_blk_size;
}
return (POSITION_FOUND);
}
/* Needed byte is not contained in the item pointed to by the
* path. Set pos_in_item out of the item. */
if (is_indirect_le_ih(p_le_ih))
pos_in_item(p_s_search_path) =
ih_item_len(p_le_ih) / UNFM_P_SIZE;
else
pos_in_item(p_s_search_path) =
ih_item_len(p_le_ih);
return (POSITION_NOT_FOUND);
}
/* Allocates blocks for a file to fulfil write request.
Maps all unmapped but prepared pages from the list.
Updates metadata with newly allocated blocknumbers as needed */
int reiserfs_allocate_blocks_for_region(
struct reiserfs_transaction_handle *th,
struct inode *inode, /* Inode we work with */
loff_t pos, /* Writing position */
int num_pages, /* number of pages write going
to touch */
int write_bytes, /* amount of bytes to write */
struct page **prepared_pages, /* array of
prepared pages
*/
int blocks_to_allocate /* Amount of blocks we
need to allocate to
fit the data into file
*/
)
{
struct cpu_key key; // cpu key of item that we are going to deal with
struct item_head *ih; // pointer to item head that we are going to deal with
struct buffer_head *bh; // Buffer head that contains items that we are going to deal with
__u32 * item; // pointer to item we are going to deal with
INITIALIZE_PATH(path); // path to item, that we are going to deal with.
b_blocknr_t *allocated_blocks; // Pointer to a place where allocated blocknumbers would be stored.
reiserfs_blocknr_hint_t hint; // hint structure for block allocator.
size_t res; // return value of various functions that we call.
int curr_block; // current block used to keep track of unmapped blocks.
int i; // loop counter
int itempos; // position in item
unsigned int from = (pos & (PAGE_CACHE_SIZE - 1)); // writing position in
// first page
unsigned int to = ((pos + write_bytes - 1) & (PAGE_CACHE_SIZE - 1)) + 1; /* last modified byte offset in last page */
__u64 hole_size ; // amount of blocks for a file hole, if it needed to be created.
int modifying_this_item = 0; // Flag for items traversal code to keep track
// of the fact that we already prepared
// current block for journal
int will_prealloc = 0;
RFALSE(!blocks_to_allocate, "green-9004: tried to allocate zero blocks?");
/* only preallocate if this is a small write */
if (REISERFS_I(inode)->i_prealloc_count ||
(!(write_bytes & (inode->i_sb->s_blocksize -1)) &&
blocks_to_allocate <
REISERFS_SB(inode->i_sb)->s_alloc_options.preallocsize))
will_prealloc = REISERFS_SB(inode->i_sb)->s_alloc_options.preallocsize;
allocated_blocks = kmalloc((blocks_to_allocate + will_prealloc) *
sizeof(b_blocknr_t), GFP_NOFS);
/* First we compose a key to point at the writing position, we want to do
that outside of any locking region. */
make_cpu_key (&key, inode, pos+1, TYPE_ANY, 3/*key length*/);
/* If we came here, it means we absolutely need to open a transaction,
since we need to allocate some blocks */
reiserfs_write_lock(inode->i_sb); // Journaling stuff and we need that.
journal_begin(th, inode->i_sb, JOURNAL_PER_BALANCE_CNT * 3 + 1); // Wish I know if this number enough
reiserfs_update_inode_transaction(inode) ;
/* Look for the in-tree position of our write, need path for block allocator */
res = search_for_position_by_key(inode->i_sb, &key, &path);
if ( res == IO_ERROR ) {
res = -EIO;
goto error_exit;
}
/* Allocate blocks */
/* First fill in "hint" structure for block allocator */
hint.th = th; // transaction handle.
hint.path = &path; // Path, so that block allocator can determine packing locality or whatever it needs to determine.
hint.inode = inode; // Inode is needed by block allocator too.
hint.search_start = 0; // We have no hint on where to search free blocks for block allocator.
hint.key = key.on_disk_key; // on disk key of file.
hint.block = inode->i_blocks>>(inode->i_sb->s_blocksize_bits-9); // Number of disk blocks this file occupies already.
hint.formatted_node = 0; // We are allocating blocks for unformatted node.
hint.preallocate = will_prealloc;
/* Call block allocator to allocate blocks */
res = reiserfs_allocate_blocknrs(&hint, allocated_blocks, blocks_to_allocate, blocks_to_allocate);
if ( res != CARRY_ON ) {
if ( res == NO_DISK_SPACE ) {
/* We flush the transaction in case of no space. This way some
blocks might become free */
SB_JOURNAL(inode->i_sb)->j_must_wait = 1;
restart_transaction(th, inode, &path);
/* We might have scheduled, so search again */
res = search_for_position_by_key(inode->i_sb, &key, &path);
if ( res == IO_ERROR ) {
res = -EIO;
goto error_exit;
}
/* update changed info for hint structure. */
res = reiserfs_allocate_blocknrs(&hint, allocated_blocks, blocks_to_allocate, blocks_to_allocate);
if ( res != CARRY_ON ) {
res = -ENOSPC;
pathrelse(&path);
goto error_exit;
}
} else {
res = -ENOSPC;
pathrelse(&path);
goto error_exit;
}
}
#ifdef __BIG_ENDIAN
// Too bad, I have not found any way to convert a given region from
// cpu format to little endian format
{
int i;
for ( i = 0; i < blocks_to_allocate ; i++)
allocated_blocks[i]=cpu_to_le32(allocated_blocks[i]);
}
#endif
/* Blocks allocating well might have scheduled and tree might have changed,
let's search the tree again */
/* find where in the tree our write should go */
res = search_for_position_by_key(inode->i_sb, &key, &path);
if ( res == IO_ERROR ) {
res = -EIO;
goto error_exit_free_blocks;
}
bh = get_last_bh( &path ); // Get a bufferhead for last element in path.
ih = get_ih( &path ); // Get a pointer to last item head in path.
item = get_item( &path ); // Get a pointer to last item in path
/* Let's see what we have found */
if ( res != POSITION_FOUND ) { /* position not found, this means that we
might need to append file with holes
first */
// Since we are writing past the file's end, we need to find out if
// there is a hole that needs to be inserted before our writing
// position, and how many blocks it is going to cover (we need to
// populate pointers to file blocks representing the hole with zeros)
{
int item_offset = 1;
/*
* if ih is stat data, its offset is 0 and we don't want to
* add 1 to pos in the hole_size calculation
*/
if (is_statdata_le_ih(ih))
item_offset = 0;
hole_size = (pos + item_offset -
(le_key_k_offset( get_inode_item_key_version(inode),
&(ih->ih_key)) +
op_bytes_number(ih, inode->i_sb->s_blocksize))) >>
inode->i_sb->s_blocksize_bits;
}
