/**
* nilfs_mdt_find_block - find and get a buffer on meta data file.
* @inode: inode of the meta data file
* @start: start block offset (inclusive)
* @end: end block offset (inclusive)
* @blkoff: block offset
* @out_bh: place to store a pointer to buffer_head struct
*
* nilfs_mdt_find_block() looks up an existing block in range of
* [@start, @end] and stores pointer to a buffer head of the block to
* @out_bh, and block offset to @blkoff, respectively. @out_bh and
* @blkoff are substituted only when zero is returned.
*
* Return Value: On success, it returns 0. On error, the following negative
* error code is returned.
*
* %-ENOMEM - Insufficient memory available.
*
* %-EIO - I/O error
*
* %-ENOENT - no block was found in the range
*/
int nilfs_mdt_find_block(struct inode *inode, unsigned long start,
unsigned long end, unsigned long *blkoff,
struct buffer_head **out_bh)
{
__u64 next;
int ret;
if (unlikely(start > end))
return -ENOENT;
ret = nilfs_mdt_read_block(inode, start, true, out_bh);
if (!ret) {
*blkoff = start;
goto out;
}
if (unlikely(ret != -ENOENT || start == ULONG_MAX))
goto out;
ret = nilfs_bmap_seek_key(NILFS_I(inode)->i_bmap, start + 1, &next);
if (!ret) {
if (next <= end) {
ret = nilfs_mdt_read_block(inode, next, true, out_bh);
if (!ret)
*blkoff = next;
} else {
ret = -ENOENT;
}
}
out:
return ret;
}
/**
* nilfs_mdt_get_block - read or create a buffer on meta data file.
* @inode: inode of the meta data file
* @blkoff: block offset
* @create: create flag
* @init_block: initializer used for newly allocated block
* @out_bh: output of a pointer to the buffer_head
*
* nilfs_mdt_get_block() looks up the specified buffer and tries to create
* a new buffer if @create is not zero. On success, the returned buffer is
* assured to be either existing or formatted using a buffer lock on success.
* @out_bh is substituted only when zero is returned.
*
* Return Value: On success, it returns 0. On error, the following negative
* error code is returned.
*
* %-ENOMEM - Insufficient memory available.
*
* %-EIO - I/O error
*
* %-ENOENT - the specified block does not exist (hole block)
*
* %-EINVAL - bmap is broken. (the caller should call nilfs_error())
*
* %-EROFS - Read only filesystem (for create mode)
*/
int nilfs_mdt_get_block(struct inode *inode, unsigned long blkoff, int create,
void (*init_block)(struct inode *,
struct buffer_head *, void *),
struct buffer_head **out_bh)
{
int ret;
/* Should be rewritten with merging nilfs_mdt_read_block() */
retry:
ret = nilfs_mdt_read_block(inode, blkoff, !create, out_bh);
if (!create || ret != -ENOENT)
return ret;
ret = nilfs_mdt_create_block(inode, blkoff, out_bh, init_block);
if (unlikely(ret == -EEXIST)) {
/* create = 0; */ /* limit read-create loop retries */
goto retry;
}
return ret;
}
