/*
* Initializes the file system manager.
*/
PUBLIC void fs_init(void)
{
binit();
inode_init();
superblock_init();
/* Sanity check. */
CHKSIZE(sizeof(struct d_dirent), sizeof(struct dirent));
rootdev = superblock_read(ROOT_DEV);
/* Failed to read root super block. */
if (rootdev == NULL)
kpanic("failed to mount root file system");
superblock_unlock(rootdev);
root = inode_get(ROOT_DEV, 1);
/* Failed to read root inode. */
if (root == NULL)
kpanic("failed to read root inode");
kprintf("fs: root file system mounted");
/* Hand craft idle process. */
IDLE->pwd = root;
IDLE->root = root;
root->count += 2;
inode_unlock(root);
}
/**
* @brief Create an indirect block.
*
* @details Creates a indirect block and saves in @param dest.
*
* @param dest Destination buffer, It is the corresponding disk block to be changed.
* @param ip File to use.
* @param offset Offset to be calculated the block.
* @param creat If 1, creates an block, otherwise, just return this value.
*
* @returns If successful, the block number created / obtained, otherwise BLOCK_NULL is
* returned.
*
* @note @p ip must be locked.
*/
PUBLIC block_t create_indirect_block
(struct buffer *dest, struct inode *ip, off_t offset, int create)
{
block_t phys; /* Physical block number. */
if (((block_t *)buffer_data(dest))[offset] == BLOCK_NULL && create)
{
/* Allocate an block. */
superblock_lock(ip->sb);
phys = block_alloc(ip->sb);
superblock_unlock(ip->sb);
if (phys != BLOCK_NULL)
{
((block_t *)buffer_data(dest))[offset] = phys;
buffer_dirty(dest, 1);
inode_touch(ip);
brelse(dest);
return (phys);
}
else
{
brelse(dest);
return (phys);
}
}
else
{
brelse(dest);
return ((block_t *)buffer_data(dest))[offset];
}
}
/**
* @brief Create an direct block.
*
* @details Creates a direct block and saves in @param dest.
*
* @param ip File to use.
* @param offset Offset to be calculated the block.
* @param creat If 1, creates an block, otherwise, just return this value.
*
* @returns If successful, the block number created/obtained, otherwise BLOCK_NULL is
* returned.
*
* @note @p ip must be locked.
*/
PUBLIC block_t create_direct_block(struct inode *ip, off_t offset, int create)
{
block_t phys; /* Physical block number. */
if (ip->blocks[offset] == BLOCK_NULL && create)
{
/* Allocate an block. */
superblock_lock(ip->sb);
phys = block_alloc(ip->sb);
superblock_unlock(ip->sb);
if (phys != BLOCK_NULL)
{
ip->blocks[offset] = phys;
inode_touch(ip);
return (phys);
}
else
return (phys);
}
else
return (ip->blocks[offset]);
}
/**
* @brief Maps a file byte offset in a disk block number.
*
* @details Maps the offset @p off in the file pointed to by @p ip in a disk
* block number. If @p create is not zero and such file by offset is
* invalid, the file is expanded accordingly to make it valid.
*
* @param ip File to use
* @param off File byte offset.
* @param create Create offset?
*
* @returns Upon successful completion, the disk block number that is associated
* with the file byte offset is returned. Upon failure, #BLOCK_NULL is
* returned instead.
*
* @note @p ip must be locked.
*/
PUBLIC block_t block_map(struct inode *ip, off_t off, int create)
{
block_t phys; /* Physical block number. */
block_t logic; /* Logical block number. */
struct buffer *buf; /* Underlying buffer. */
unsigned tmp; /* Logical block number tmp. */
logic = off/BLOCK_SIZE;
/* File offset too big. */
if (off >= ip->sb->max_size)
{
curr_proc->errno = -EFBIG;
return (BLOCK_NULL);
}
/*
* Create blocks that are
* in a valid offset.
*/
if (off < ip->size)
create = 1;
/* Direct block. */
if (logic < NR_ZONES_DIRECT)
{
/* Create direct block. */
if (ip->blocks[logic] == BLOCK_NULL && create)
{
superblock_lock(ip->sb);
phys = block_alloc(ip->sb);
superblock_unlock(ip->sb);
if (phys != BLOCK_NULL)
{
ip->blocks[logic] = phys;
inode_touch(ip);
}
}
return (ip->blocks[logic]);
}
logic -= NR_ZONES_DIRECT;
/* Single indirect block. */
if (logic < NR_SINGLE)
{
/* Create single indirect block. */
if (ip->blocks[ZONE_SINGLE] == BLOCK_NULL && create)
{
superblock_lock(ip->sb);
phys = block_alloc(ip->sb);
superblock_unlock(ip->sb);
if (phys != BLOCK_NULL)
{
ip->blocks[ZONE_SINGLE] = phys;
inode_touch(ip);
}
}
/* We cannot go any further. */
if ((phys = ip->blocks[ZONE_SINGLE]) == BLOCK_NULL)
return (BLOCK_NULL);
buf = bread(ip->dev, phys);
/* Create direct block. */
if (((block_t *)buffer_data(buf))[logic] == BLOCK_NULL && create)
{
superblock_lock(ip->sb);
phys = block_alloc(ip->sb);
superblock_unlock(ip->sb);
if (phys != BLOCK_NULL)
{
((block_t *)buffer_data(buf))[logic] = phys;
buffer_dirty(buf, 1);
inode_touch(ip);
}
}
brelse(buf);
return (((block_t *)buffer_data(buf))[logic]);
}
logic = off - REMAINING_OFFSET;
/* Double indirect block. */
tmp = logic / BLOCK_SIZE;
if (tmp < NR_DOUBLE)
{
size_t logicSingle = logic / (NR_SINGLE * BLOCK_SIZE);
size_t logicDouble = logic / BLOCK_SIZE;
/* Create single, double and/or direct block. */
if ( (phys = create_direct_block(ip,ZONE_DOUBLE,create)) != BLOCK_NULL)
{
buf = bread(ip->dev, phys);
if ( (phys = create_indirect_block(buf,ip,logicSingle,create))
!= BLOCK_NULL)
{
buf = bread(ip->dev, phys);
if ( (phys = create_indirect_block(buf,ip,logicDouble,create))
!= BLOCK_NULL)
return (phys);
else
return (BLOCK_NULL);
}
else
return (BLOCK_NULL);
}
else
return (BLOCK_NULL);
}
/* Triple indirect zone. */
kpanic("triple indirect zones not supported");
return (BLOCK_NULL);
}