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super.c
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super.c
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#include <linux/fs.h>
#include "super.h"
static void simplefs_sync_metadata_buffer(struct bufffer_head **bh_table)
{
struct buffer_head **walker = *bh_table;
while(walker) {
struct buffer_head *bh = *walker;
do
{
if(!buffer_uptodate(bh))
sync_dirty_buffer(bh);
bh=bh->b_this_page;
}while(bh->b_this_page != *walker);
walker++;
}
}
void simplefs_sync_metadata(struct super_block *sb)
{
struct simple_fs_sb_i *msblk = SIMPLEFS_SB(sb);
/*
* Start with inodes.
*/
simplefs_sync_metadata_buffer(msblk->inode_table);
simplefs_sync_metadata_buffer(msblk->inode_bitmap);
simeplfs_sync_metadata_buffer(msblk->block_bitmap);
}
static struct inode* simplefs_alloc_inode(struct super_block *sb)
{
struct simple_fs_sb_i *msblk = SIMPLEFS_SB(sb);
struct simple_fs_inode_i *inode =
kmem_cache_alloc(msblk->inode_cachep,GFP_KERNEL);
if(!inode)
return NULL;
return &inode->vfs_inode;
}
static void simplefs_destroy_inode(struct inode *vfs_inode)
{
struct simple_fs_inode_i *inode = SIMPLEFS_INODE(vfs_inode);
struct simple_fs_sb_i *sb = SIMPLEFS_SB(vfs_inode->i_sb);
if (inode->indirect_block) {
if(!buffer_uptodate(inode->indirect_block))
sync_dirty_buffer(inode->indirect_block);
bforget(inode->indirect_block);
}
kmem_cache_free(sb->inode_cachep,inode);
}
static void simplefs_put_super(struct super_block *sb)
{
struct simple_fs_sb_i *msblk = SIMPLEFS_SB(sb);
if(msblk->inode_cachep)
kmem_cache_destroy(msblk->inode_cachep);
kfree(msblk);
sb->s_private = NULL;
}
static int simplefs_write_inode(struct inode *vfs_inode, struct writeback_control *wbc)
{
/*
* We just need to write the inode here not it's pages.
*/
struct simple_fs_inode_i *minode = SIMPLEFS_INODE(vfs_inode);
struct simple_fs_sb_i *msblk = SIMPLEFS_SB(vfs_inode->i_sb);
int inodes_per_block = SIMPLEFS_INODE_SIZE/msblk->sb.block_size;
/*
* Find the inode table where we need to write this inode.
*/
struct buffer_head *inode_table = msblk->inode_table[(minode->inode.inode_no - 1)/inodes_per_block];
struct simplefs_inode *disk_inode =
(struct simplefs_inode*)(inode_table->b_data + (minode->inode.inode_no - 1) % inodes_per_block);
minode->inode.m_time = timespec_to_ns(vfs_inode.m_time);
minode->inode.m_time = cpu_to_le64(minode->inode.m_time);
if(!(vfs_inode->i_mode & S_IFDIR)) {
minode->inode.file_size = i_size_read(vfs_inode);
minode->inode.file_size = cpu_to_le64(minode->inode.file_size);
}
memcpy(disk_inode,&minode->inode,sizeof(struct simplefs_inode));
mark_buffer_dirty(inode_table);
if(wbc->sync_mode == WB_SYNC_ALL) {
SFSDBG("[SFS] Writeback control was to sync all in %s \n",__FUNCTION__);
sync_dirty_buffer(inode_table);
}
/*
* Perhaps we should sync dirty buffer here,
* but let's see how far we can go. The inode
* may actually not be written if we don't force
* sync and let the flush thread do it for us.
*/
SFSDBG("Not syncing in %s\n",__FUNCTION__);
}
static int allocate_data_blocks(struct inode *vfs_inode,int nr_blocks)
{
struct simple_fs_sb_i *msblk = SIMPLEFS_SB(vfs_inode->i_sb);
struct simple_fs_inode_i *minode = SIMPLEFS_INODE(vfs_inode);
struct buffer_head *sb_buffer_bitmap = NULL;
char *bitmap_buffer = NULL;
int block_start = 0,block_no = 0;
int bitmap_index = 0;
int blocks_alloced = 0;
int buffer_offset = 0; /*How many b_this_page has been done on a single bh*/
int block_start_buffer_offset = 0;
int block_start_bitmap_index = 0;
if(!nr_blocks)
return 0;
mutex_lock(&msblk->sb_mutex);
new_bitmap_buffer:
sb_buffer_bitmap = msblk->block_bitmap[bitmap_index];
if(!sb_buffer_bitmap)
goto out_failed;
allocate_block:
bitmap_buffer = sb_buffer_bitmap->b_data;
if( nr_blocks &&
(block_no =
alloc_bmap(bitmap_buffer,sb_buffer_bitmap->b_size)) < 0) {
sb_buffer_bitmap = sb_buffer_bitmap->b_this_page;
if(sb_buffer_bitmap == mbslk->block_bitmap[bitmap_index]) {
bitmap_index++; /*Move to next buffer head in the array*/
buffer_offset = 0;
goto new_bitmap_buffer;
}
else
buffer_offset++;
goto allocate_block;
}
else if(block_no >= 0) {
nr_blocks--;
blocks_alloced++;
if(!block_start) {
block_start = block_no +
(((sb_buffer_bitmap->b_size * buffer_offset)
+ (PAGE_SIZE*bitmap_index)) << 3);
block_start_buffer_offset = buffer_offset;
block_start_bitmap_index = bitmap_index;
}
if(buffer_uptodate(sb_buffer_bitmap))
mark_buffer_dirty(sb_buffer_bitmap);
block_no = -1;
if(nr_blocks)
goto allocate_block;
}
simplefs_sync_metadata(sb);
mutex_unlock(&msblk->sb_mutex);
return block_start; /*Return starting block number of the allocated blocks*/
out_failed:
if(blocks_alloced) {
/*
* Get the starting buffer head from where allocations
* were started.
*/
sb_buffer_bitmap = msblk->block_bitmap[block_start_bitmap_index];
/*
* Get the starting block number relative to the buffer head.
*/
block_no = block_start - ((
(sb_buffer_bitmap->b_size * block_start_buffer_offset)
+(PAGE_SIZE * block_start_bitmap_index))) * 8;
/*
* Move to the correct buffer head within the page.
*/
while(block_start_buffer_offset) {
sb_buffer_bitmap = sb_buffer_bitmap->b_this_page;
block_start_buffer_offset--;
}
bitmap_buffer = sb_buffer_bitmap->b_data;
while(blocks_alloced) {
if(free_bmap(bitmap_buffer,sb_buffer_bitmap->b_size,block_no++)){
blocks_alloced--;
if(buffer_uptodate(sb_buffer_bitmap))
mark_buffer_dirty(sb_buffer_bitmap);
}
/*
* There was no freeing of block because this block_no didn't
* belonged the starting buffer head. We need to move the
* buffer head to new buffer or perhaps we might need to
* get a new msblk->block_bitmap[j].
*/
else {
sb_buffer_bitmap = sb_buffer_bitmap->b_this_page;
if( sb_buffer_bitmap == msblk->block_bitmap[block_start_bitmap_index] )
sb_buffer_bitmap = msblk->block_bitmap[++block_start_bitmap_index];
block_no = 0; /*This is relative to the buffer head*/
bitmap_buffer = sb_buffer_bitmap->b_data;
}
}
}
simplefs_sync_metadata(sb);
mutex_unlock(msblk->sb_mutex);
return 0;
}
/*
* This one is the heart and soul. Most of the stuff is taken care of
* by libfs. All we need to do is write this one here and fill up the
* buffer head with the information it wants.
*
* This buffer head is actually a local variable, see mpage_readpages
* so don't do anything unusual with this specially don't search for it
* in the buffer head list for block device you won't find it however
* you'll create it and then it won't be good. This buffer has been
* attached with the page so we need not worry about that.
*
* What you do here is you create mapping of the iblock, its actually
* a block in file. So based on the inode you'll map it to get the
* actual file system block number to read.
*
* So you just churn up some blocks if required since same routine
* would be called for writing data. For reads i guess this would be
* pretty simple however in any case we need to use same stuff for
* read/write so be careful.
*
* Not sure about the return value, Perhaps the number of mapped blocks
* however mpage_readpages then sends it to "confused". Arrhh.....
*/
static int simplefs_get_block(struct inode *vfs_inode, sector_t iblock,
struct buffer_head *bh_result, int create)
{
struct simple_fs_sb_i *msblk = SIMPLEFS_SB(vfs_inode->i_sb);
struct simple_fs_inode_i *minode = SIMPLEFS_INODE(vfs_inode);
uint64_t mapped_block = -1;
if(iblock > msblk->sb.block_size/sizeof(uint64_t))
goto fail_get_block;
if(create) {
/* Do we already have allocated the indirect block.
* If yes then all we need to do is check the block location
* for being 0 within that.
*/
if(iblock) {
allocate_indirect_block:
if(minode->inode.indirect_block_number) {
if(!minode->indirect_block) {
minode->indirect_block =
sb_bread(vfs_inode->i_sb,
minode->inode.indirect_block_number);
if(!minode->indirect_block)
goto fail_get_block;
}
uint64_t *block_offset =
((uint64_t*)(minode->indirect_block->b_data) + (iblock-1));
mapped_block = le64_to_cpu(*block_offset);
if(!mapped_block) {
mapped_block = allocate_data_blocks(vfs_inode,1);
if (!mapped_block) {
SFSDBG(KERN_INFO "Error allocating indirect data block %s %d\n"
,__FUNCTION__,__LINE__);
goto fail_get_block;
}
}
*block_offset = cpu_to_le64(mapped_block);
mark_buffer_dirty(minode->indirect_block);
mapped_block = block_offset;
}
else { /*Allocate that indirect block and the block within*/
minode->inode.indirect_block_number = allocate_data_blocks(vfs_inode,1);
if(!minode->inode.indirect_block_number) {
SFSDBG(KERN_INFO "Error allocating indirect block %s %d\n"
,__FUNCTION__,__LINE__);
goto fail_get_block;
}
else
goto allocate_indirect_block;
}
}
else { /*This is the first block for the file*/
if( minode->inode.data_block_number ){
mapped_block = le64_to_cpu(minode->inode.data_block_number);
}
else
{
minode->inode.data_block_number = allocate_data_blocks(vfs_inode,1);
if(!minode->inode.data_block_number) {
SFSDBG(KERN_INFO "Error allocating direct block %s %d\n"
,__FUNCTION__,__LINE__);
goto fail_get_block;
}
mapped_block = minode->inode.data_block_number;
minode->inode.data_block_number = cpu_to_le64(
minode->inode.data_block_number);
}
}
}
else {
/*
* Find the mapping but don't create it.
*/
if(iblock) {
if(minode->inode.indirect_block_number) {
if(!minode->indirect_block) {
minode->indirect_block =
sb_bread(vfs_inode->i_sb,
minode->inode.indirect_block_number);
if(!minode->indirect_block)
goto fail_get_block;
}
uint64_t *block_offset =
((uint64_t*)(minode->indirect_block->b_data) + (iblock-1));
mapped_block = le64_to_cpu(*block_offset);
if(!mapped_block)
goto fail_get_block;
}
else
goto fail_get_block;
}
else {
if(!minode->inode.data_block_number)
goto fail_get_block;
mapped_block = le64_to_cpu(minode->inode.data_block_number);
}
}
set_buffer_new(bh_result);
map_bh(bh_result,vfs_inode->i_sb,mapped_block);
return 0;
fail_get_block:
return -EOF;
}
static int simplefs_read_pages(struct file *filp,struct address_space *mapping
,struct list_head *pages,unsigned nr_pages)
{
SFSDBG(KERN_INFO "Read pages started \n");
dump_stack();
return mpage_readpages(mapping,pages,nr_pages,simplefs_get_block);
}
static int simplefs_write_pages(struct address_space *mapping,
struct writeback_control *wbc)
{
SFSDBG(KERN_INFO "Write pages started \n");
dump_stack();
return mpage_writepages(mapping,wbc,simplefs_get_block);
}
static int simplefs_read_page(struct file *filp,struct page *page)
{
SFSDBG(KERN_INFO "Read page started \n");
dump_stack();
return mpage_readpage(page,simplefs_get_block);
}
static int simplefs_write_page(struct page *page,struct writeback_control *wbc)
{
SFSDBG(KERN_INFO "Write page started \n");
dump_stack();
return mpage_writepage(page,simplefs_get_block,wbc);
}
int simplefs_write_begin(struct file *, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
SFSDBG(KERN_INFO "Write begin started \n");
dump_stack();
return block_write_begin(mapping,pos,
len,flags,pagep,simplefs_get_block);
}
int simplefs_write_end(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata)
{
SFSDBG(KERN_INFO "Write end started \n");
dump_stack();
return generic_write_end(file,mapping,pos,
len,copied,page,fsdata);
}
struct address_space_operations simplefs_aops ={
.readpage = simplefs_read_page;
.readpages = simplefs_read_pages;
.writepage = simplefs_write_page;
.writepages = simplefs_write_pages;
.write_begin = simplefs_write_begin;
.write_end = simeplfs_write_end;
};
struct super_operations simplefs_sops= {
.alloc_inode = simplefs_alloc_inode,
.destroy_inode = simplefs_destroy_inode,
.put_super = simplefs_put_super,
.write_inode = simplefs_write_inode,
};