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Commit 8f09e987 authored by Bob Copeland's avatar Bob Copeland Committed by Linus Torvalds
Browse files

omfs: add file routines 



Add functions for reading and manipulating the storage of file data in
the extent-based OMFS.

Signed-off-by: default avatarBob Copeland <me@bobcopeland.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a3ab7155

fs/omfs/file.c

0 → 100644
+346 −0
Original line number Diff line number Diff line 
/*

 * OMFS (as used by RIO Karma) file operations.

 * Copyright (C) 2005 Bob Copeland <me@bobcopeland.com>

 * Released under GPL v2.

 */



#include <linux/version.h>

#include <linux/module.h>

#include <linux/fs.h>

#include <linux/buffer_head.h>

#include <linux/mpage.h>

#include "omfs.h"



static int omfs_sync_file(struct file *file, struct dentry *dentry,

		int datasync)

{

	struct inode *inode = dentry->d_inode;

	int err;



	err = sync_mapping_buffers(inode->i_mapping);

	if (!(inode->i_state & I_DIRTY))

		return err;

	if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))

		return err;

	err |= omfs_sync_inode(inode);

	return err ? -EIO : 0;

}



void omfs_make_empty_table(struct buffer_head *bh, int offset)

{

	struct omfs_extent *oe = (struct omfs_extent *) &bh->b_data[offset];



	oe->e_next = ~0ULL;

	oe->e_extent_count = cpu_to_be32(1),

	oe->e_fill = cpu_to_be32(0x22),

	oe->e_entry.e_cluster = ~0ULL;

	oe->e_entry.e_blocks = ~0ULL;

}



int omfs_shrink_inode(struct inode *inode)

{

	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);

	struct omfs_extent *oe;

	struct omfs_extent_entry *entry;

	struct buffer_head *bh;

	u64 next, last;

	u32 extent_count;

	int ret;



	/* traverse extent table, freeing each entry that is greater

	 * than inode->i_size;

	 */

	next = inode->i_ino;



	/* only support truncate -> 0 for now */

	ret = -EIO;

	if (inode->i_size != 0)

		goto out;



	bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));

	if (!bh)

		goto out;



	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);



	for (;;) {



		if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next)) {

			brelse(bh);

			goto out;

		}



		extent_count = be32_to_cpu(oe->e_extent_count);

		last = next;

		next = be64_to_cpu(oe->e_next);

		entry = &oe->e_entry;



		/* ignore last entry as it is the terminator */

		for (; extent_count > 1; extent_count--) {

			u64 start, count;

			start = be64_to_cpu(entry->e_cluster);

			count = be64_to_cpu(entry->e_blocks);



			omfs_clear_range(inode->i_sb, start, (int) count);

			entry++;

		}

		omfs_make_empty_table(bh, (char *) oe - bh->b_data);

		mark_buffer_dirty(bh);

		brelse(bh);



		if (last != inode->i_ino)

			omfs_clear_range(inode->i_sb, last, sbi->s_mirrors);



		if (next == ~0)

			break;



		bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));

		if (!bh)

			goto out;

		oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);

	}

	ret = 0;

out:

	return ret;

}



static void omfs_truncate(struct inode *inode)

{

	omfs_shrink_inode(inode);

	mark_inode_dirty(inode);

}



/*

 * Add new blocks to the current extent, or create new entries/continuations

 * as necessary.

 */

static int omfs_grow_extent(struct inode *inode, struct omfs_extent *oe,

			u64 *ret_block)

{

	struct omfs_extent_entry *terminator;

	struct omfs_extent_entry *entry = &oe->e_entry;

	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);

	u32 extent_count = be32_to_cpu(oe->e_extent_count);

	u64 new_block = 0;

	u32 max_count;

	int new_count;

	int ret = 0;



	/* reached the end of the extent table with no blocks mapped.

	 * there are three possibilities for adding: grow last extent,

	 * add a new extent to the current extent table, and add a

	 * continuation inode.  in last two cases need an allocator for

	 * sbi->s_cluster_size

	 */



	/* TODO: handle holes */



	/* should always have a terminator */

	if (extent_count < 1)

		return -EIO;



	/* trivially grow current extent, if next block is not taken */

	terminator = entry + extent_count - 1;

	if (extent_count > 1) {

		entry = terminator-1;

		new_block = be64_to_cpu(entry->e_cluster) +

			be64_to_cpu(entry->e_blocks);



		if (omfs_allocate_block(inode->i_sb, new_block)) {

			entry->e_blocks =

				cpu_to_be64(be64_to_cpu(entry->e_blocks) + 1);

			terminator->e_blocks = ~(cpu_to_be64(

				be64_to_cpu(~terminator->e_blocks) + 1));

			goto out;

		}

	}

	max_count = (sbi->s_sys_blocksize - OMFS_EXTENT_START -

		sizeof(struct omfs_extent)) /

		sizeof(struct omfs_extent_entry) + 1;



	/* TODO: add a continuation block here */

	if (be32_to_cpu(oe->e_extent_count) > max_count-1)

		return -EIO;



	/* try to allocate a new cluster */

	ret = omfs_allocate_range(inode->i_sb, 1, sbi->s_clustersize,

		&new_block, &new_count);

	if (ret)

		goto out_fail;



	/* copy terminator down an entry */

	entry = terminator;

	terminator++;

	memcpy(terminator, entry, sizeof(struct omfs_extent_entry));



	entry->e_cluster = cpu_to_be64(new_block);

	entry->e_blocks = cpu_to_be64((u64) new_count);



	terminator->e_blocks = ~(cpu_to_be64(

		be64_to_cpu(~terminator->e_blocks) + (u64) new_count));



	/* write in new entry */

	oe->e_extent_count = cpu_to_be32(1 + be32_to_cpu(oe->e_extent_count));



out:

	*ret_block = new_block;

out_fail:

	return ret;

}



/*

 * Scans across the directory table for a given file block number.

 * If block not found, return 0.

 */

static sector_t find_block(struct inode *inode, struct omfs_extent_entry *ent,

			sector_t block, int count, int *left)

{

	/* count > 1 because of terminator */

	sector_t searched = 0;

	for (; count > 1; count--) {

		int numblocks = clus_to_blk(OMFS_SB(inode->i_sb),

			be64_to_cpu(ent->e_blocks));



		if (block >= searched  &&

		    block < searched + numblocks) {

			/*

			 * found it at cluster + (block - searched)

			 * numblocks - (block - searched) is remainder

			 */

			*left = numblocks - (block - searched);

			return clus_to_blk(OMFS_SB(inode->i_sb),

				be64_to_cpu(ent->e_cluster)) +

				block - searched;

		}

		searched += numblocks;

		ent++;

	}

	return 0;

}



static int omfs_get_block(struct inode *inode, sector_t block,

			  struct buffer_head *bh_result, int create)

{

	struct buffer_head *bh;

	sector_t next, offset;

	int ret;

	u64 new_block;

	int extent_count;

	struct omfs_extent *oe;

	struct omfs_extent_entry *entry;

	struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);

	int max_blocks = bh_result->b_size >> inode->i_blkbits;

	int remain;



	ret = -EIO;

	bh = sb_bread(inode->i_sb, clus_to_blk(sbi, inode->i_ino));

	if (!bh)

		goto out;



	oe = (struct omfs_extent *)(&bh->b_data[OMFS_EXTENT_START]);

	next = inode->i_ino;



	for (;;) {



		if (omfs_is_bad(sbi, (struct omfs_header *) bh->b_data, next))

			goto out_brelse;



		extent_count = be32_to_cpu(oe->e_extent_count);

		next = be64_to_cpu(oe->e_next);

		entry = &oe->e_entry;



		offset = find_block(inode, entry, block, extent_count, &remain);

		if (offset > 0) {

			ret = 0;

			map_bh(bh_result, inode->i_sb, offset);

			if (remain > max_blocks)

				remain = max_blocks;

			bh_result->b_size = (remain << inode->i_blkbits);

			goto out_brelse;

		}

		if (next == ~0)

			break;



		brelse(bh);

		bh = sb_bread(inode->i_sb, clus_to_blk(sbi, next));

		if (!bh)

			goto out;

		oe = (struct omfs_extent *) (&bh->b_data[OMFS_EXTENT_CONT]);

	}

	if (create) {

		ret = omfs_grow_extent(inode, oe, &new_block);

		if (ret == 0) {

			mark_buffer_dirty(bh);

			mark_inode_dirty(inode);

			map_bh(bh_result, inode->i_sb,

					clus_to_blk(sbi, new_block));

		}

	}

out_brelse:

	brelse(bh);

out:

	return ret;

}



static int omfs_readpage(struct file *file, struct page *page)

{

	return block_read_full_page(page, omfs_get_block);

}



static int omfs_readpages(struct file *file, struct address_space *mapping,

		struct list_head *pages, unsigned nr_pages)

{

	return mpage_readpages(mapping, pages, nr_pages, omfs_get_block);

}



static int omfs_writepage(struct page *page, struct writeback_control *wbc)

{

	return block_write_full_page(page, omfs_get_block, wbc);

}



static int

omfs_writepages(struct address_space *mapping, struct writeback_control *wbc)

{

	return mpage_writepages(mapping, wbc, omfs_get_block);

}



static int omfs_write_begin(struct file *file, struct address_space *mapping,

			loff_t pos, unsigned len, unsigned flags,

			struct page **pagep, void **fsdata)

{

	*pagep = NULL;

	return block_write_begin(file, mapping, pos, len, flags,

				pagep, fsdata, omfs_get_block);

}



static sector_t omfs_bmap(struct address_space *mapping, sector_t block)

{

	return generic_block_bmap(mapping, block, omfs_get_block);

}



struct file_operations omfs_file_operations = {

	.llseek = generic_file_llseek,

	.read = do_sync_read,

	.write = do_sync_write,

	.aio_read = generic_file_aio_read,

	.aio_write = generic_file_aio_write,

	.mmap = generic_file_mmap,

	.fsync = omfs_sync_file,

	.splice_read = generic_file_splice_read,

};



struct inode_operations omfs_file_inops = {

	.truncate = omfs_truncate

};



struct address_space_operations omfs_aops = {

	.readpage = omfs_readpage,

	.readpages = omfs_readpages,

	.writepage = omfs_writepage,

	.writepages = omfs_writepages,

	.sync_page = block_sync_page,

	.write_begin = omfs_write_begin,

	.write_end = generic_write_end,

	.bmap = omfs_bmap,

};