inode.c

linux 内核源代码

/*
 * inode.c
 *
 * PURPOSE
 *  Inode handling routines for the OSTA-UDF(tm) filesystem.
 *
 * COPYRIGHT
 *  This file is distributed under the terms of the GNU General Public
 *  License (GPL). Copies of the GPL can be obtained from:
 *    ftp://prep.ai.mit.edu/pub/gnu/GPL
 *  Each contributing author retains all rights to their own work.
 *
 *  (C) 1998 Dave Boynton
 *  (C) 1998-2004 Ben Fennema
 *  (C) 1999-2000 Stelias Computing Inc
 *
 * HISTORY
 *
 *  10/04/98 dgb  Added rudimentary directory functions
 *  10/07/98      Fully working udf_block_map! It works!
 *  11/25/98      bmap altered to better support extents
 *  12/06/98 blf  partition support in udf_iget, udf_block_map and udf_read_inode
 *  12/12/98      rewrote udf_block_map to handle next extents and descs across
 *                block boundaries (which is not actually allowed)
 *  12/20/98      added support for strategy 4096
 *  03/07/99      rewrote udf_block_map (again)
 *                New funcs, inode_bmap, udf_next_aext
 *  04/19/99      Support for writing device EA's for major/minor #
 */

#include "udfdecl.h"
#include <linux/mm.h>
#include <linux/smp_lock.h>
#include <linux/module.h>
#include <linux/pagemap.h>
#include <linux/buffer_head.h>
#include <linux/writeback.h>
#include <linux/slab.h>

#include "udf_i.h"
#include "udf_sb.h"

MODULE_AUTHOR("Ben Fennema");
MODULE_DESCRIPTION("Universal Disk Format Filesystem");
MODULE_LICENSE("GPL");

#define EXTENT_MERGE_SIZE 5

static mode_t udf_convert_permissions(struct fileEntry *);
static int udf_update_inode(struct inode *, int);
static void udf_fill_inode(struct inode *, struct buffer_head *);
static int udf_alloc_i_data(struct inode *inode, size_t size);
static struct buffer_head *inode_getblk(struct inode *, sector_t, int *,
					long *, int *);
static int8_t udf_insert_aext(struct inode *, struct extent_position,
			      kernel_lb_addr, uint32_t);
static void udf_split_extents(struct inode *, int *, int, int,
			      kernel_long_ad[EXTENT_MERGE_SIZE], int *);
static void udf_prealloc_extents(struct inode *, int, int,
				 kernel_long_ad[EXTENT_MERGE_SIZE], int *);
static void udf_merge_extents(struct inode *,
			      kernel_long_ad[EXTENT_MERGE_SIZE], int *);
static void udf_update_extents(struct inode *,
			       kernel_long_ad[EXTENT_MERGE_SIZE], int, int,
			       struct extent_position *);
static int udf_get_block(struct inode *, sector_t, struct buffer_head *, int);

/*
 * udf_delete_inode
 *
 * PURPOSE
 *	Clean-up before the specified inode is destroyed.
 *
 * DESCRIPTION
 *	This routine is called when the kernel destroys an inode structure
 *	ie. when iput() finds i_count == 0.
 *
 * HISTORY
 *	July 1, 1997 - Andrew E. Mileski
 *	Written, tested, and released.
 *
 *  Called at the last iput() if i_nlink is zero.
 */
void udf_delete_inode(struct inode *inode)
{
	truncate_inode_pages(&inode->i_data, 0);

	if (is_bad_inode(inode))
		goto no_delete;

	inode->i_size = 0;
	udf_truncate(inode);
	lock_kernel();

	udf_update_inode(inode, IS_SYNC(inode));
	udf_free_inode(inode);

	unlock_kernel();
	return;

no_delete:
	clear_inode(inode);
}

/*
 * If we are going to release inode from memory, we discard preallocation and
 * truncate last inode extent to proper length. We could use drop_inode() but
 * it's called under inode_lock and thus we cannot mark inode dirty there.  We
 * use clear_inode() but we have to make sure to write inode as it's not written
 * automatically.
 */
void udf_clear_inode(struct inode *inode)
{
	if (!(inode->i_sb->s_flags & MS_RDONLY)) {
		lock_kernel();
		/* Discard preallocation for directories, symlinks, etc. */
		udf_discard_prealloc(inode);
		udf_truncate_tail_extent(inode);
		unlock_kernel();
		write_inode_now(inode, 1);
	}
	kfree(UDF_I_DATA(inode));
	UDF_I_DATA(inode) = NULL;
}

static int udf_writepage(struct page *page, struct writeback_control *wbc)
{
	return block_write_full_page(page, udf_get_block, wbc);
}

static int udf_readpage(struct file *file, struct page *page)
{
	return block_read_full_page(page, udf_get_block);
}

static int udf_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,
				udf_get_block);
}

static sector_t udf_bmap(struct address_space *mapping, sector_t block)
{
	return generic_block_bmap(mapping, block, udf_get_block);
}

const struct address_space_operations udf_aops = {
	.readpage	= udf_readpage,
	.writepage	= udf_writepage,
	.sync_page	= block_sync_page,
	.write_begin		= udf_write_begin,
	.write_end		= generic_write_end,
	.bmap		= udf_bmap,
};

void udf_expand_file_adinicb(struct inode *inode, int newsize, int *err)
{
	struct page *page;
	char *kaddr;
	struct writeback_control udf_wbc = {
		.sync_mode = WB_SYNC_NONE,
		.nr_to_write = 1,
	};

	/* from now on we have normal address_space methods */
	inode->i_data.a_ops = &udf_aops;

	if (!UDF_I_LENALLOC(inode)) {
		if (UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_USE_SHORT_AD))
			UDF_I_ALLOCTYPE(inode) = ICBTAG_FLAG_AD_SHORT;
		else
			UDF_I_ALLOCTYPE(inode) = ICBTAG_FLAG_AD_LONG;
		mark_inode_dirty(inode);
		return;
	}

	page = grab_cache_page(inode->i_mapping, 0);
	BUG_ON(!PageLocked(page));

	if (!PageUptodate(page)) {
		kaddr = kmap(page);
		memset(kaddr + UDF_I_LENALLOC(inode), 0x00,
		       PAGE_CACHE_SIZE - UDF_I_LENALLOC(inode));
		memcpy(kaddr, UDF_I_DATA(inode) + UDF_I_LENEATTR(inode),
		       UDF_I_LENALLOC(inode));
		flush_dcache_page(page);
		SetPageUptodate(page);
		kunmap(page);
	}
	memset(UDF_I_DATA(inode) + UDF_I_LENEATTR(inode), 0x00,
	       UDF_I_LENALLOC(inode));
	UDF_I_LENALLOC(inode) = 0;
	if (UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_USE_SHORT_AD))
		UDF_I_ALLOCTYPE(inode) = ICBTAG_FLAG_AD_SHORT;
	else
		UDF_I_ALLOCTYPE(inode) = ICBTAG_FLAG_AD_LONG;

	inode->i_data.a_ops->writepage(page, &udf_wbc);
	page_cache_release(page);

	mark_inode_dirty(inode);
}

struct buffer_head *udf_expand_dir_adinicb(struct inode *inode, int *block,
					   int *err)
{
	int newblock;
	struct buffer_head *dbh = NULL;
	kernel_lb_addr eloc;
	uint32_t elen;
	uint8_t alloctype;
	struct extent_position epos;

	struct udf_fileident_bh sfibh, dfibh;
	loff_t f_pos = udf_ext0_offset(inode) >> 2;
	int size = (udf_ext0_offset(inode) + inode->i_size) >> 2;
	struct fileIdentDesc cfi, *sfi, *dfi;

	if (UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_USE_SHORT_AD))
		alloctype = ICBTAG_FLAG_AD_SHORT;
	else
		alloctype = ICBTAG_FLAG_AD_LONG;

	if (!inode->i_size) {
		UDF_I_ALLOCTYPE(inode) = alloctype;
		mark_inode_dirty(inode);
		return NULL;
	}

	/* alloc block, and copy data to it */
	*block = udf_new_block(inode->i_sb, inode,
			       UDF_I_LOCATION(inode).partitionReferenceNum,
			       UDF_I_LOCATION(inode).logicalBlockNum, err);
	if (!(*block))
		return NULL;
	newblock = udf_get_pblock(inode->i_sb, *block,
				  UDF_I_LOCATION(inode).partitionReferenceNum, 0);
	if (!newblock)
		return NULL;
	dbh = udf_tgetblk(inode->i_sb, newblock);
	if (!dbh)
		return NULL;
	lock_buffer(dbh);
	memset(dbh->b_data, 0x00, inode->i_sb->s_blocksize);
	set_buffer_uptodate(dbh);
	unlock_buffer(dbh);
	mark_buffer_dirty_inode(dbh, inode);

	sfibh.soffset = sfibh.eoffset = (f_pos & ((inode->i_sb->s_blocksize - 1) >> 2)) << 2;
	sfibh.sbh = sfibh.ebh = NULL;
	dfibh.soffset = dfibh.eoffset = 0;
	dfibh.sbh = dfibh.ebh = dbh;
	while ((f_pos < size)) {
		UDF_I_ALLOCTYPE(inode) = ICBTAG_FLAG_AD_IN_ICB;
		sfi = udf_fileident_read(inode, &f_pos, &sfibh, &cfi, NULL, NULL, NULL, NULL);
		if (!sfi) {
			brelse(dbh);
			return NULL;
		}
		UDF_I_ALLOCTYPE(inode) = alloctype;
		sfi->descTag.tagLocation = cpu_to_le32(*block);
		dfibh.soffset = dfibh.eoffset;
		dfibh.eoffset += (sfibh.eoffset - sfibh.soffset);
		dfi = (struct fileIdentDesc *)(dbh->b_data + dfibh.soffset);
		if (udf_write_fi(inode, sfi, dfi, &dfibh, sfi->impUse,
				 sfi->fileIdent + le16_to_cpu(sfi->lengthOfImpUse))) {
			UDF_I_ALLOCTYPE(inode) = ICBTAG_FLAG_AD_IN_ICB;
			brelse(dbh);
			return NULL;
		}
	}
	mark_buffer_dirty_inode(dbh, inode);

	memset(UDF_I_DATA(inode) + UDF_I_LENEATTR(inode), 0, UDF_I_LENALLOC(inode));
	UDF_I_LENALLOC(inode) = 0;
	eloc.logicalBlockNum = *block;
	eloc.partitionReferenceNum = UDF_I_LOCATION(inode).partitionReferenceNum;
	elen = inode->i_size;
	UDF_I_LENEXTENTS(inode) = elen;
	epos.bh = NULL;
	epos.block = UDF_I_LOCATION(inode);
	epos.offset = udf_file_entry_alloc_offset(inode);
	udf_add_aext(inode, &epos, eloc, elen, 0);
	/* UniqueID stuff */

	brelse(epos.bh);
	mark_inode_dirty(inode);
	return dbh;
}

static int udf_get_block(struct inode *inode, sector_t block,
			 struct buffer_head *bh_result, int create)
{
	int err, new;
	struct buffer_head *bh;
	unsigned long phys;

	if (!create) {
		phys = udf_block_map(inode, block);
		if (phys)
			map_bh(bh_result, inode->i_sb, phys);
		return 0;
	}

	err = -EIO;
	new = 0;
	bh = NULL;

	lock_kernel();

	if (block < 0)
		goto abort_negative;

	if (block == UDF_I_NEXT_ALLOC_BLOCK(inode) + 1) {
		UDF_I_NEXT_ALLOC_BLOCK(inode)++;
		UDF_I_NEXT_ALLOC_GOAL(inode)++;
	}

	err = 0;

	bh = inode_getblk(inode, block, &err, &phys, &new);
	BUG_ON(bh);
	if (err)
		goto abort;
	BUG_ON(!phys);

	if (new)
		set_buffer_new(bh_result);
	map_bh(bh_result, inode->i_sb, phys);

abort:
	unlock_kernel();
	return err;

abort_negative:
	udf_warning(inode->i_sb, "udf_get_block", "block < 0");
	goto abort;
}

static struct buffer_head *udf_getblk(struct inode *inode, long block,
				      int create, int *err)
{
	struct buffer_head *bh;
	struct buffer_head dummy;

	dummy.b_state = 0;
	dummy.b_blocknr = -1000;
	*err = udf_get_block(inode, block, &dummy, create);
	if (!*err && buffer_mapped(&dummy)) {
		bh = sb_getblk(inode->i_sb, dummy.b_blocknr);
		if (buffer_new(&dummy)) {
			lock_buffer(bh);
			memset(bh->b_data, 0x00, inode->i_sb->s_blocksize);
			set_buffer_uptodate(bh);
			unlock_buffer(bh);
			mark_buffer_dirty_inode(bh, inode);
		}
		return bh;
	}

	return NULL;
}

/* Extend the file by 'blocks' blocks, return the number of extents added */
int udf_extend_file(struct inode *inode, struct extent_position *last_pos,
		    kernel_long_ad * last_ext, sector_t blocks)
{
	sector_t add;
	int count = 0, fake = !(last_ext->extLength & UDF_EXTENT_LENGTH_MASK);
	struct super_block *sb = inode->i_sb;
	kernel_lb_addr prealloc_loc = {};
	int prealloc_len = 0;

	/* The previous extent is fake and we should not extend by anything
	 * - there's nothing to do... */
	if (!blocks && fake)
		return 0;

	/* Round the last extent up to a multiple of block size */
	if (last_ext->extLength & (sb->s_blocksize - 1)) {
		last_ext->extLength =
			(last_ext->extLength & UDF_EXTENT_FLAG_MASK) |
			(((last_ext->extLength & UDF_EXTENT_LENGTH_MASK) +
			  sb->s_blocksize - 1) & ~(sb->s_blocksize - 1));
		UDF_I_LENEXTENTS(inode) =
			(UDF_I_LENEXTENTS(inode) + sb->s_blocksize - 1) &
			~(sb->s_blocksize - 1);
	}

	/* Last extent are just preallocated blocks? */
	if ((last_ext->extLength & UDF_EXTENT_FLAG_MASK) == EXT_NOT_RECORDED_ALLOCATED) {
		/* Save the extent so that we can reattach it to the end */
		prealloc_loc = last_ext->extLocation;
		prealloc_len = last_ext->extLength;
		/* Mark the extent as a hole */
		last_ext->extLength = EXT_NOT_RECORDED_NOT_ALLOCATED |
			(last_ext->extLength & UDF_EXTENT_LENGTH_MASK);
		last_ext->extLocation.logicalBlockNum = 0;
       		last_ext->extLocation.partitionReferenceNum = 0;
	}

	/* Can we merge with the previous extent? */
	if ((last_ext->extLength & UDF_EXTENT_FLAG_MASK) == EXT_NOT_RECORDED_NOT_ALLOCATED) {
		add = ((1 << 30) - sb->s_blocksize - (last_ext->extLength &
						      UDF_EXTENT_LENGTH_MASK)) >> sb->s_blocksize_bits;
		if (add > blocks)
			add = blocks;
		blocks -= add;
		last_ext->extLength += add << sb->s_blocksize_bits;
	}

	if (fake) {
		udf_add_aext(inode, last_pos, last_ext->extLocation,
			     last_ext->extLength, 1);
		count++;
	} else {
		udf_write_aext(inode, last_pos, last_ext->extLocation, last_ext->extLength, 1);
	}

	/* Managed to do everything necessary? */
	if (!blocks)
		goto out;

	/* All further extents will be NOT_RECORDED_NOT_ALLOCATED */
	last_ext->extLocation.logicalBlockNum = 0;
       	last_ext->extLocation.partitionReferenceNum = 0;
	add = (1 << (30-sb->s_blocksize_bits)) - 1;
	last_ext->extLength = EXT_NOT_RECORDED_NOT_ALLOCATED | (add << sb->s_blocksize_bits);

	/* Create enough extents to cover the whole hole */
	while (blocks > add) {
		blocks -= add;
		if (udf_add_aext(inode, last_pos, last_ext->extLocation,
				 last_ext->extLength, 1) == -1)
			return -1;
		count++;
	}
	if (blocks) {
		last_ext->extLength = EXT_NOT_RECORDED_NOT_ALLOCATED |
			(blocks << sb->s_blocksize_bits);
		if (udf_add_aext(inode, last_pos, last_ext->extLocation,
				 last_ext->extLength, 1) == -1)
			return -1;
		count++;
	}

out:
	/* Do we have some preallocated blocks saved? */
	if (prealloc_len) {
		if (udf_add_aext(inode, last_pos, prealloc_loc, prealloc_len, 1) == -1)
			return -1;
		last_ext->extLocation = prealloc_loc;
		last_ext->extLength = prealloc_len;
		count++;
	}

	/* last_pos should point to the last written extent... */
	if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_SHORT)
		last_pos->offset -= sizeof(short_ad);
	else if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_LONG)
		last_pos->offset -= sizeof(long_ad);
	else
		return -1;

	return count;
}

static struct buffer_head *inode_getblk(struct inode *inode, sector_t block,
					int *err, long *phys, int *new)
{
	static sector_t last_block;
	struct buffer_head *result = NULL;
	kernel_long_ad laarr[EXTENT_MERGE_SIZE];
	struct extent_position prev_epos, cur_epos, next_epos;
	int count = 0, startnum = 0, endnum = 0;
	uint32_t elen = 0, tmpelen;
	kernel_lb_addr eloc, tmpeloc;
	int c = 1;
	loff_t lbcount = 0, b_off = 0;
	uint32_t newblocknum, newblock;
	sector_t offset = 0;
	int8_t etype;
	int goal = 0, pgoal = UDF_I_LOCATION(inode).logicalBlockNum;
	int lastblock = 0;

	prev_epos.offset = udf_file_entry_alloc_offset(inode);
	prev_epos.block = UDF_I_LOCATION(inode);
	prev_epos.bh = NULL;
	cur_epos = next_epos = prev_epos;
	b_off = (loff_t)block << inode->i_sb->s_blocksize_bits;

	/* find the extent which contains the block we are looking for.
	   alternate between laarr[0] and laarr[1] for locations of the
	   current extent, and the previous extent */
	do {
		if (prev_epos.bh != cur_epos.bh) {