path: root/fs/ext2/inode.c

/*
 *  linux/fs/ext2/inode.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/inode.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Goal-directed block allocation by Stephen Tweedie
 * 	(sct@dcs.ed.ac.uk), 1993, 1998
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 *  64-bit file support on 64-bit platforms by Jakub Jelinek
 * 	(jj@sunsite.ms.mff.cuni.cz)
 *
 *  Assorted race fixes, rewrite of ext2_get_block() by Al Viro, 2000
 */

#include <linux/time.h>
#include <linux/highuid.h>
#include <linux/pagemap.h>
#include <linux/dax.h>
#include <linux/blkdev.h>
#include <linux/quotaops.h>
#include <linux/writeback.h>
#include <linux/buffer_head.h>
#include <linux/mpage.h>
#include <linux/fiemap.h>
#include <linux/namei.h>
#include <linux/uio.h>
#include "ext2.h"
#include "acl.h"
#include "xattr.h"

static int __ext2_write_inode(struct inode *inode, int do_sync);

/*
 * Test whether an inode is a fast symlink.
 */
static inline int ext2_inode_is_fast_symlink(struct inode *inode)
{
	int ea_blocks = EXT2_I(inode)->i_file_acl ?
		(inode->i_sb->s_blocksize >> 9) : 0;

	return (S_ISLNK(inode->i_mode) &&
		inode->i_blocks - ea_blocks == 0);
}

static void ext2_truncate_blocks(struct inode *inode, loff_t offset);

static void ext2_write_failed(struct address_space *mapping, loff_t to)
{
	struct inode *inode = mapping->host;

	if (to > inode->i_size) {
		truncate_pagecache(inode, inode->i_size);
		ext2_truncate_blocks(inode, inode->i_size);
	}
}

/*
 * Called at the last iput() if i_nlink is zero.
 */
void ext2_evict_inode(struct inode * inode)
{
	struct ext2_block_alloc_info *rsv;
	int want_delete = 0;

	if (!inode->i_nlink && !is_bad_inode(inode)) {
		want_delete = 1;
		dquot_initialize(inode);
	} else {
		dquot_drop(inode);
	}

	truncate_inode_pages_final(&inode->i_data);

	if (want_delete) {
		sb_start_intwrite(inode->i_sb);
		/* set dtime */
		EXT2_I(inode)->i_dtime	= get_seconds();
		mark_inode_dirty(inode);
		__ext2_write_inode(inode, inode_needs_sync(inode));
		/* truncate to 0 */
		inode->i_size = 0;
		if (inode->i_blocks)
			ext2_truncate_blocks(inode, 0);
		ext2_xattr_delete_inode(inode);
	}

	invalidate_inode_buffers(inode);
	clear_inode(inode);

	ext2_discard_reservation(inode);
	rsv = EXT2_I(inode)->i_block_alloc_info;
	EXT2_I(inode)->i_block_alloc_info = NULL;
	if (unlikely(rsv))
		kfree(rsv);

	if (want_delete) {
		ext2_free_inode(inode);
		sb_end_intwrite(inode->i_sb);
	}
}

typedef struct {
	__le32	*p;
	__le32	key;
	struct buffer_head *bh;
} Indirect;

static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
{
	p->key = *(p->p = v);
	p->bh = bh;
}

static inline int verify_chain(Indirect *from, Indirect *to)
{
	while (from <= to && from->key == *from->p)
		from++;
	return (from > to);
}

/**
 *	ext2_block_to_path - parse the block number into array of offsets
 *	@inode: inode in question (we are only interested in its superblock)
 *	@i_block: block number to be parsed
 *	@offsets: array to store the offsets in
 *      @boundary: set this non-zero if the referred-to block is likely to be
 *             followed (on disk) by an indirect block.
 *	To store the locations of file's data ext2 uses a data structure common
 *	for UNIX filesystems - tree of pointers anchored in the inode, with
 *	data blocks at leaves and indirect blocks in intermediate nodes.
 *	This function translates the block number into path in that tree -
 *	return value is the path length and @offsets[n] is the offset of
 *	pointer to (n+1)th node in the nth one. If @block is out of range
 *	(negative or too large) warning is printed and zero returned.
 *
 *	Note: function doesn't find node addresses, so no IO is needed. All
 *	we need to know is the capacity of indirect blocks (taken from the
 *	inode->i_sb).
 */

/*
 * Portability note: the last comparison (check that we fit into triple
 * indirect block) is spelled differently, because otherwise on an
 * architecture with 32-bit longs and 8Kb pages we might get into trouble
 * if our filesystem had 8Kb blocks. We might use long long, but that would
 * kill us on x86. Oh, well, at least the sign propagation does not matter -
 * i_block would have to be negative in the very beginning, so we would not
 * get there at all.
 */

static int ext2_block_to_path(struct inode *inode,
			long i_block, int offsets[4], int *boundary)
{
	int ptrs = EXT2_ADDR_PER_BLOCK(inode->