inode.c

linux 内核源代码

/**
 * inode.c - NTFS kernel inode handling. Part of the Linux-NTFS project.
 *
 * Copyright (c) 2001-2007 Anton Altaparmakov
 *
 * This program/include file is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program/include file is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program (in the main directory of the Linux-NTFS
 * distribution in the file COPYING); if not, write to the Free Software
 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/buffer_head.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/mount.h>
#include <linux/mutex.h>
#include <linux/pagemap.h>
#include <linux/quotaops.h>
#include <linux/slab.h>

#include "aops.h"
#include "attrib.h"
#include "bitmap.h"
#include "dir.h"
#include "debug.h"
#include "inode.h"
#include "lcnalloc.h"
#include "malloc.h"
#include "mft.h"
#include "time.h"
#include "ntfs.h"

/**
 * ntfs_test_inode - compare two (possibly fake) inodes for equality
 * @vi:		vfs inode which to test
 * @na:		ntfs attribute which is being tested with
 *
 * Compare the ntfs attribute embedded in the ntfs specific part of the vfs
 * inode @vi for equality with the ntfs attribute @na.
 *
 * If searching for the normal file/directory inode, set @na->type to AT_UNUSED.
 * @na->name and @na->name_len are then ignored.
 *
 * Return 1 if the attributes match and 0 if not.
 *
 * NOTE: This function runs with the inode_lock spin lock held so it is not
 * allowed to sleep.
 */
int ntfs_test_inode(struct inode *vi, ntfs_attr *na)
{
	ntfs_inode *ni;

	if (vi->i_ino != na->mft_no)
		return 0;
	ni = NTFS_I(vi);
	/* If !NInoAttr(ni), @vi is a normal file or directory inode. */
	if (likely(!NInoAttr(ni))) {
		/* If not looking for a normal inode this is a mismatch. */
		if (unlikely(na->type != AT_UNUSED))
			return 0;
	} else {
		/* A fake inode describing an attribute. */
		if (ni->type != na->type)
			return 0;
		if (ni->name_len != na->name_len)
			return 0;
		if (na->name_len && memcmp(ni->name, na->name,
				na->name_len * sizeof(ntfschar)))
			return 0;
	}
	/* Match! */
	return 1;
}

/**
 * ntfs_init_locked_inode - initialize an inode
 * @vi:		vfs inode to initialize
 * @na:		ntfs attribute which to initialize @vi to
 *
 * Initialize the vfs inode @vi with the values from the ntfs attribute @na in
 * order to enable ntfs_test_inode() to do its work.
 *
 * If initializing the normal file/directory inode, set @na->type to AT_UNUSED.
 * In that case, @na->name and @na->name_len should be set to NULL and 0,
 * respectively. Although that is not strictly necessary as
 * ntfs_read_locked_inode() will fill them in later.
 *
 * Return 0 on success and -errno on error.
 *
 * NOTE: This function runs with the inode_lock spin lock held so it is not
 * allowed to sleep. (Hence the GFP_ATOMIC allocation.)
 */
static int ntfs_init_locked_inode(struct inode *vi, ntfs_attr *na)
{
	ntfs_inode *ni = NTFS_I(vi);

	vi->i_ino = na->mft_no;

	ni->type = na->type;
	if (na->type == AT_INDEX_ALLOCATION)
		NInoSetMstProtected(ni);

	ni->name = na->name;
	ni->name_len = na->name_len;

	/* If initializing a normal inode, we are done. */
	if (likely(na->type == AT_UNUSED)) {
		BUG_ON(na->name);
		BUG_ON(na->name_len);
		return 0;
	}

	/* It is a fake inode. */
	NInoSetAttr(ni);

	/*
	 * We have I30 global constant as an optimization as it is the name
	 * in >99.9% of named attributes! The other <0.1% incur a GFP_ATOMIC
	 * allocation but that is ok. And most attributes are unnamed anyway,
	 * thus the fraction of named attributes with name != I30 is actually
	 * absolutely tiny.
	 */
	if (na->name_len && na->name != I30) {
		unsigned int i;

		BUG_ON(!na->name);
		i = na->name_len * sizeof(ntfschar);
		ni->name = kmalloc(i + sizeof(ntfschar), GFP_ATOMIC);
		if (!ni->name)
			return -ENOMEM;
		memcpy(ni->name, na->name, i);
		ni->name[na->name_len] = 0;
	}
	return 0;
}

typedef int (*set_t)(struct inode *, void *);
static int ntfs_read_locked_inode(struct inode *vi);
static int ntfs_read_locked_attr_inode(struct inode *base_vi, struct inode *vi);
static int ntfs_read_locked_index_inode(struct inode *base_vi,
		struct inode *vi);

/**
 * ntfs_iget - obtain a struct inode corresponding to a specific normal inode
 * @sb:		super block of mounted volume
 * @mft_no:	mft record number / inode number to obtain
 *
 * Obtain the struct inode corresponding to a specific normal inode (i.e. a
 * file or directory).
 *
 * If the inode is in the cache, it is just returned with an increased
 * reference count. Otherwise, a new struct inode is allocated and initialized,
 * and finally ntfs_read_locked_inode() is called to read in the inode and
 * fill in the remainder of the inode structure.
 *
 * Return the struct inode on success. Check the return value with IS_ERR() and
 * if true, the function failed and the error code is obtained from PTR_ERR().
 */
struct inode *ntfs_iget(struct super_block *sb, unsigned long mft_no)
{
	struct inode *vi;
	int err;
	ntfs_attr na;

	na.mft_no = mft_no;
	na.type = AT_UNUSED;
	na.name = NULL;
	na.name_len = 0;

	vi = iget5_locked(sb, mft_no, (test_t)ntfs_test_inode,
			(set_t)ntfs_init_locked_inode, &na);
	if (unlikely(!vi))
		return ERR_PTR(-ENOMEM);

	err = 0;

	/* If this is a freshly allocated inode, need to read it now. */
	if (vi->i_state & I_NEW) {
		err = ntfs_read_locked_inode(vi);
		unlock_new_inode(vi);
	}
	/*
	 * There is no point in keeping bad inodes around if the failure was
	 * due to ENOMEM. We want to be able to retry again later.
	 */
	if (unlikely(err == -ENOMEM)) {
		iput(vi);
		vi = ERR_PTR(err);
	}
	return vi;
}

/**
 * ntfs_attr_iget - obtain a struct inode corresponding to an attribute
 * @base_vi:	vfs base inode containing the attribute
 * @type:	attribute type
 * @name:	Unicode name of the attribute (NULL if unnamed)
 * @name_len:	length of @name in Unicode characters (0 if unnamed)
 *
 * Obtain the (fake) struct inode corresponding to the attribute specified by
 * @type, @name, and @name_len, which is present in the base mft record
 * specified by the vfs inode @base_vi.
 *
 * If the attribute inode is in the cache, it is just returned with an
 * increased reference count. Otherwise, a new struct inode is allocated and
 * initialized, and finally ntfs_read_locked_attr_inode() is called to read the
 * attribute and fill in the inode structure.
 *
 * Note, for index allocation attributes, you need to use ntfs_index_iget()
 * instead of ntfs_attr_iget() as working with indices is a lot more complex.
 *
 * Return the struct inode of the attribute inode on success. Check the return
 * value with IS_ERR() and if true, the function failed and the error code is
 * obtained from PTR_ERR().
 */
struct inode *ntfs_attr_iget(struct inode *base_vi, ATTR_TYPE type,
		ntfschar *name, u32 name_len)
{
	struct inode *vi;
	int err;
	ntfs_attr na;

	/* Make sure no one calls ntfs_attr_iget() for indices. */
	BUG_ON(type == AT_INDEX_ALLOCATION);

	na.mft_no = base_vi->i_ino;
	na.type = type;
	na.name = name;
	na.name_len = name_len;

	vi = iget5_locked(base_vi->i_sb, na.mft_no, (test_t)ntfs_test_inode,
			(set_t)ntfs_init_locked_inode, &na);
	if (unlikely(!vi))
		return ERR_PTR(-ENOMEM);

	err = 0;

	/* If this is a freshly allocated inode, need to read it now. */
	if (vi->i_state & I_NEW) {
		err = ntfs_read_locked_attr_inode(base_vi, vi);
		unlock_new_inode(vi);
	}
	/*
	 * There is no point in keeping bad attribute inodes around. This also
	 * simplifies things in that we never need to check for bad attribute
	 * inodes elsewhere.
	 */
	if (unlikely(err)) {
		iput(vi);
		vi = ERR_PTR(err);
	}
	return vi;
}

/**
 * ntfs_index_iget - obtain a struct inode corresponding to an index
 * @base_vi:	vfs base inode containing the index related attributes
 * @name:	Unicode name of the index
 * @name_len:	length of @name in Unicode characters
 *
 * Obtain the (fake) struct inode corresponding to the index specified by @name
 * and @name_len, which is present in the base mft record specified by the vfs
 * inode @base_vi.
 *
 * If the index inode is in the cache, it is just returned with an increased
 * reference count.  Otherwise, a new struct inode is allocated and
 * initialized, and finally ntfs_read_locked_index_inode() is called to read
 * the index related attributes and fill in the inode structure.
 *
 * Return the struct inode of the index inode on success. Check the return
 * value with IS_ERR() and if true, the function failed and the error code is
 * obtained from PTR_ERR().
 */
struct inode *ntfs_index_iget(struct inode *base_vi, ntfschar *name,
		u32 name_len)
{
	struct inode *vi;
	int err;
	ntfs_attr na;

	na.mft_no = base_vi->i_ino;
	na.type = AT_INDEX_ALLOCATION;
	na.name = name;
	na.name_len = name_len;

	vi = iget5_locked(base_vi->i_sb, na.mft_no, (test_t)ntfs_test_inode,
			(set_t)ntfs_init_locked_inode, &na);
	if (unlikely(!vi))
		return ERR_PTR(-ENOMEM);

	err = 0;

	/* If this is a freshly allocated inode, need to read it now. */
	if (vi->i_state & I_NEW) {
		err = ntfs_read_locked_index_inode(base_vi, vi);
		unlock_new_inode(vi);
	}
	/*
	 * There is no point in keeping bad index inodes around.  This also
	 * simplifies things in that we never need to check for bad index
	 * inodes elsewhere.
	 */
	if (unlikely(err)) {
		iput(vi);
		vi = ERR_PTR(err);
	}
	return vi;
}

struct inode *ntfs_alloc_big_inode(struct super_block *sb)
{
	ntfs_inode *ni;

	ntfs_debug("Entering.");
	ni = kmem_cache_alloc(ntfs_big_inode_cache, GFP_NOFS);
	if (likely(ni != NULL)) {
		ni->state = 0;
		return VFS_I(ni);
	}
	ntfs_error(sb, "Allocation of NTFS big inode structure failed.");
	return NULL;
}

void ntfs_destroy_big_inode(struct inode *inode)
{
	ntfs_inode *ni = NTFS_I(inode);

	ntfs_debug("Entering.");
	BUG_ON(ni->page);
	if (!atomic_dec_and_test(&ni->count))
		BUG();
	kmem_cache_free(ntfs_big_inode_cache, NTFS_I(inode));
}

static inline ntfs_inode *ntfs_alloc_extent_inode(void)
{
	ntfs_inode *ni;

	ntfs_debug("Entering.");
	ni = kmem_cache_alloc(ntfs_inode_cache, GFP_NOFS);
	if (likely(ni != NULL)) {
		ni->state = 0;
		return ni;
	}
	ntfs_error(NULL, "Allocation of NTFS inode structure failed.");
	return NULL;
}

static void ntfs_destroy_extent_inode(ntfs_inode *ni)
{
	ntfs_debug("Entering.");
	BUG_ON(ni->page);
	if (!atomic_dec_and_test(&ni->count))
		BUG();
	kmem_cache_free(ntfs_inode_cache, ni);
}

/*
 * The attribute runlist lock has separate locking rules from the
 * normal runlist lock, so split the two lock-classes:
 */
static struct lock_class_key attr_list_rl_lock_class;

/**
 * __ntfs_init_inode - initialize ntfs specific part of an inode
 * @sb:		super block of mounted volume
 * @ni:		freshly allocated ntfs inode which to initialize
 *
 * Initialize an ntfs inode to defaults.
 *
 * NOTE: ni->mft_no, ni->state, ni->type, ni->name, and ni->name_len are left
 * untouched. Make sure to initialize them elsewhere.
 *
 * Return zero on success and -ENOMEM on error.
 */
void __ntfs_init_inode(struct super_block *sb, ntfs_inode *ni)
{
	ntfs_debug("Entering.");
	rwlock_init(&ni->size_lock);
	ni->initialized_size = ni->allocated_size = 0;
	ni->seq_no = 0;
	atomic_set(&ni->count, 1);
	ni->vol = NTFS_SB(sb);
	ntfs_init_runlist(&ni->runlist);
	mutex_init(&ni->mrec_lock);
	ni->page = NULL;
	ni->page_ofs = 0;
	ni->attr_list_size = 0;
	ni->attr_list = NULL;
	ntfs_init_runlist(&ni->attr_list_rl);
	lockdep_set_class(&ni->attr_list_rl.lock,
				&attr_list_rl_lock_class);
	ni->itype.index.block_size = 0;
	ni->itype.index.vcn_size = 0;
	ni->itype.index.collation_rule = 0;
	ni->itype.index.block_size_bits = 0;
	ni->itype.index.vcn_size_bits = 0;
	mutex_init(&ni->extent_lock);
	ni->nr_extents = 0;
	ni->ext.base_ntfs_ino = NULL;
}

/*
 * Extent inodes get MFT-mapped in a nested way, while the base inode