fs/inode.c


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/*
 * linux/fs/inode.c
 *
 * (C) 1997 Linus Torvalds
 */

#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/dcache.h>
#include <linux/init.h>
#include <linux/quotaops.h>
#include <linux/slab.h>
#include <linux/writeback.h>
#include <linux/module.h>
#include <linux/backing-dev.h>
#include <linux/wait.h>
#include <linux/hash.h>
#include <linux/swap.h>
#include <linux/security.h>
#include <linux/ima.h>
#include <linux/pagemap.h>
#include <linux/cdev.h>
#include <linux/bootmem.h>
#include <linux/inotify.h>
#include <linux/fsnotify.h>
#include <linux/mount.h>
#include <linux/async.h>
#include <linux/posix_acl.h>

/*
 * This is needed for the following functions:
 *  - inode_has_buffers
 *  - invalidate_inode_buffers
 *  - invalidate_bdev
 *
 * FIXME: remove all knowledge of the buffer layer from this file
 */
#include <linux/buffer_head.h>

/*
 * New inode.c implementation.
 *
 * This implementation has the basic premise of trying
 * to be extremely low-overhead and SMP-safe, yet be
 * simple enough to be "obviously correct".
 *
 * Famous last words.
 */

/* inode dynamic allocation 1999, Andrea Arcangeli <andrea@suse.de> */

/* #define INODE_PARANOIA 1 */
/* #define INODE_DEBUG 1 */

/*
 * Inode lookup is no longer as critical as it used to be:
 * most of the lookups are going to be through the dcache.
 */
#define I_HASHBITS	i_hash_shift
#define I_HASHMASK	i_hash_mask

static unsigned int i_hash_mask __read_mostly;
static unsigned int i_hash_shift __read_mostly;

/*
 * Each inode can be on two separate lists. One is
 * the hash list of the inode, used for lookups. The
 * other linked list is the "type" list:
 *  "in_use" - valid inode, i_count > 0, i_nlink > 0
 *  "dirty"  - as "in_use" but also dirty
 *  "unused" - valid inode, i_count = 0
 *
 * A "dirty" list is maintained for each super block,
 * allowing for low-overhead inode sync() operations.
 */

LIST_HEAD(inode_in_use);
LIST_HEAD(inode_unused);
static struct hlist_head *inode_hashtable __read_mostly;

/*
 * A simple spinlock to protect the list manipulations.
 *
 * NOTE! You also have to own the lock if you change
 * the i_state of an inode while it is in use..
 */
DEFINE_SPINLOCK(inode_lock);

/*
 * iprune_mutex provides exclusion between the kswapd or try_to_free_pages
 * icache shrinking path, and the umount path.  Without this exclusion,
 * by the time prune_icache calls iput for the inode whose pages it has
 * been invalidating, or by the time it calls clear_inode & destroy_inode
 * from its final dispose_list, the struct super_block they refer to
 * (for inode->i_sb->s_op) may already have been freed and reused.
 */
static DEFINE_MUTEX(iprune_mutex);

/*
 * Statistics gathering..
 */
struct inodes_stat_t inodes_stat;

static struct kmem_cache *inode_cachep __read_mostly;

static void wake_up_inode(struct inode *inode)
{
	/*
	 * Prevent speculative execution through spin_unlock(&inode_lock);
	 */
	smp_mb();
	wake_up_bit(&inode->i_state, __I_LOCK);
}

/**
 * inode_init_always - perform inode structure intialisation
 * @sb: superblock inode belongs to
 * @inode: inode to initialise
 *
 * These are initializations that need to be done on every inode
 * allocation as the fields are not initialised by slab allocation.
 */
int inode_init_always(struct super_block *sb, struct inode *inode)
{
	static const struct address_space_operations empty_aops;
	static struct inode_operations empty_iops;
	static const struct file_operations empty_fops;
	struct address_space *const mapping = &inode->i_data;

	inode->i_sb = sb;
	inode->i_blkbits = sb->s_blocksize_bits;
	inode->i_flags = 0;
	atomic_set(&inode->i_count, 1);
	inode->i_op = &empty_iops;
	inode->i_fop = &empty_fops;
	inode->i_nlink = 1;
	inode->i_uid = 0;
	inode->i_gid = 0;
	atomic_set(&inode->i_writecount, 0);
	inode->i_size = 0;
	inode->i_blocks = 0;
	inode->i_bytes = 0;
	inode->i_generation = 0;
#ifdef CONFIG_QUOTA
	memset(&inode->i_dquot, 0, sizeof(inode->i_dquot));
#endif
	inode->i_pipe = NULL;
	inode->i_bdev = NULL;
	inode->i_cdev = NULL;
	inode->i_rdev = 0;
	inode->dirtied_when = 0;

	if (security_inode_alloc(inode))
		goto out;

	/* allocate and initialize an i_integrity */
	if (ima_inode_alloc(inode))
		goto out_free_security;

	spin_lock_init(&inode->i_lock);
	lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key);

	mutex_init(&inode->i_mutex);
	lockdep_set_class(&inode->i_mutex, &sb->s_type->i_mutex_key);

	init_rwsem(&inode->i_alloc_sem);
	lockdep_set_class(&inode->i_alloc_sem, &sb->s_type->i_alloc_sem_key);

	mapping->a_ops = &empty_aops;
	mapping->host = inode;
	mapping->flags = 0;
	mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
	mapping->assoc_mapping = NULL;
	mapping->backing_dev_info = &default_backing_dev_info;
	mapping->writeback_index = 0;

	/*
	 * If the block_device provides a backing_dev_info for client
	 * inodes then use that.  Otherwise the inode share the bdev's
	 * backing_dev_info.
	 */
	if (sb->s_bdev) {
		struct backing_dev_info *bdi;

		bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
		mapping->backing_dev_info = bdi;
	}
	inode->i_private = NULL;
	inode->i_mapping = mapping;
#ifdef CONFIG_FS_POSIX_ACL
	inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED;
#endif

#ifdef CONFIG_FSNOTIFY
	inode->i_fsnotify_mask = 0;
#endif

	return 0;

out_free_security:
	security_inode_free(inode);
out:
	return -ENOMEM;
}
EXPORT_SYMBOL(inode_init_always);

static struct inode *alloc_inode(struct super_block *sb)
{
	struct inode *inode;

	if (sb->s_op->alloc_inode)
		inode = sb->s_op->alloc_inode(sb);
	else
		inode = kmem_cache_alloc(inode_cachep, GFP_KERNEL);

	if (!inode)
		return NULL;

	if (unlikely(inode_init_always(sb, inode))) {
		if (inode->i_sb->s_op->destroy_inode)
			inode->i_sb->s_op->destroy_inode(inode);
		else
			kmem_cache_free(inode_cachep, inode);
		return NULL;
	}

	return inode;
}

void __destroy_inode(struct inode *inode)
{
	BUG_ON(inode_has_buffers(inode));
	ima_inode_free(inode);
	security_inode_free(inode);
	fsnotify_inode_delete(inode);
#ifdef CONFIG_FS_POSIX_ACL
	if (inode->i_acl && inode->i_acl != ACL_NOT_CACHED)
		posix_acl_release(inode->i_acl);
	if (inode->i_default_acl && inode->i_default_acl != ACL_NOT_CACHED)
		posix_acl_release(inode->i_default_acl);
#endif
}
EXPORT_SYMBOL(__destroy_inode);

void destroy_inode(struct inode *inode)
{
	__destroy_inode(inode);
	if (inode->i_sb->s_op->destroy_inode)
		inode->i_sb->s_op->destroy_inode(inode);
	else
		kmem_cache_free(inode_cachep, (inode));
}

/*
 * These are initializations that only need to be done
 * once, because the fields are idempotent across use
 * of the inode, so let the slab aware of that.
 */
void inode_init_once(struct inode *inode)
{
	memset(inode, 0, sizeof(*inode));
	INIT_HLIST_NODE(&inode->i_hash);
	INIT_LIST_HEAD(&inode->i_dentry);
	INIT_LIST_HEAD(&inode->i_devices);
	INIT_RADIX_TREE(&inode->i_data.page_tree, GFP_ATOMIC);
	spin_lock_init(&inode->i_data.tree_lock);
	spin_lock_init(&inode->i_data.i_mmap_lock);
	INIT_LIST_HEAD(&inode->i_data.private_list);
	spin_lock_init(&inode->i_data.private_lock);
	INIT_RAW_PRIO_TREE_ROOT(&inode->i_data.i_mmap);
	INIT_LIST_HEAD(&inode->i_data.i_mmap_nonlinear);
	i_size_ordered_init(inode);
#ifdef CONFIG_INOTIFY
	INIT_LIST_HEAD(&inode->inotify_watches);
	mutex_init(&inode->inotify_mutex);
#endif
#ifdef CONFIG_FSNOTIFY
	INIT_HLIST_HEAD(&inode->i_fsnotify_mark_entries);
#endif
}
EXPORT_SYMBOL(inode_init_once);

static void init_once(void *foo)
{
	struct inode *inode = (struct inode *) foo;

	inode_init_once(inode);
}

/*
 * inode_lock must be held
 */
void __iget(struct inode *inode)
{