/* *  linux/fs/ext4/dir.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/dir.c * *  Copyright (C) 1991, 1992  Linus Torvalds * *  ext4 directory handling functions * *  Big-endian to little-endian byte-swapping/bitmaps by *        David S. Miller (davem@caip.rutgers.edu), 1995 * * Hash Tree Directory indexing (c) 2001  Daniel Phillips * */ #include <linux/fs.h>#include <linux/jbd2.h>#include <linux/buffer_head.h>#include <linux/slab.h>#include <linux/rbtree.h>#include "ext4.h" static unsigned char ext4_filetype_table[] = {	DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK}; static int ext4_dx_readdir(struct file *filp,			   void *dirent, filldir_t filldir); static unsigned char get_dtype(struct super_block *sb, int filetype){	if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) ||	    (filetype >= EXT4_FT_MAX))		return DT_UNKNOWN; 	return (ext4_filetype_table[filetype]);} /** * Check if the given dir-inode refers to an htree-indexed directory * (or a directory which chould potentially get coverted to use htree * indexing). * * Return 1 if it is a dx dir, 0 if not */static int is_dx_dir(struct inode *inode){	struct super_block *sb = inode->i_sb; 	if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,		     EXT4_FEATURE_COMPAT_DIR_INDEX) &&	    ((ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) ||	     ((inode->i_size >> sb->s_blocksize_bits) == 1)))		return 1; 	return 0;} /* * Return 0 if the directory entry is OK, and 1 if there is a problem * * Note: this is the opposite of what ext2 and ext3 historically returned... */int __ext4_check_dir_entry(const char *function, unsigned int line,			   struct inode *dir, struct file *filp,			   struct ext4_dir_entry_2 *de,			   struct buffer_head *bh,			   unsigned int offset){	const char *error_msg = NULL;	const int rlen = ext4_rec_len_from_disk(de->rec_len,						dir->i_sb->s_blocksize); 	if (unlikely(rlen < EXT4_DIR_REC_LEN(1)))		error_msg = "rec_len is smaller than minimal";	else if (unlikely(rlen % 4 != 0))		error_msg = "rec_len % 4 != 0";	else if (unlikely(rlen < EXT4_DIR_REC_LEN(de->name_len)))		error_msg = "rec_len is too small for name_len";	else if (unlikely(((char *) de - bh->b_data) + rlen >			  dir->i_sb->s_blocksize))		error_msg = "directory entry across blocks";	else if (unlikely(le32_to_cpu(de->inode) >			le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)))		error_msg = "inode out of bounds";	else		return 0; 	if (filp)		ext4_error_file(filp, function, line, bh->b_blocknr,				"bad entry in directory: %s - offset=%u(%u), "				"inode=%u, rec_len=%d, name_len=%d",				error_msg, (unsigned) (offset % bh->b_size),				offset, le32_to_cpu(de->inode),				rlen, de->name_len);	else		ext4_error_inode(dir, function, line, bh->b_blocknr,				"bad entry in directory: %s - offset=%u(%u), "				"inode=%u, rec_len=%d, name_len=%d",				error_msg, (unsigned) (offset % bh->b_size),				offset, le32_to_cpu(de->inode),				rlen, de->name_len); 	return 1;} static int ext4_readdir(struct file *filp,			 void *dirent, filldir_t filldir){	int error = 0;	unsigned int offset;	int i, stored;	struct ext4_dir_entry_2 *de;	int err;	struct inode *inode = filp->f_path.dentry->d_inode;	struct super_block *sb = inode->i_sb;	int ret = 0;	int dir_has_error = 0; 	if (is_dx_dir(inode)) {		err = ext4_dx_readdir(filp, dirent, filldir);		if (err != ERR_BAD_DX_DIR) {			ret = err;			goto out;		}		/*		 * We don't set the inode dirty flag since it's not		 * critical that it get flushed back to the disk.		 */		ext4_clear_inode_flag(filp->f_path.dentry->d_inode,				      EXT4_INODE_INDEX);	}	stored = 0;	offset = filp->f_pos & (sb->s_blocksize - 1); 	while (!error && !stored && filp->f_pos < inode->i_size) {		struct ext4_map_blocks map;		struct buffer_head *bh = NULL; 		map.m_lblk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb);		map.m_len = 1;		err = ext4_map_blocks(NULL, inode, &map, 0);		if (err > 0) {			pgoff_t index = map.m_pblk >>					(PAGE_CACHE_SHIFT - inode->i_blkbits);			if (!ra_has_index(&filp->f_ra, index))				page_cache_sync_readahead(					sb->s_bdev->bd_inode->i_mapping,					&filp->f_ra, filp,					index, 1);			filp->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;			bh = ext4_bread(NULL, inode, map.m_lblk, 0, &err);		} 		/*		 * We ignore I/O errors on directories so users have a chance		 * of recovering data when there's a bad sector		 */		if (!bh) {			if (!dir_has_error) {				EXT4_ERROR_FILE(filp, 0,						"directory contains a "						"hole at offset %llu",					   (unsigned long long) filp->f_pos);				dir_has_error = 1;			}			/* corrupt size?  Maybe no more blocks to read */			if (filp->f_pos > inode->i_blocks << 9)				break;			filp->f_pos += sb->s_blocksize - offset;			continue;		} 		/* Check the checksum */		if (!buffer_verified(bh) &&		    !ext4_dirent_csum_verify(inode,				(struct ext4_dir_entry *)bh->b_data)) {			EXT4_ERROR_FILE(filp, 0, "directory fails checksum "					"at offset %llu",					(unsigned long long)filp->f_pos);			filp->f_pos += sb->s_blocksize - offset;			continue;		}		set_buffer_verified(bh); revalidate:		/* If the dir block has changed since the last call to		 * readdir(2), then we might be pointing to an invalid		 * dirent right now.  Scan from the start of the block		 * to make sure. */		if (filp->f_version != inode->i_version) {			for (i = 0; i < sb->s_blocksize && i < offset; ) {				de = (struct ext4_dir_entry_2 *)					(bh->b_data + i);				/* It's too expensive to do a full				 * dirent test each time round this				 * loop, but we do have to test at				 * least that it is non-zero.  A				 * failure will be detected in the				 * dirent test below. */				if (ext4_rec_len_from_disk(de->rec_len,					sb->s_blocksize) < EXT4_DIR_REC_LEN(1))					break;				i += ext4_rec_len_from_disk(de->rec_len,							    sb->s_blocksize);			}			offset = i;			filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))				| offset;			filp->f_version = inode->i_version;		} 		while (!error && filp->f_pos < inode->i_size		       && offset < sb->s_blocksize) {			de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);			if (ext4_check_dir_entry(inode, filp, de,						 bh, offset)) {				/*				 * On error, skip the f_pos to the next block				 */				filp->f_pos = (filp->f_pos |						(sb->s_blocksize - 1)) + 1;				brelse(bh);				ret = stored;				goto out;			}			offset += ext4_rec_len_from_disk(de->rec_len,					sb->s_blocksize);			if (le32_to_cpu(de->inode)) {				/* We might block in the next section				 * if the data destination is				 * currently swapped out.  So, use a				 * version stamp to detect whether or				 * not the directory has been modified				 * during the copy operation.				 */				u64 version = filp->f_version; 				error = filldir(dirent, de->name,						de->name_len,						filp->f_pos,						le32_to_cpu(de->inode),						get_dtype(sb, de->file_type));				if (error)					break;				if (version != filp->f_version)					goto revalidate;				stored++;			}			filp->f_pos += ext4_rec_len_from_disk(de->rec_len,						sb->s_blocksize);		}		offset = 0;		brelse(bh);	}out:	return ret;} static inline int is_32bit_api(void){#ifdef CONFIG_COMPAT	return is_compat_task();#else	return (BITS_PER_LONG == 32);#endif} /* * These functions convert from the major/minor hash to an f_pos * value for dx directories * * Upper layer (for example NFS) should specify FMODE_32BITHASH or * FMODE_64BITHASH explicitly. On the other hand, we allow ext4 to be mounted * directly on both 32-bit and 64-bit nodes, under such case, neither * FMODE_32BITHASH nor FMODE_64BITHASH is specified. */static inline loff_t hash2pos(struct file *filp, __u32 major, __u32 minor){	if ((filp->f_mode & FMODE_32BITHASH) ||	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))		return major >> 1;	else		return ((__u64)(major >> 1) << 32) | (__u64)minor;} static inline __u32 pos2maj_hash(struct file *filp, loff_t pos){	if ((filp->f_mode & FMODE_32BITHASH) ||	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))		return (pos << 1) & 0xffffffff;	else		return ((pos >> 32) << 1) & 0xffffffff;} static inline __u32 pos2min_hash(struct file *filp, loff_t pos){	if ((filp->f_mode & FMODE_32BITHASH) ||	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))		return 0;	else		return pos & 0xffffffff;} /* * Return 32- or 64-bit end-of-file for dx directories */static inline loff_t ext4_get_htree_eof(struct file *filp){	if ((filp->f_mode & FMODE_32BITHASH) ||	    (!(filp->f_mode & FMODE_64BITHASH) && is_32bit_api()))		return EXT4_HTREE_EOF_32BIT;	else		return EXT4_HTREE_EOF_64BIT;}  /* * ext4_dir_llseek() based on generic_file_llseek() to handle both * non-htree and htree directories, where the "offset" is in terms * of the filename hash value instead of the byte offset. * * NOTE: offsets obtained *before* ext4_set_inode_flag(dir, EXT4_INODE_INDEX) *       will be invalid once the directory was converted into a dx directory */loff_t ext4_dir_llseek(struct file *file, loff_t offset, int origin){	struct inode *inode = file->f_mapping->host;	loff_t ret = -EINVAL;	int dx_dir = is_dx_dir(inode); 	mutex_lock(&inode->i_mutex); 	/* NOTE: relative offsets with dx directories might not work	 *       as expected, as it is difficult to figure out the	 *       correct offset between dx hashes */ 	switch (origin) {	case SEEK_END:		if (unlikely(offset > 0))			goto out_err; /* not supported for directories */ 		/* so only negative offsets are left, does that have a		 * meaning for directories at all? */		if (dx_dir)			offset += ext4_get_htree_eof(file);		else			offset += inode->i_size;		break;	case SEEK_CUR:		/*		 * Here we special-case the lseek(fd, 0, SEEK_CUR)		 * position-querying operation.  Avoid rewriting the "same"		 * f_pos value back to the file because a concurrent read(),		 * write() or lseek() might have altered it		 */		if (offset == 0) {			offset = file->f_pos;			goto out_ok;		} 		offset += file->f_pos;		break;	} 	if (unlikely(offset < 0))		goto out_err; 	if (!dx_dir) {		if (offset > inode->i_sb->s_maxbytes)			goto out_err;	} else if (offset > ext4_get_htree_eof(file))		goto out_err; 	/* Special lock needed here? */	if (offset != file->f_pos) {		file->f_pos = offset;		file->f_version = 0;	} out_ok:	ret = offset;out_err:	mutex_unlock(&inode->i_mutex); 	return ret;} /* * This structure holds the nodes of the red-black tree used to store * the directory entry in hash order. */struct fname {	__u32		hash;	__u32		minor_hash;	struct rb_node	rb_hash;	struct fname	*next;	__u32		inode;	__u8		name_len;	__u8		file_type;	char		name[0];}; /* * This functoin implements a non-recursive way of freeing all of the * nodes in the red-black tree. */static void free_rb_tree_fname(struct rb_root *root){	struct rb_node	*n = root->rb_node;	struct rb_node	*parent;	struct fname	*fname; 	while (n) {		/* Do the node's children first */		if (n->rb_left) {			n = n->rb_left;			continue;		}		if (n->rb_right) {			n = n->rb_right;			continue;		}		/*		 * The node has no children; free it, and then zero		 * out parent's link to it.  Finally go to the		 * beginning of the loop and try to free the parent		 * node.		 */		parent = rb_parent(n);		fname = rb_entry(n, struct fname, rb_hash);		while (fname) {			struct fname *old = fname;			fname = fname->next;			kfree(old);		}		if (!parent)			*root = RB_ROOT;		else if (parent->rb_left == n)			parent->rb_left = NULL;		else if (parent->rb_right == n)			parent->rb_right = NULL;		n = parent;	}}  static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,							   loff_t pos){	struct dir_private_info *p; 	p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);	if (!p)		return NULL;	p->curr_hash = pos2maj_hash(filp, pos);	p->curr_minor_hash = pos2min_hash(filp, pos);	return p;} void ext4_htree_free_dir_info(struct dir_private_info *p){	free_rb_tree_fname(&p->root);	kfree(p);} /* * Given a directory entry, enter it into the fname rb tree. */int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,			     __u32 minor_hash,			     struct ext4_dir_entry_2 *dirent){	struct rb_node **p, *parent = NULL;	struct fname *fname, *new_fn;	struct dir_private_info *info;	int len; 	info = dir_file->private_data;	p = &info->root.rb_node; 	/* Create and allocate the fname structure */	len = sizeof(struct fname) + dirent->name_len + 1;	new_fn = kzalloc(len, GFP_KERNEL);	if (!new_fn)		return -ENOMEM;	new_fn->hash = hash;	new_fn->minor_hash = minor_hash;	new_fn->inode = le32_to_cpu(dirent->inode);	new_fn->name_len = dirent->name_len;	new_fn->file_type = dirent->file_type;	memcpy(new_fn->name, dirent->name, dirent->name_len);

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