Eric Lee / smarc-fsl-linux-kernel

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fs/efs/dir.c 2.38 KB
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81f7e3824   Eric Lee   Initial Release, ... 
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  // SPDX-License-Identifier: GPL-2.0
  /*
   * dir.c
   *
   * Copyright (c) 1999 Al Smith
   */
  
  #include <linux/buffer_head.h>
  #include "efs.h"
  
  static int efs_readdir(struct file *, struct dir_context *);
  
  const struct file_operations efs_dir_operations = {
  	.llseek		= generic_file_llseek,
  	.read		= generic_read_dir,
  	.iterate_shared	= efs_readdir,
  };
  
  const struct inode_operations efs_dir_inode_operations = {
  	.lookup		= efs_lookup,
  };
  
  static int efs_readdir(struct file *file, struct dir_context *ctx)
  {
  	struct inode *inode = file_inode(file);
  	efs_block_t		block;
  	int			slot;
  
  	if (inode->i_size & (EFS_DIRBSIZE-1))
  		pr_warn("%s(): directory size not a multiple of EFS_DIRBSIZE
  ",
  			__func__);
  
  	/* work out where this entry can be found */
  	block = ctx->pos >> EFS_DIRBSIZE_BITS;
  
  	/* each block contains at most 256 slots */
  	slot  = ctx->pos & 0xff;
  
  	/* look at all blocks */
  	while (block < inode->i_blocks) {
  		struct efs_dir		*dirblock;
  		struct buffer_head *bh;
  
  		/* read the dir block */
  		bh = sb_bread(inode->i_sb, efs_bmap(inode, block));
  
  		if (!bh) {
  			pr_err("%s(): failed to read dir block %d
  ",
  			       __func__, block);
  			break;
  		}
  
  		dirblock = (struct efs_dir *) bh->b_data; 
  
  		if (be16_to_cpu(dirblock->magic) != EFS_DIRBLK_MAGIC) {
  			pr_err("%s(): invalid directory block
  ", __func__);
  			brelse(bh);
  			break;
  		}
  
  		for (; slot < dirblock->slots; slot++) {
  			struct efs_dentry *dirslot;
  			efs_ino_t inodenum;
  			const char *nameptr;
  			int namelen;
  
  			if (dirblock->space[slot] == 0)
  				continue;
  
  			dirslot  = (struct efs_dentry *) (((char *) bh->b_data) + EFS_SLOTAT(dirblock, slot));
  
  			inodenum = be32_to_cpu(dirslot->inode);
  			namelen  = dirslot->namelen;
  			nameptr  = dirslot->name;
  			pr_debug("%s(): block %d slot %d/%d: inode %u, name \"%s\", namelen %u
  ",
  				 __func__, block, slot, dirblock->slots-1,
  				 inodenum, nameptr, namelen);
  			if (!namelen)
  				continue;
  			/* found the next entry */
  			ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot;
  
  			/* sanity check */
  			if (nameptr - (char *) dirblock + namelen > EFS_DIRBSIZE) {
  				pr_warn("directory entry %d exceeds directory block
  ",
  					slot);
  				continue;
  			}
  
  			/* copy filename and data in dirslot */
  			if (!dir_emit(ctx, nameptr, namelen, inodenum, DT_UNKNOWN)) {
  				brelse(bh);
  				return 0;
  			}
  		}
  		brelse(bh);
  
  		slot = 0;
  		block++;
  	}
  	ctx->pos = (block << EFS_DIRBSIZE_BITS) | slot;
  	return 0;
  }