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kernel add
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/*
* 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 = 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;
}
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