| /* |
| * 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/ext4_fs.h> |
| #include <linux/buffer_head.h> |
| #include <linux/slab.h> |
| #include <linux/rbtree.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_readdir(struct file *, void *, filldir_t); |
| static int ext4_dx_readdir(struct file * filp, |
| void * dirent, filldir_t filldir); |
| static int ext4_release_dir (struct inode * inode, |
| struct file * filp); |
| |
| const struct file_operations ext4_dir_operations = { |
| .llseek = generic_file_llseek, |
| .read = generic_read_dir, |
| .readdir = ext4_readdir, /* we take BKL. needed?*/ |
| .unlocked_ioctl = ext4_ioctl, |
| #ifdef CONFIG_COMPAT |
| .compat_ioctl = ext4_compat_ioctl, |
| #endif |
| .fsync = ext4_sync_file, |
| .release = ext4_release_dir, |
| }; |
| |
| |
| 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]); |
| } |
| |
| |
| int ext4_check_dir_entry (const char * function, struct inode * dir, |
| struct ext4_dir_entry_2 * de, |
| struct buffer_head * bh, |
| unsigned long offset) |
| { |
| const char * error_msg = NULL; |
| const int rlen = ext4_rec_len_from_disk(de->rec_len); |
| |
| if (rlen < EXT4_DIR_REC_LEN(1)) |
| error_msg = "rec_len is smaller than minimal"; |
| else if (rlen % 4 != 0) |
| error_msg = "rec_len % 4 != 0"; |
| else if (rlen < EXT4_DIR_REC_LEN(de->name_len)) |
| error_msg = "rec_len is too small for name_len"; |
| else if (((char *) de - bh->b_data) + rlen > dir->i_sb->s_blocksize) |
| error_msg = "directory entry across blocks"; |
| else if (le32_to_cpu(de->inode) > |
| le32_to_cpu(EXT4_SB(dir->i_sb)->s_es->s_inodes_count)) |
| error_msg = "inode out of bounds"; |
| |
| if (error_msg != NULL) |
| ext4_error (dir->i_sb, function, |
| "bad entry in directory #%lu: %s - " |
| "offset=%lu, inode=%lu, rec_len=%d, name_len=%d", |
| dir->i_ino, error_msg, offset, |
| (unsigned long) le32_to_cpu(de->inode), |
| rlen, de->name_len); |
| return error_msg == NULL ? 1 : 0; |
| } |
| |
| static int ext4_readdir(struct file * filp, |
| void * dirent, filldir_t filldir) |
| { |
| int error = 0; |
| unsigned long offset; |
| int i, stored; |
| struct ext4_dir_entry_2 *de; |
| struct super_block *sb; |
| int err; |
| struct inode *inode = filp->f_path.dentry->d_inode; |
| int ret = 0; |
| |
| sb = inode->i_sb; |
| |
| if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb, |
| EXT4_FEATURE_COMPAT_DIR_INDEX) && |
| ((EXT4_I(inode)->i_flags & EXT4_INDEX_FL) || |
| ((inode->i_size >> sb->s_blocksize_bits) == 1))) { |
| 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_I(filp->f_path.dentry->d_inode)->i_flags &= ~EXT4_INDEX_FL; |
| } |
| stored = 0; |
| offset = filp->f_pos & (sb->s_blocksize - 1); |
| |
| while (!error && !stored && filp->f_pos < inode->i_size) { |
| ext4_lblk_t blk = filp->f_pos >> EXT4_BLOCK_SIZE_BITS(sb); |
| struct buffer_head map_bh; |
| struct buffer_head *bh = NULL; |
| |
| map_bh.b_state = 0; |
| err = ext4_get_blocks_wrap(NULL, inode, blk, 1, &map_bh, 0, 0); |
| if (err > 0) { |
| pgoff_t index = map_bh.b_blocknr >> |
| (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, blk, 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) { |
| ext4_error (sb, "ext4_readdir", |
| "directory #%lu contains a hole at offset %lu", |
| inode->i_ino, (unsigned long)filp->f_pos); |
| /* 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; |
| } |
| |
| 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) |
| < EXT4_DIR_REC_LEN(1)) |
| break; |
| i += ext4_rec_len_from_disk(de->rec_len); |
| } |
| 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 ("ext4_readdir", inode, 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); |
| 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); |
| } |
| offset = 0; |
| brelse (bh); |
| } |
| out: |
| return ret; |
| } |
| |
| /* |
| * These functions convert from the major/minor hash to an f_pos |
| * value. |
| * |
| * Currently we only use major hash numer. This is unfortunate, but |
| * on 32-bit machines, the same VFS interface is used for lseek and |
| * llseek, so if we use the 64 bit offset, then the 32-bit versions of |
| * lseek/telldir/seekdir will blow out spectacularly, and from within |
| * the ext2 low-level routine, we don't know if we're being called by |
| * a 64-bit version of the system call or the 32-bit version of the |
| * system call. Worse yet, NFSv2 only allows for a 32-bit readdir |
| * cookie. Sigh. |
| */ |
| #define hash2pos(major, minor) (major >> 1) |
| #define pos2maj_hash(pos) ((pos << 1) & 0xffffffff) |
| #define pos2min_hash(pos) (0) |
| |
| /* |
| * 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_node = NULL; |
| else if (parent->rb_left == n) |
| parent->rb_left = NULL; |
| else if (parent->rb_right == n) |
| parent->rb_right = NULL; |
| n = parent; |
| } |
| root->rb_node = NULL; |
| } |
| |
| |
| static struct dir_private_info *create_dir_info(loff_t pos) |
| { |
| struct dir_private_info *p; |
| |
| p = kmalloc(sizeof(struct dir_private_info), GFP_KERNEL); |
| if (!p) |
| return NULL; |
| p->root.rb_node = NULL; |
| p->curr_node = NULL; |
| p->extra_fname = NULL; |
| p->last_pos = 0; |
| p->curr_hash = pos2maj_hash(pos); |
| p->curr_minor_hash = pos2min_hash(pos); |
| p->next_hash = 0; |
| 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 = (struct dir_private_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); |
| new_fn->name[dirent->name_len] = 0; |
| |
| while (*p) { |
| parent = *p; |
| fname = rb_entry(parent, struct fname, rb_hash); |
| |
| /* |
| * If the hash and minor hash match up, then we put |
| * them on a linked list. This rarely happens... |
| */ |
| if ((new_fn->hash == fname->hash) && |
| (new_fn->minor_hash == fname->minor_hash)) { |
| new_fn->next = fname->next; |
| fname->next = new_fn; |
| return 0; |
| } |
| |
| if (new_fn->hash < fname->hash) |
| p = &(*p)->rb_left; |
| else if (new_fn->hash > fname->hash) |
| p = &(*p)->rb_right; |
| else if (new_fn->minor_hash < fname->minor_hash) |
| p = &(*p)->rb_left; |
| else /* if (new_fn->minor_hash > fname->minor_hash) */ |
| p = &(*p)->rb_right; |
| } |
| |
| rb_link_node(&new_fn->rb_hash, parent, p); |
| rb_insert_color(&new_fn->rb_hash, &info->root); |
| return 0; |
| } |
| |
| |
| |
| /* |
| * This is a helper function for ext4_dx_readdir. It calls filldir |
| * for all entres on the fname linked list. (Normally there is only |
| * one entry on the linked list, unless there are 62 bit hash collisions.) |
| */ |
| static int call_filldir(struct file * filp, void * dirent, |
| filldir_t filldir, struct fname *fname) |
| { |
| struct dir_private_info *info = filp->private_data; |
| loff_t curr_pos; |
| struct inode *inode = filp->f_path.dentry->d_inode; |
| struct super_block * sb; |
| int error; |
| |
| sb = inode->i_sb; |
| |
| if (!fname) { |
| printk("call_filldir: called with null fname?!?\n"); |
| return 0; |
| } |
| curr_pos = hash2pos(fname->hash, fname->minor_hash); |
| while (fname) { |
| error = filldir(dirent, fname->name, |
| fname->name_len, curr_pos, |
| fname->inode, |
| get_dtype(sb, fname->file_type)); |
| if (error) { |
| filp->f_pos = curr_pos; |
| info->extra_fname = fname->next; |
| return error; |
| } |
| fname = fname->next; |
| } |
| return 0; |
| } |
| |
| static int ext4_dx_readdir(struct file * filp, |
| void * dirent, filldir_t filldir) |
| { |
| struct dir_private_info *info = filp->private_data; |
| struct inode *inode = filp->f_path.dentry->d_inode; |
| struct fname *fname; |
| int ret; |
| |
| if (!info) { |
| info = create_dir_info(filp->f_pos); |
| if (!info) |
| return -ENOMEM; |
| filp->private_data = info; |
| } |
| |
| if (filp->f_pos == EXT4_HTREE_EOF) |
| return 0; /* EOF */ |
| |
| /* Some one has messed with f_pos; reset the world */ |
| if (info->last_pos != filp->f_pos) { |
| free_rb_tree_fname(&info->root); |
| info->curr_node = NULL; |
| info->extra_fname = NULL; |
| info->curr_hash = pos2maj_hash(filp->f_pos); |
| info->curr_minor_hash = pos2min_hash(filp->f_pos); |
| } |
| |
| /* |
| * If there are any leftover names on the hash collision |
| * chain, return them first. |
| */ |
| if (info->extra_fname && |
| call_filldir(filp, dirent, filldir, info->extra_fname)) |
| goto finished; |
| |
| if (!info->curr_node) |
| info->curr_node = rb_first(&info->root); |
| |
| while (1) { |
| /* |
| * Fill the rbtree if we have no more entries, |
| * or the inode has changed since we last read in the |
| * cached entries. |
| */ |
| if ((!info->curr_node) || |
| (filp->f_version != inode->i_version)) { |
| info->curr_node = NULL; |
| free_rb_tree_fname(&info->root); |
| filp->f_version = inode->i_version; |
| ret = ext4_htree_fill_tree(filp, info->curr_hash, |
| info->curr_minor_hash, |
| &info->next_hash); |
| if (ret < 0) |
| return ret; |
| if (ret == 0) { |
| filp->f_pos = EXT4_HTREE_EOF; |
| break; |
| } |
| info->curr_node = rb_first(&info->root); |
| } |
| |
| fname = rb_entry(info->curr_node, struct fname, rb_hash); |
| info->curr_hash = fname->hash; |
| info->curr_minor_hash = fname->minor_hash; |
| if (call_filldir(filp, dirent, filldir, fname)) |
| break; |
| |
| info->curr_node = rb_next(info->curr_node); |
| if (!info->curr_node) { |
| if (info->next_hash == ~0) { |
| filp->f_pos = EXT4_HTREE_EOF; |
| break; |
| } |
| info->curr_hash = info->next_hash; |
| info->curr_minor_hash = 0; |
| } |
| } |
| finished: |
| info->last_pos = filp->f_pos; |
| return 0; |
| } |
| |
| static int ext4_release_dir (struct inode * inode, struct file * filp) |
| { |
| if (filp->private_data) |
| ext4_htree_free_dir_info(filp->private_data); |
| |
| return 0; |
| } |