--- /dev/null
+/*
+ * 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/buffer_head.h>
+#include <linux/slab.h>
+#include "ext4.h"
+#include "xattr.h"
+
+static int ext4_dx_readdir(struct file *, struct dir_context *);
+
+/**
+ * Check if the given dir-inode refers to an htree-indexed directory
+ * (or a directory which could potentially get converted 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) ||
+ ext4_has_inline_data(inode)))
+ 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...
+ *
+ * bh passed here can be an inode block or a dir data block, depending
+ * on the inode inline data flag.
+ */
+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, char *buf, int size,
+ 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 - buf) + rlen > size))
+ error_msg = "directory entry across range";
+ 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 % 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 % size),
+ offset, le32_to_cpu(de->inode),
+ rlen, de->name_len);
+
+ return 1;
+}
+
+static int ext4_readdir(struct file *file, struct dir_context *ctx)
+{
+ unsigned int offset;
+ int i;
+ struct ext4_dir_entry_2 *de;
+ int err;
+ struct inode *inode = file_inode(file);
+ struct super_block *sb = inode->i_sb;
+ struct buffer_head *bh = NULL;
+ int dir_has_error = 0;
+ struct ext4_fname_crypto_ctx *enc_ctx = NULL;
+ struct ext4_str fname_crypto_str = {.name = NULL, .len = 0};
+
+ if (is_dx_dir(inode)) {
+ err = ext4_dx_readdir(file, ctx);
+ if (err != ERR_BAD_DX_DIR) {
+ return err;
+ }
+ /*
+ * 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(file_inode(file),
+ EXT4_INODE_INDEX);
+ }
+
+ if (ext4_has_inline_data(inode)) {
+ int has_inline_data = 1;
+ err = ext4_read_inline_dir(file, ctx,
+ &has_inline_data);
+ if (has_inline_data)
+ return err;
+ }
+
+ enc_ctx = ext4_get_fname_crypto_ctx(inode, EXT4_NAME_LEN);
+ if (IS_ERR(enc_ctx))
+ return PTR_ERR(enc_ctx);
+ if (enc_ctx) {
+ err = ext4_fname_crypto_alloc_buffer(enc_ctx, EXT4_NAME_LEN,
+ &fname_crypto_str);
+ if (err < 0) {
+ ext4_put_fname_crypto_ctx(&enc_ctx);
+ return err;
+ }
+ }
+
+ offset = ctx->pos & (sb->s_blocksize - 1);
+
+ while (ctx->pos < inode->i_size) {
+ struct ext4_map_blocks map;
+
+ map.m_lblk = ctx->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(&file->f_ra, index))
+ page_cache_sync_readahead(
+ sb->s_bdev->bd_inode->i_mapping,
+ &file->f_ra, file,
+ index, 1);
+ file->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
+ bh = ext4_bread(NULL, inode, map.m_lblk, 0);
+ if (IS_ERR(bh))
+ return PTR_ERR(bh);
+ }
+
+ if (!bh) {
+ if (!dir_has_error) {
+ EXT4_ERROR_FILE(file, 0,
+ "directory contains a "
+ "hole at offset %llu",
+ (unsigned long long) ctx->pos);
+ dir_has_error = 1;
+ }
+ /* corrupt size? Maybe no more blocks to read */
+ if (ctx->pos > inode->i_blocks << 9)
+ break;
+ ctx->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(file, 0, "directory fails checksum "
+ "at offset %llu",
+ (unsigned long long)ctx->pos);
+ ctx->pos += sb->s_blocksize - offset;
+ brelse(bh);
+ bh = NULL;
+ continue;
+ }
+ set_buffer_verified(bh);
+
+ /* 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 (file->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;
+ ctx->pos = (ctx->pos & ~(sb->s_blocksize - 1))
+ | offset;
+ file->f_version = inode->i_version;
+ }
+
+ while (ctx->pos < inode->i_size
+ && offset < sb->s_blocksize) {
+ de = (struct ext4_dir_entry_2 *) (bh->b_data + offset);
+ if (ext4_check_dir_entry(inode, file, de, bh,
+ bh->b_data, bh->b_size,
+ offset)) {
+ /*
+ * On error, skip to the next block
+ */
+ ctx->pos = (ctx->pos |
+ (sb->s_blocksize - 1)) + 1;
+ break;
+ }
+ offset += ext4_rec_len_from_disk(de->rec_len,
+ sb->s_blocksize);
+ if (le32_to_cpu(de->inode)) {
+ if (enc_ctx == NULL) {
+ /* Directory is not encrypted */
+ if (!dir_emit(ctx, de->name,
+ de->name_len,
+ le32_to_cpu(de->inode),
+ get_dtype(sb, de->file_type)))
+ goto done;
+ } else {
+ /* Directory is encrypted */
+ err = ext4_fname_disk_to_usr(enc_ctx,
+ NULL, de, &fname_crypto_str);
+ if (err < 0)
+ goto errout;
+ if (!dir_emit(ctx,
+ fname_crypto_str.name, err,
+ le32_to_cpu(de->inode),
+ get_dtype(sb, de->file_type)))
+ goto done;
+ }
+ }
+ ctx->pos += ext4_rec_len_from_disk(de->rec_len,
+ sb->s_blocksize);
+ }
+ if ((ctx->pos < inode->i_size) && !dir_relax(inode))
+ goto done;
+ brelse(bh);
+ bh = NULL;
+ offset = 0;
+ }
+done:
+ err = 0;
+errout:
+#ifdef CONFIG_EXT4_FS_ENCRYPTION
+ ext4_put_fname_crypto_ctx(&enc_ctx);
+ ext4_fname_crypto_free_buffer(&fname_crypto_str);
+#endif
+ brelse(bh);
+ return err;
+}
+
+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() calls generic_file_llseek_size to handle htree
+ * directories, where the "offset" is in terms of the filename hash
+ * value instead of the byte offset.
+ *
+ * Because we may return a 64-bit hash that is well beyond offset limits,
+ * we need to pass the max hash as the maximum allowable offset in
+ * the htree directory case.
+ *
+ * For non-htree, ext4_llseek already chooses the proper max offset.
+ */
+static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence)
+{
+ struct inode *inode = file->f_mapping->host;
+ int dx_dir = is_dx_dir(inode);
+ loff_t htree_max = ext4_get_htree_eof(file);
+
+ if (likely(dx_dir))
+ return generic_file_llseek_size(file, offset, whence,
+ htree_max, htree_max);
+ else
+ return ext4_llseek(file, offset, whence);
+}
+
+/*
+ * 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 fname *fname, *next;
+
+ rbtree_postorder_for_each_entry_safe(fname, next, root, rb_hash)
+ while (fname) {
+ struct fname *old = fname;
+ fname = fname->next;
+ kfree(old);
+ }
+
+ *root = RB_ROOT;
+}
+
+
+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.
+ *
+ * When filename encryption is enabled, the dirent will hold the
+ * encrypted filename, while the htree will hold decrypted filename.
+ * The decrypted filename is passed in via ent_name. parameter.
+ */
+int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
+ __u32 minor_hash,
+ struct ext4_dir_entry_2 *dirent,
+ struct ext4_str *ent_name)
+{
+ 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) + ent_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 = ent_name->len;
+ new_fn->file_type = dirent->file_type;
+ memcpy(new_fn->name, ent_name->name, ent_name->len);
+ new_fn->name[ent_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 *file, struct dir_context *ctx,
+ struct fname *fname)
+{
+ struct dir_private_info *info = file->private_data;
+ struct inode *inode = file_inode(file);
+ struct super_block *sb = inode->i_sb;
+
+ if (!fname) {
+ ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: comm %s: "
+ "called with null fname?!?", __func__, __LINE__,
+ inode->i_ino, current->comm);
+ return 0;
+ }
+ ctx->pos = hash2pos(file, fname->hash, fname->minor_hash);
+ while (fname) {
+ if (!dir_emit(ctx, fname->name,
+ fname->name_len,
+ fname->inode,
+ get_dtype(sb, fname->file_type))) {
+ info->extra_fname = fname;
+ return 1;
+ }
+ fname = fname->next;
+ }
+ return 0;
+}
+
+static int ext4_dx_readdir(struct file *file, struct dir_context *ctx)
+{
+ struct dir_private_info *info = file->private_data;
+ struct inode *inode = file_inode(file);
+ struct fname *fname;
+ int ret;
+
+ if (!info) {
+ info = ext4_htree_create_dir_info(file, ctx->pos);
+ if (!info)
+ return -ENOMEM;
+ file->private_data = info;
+ }
+
+ if (ctx->pos == ext4_get_htree_eof(file))
+ return 0; /* EOF */
+
+ /* Some one has messed with f_pos; reset the world */
+ if (info->last_pos != ctx->pos) {
+ free_rb_tree_fname(&info->root);
+ info->curr_node = NULL;
+ info->extra_fname = NULL;
+ info->curr_hash = pos2maj_hash(file, ctx->pos);
+ info->curr_minor_hash = pos2min_hash(file, ctx->pos);
+ }
+
+ /*
+ * If there are any leftover names on the hash collision
+ * chain, return them first.
+ */
+ if (info->extra_fname) {
+ if (call_filldir(file, ctx, info->extra_fname))
+ goto finished;
+ info->extra_fname = NULL;
+ goto next_node;
+ } else 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) ||
+ (file->f_version != inode->i_version)) {
+ info->curr_node = NULL;
+ free_rb_tree_fname(&info->root);
+ file->f_version = inode->i_version;
+ ret = ext4_htree_fill_tree(file, info->curr_hash,
+ info->curr_minor_hash,
+ &info->next_hash);
+ if (ret < 0)
+ return ret;
+ if (ret == 0) {
+ ctx->pos = ext4_get_htree_eof(file);
+ 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(file, ctx, fname))
+ break;
+ next_node:
+ info->curr_node = rb_next(info->curr_node);
+ if (info->curr_node) {
+ fname = rb_entry(info->curr_node, struct fname,
+ rb_hash);
+ info->curr_hash = fname->hash;
+ info->curr_minor_hash = fname->minor_hash;
+ } else {
+ if (info->next_hash == ~0) {
+ ctx->pos = ext4_get_htree_eof(file);
+ break;
+ }
+ info->curr_hash = info->next_hash;
+ info->curr_minor_hash = 0;
+ }
+ }
+finished:
+ info->last_pos = ctx->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;
+}
+
+int ext4_check_all_de(struct inode *dir, struct buffer_head *bh, void *buf,
+ int buf_size)
+{
+ struct ext4_dir_entry_2 *de;
+ int nlen, rlen;
+ unsigned int offset = 0;
+ char *top;
+
+ de = (struct ext4_dir_entry_2 *)buf;
+ top = buf + buf_size;
+ while ((char *) de < top) {
+ if (ext4_check_dir_entry(dir, NULL, de, bh,
+ buf, buf_size, offset))
+ return -EIO;
+ nlen = EXT4_DIR_REC_LEN(de->name_len);
+ rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
+ de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
+ offset += rlen;
+ }
+ if ((char *) de > top)
+ return -EIO;
+
+ return 0;
+}
+
+const struct file_operations ext4_dir_operations = {
+ .llseek = ext4_dir_llseek,
+ .read = generic_read_dir,
+ .iterate = ext4_readdir,
+ .unlocked_ioctl = ext4_ioctl,
+#ifdef CONFIG_COMPAT
+ .compat_ioctl = ext4_compat_ioctl,
+#endif
+ .fsync = ext4_sync_file,
+ .release = ext4_release_dir,
+};
Code Review / kvmfornfv.git / blobdiff