ext4: Avoid rec_len overflow with 64KB block size

With 64KB blocksize, a directory entry can have size 64KB which does not fit
into 16 bits we have for entry lenght. So we store 0xffff instead and convert
value when read from / written to disk. The patch also converts some places
to use ext4_next_entry() when we are changing them anyway.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>

diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index f612bef..145a9c0 100644 (file)
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -67,7 +67,7 @@ int ext4_check_dir_entry (const char * function, struct inode * dir,
                          unsigned long offset)
 {
        const char * error_msg = NULL;
-       const int rlen = le16_to_cpu(de->rec_len);
+       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";
@@ -172,10 +172,10 @@ revalidate:
                                 * least that it is non-zero.  A
                                 * failure will be detected in the
                                 * dirent test below. */
-                               if (le16_to_cpu(de->rec_len) <
-                                               EXT4_DIR_REC_LEN(1))
+                               if (ext4_rec_len_from_disk(de->rec_len)
+                                               < EXT4_DIR_REC_LEN(1))
                                        break;
-                               i += le16_to_cpu(de->rec_len);
+                               i += ext4_rec_len_from_disk(de->rec_len);
                        }
                        offset = i;
                        filp->f_pos = (filp->f_pos & ~(sb->s_blocksize - 1))
@@ -197,7 +197,7 @@ revalidate:
                                ret = stored;
                                goto out;
                        }
-                       offset += le16_to_cpu(de->rec_len);
+                       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
@@ -219,7 +219,7 @@ revalidate:
                                        goto revalidate;
                                stored ++;
                        }
-                       filp->f_pos += le16_to_cpu(de->rec_len);
+                       filp->f_pos += ext4_rec_len_from_disk(de->rec_len);
                }
                offset = 0;
                brelse (bh);

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 94ee6f3..d9a3a2f 100644 (file)
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -280,7 +280,7 @@ static struct stats dx_show_leaf(struct dx_hash_info *hinfo, struct ext4_dir_ent
                        space += EXT4_DIR_REC_LEN(de->name_len);
                        names++;
                }
-               de = (struct ext4_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len));
+               de = ext4_next_entry(de);
        }
        printk("(%i)\n", names);
        return (struct stats) { names, space, 1 };
@@ -551,7 +551,8 @@ static int ext4_htree_next_block(struct inode *dir, __u32 hash,
  */
 static inline struct ext4_dir_entry_2 *ext4_next_entry(struct ext4_dir_entry_2 *p)
 {
-       return (struct ext4_dir_entry_2 *)((char*)p + le16_to_cpu(p->rec_len));
+       return (struct ext4_dir_entry_2 *)((char *)p +
+               ext4_rec_len_from_disk(p->rec_len));
 }
 
 /*
@@ -720,7 +721,7 @@ static int dx_make_map (struct ext4_dir_entry_2 *de, int size,
                        cond_resched();
                }
                /* XXX: do we need to check rec_len == 0 case? -Chris */
-               de = (struct ext4_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len));
+               de = ext4_next_entry(de);
        }
        return count;
 }
@@ -820,7 +821,7 @@ static inline int search_dirblock(struct buffer_head * bh,
                        return 1;
                }
                /* prevent looping on a bad block */
-               de_len = le16_to_cpu(de->rec_len);
+               de_len = ext4_rec_len_from_disk(de->rec_len);
                if (de_len <= 0)
                        return -1;
                offset += de_len;
@@ -1128,7 +1129,7 @@ dx_move_dirents(char *from, char *to, struct dx_map_entry *map, int count)
                rec_len = EXT4_DIR_REC_LEN(de->name_len);
                memcpy (to, de, rec_len);
                ((struct ext4_dir_entry_2 *) to)->rec_len =
-                               cpu_to_le16(rec_len);
+                               ext4_rec_len_to_disk(rec_len);
                de->inode = 0;
                map++;
                to += rec_len;
@@ -1147,13 +1148,12 @@ static struct ext4_dir_entry_2* dx_pack_dirents(char *base, int size)
 
        prev = to = de;
        while ((char*)de < base + size) {
-               next = (struct ext4_dir_entry_2 *) ((char *) de +
-                                                   le16_to_cpu(de->rec_len));
+               next = ext4_next_entry(de);
                if (de->inode && de->name_len) {
                        rec_len = EXT4_DIR_REC_LEN(de->name_len);
                        if (de > to)
                                memmove(to, de, rec_len);
-                       to->rec_len = cpu_to_le16(rec_len);
+                       to->rec_len = ext4_rec_len_to_disk(rec_len);
                        prev = to;
                        to = (struct ext4_dir_entry_2 *) (((char *) to) + rec_len);
                }
@@ -1227,8 +1227,8 @@ static struct ext4_dir_entry_2 *do_split(handle_t *handle, struct inode *dir,
        /* Fancy dance to stay within two buffers */
        de2 = dx_move_dirents(data1, data2, map + split, count - split);
        de = dx_pack_dirents(data1,blocksize);
-       de->rec_len = cpu_to_le16(data1 + blocksize - (char *) de);
-       de2->rec_len = cpu_to_le16(data2 + blocksize - (char *) de2);
+       de->rec_len = ext4_rec_len_to_disk(data1 + blocksize - (char *) de);
+       de2->rec_len = ext4_rec_len_to_disk(data2 + blocksize - (char *) de2);
        dxtrace(dx_show_leaf (hinfo, (struct ext4_dir_entry_2 *) data1, blocksize, 1));
        dxtrace(dx_show_leaf (hinfo, (struct ext4_dir_entry_2 *) data2, blocksize, 1));
 
@@ -1297,7 +1297,7 @@ static int add_dirent_to_buf(handle_t *handle, struct dentry *dentry,
                                return -EEXIST;
                        }
                        nlen = EXT4_DIR_REC_LEN(de->name_len);
-                       rlen = le16_to_cpu(de->rec_len);
+                       rlen = ext4_rec_len_from_disk(de->rec_len);
                        if ((de->inode? rlen - nlen: rlen) >= reclen)
                                break;
                        de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
@@ -1316,11 +1316,11 @@ static int add_dirent_to_buf(handle_t *handle, struct dentry *dentry,
 
        /* By now the buffer is marked for journaling */
        nlen = EXT4_DIR_REC_LEN(de->name_len);
-       rlen = le16_to_cpu(de->rec_len);
+       rlen = ext4_rec_len_from_disk(de->rec_len);
        if (de->inode) {
                struct ext4_dir_entry_2 *de1 = (struct ext4_dir_entry_2 *)((char *)de + nlen);
-               de1->rec_len = cpu_to_le16(rlen - nlen);
-               de->rec_len = cpu_to_le16(nlen);
+               de1->rec_len = ext4_rec_len_to_disk(rlen - nlen);
+               de->rec_len = ext4_rec_len_to_disk(nlen);
                de = de1;
        }
        de->file_type = EXT4_FT_UNKNOWN;
@@ -1397,17 +1397,18 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry,
 
        /* The 0th block becomes the root, move the dirents out */
        fde = &root->dotdot;
-       de = (struct ext4_dir_entry_2 *)((char *)fde + le16_to_cpu(fde->rec_len));
+       de = (struct ext4_dir_entry_2 *)((char *)fde +
+               ext4_rec_len_from_disk(fde->rec_len));
        len = ((char *) root) + blocksize - (char *) de;
        memcpy (data1, de, len);
        de = (struct ext4_dir_entry_2 *) data1;
        top = data1 + len;
-       while ((char *)(de2=(void*)de+le16_to_cpu(de->rec_len)) < top)
+       while ((char *)(de2 = ext4_next_entry(de)) < top)
                de = de2;
-       de->rec_len = cpu_to_le16(data1 + blocksize - (char *) de);
+       de->rec_len = ext4_rec_len_to_disk(data1 + blocksize - (char *) de);
        /* Initialize the root; the dot dirents already exist */
        de = (struct ext4_dir_entry_2 *) (&root->dotdot);
-       de->rec_len = cpu_to_le16(blocksize - EXT4_DIR_REC_LEN(2));
+       de->rec_len = ext4_rec_len_to_disk(blocksize - EXT4_DIR_REC_LEN(2));
        memset (&root->info, 0, sizeof(root->info));
        root->info.info_length = sizeof(root->info);
        root->info.hash_version = EXT4_SB(dir->i_sb)->s_def_hash_version;
@@ -1487,7 +1488,7 @@ static int ext4_add_entry (handle_t *handle, struct dentry *dentry,
                return retval;
        de = (struct ext4_dir_entry_2 *) bh->b_data;
        de->inode = 0;
-       de->rec_len = cpu_to_le16(blocksize);
+       de->rec_len = ext4_rec_len_to_disk(blocksize);
        return add_dirent_to_buf(handle, dentry, inode, de, bh);
 }
 
@@ -1550,7 +1551,7 @@ static int ext4_dx_add_entry(handle_t *handle, struct dentry *dentry,
                        goto cleanup;
                node2 = (struct dx_node *)(bh2->b_data);
                entries2 = node2->entries;
-               node2->fake.rec_len = cpu_to_le16(sb->s_blocksize);
+               node2->fake.rec_len = ext4_rec_len_to_disk(sb->s_blocksize);
                node2->fake.inode = 0;
                BUFFER_TRACE(frame->bh, "get_write_access");
                err = ext4_journal_get_write_access(handle, frame->bh);
@@ -1648,9 +1649,9 @@ static int ext4_delete_entry (handle_t *handle,
                        BUFFER_TRACE(bh, "get_write_access");
                        ext4_journal_get_write_access(handle, bh);
                        if (pde)
-                               pde->rec_len =
-                                       cpu_to_le16(le16_to_cpu(pde->rec_len) +
-                                                   le16_to_cpu(de->rec_len));
+                               pde->rec_len = ext4_rec_len_to_disk(
+                                       ext4_rec_len_from_disk(pde->rec_len) +
+                                       ext4_rec_len_from_disk(de->rec_len));
                        else
                                de->inode = 0;
                        dir->i_version++;
@@ -1658,10 +1659,9 @@ static int ext4_delete_entry (handle_t *handle,
                        ext4_journal_dirty_metadata(handle, bh);
                        return 0;
                }
-               i += le16_to_cpu(de->rec_len);
+               i += ext4_rec_len_from_disk(de->rec_len);
                pde = de;
-               de = (struct ext4_dir_entry_2 *)
-                       ((char *) de + le16_to_cpu(de->rec_len));
+               de = ext4_next_entry(de);
        }
        return -ENOENT;
 }
@@ -1824,13 +1824,13 @@ retry:
        de = (struct ext4_dir_entry_2 *) dir_block->b_data;
        de->inode = cpu_to_le32(inode->i_ino);
        de->name_len = 1;
-       de->rec_len = cpu_to_le16(EXT4_DIR_REC_LEN(de->name_len));
+       de->rec_len = ext4_rec_len_to_disk(EXT4_DIR_REC_LEN(de->name_len));
        strcpy (de->name, ".");
        ext4_set_de_type(dir->i_sb, de, S_IFDIR);
-       de = (struct ext4_dir_entry_2 *)
-                       ((char *) de + le16_to_cpu(de->rec_len));
+       de = ext4_next_entry(de);
        de->inode = cpu_to_le32(dir->i_ino);
-       de->rec_len = cpu_to_le16(inode->i_sb->s_blocksize-EXT4_DIR_REC_LEN(1));
+       de->rec_len = ext4_rec_len_to_disk(inode->i_sb->s_blocksize -
+                                               EXT4_DIR_REC_LEN(1));
        de->name_len = 2;
        strcpy (de->name, "..");
        ext4_set_de_type(dir->i_sb, de, S_IFDIR);
@@ -1882,8 +1882,7 @@ static int empty_dir (struct inode * inode)
                return 1;
        }
        de = (struct ext4_dir_entry_2 *) bh->b_data;
-       de1 = (struct ext4_dir_entry_2 *)
-                       ((char *) de + le16_to_cpu(de->rec_len));
+       de1 = ext4_next_entry(de);
        if (le32_to_cpu(de->inode) != inode->i_ino ||
                        !le32_to_cpu(de1->inode) ||
                        strcmp (".", de->name) ||
@@ -1894,9 +1893,9 @@ static int empty_dir (struct inode * inode)
                brelse (bh);
                return 1;
        }
-       offset = le16_to_cpu(de->rec_len) + le16_to_cpu(de1->rec_len);
-       de = (struct ext4_dir_entry_2 *)
-                       ((char *) de1 + le16_to_cpu(de1->rec_len));
+       offset = ext4_rec_len_from_disk(de->rec_len) +
+                ext4_rec_len_from_disk(de1->rec_len);
+       de = ext4_next_entry(de1);
        while (offset < inode->i_size ) {
                if (!bh ||
                        (void *) de >= (void *) (bh->b_data+sb->s_blocksize)) {
@@ -1925,9 +1924,8 @@ static int empty_dir (struct inode * inode)
                        brelse (bh);
                        return 0;
                }
-               offset += le16_to_cpu(de->rec_len);
-               de = (struct ext4_dir_entry_2 *)
-                               ((char *) de + le16_to_cpu(de->rec_len));
+               offset += ext4_rec_len_from_disk(de->rec_len);
+               de = ext4_next_entry(de);
        }
        brelse (bh);
        return 1;
@@ -2282,8 +2280,7 @@ retry:
 }
 
 #define PARENT_INO(buffer) \
-       ((struct ext4_dir_entry_2 *) ((char *) buffer + \
-       le16_to_cpu(((struct ext4_dir_entry_2 *) buffer)->rec_len)))->inode
+       (ext4_next_entry((struct ext4_dir_entry_2 *)(buffer))->inode)
 
 /*
  * Anybody can rename anything with this: the permission checks are left to the

diff --git a/include/linux/ext4_fs.h b/include/linux/ext4_fs.h
index dfe4487..fb31c1a 100644 (file)
--- a/include/linux/ext4_fs.h
+++ b/include/linux/ext4_fs.h
@@ -767,6 +767,26 @@ struct ext4_dir_entry_2 {
 #define EXT4_DIR_ROUND                 (EXT4_DIR_PAD - 1)
 #define EXT4_DIR_REC_LEN(name_len)     (((name_len) + 8 + EXT4_DIR_ROUND) & \
                                         ~EXT4_DIR_ROUND)
+#define EXT4_MAX_REC_LEN               ((1<<16)-1)
+
+static inline unsigned ext4_rec_len_from_disk(__le16 dlen)
+{
+       unsigned len = le16_to_cpu(dlen);
+
+       if (len == EXT4_MAX_REC_LEN)
+               return 1 << 16;
+       return len;
+}
+
+static inline __le16 ext4_rec_len_to_disk(unsigned len)
+{
+       if (len == (1 << 16))
+               return cpu_to_le16(EXT4_MAX_REC_LEN);
+       else if (len > (1 << 16))
+               BUG();
+       return cpu_to_le16(len);
+}
+
 /*
  * Hash Tree Directory indexing
  * (c) Daniel Phillips, 2001