ext4: Avoid rec_len overflow with 64KB block size From: Jan Kara 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 Signed-off-by: Mingming Cao --- fs/ext4/dir.c | 12 +++---- fs/ext4/namei.c | 76 ++++++++++++++++++++++-------------------------- include/linux/ext4_fs.h | 20 ++++++++++++ 3 files changed, 62 insertions(+), 46 deletions(-) Index: linux-2.6.23-rc9/fs/ext4/dir.c =================================================================== --- linux-2.6.23-rc9.orig/fs/ext4/dir.c 2007-10-05 10:13:17.000000000 -0700 +++ linux-2.6.23-rc9/fs/ext4/dir.c 2007-10-05 10:13:35.000000000 -0700 @@ -67,7 +67,7 @@ int ext4_check_dir_entry (const char * f 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); Index: linux-2.6.23-rc9/fs/ext4/namei.c =================================================================== --- linux-2.6.23-rc9.orig/fs/ext4/namei.c 2007-10-05 10:13:17.000000000 -0700 +++ linux-2.6.23-rc9/fs/ext4/namei.c 2007-10-05 10:13:35.000000000 -0700 @@ -280,7 +280,7 @@ static struct stats dx_show_leaf(struct 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 */ 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_ 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 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, st 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_ 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 /* 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 *h 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 *h /* 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 *ha /* 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 *han 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 *h 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 * 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 * 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 +1824,12 @@ 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 +1881,7 @@ static int empty_dir (struct inode * ino 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 +1892,9 @@ static int empty_dir (struct inode * ino 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 +1923,8 @@ static int empty_dir (struct inode * ino 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 +2279,7 @@ 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 Index: linux-2.6.23-rc9/include/linux/ext4_fs.h =================================================================== --- linux-2.6.23-rc9.orig/include/linux/ext4_fs.h 2007-10-05 10:13:31.000000000 -0700 +++ linux-2.6.23-rc9/include/linux/ext4_fs.h 2007-10-05 10:13:35.000000000 -0700 @@ -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