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Date: Sun, 21 Oct 2007 16:41:40 -0700
From: akpm@...ux-foundation.org
To: torvalds@...ux-foundation.org
Cc: akpm@...ux-foundation.org, jack@...e.cz, linux-ext4@...r.kernel.org
Subject: [patch 09/41] ext2: avoid rec_len overflow with 64KB block size
From: Jan Kara <jack@...e.cz>
With 64KB blocksize, a directory entry can have size 64KB which does not
fit into 16 bits we have for entry length. So we store 0xffff instead and
convert the value when read from / written to disk.
[akpm@...ux-foundation.org: coding-style fixes]
Signed-off-by: Jan Kara <jack@...e.cz>
Cc: <linux-ext4@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---
fs/ext2/dir.c | 44 +++++++++++++++++++++++++++-----------
include/linux/ext2_fs.h | 1
2 files changed, 33 insertions(+), 12 deletions(-)
diff -puN fs/ext2/dir.c~ext2-avoid-rec_len-overflow-with-64kb-block-size fs/ext2/dir.c
--- a/fs/ext2/dir.c~ext2-avoid-rec_len-overflow-with-64kb-block-size
+++ a/fs/ext2/dir.c
@@ -28,6 +28,24 @@
typedef struct ext2_dir_entry_2 ext2_dirent;
+static inline unsigned ext2_rec_len_from_disk(__le16 dlen)
+{
+ unsigned len = le16_to_cpu(dlen);
+
+ if (len == EXT2_MAX_REC_LEN)
+ return 1 << 16;
+ return len;
+}
+
+static inline __le16 ext2_rec_len_to_disk(unsigned len)
+{
+ if (len == (1 << 16))
+ return cpu_to_le16(EXT2_MAX_REC_LEN);
+ else if (len > (1 << 16))
+ BUG();
+ return cpu_to_le16(len);
+}
+
/*
* ext2 uses block-sized chunks. Arguably, sector-sized ones would be
* more robust, but we have what we have
@@ -106,7 +124,7 @@ static void ext2_check_page(struct page
}
for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {
p = (ext2_dirent *)(kaddr + offs);
- rec_len = le16_to_cpu(p->rec_len);
+ rec_len = ext2_rec_len_from_disk(p->rec_len);
if (rec_len < EXT2_DIR_REC_LEN(1))
goto Eshort;
@@ -204,7 +222,8 @@ static inline int ext2_match (int len, c
*/
static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
{
- return (ext2_dirent *)((char*)p + le16_to_cpu(p->rec_len));
+ return (ext2_dirent *)((char *)p +
+ ext2_rec_len_from_disk(p->rec_len));
}
static inline unsigned
@@ -316,7 +335,7 @@ ext2_readdir (struct file * filp, void *
return 0;
}
}
- filp->f_pos += le16_to_cpu(de->rec_len);
+ filp->f_pos += ext2_rec_len_from_disk(de->rec_len);
}
ext2_put_page(page);
}
@@ -425,7 +444,7 @@ void ext2_set_link(struct inode *dir, st
{
loff_t pos = page_offset(page) +
(char *) de - (char *) page_address(page);
- unsigned len = le16_to_cpu(de->rec_len);
+ unsigned len = ext2_rec_len_from_disk(de->rec_len);
int err;
lock_page(page);
@@ -482,7 +501,7 @@ int ext2_add_link (struct dentry *dentry
/* We hit i_size */
name_len = 0;
rec_len = chunk_size;
- de->rec_len = cpu_to_le16(chunk_size);
+ de->rec_len = ext2_rec_len_to_disk(chunk_size);
de->inode = 0;
goto got_it;
}
@@ -496,7 +515,7 @@ int ext2_add_link (struct dentry *dentry
if (ext2_match (namelen, name, de))
goto out_unlock;
name_len = EXT2_DIR_REC_LEN(de->name_len);
- rec_len = le16_to_cpu(de->rec_len);
+ rec_len = ext2_rec_len_from_disk(de->rec_len);
if (!de->inode && rec_len >= reclen)
goto got_it;
if (rec_len >= name_len + reclen)
@@ -518,8 +537,8 @@ got_it:
goto out_unlock;
if (de->inode) {
ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
- de1->rec_len = cpu_to_le16(rec_len - name_len);
- de->rec_len = cpu_to_le16(name_len);
+ de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
+ de->rec_len = ext2_rec_len_to_disk(name_len);
de = de1;
}
de->name_len = namelen;
@@ -550,7 +569,8 @@ int ext2_delete_entry (struct ext2_dir_e
struct inode *inode = mapping->host;
char *kaddr = page_address(page);
unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
- unsigned to = ((char*)dir - kaddr) + le16_to_cpu(dir->rec_len);
+ unsigned to = ((char *)dir - kaddr) +
+ ext2_rec_len_from_disk(dir->rec_len);
loff_t pos;
ext2_dirent * pde = NULL;
ext2_dirent * de = (ext2_dirent *) (kaddr + from);
@@ -574,7 +594,7 @@ int ext2_delete_entry (struct ext2_dir_e
&page, NULL);
BUG_ON(err);
if (pde)
- pde->rec_len = cpu_to_le16(to - from);
+ pde->rec_len = ext2_rec_len_to_disk(to - from);
dir->inode = 0;
err = ext2_commit_chunk(page, pos, to - from);
inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
@@ -610,14 +630,14 @@ int ext2_make_empty(struct inode *inode,
memset(kaddr, 0, chunk_size);
de = (struct ext2_dir_entry_2 *)kaddr;
de->name_len = 1;
- de->rec_len = cpu_to_le16(EXT2_DIR_REC_LEN(1));
+ de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1));
memcpy (de->name, ".\0\0", 4);
de->inode = cpu_to_le32(inode->i_ino);
ext2_set_de_type (de, inode);
de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
de->name_len = 2;
- de->rec_len = cpu_to_le16(chunk_size - EXT2_DIR_REC_LEN(1));
+ de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1));
de->inode = cpu_to_le32(parent->i_ino);
memcpy (de->name, "..\0", 4);
ext2_set_de_type (de, inode);
diff -puN include/linux/ext2_fs.h~ext2-avoid-rec_len-overflow-with-64kb-block-size include/linux/ext2_fs.h
--- a/include/linux/ext2_fs.h~ext2-avoid-rec_len-overflow-with-64kb-block-size
+++ a/include/linux/ext2_fs.h
@@ -561,6 +561,7 @@ enum {
#define EXT2_DIR_ROUND (EXT2_DIR_PAD - 1)
#define EXT2_DIR_REC_LEN(name_len) (((name_len) + 8 + EXT2_DIR_ROUND) & \
~EXT2_DIR_ROUND)
+#define EXT2_MAX_REC_LEN ((1<<16)-1)
static inline ext2_fsblk_t
ext2_group_first_block_no(struct super_block *sb, unsigned long group_no)
_
-
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