+ ext2-fix-support-for-empty-directory-blocks-in-64k-blocksize-filesystems.patch added to -mm tree
diff mbox

Message ID 200902102257.n1AMvwKl006860@imap1.linux-foundation.org
State Not Applicable, archived
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Commit Message

Andrew Morton Feb. 10, 2009, 10:57 p.m. UTC
The patch titled
     ext2: fix support for empty directory blocks in 64k blocksize filesystems
has been added to the -mm tree.  Its filename is
     ext2-fix-support-for-empty-directory-blocks-in-64k-blocksize-filesystems.patch

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------------------------------------------------------
Subject: ext2: fix support for empty directory blocks in 64k blocksize filesystems
From: Wei Yongjun <yjwei@cn.fujitsu.com>

The rec_len field in the directory entry is 16 bits, so if the filesystem
is completely empty, rec_len of 0 is used to designate 65536 in e2fsprogs,
for the case where the directory entry takes the entire 64k block.

But if an empty directory is read, an error message will be output by
current kernels.  You can use the following commands to reproduce it.

  - mkfs.ext2 -b $(( 64 * 1024 )) /dev/sdc1
  - mount /dev/sda1 /mnt
  - cd /mnt/lost+found
  - ll
  - tail /var/log/messages
  EXT2-fs error (device sdc1): ext2_check_page: bad entry in \
  directory #11: : rec_len is smaller than minimal - offset=65536, \
  inode=0, rec_len=0, name_len=0
  EXT2-fs error (device sdc1): ext2_readdir: bad page in #11

Treat a rec_len of 0 as 65536, as e2fsprogs does.

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/ext2/dir.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Theodore Y. Ts'o Feb. 11, 2009, 3:02 p.m. UTC | #1
On Tue, Feb 10, 2009 at 02:57:58PM -0800, akpm@linux-foundation.org wrote:
> 
> The patch titled
>      ext2: fix support for empty directory blocks in 64k blocksize filesystems
> has been added to the -mm tree.  Its filename is
>      ext2-fix-support-for-empty-directory-blocks-in-64k-blocksize-filesystems.patch

NACK.  The commit description is incomplete, we need to discuss more
what's the best way of handling this.  See the discussion around the
ext4 patch on linux-ext4 for more details.

This patch is entirely moot for ext2 in any case, since
EXT2_MAX_BLOCK_SIZE was never changed from 4096.

								- Ted
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Patch
diff mbox

diff -puN fs/ext2/dir.c~ext2-fix-support-for-empty-directory-blocks-in-64k-blocksize-filesystems fs/ext2/dir.c
--- a/fs/ext2/dir.c~ext2-fix-support-for-empty-directory-blocks-in-64k-blocksize-filesystems
+++ a/fs/ext2/dir.c
@@ -33,7 +33,7 @@  static inline unsigned ext2_rec_len_from
 {
 	unsigned len = le16_to_cpu(dlen);
 
-	if (len == EXT2_MAX_REC_LEN)
+	if (len == EXT2_MAX_REC_LEN || len == 0)
 		return 1 << 16;
 	return len;
 }
@@ -41,7 +41,7 @@  static inline unsigned ext2_rec_len_from
 static inline __le16 ext2_rec_len_to_disk(unsigned len)
 {
 	if (len == (1 << 16))
-		return cpu_to_le16(EXT2_MAX_REC_LEN);
+		return cpu_to_le16(0);
 	else
 		BUG_ON(len > (1 << 16));
 	return cpu_to_le16(len);