[lkml]   [2007]   [Oct]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH 1/2] ext4: Support large blocksize up to PAGESIZE
Support large blocksize up to PAGESIZE (max 64KB) for ext4. 

From: Takashi Sato <>

This patch set supports large block size(>4k, <=64k) in ext4,
just enlarging the block size limit. But it is NOT possible to have 64kB
blocksize on ext4 without some changes to the directory handling
code. The reason is that an empty 64kB directory block would have a
rec_len == (__u16)2^16 == 0, and this would cause an error to be hit in
the filesystem. The proposed solution is treat 64k rec_len
with a an impossible value like rec_len = 0xffff to handle this.

The Patch-set consists of the following 2 patches.
[1/2] ext4: enlarge blocksize
- Allow blocksize up to pagesize

[2/2] ext4: fix rec_len overflow
- prevent rec_len from overflow with 64KB blocksize

Now on 64k page ppc64 box runs with this patch set we could create a 64k
block size ext4dev, and able to handle empty directory block.
Patch consider to be merge to 2.6.24-rc1.

Signed-off-by: Takashi Sato <>
Signed-off-by: Mingming Cao <>

fs/ext4/super.c | 5 +++++
include/linux/ext4_fs.h | 4 ++--
2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 619db84..d8bb279 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1548,6 +1548,11 @@ static int ext4_fill_super (struct super_block *sb, void *data, int silent)
goto out_fail;

+ if (!sb_set_blocksize(sb, blocksize)) {
+ printk(KERN_ERR "EXT4-fs: bad blocksize %d.\n", blocksize);
+ goto out_fail;
+ }
* The ext4 superblock will not be buffer aligned for other than 1kB
* block sizes. We need to calculate the offset from buffer start.
diff --git a/include/linux/ext4_fs.h b/include/linux/ext4_fs.h
index f9881b6..d15a15e 100644
--- a/include/linux/ext4_fs.h
+++ b/include/linux/ext4_fs.h
@@ -77,8 +77,8 @@
* Macro-instructions used to manage several block sizes
#define EXT4_MIN_BLOCK_SIZE 1024
-#define EXT4_MAX_BLOCK_SIZE 4096
+#define EXT4_MAX_BLOCK_SIZE 65536
#ifdef __KERNEL__
# define EXT4_BLOCK_SIZE(s) ((s)->s_blocksize)

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2007-10-02 02:37    [W:0.184 / U:0.488 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site