ext4: Support large blocksize up to PAGESIZE
authorTakashi Sato <sho@tnes.nec.co.jp>
Tue, 29 Jan 2008 04:58:27 +0000 (23:58 -0500)
committerTheodore Ts'o <tytso@mit.edu>
Tue, 29 Jan 2008 04:58:27 +0000 (23:58 -0500)
commitafc7cbca5bfd556c3e12d3acefbee5ab0cbd4670
tree90e6daf4a3f41433221d9cb8d7ce909cde0d62d1
parent8561b089afbaed2651591e5a4574fdca451d82f2
ext4:  Support large blocksize up to PAGESIZE

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.

Signed-off-by: Takashi Sato <sho@tnes.nec.co.jp>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
fs/ext4/super.c
include/linux/ext4_fs.h