Re: [PATCH] Ext4: Uninitialized Block Groups
From: Avantika Mathur
Date: Wed Sep 19 2007 - 18:53:50 EST
Andreas Dilger wrote:
On Sep 18, 2007 20:03 -0700, Andrew Morton wrote:
On Tue, 18 Sep 2007 17:25:31 -0700 Avantika Mathur <mathur@xxxxxxxxxxxxxxxxxx> wrote:
+#if !defined(CONFIG_CRC16)
+/** CRC table for the CRC-16. The poly is 0x8005 (x16 + x15 + x2 + 1) */
+__u16 const crc16_table[256] = { me
+ 0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
That's rather sad. A plain old "depends on" would be better.
My bad. We wrote this patch and it had to run on older kernels that might
not even have lib/crc16.c (it was added around 2.6.15 or so, so e.g. RHEL4
doesn't have it). I forgot to remove it from the upstream submission,
and since it didn't cause problems nobody else complained...
The incremental patch below removes the local crc16 code, and also resolves an
issue with properly updating bg_itable_unused when an inode is allocated in an
unused block groups.
Thanks
Avantika
---
fs/Kconfig | 1 +
fs/ext4/ialloc.c | 8 +++++++-
fs/ext4/super.c | 51 +--------------------------------------------------
3 files changed, 9 insertions(+), 51 deletions(-)
Index: linux-2.6.23-rc6/fs/ext4/ialloc.c
===================================================================
--- linux-2.6.23-rc6.orig/fs/ext4/ialloc.c 2007-09-19 15:38:21.000000000 -0700
+++ linux-2.6.23-rc6/fs/ext4/ialloc.c 2007-09-19 15:41:11.000000000 -0700
@@ -635,12 +635,18 @@
if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
if (gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)) {
gdp->bg_flags &= cpu_to_le16(~EXT4_BG_INODE_UNINIT);
- free = EXT4_INODES_PER_GROUP(sb);
+ free = 0;
} else {
free = EXT4_INODES_PER_GROUP(sb) -
le16_to_cpu(gdp->bg_itable_unused);
}
+ /*
+ * Check the relative inode number against the last used
+ * relative inode number in this group. if it is greater
+ * we need to update the bg_itable_unused count
+ *
+ */
if (ino > free)
gdp->bg_itable_unused =
cpu_to_le16(EXT4_INODES_PER_GROUP(sb) - ino);
Index: linux-2.6.23-rc6/fs/ext4/super.c
===================================================================
--- linux-2.6.23-rc6.orig/fs/ext4/super.c 2007-09-19 15:38:21.000000000 -0700
+++ linux-2.6.23-rc6/fs/ext4/super.c 2007-09-19 15:38:51.000000000 -0700
@@ -37,6 +37,7 @@
#include <linux/quotaops.h>
#include <linux/seq_file.h>
#include <linux/log2.h>
+#include <linux/crc16.h>
#include <asm/uaccess.h>
@@ -1248,56 +1249,6 @@
return res;
}
-#if !defined(CONFIG_CRC16)
-/** CRC table for the CRC-16. The poly is 0x8005 (x16 + x15 + x2 + 1) */
-__u16 const crc16_table[256] = {
- 0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
- 0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
- 0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
- 0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
- 0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
- 0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
- 0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
- 0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
- 0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
- 0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
- 0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
- 0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
- 0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
- 0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
- 0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
- 0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
- 0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
- 0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
- 0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
- 0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
- 0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
- 0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
- 0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
- 0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
- 0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
- 0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
- 0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
- 0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
- 0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
- 0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
- 0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
- 0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040
-};
-
-static inline __u16 crc16_byte(__u16 crc, const __u8 data)
-{
- return (crc >> 8) ^ crc16_table[(crc ^ data) & 0xff];
-}
-
-__u16 crc16(__u16 crc, __u8 const *buffer, size_t len)
-{
- while (len--)
- crc = crc16_byte(crc, *buffer++);
- return crc;
-}
-#endif
-
__le16 ext4_group_desc_csum(struct ext4_sb_info *sbi, __u32 block_group,
struct ext4_group_desc *gdp)
{
Index: linux-2.6.23-rc6/fs/Kconfig
===================================================================
--- linux-2.6.23-rc6.orig/fs/Kconfig 2007-09-19 15:38:21.000000000 -0700
+++ linux-2.6.23-rc6/fs/Kconfig 2007-09-19 15:38:51.000000000 -0700
@@ -140,6 +140,7 @@
tristate "Ext4dev/ext4 extended fs support development (EXPERIMENTAL)"
depends on EXPERIMENTAL
select JBD2
+ select CRC16
help
Ext4dev is a predecessor filesystem of the next generation
extended fs ext4, based on ext3 filesystem code. It will be
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