Re: + ext4-uninitialized-block-groups-fix.patch added to -mm tree

Aneesh Kumar K.V Thu, 20 Sep 2007 22:50:28 -0700


[EMAIL PROTECTED] wrote:

The patch titled
     Ext4: Uninitialized Block Groups (fix)
has been added to the -mm tree.  Its filename is
     ext4-uninitialized-block-groups-fix.patch

*** Remember to use Documentation/SubmitChecklist when testing your code ***

See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this

------------------------------------------------------
Subject: Ext4: Uninitialized Block Groups (fix)
From: Avantika Mathur <[EMAIL PROTECTED]>

Andreas Dilger wrote:

On Sep 18, 2007  20:03 -0700, Andrew Morton wrote:

On Tue, 18 Sep 2007 17:25:31 -0700 Avantika Mathur <[EMAIL PROTECTED]> 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.

Cc: Andreas Dilger <[EMAIL PROTECTED]>
Cc: Avantika Mathur <[EMAIL PROTECTED]>
Cc: Mingming Cao <[EMAIL PROTECTED]>
Cc: Aneesh Kumar K.V <[EMAIL PROTECTED]>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>


Signed-off-by: Aneesh Kumar K.V <[EMAIL PROTECTED]>

---

fs/Kconfig | 1fs/ext4/ialloc.c | 8 ++++++-

 fs/ext4/super.c  |   51 ---------------------------------------------
 3 files changed, 9 insertions(+), 51 deletions(-)

diff -puN fs/ext4/ialloc.c~ext4-uninitialized-block-groups-fix fs/ext4/ialloc.c
--- a/fs/ext4/ialloc.c~ext4-uninitialized-block-groups-fix
+++ a/fs/ext4/ialloc.c
@@ -632,12 +632,18 @@ got:
        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);



I guess a comment as below would help to explain why are we not decrementing
bg_itable_unused by 1.


/* When marking the block group with ~EXT4_BG_INODE_UNINIT we don't want to 
depend

* on the value of bg_itable_unsed even though mke2fs could have initialized the* same for us. Instead we calculated the value below

*/

+                       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);
diff -puN fs/ext4/super.c~ext4-uninitialized-block-groups-fix fs/ext4/super.c
--- a/fs/ext4/super.c~ext4-uninitialized-block-groups-fix
+++ a/fs/ext4/super.c
@@ -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>

@@ -1337,56 +1338,6 @@ static int ext4_setup_super(struct super
        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)
 {
diff -puN fs/Kconfig~ext4-uninitialized-block-groups-fix fs/Kconfig
--- a/fs/Kconfig~ext4-uninitialized-block-groups-fix
+++ a/fs/Kconfig
@@ -140,6 +140,7 @@ config EXT4DEV_FS
        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
_

Patches currently in -mm which might be from [EMAIL PROTECTED] are

ext4-uninitialized-block-groups-fix.patch

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Re: + ext4-uninitialized-block-groups-fix.patch added to -mm tree

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