ext3-uninit-2.6.9.patch

非常经典的一个分布式系统

Add support for the uninit_groups feature to the kernel.

Keep a high water mark of used inodes for each group to improve e2fsck time.
Block and inode bitmaps can be uninitialized on disk via a flag in the
group descriptor to avoid reading or scanning them at e2fsck time.
A checksum of each group descriptor is used to ensure that corruption in
the group descriptor's bit flags does not cause incorrect operation.

Index: linux-2.6.9-full/include/linux/ext3_fs.h
===================================================================
--- linux-2.6.9-full.orig/include/linux/ext3_fs.h	2007-03-28 18:35:41.000000000 +0400
+++ linux-2.6.9-full/include/linux/ext3_fs.h	2007-03-28 18:36:16.000000000 +0400
@@ -153,16 +153,22 @@ struct ext3_allocation_request {
  */
 struct ext3_group_desc
 {
-	__le32	bg_block_bitmap;		/* Blocks bitmap block */
-	__le32	bg_inode_bitmap;		/* Inodes bitmap block */
+	__le32	bg_block_bitmap;	/* Blocks bitmap block */
+	__le32	bg_inode_bitmap;	/* Inodes bitmap block */
 	__le32	bg_inode_table;		/* Inodes table block */
 	__le16	bg_free_blocks_count;	/* Free blocks count */
 	__le16	bg_free_inodes_count;	/* Free inodes count */
 	__le16	bg_used_dirs_count;	/* Directories count */
-	__u16	bg_pad;
-	__le32	bg_reserved[3];
+	__le16  bg_flags;		/* EXT3_BG_flags (UNINIT, etc) */
+	__le32	bg_reserved[2];		/* Likely block/inode bitmap checksum */
+	__le16	bg_itable_unused;	/* Unused inodes count */
+	__le16	bg_checksum;		/* crc16(sb_uuid+group+desc) */
 };
 
+#define EXT3_BG_INODE_UNINIT	0x0001 /* Inode table/bitmap not in use */
+#define EXT3_BG_BLOCK_UNINIT	0x0002 /* Block bitmap not in use */
+#define EXT3_BG_INODE_ZEROED	0x0004 /* On-disk itable initialized to zero */
+
 /*
  * Macro-instructions used to manage group descriptors
  */
@@ -572,6 +578,7 @@ static inline struct ext3_inode_info *EX
 #define EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER	0x0001
 #define EXT3_FEATURE_RO_COMPAT_LARGE_FILE	0x0002
 #define EXT3_FEATURE_RO_COMPAT_BTREE_DIR	0x0004
+#define EXT4_FEATURE_RO_COMPAT_GDT_CSUM		0x0010
 #define EXT4_FEATURE_RO_COMPAT_DIR_NLINK	0x0020
 
 #define EXT3_FEATURE_INCOMPAT_COMPRESSION	0x0001
@@ -588,6 +595,7 @@ static inline struct ext3_inode_info *EX
 					 EXT3_FEATURE_INCOMPAT_EXTENTS)
 #define EXT3_FEATURE_RO_COMPAT_SUPP	(EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER| \
 					 EXT3_FEATURE_RO_COMPAT_LARGE_FILE| \
+					 EXT4_FEATURE_RO_COMPAT_GDT_CSUM| \
 					 EXT4_FEATURE_RO_COMPAT_DIR_NLINK| \
 					 EXT3_FEATURE_RO_COMPAT_BTREE_DIR)
 
Index: linux-2.6.9-full/fs/ext3/resize.c
===================================================================
--- linux-2.6.9-full.orig/fs/ext3/resize.c	2006-03-10 18:20:03.000000000 +0300
+++ linux-2.6.9-full/fs/ext3/resize.c	2007-03-28 18:36:16.000000000 +0400
@@ -19,6 +19,7 @@
 #include <linux/errno.h>
 #include <linux/slab.h>
 
+#include "group.h"
 
 #define outside(b, first, last)	((b) < (first) || (b) >= (last))
 #define inside(b, first, last)	((b) >= (first) && (b) < (last))
@@ -807,6 +808,7 @@ int ext3_group_add(struct super_block *s
 	gdp->bg_inode_table = cpu_to_le32(input->inode_table);
 	gdp->bg_free_blocks_count = cpu_to_le16(input->free_blocks_count);
 	gdp->bg_free_inodes_count = cpu_to_le16(EXT3_INODES_PER_GROUP(sb));
+	gdp->bg_checksum = ext3_group_desc_csum(sbi, input->group, gdp);
 
 	/*
 	 * Make the new blocks and inodes valid next.  We do this before
Index: linux-2.6.9-full/fs/ext3/super.c
===================================================================
--- linux-2.6.9-full.orig/fs/ext3/super.c	2007-03-28 18:35:42.000000000 +0400
+++ linux-2.6.9-full/fs/ext3/super.c	2007-03-28 18:36:16.000000000 +0400
@@ -38,6 +38,7 @@
 #include <asm/uaccess.h>
 #include "xattr.h"
 #include "acl.h"
+#include "group.h"
 
 static int ext3_load_journal(struct super_block *, struct ext3_super_block *,
 			     unsigned long journal_devnum);
@@ -1090,6 +1091,90 @@ static int ext3_setup_super(struct super
 	return res;
 }
 
+#if !defined(CONFIG_CRC16) && !defined(CONFIG_CRC16_MODULE)
+/** CRC table for the CRC-16. The poly is 0x8005 (x^16 + x^15 + x^2 + 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 ext3_group_desc_csum(struct ext3_sb_info *sbi, __u32 block_group,
+			    struct ext3_group_desc *gdp)
+{
+	__u16 crc = 0;
+
+	if (sbi->s_es->s_feature_ro_compat &
+	    cpu_to_le32(EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
+		int offset = offsetof(struct ext3_group_desc, bg_checksum);
+		__le32 le_group = cpu_to_le32(block_group);
+
+		crc = crc16(~0, sbi->s_es->s_uuid, sizeof(sbi->s_es->s_uuid));
+		crc = crc16(crc, (__u8 *)&le_group, sizeof(le_group));
+		crc = crc16(crc, (__u8 *)gdp, offset);
+		offset += sizeof(gdp->bg_checksum); /* skip checksum */
+		BUG_ON(offset != sizeof(*gdp)); /* XXX handle s_desc_size */
+		/* for checksum of struct ext4_group_desc do the rest...
+		if (offset < sbi->s_es->s_desc_size) {
+			crc = crc16(crc, (__u8 *)gdp + offset,
+				    sbi->s_es->s_desc_size - offset);
+		 */
+	}
+
+	return cpu_to_le16(crc);
+}
+
+int ext3_group_desc_csum_verify(struct ext3_sb_info *sbi, __u32 block_group,
+				struct ext3_group_desc *gdp)
+{
+	if (gdp->bg_checksum != ext3_group_desc_csum(sbi, block_group, gdp))
+		return 0;
+
+	return 1;
+}
+
 /* Called at mount-time, super-block is locked */
 static int ext3_check_descriptors (struct super_block * sb)
 {
@@ -1139,6 +1224,13 @@ static int ext3_check_descriptors (struc
 					le32_to_cpu(gdp->bg_inode_table));
 			return 0;
 		}
+		if (!ext3_group_desc_csum_verify(sbi, i, gdp)) {
+			ext3_error(sb, __FUNCTION__,
+				   "Checksum for group %d failed (%u!=%u)\n", i,
+				   le16_to_cpu(ext3_group_desc_csum(sbi,i,gdp)),
+				   le16_to_cpu(gdp->bg_checksum));
+			return 0;
+		}
 		block += EXT3_BLOCKS_PER_GROUP(sb);
 		gdp++;
 	}
Index: linux-2.6.9-full/fs/ext3/group.h
===================================================================
--- linux-2.6.9-full.orig/fs/ext3/group.h	2007-02-13 18:39:59.640066087 +0300
+++ linux-2.6.9-full/fs/ext3/group.h	2007-03-28 18:36:16.000000000 +0400
@@ -0,0 +1,29 @@
+/*
+ *  linux/fs/ext3/group.h
+ *
+ * Copyright (C) 2007 Cluster File Systems, Inc
+ *
+ * Author: Andreas Dilger <[e-mail]>
+ */
+
+#ifndef _LINUX_EXT3_GROUP_H
+#define _LINUX_EXT3_GROUP_H
+#if defined(CONFIG_CRC16) || defined(CONFIG_CRC16_MODULE)
+#include <linux/crc16.h>
+#endif
+
+extern __le16 ext3_group_desc_csum(struct ext3_sb_info *sbi, __u32 group,
+				   struct ext3_group_desc *gdp);
+extern int ext3_group_desc_csum_verify(struct ext3_sb_info *sbi, __u32 group,
+				       struct ext3_group_desc *gdp);
+struct buffer_head *read_block_bitmap(struct super_block *sb,
+				      unsigned int block_group);
+extern unsigned ext3_init_block_bitmap(struct super_block *sb,
+				       struct buffer_head *bh, int group,
+				       struct ext3_group_desc *desc);
+#define ext3_free_blocks_after_init(sb, group, desc)			\
+		ext3_init_block_bitmap(sb, NULL, group, desc)
+extern unsigned ext3_init_inode_bitmap(struct super_block *sb,
+				       struct buffer_head *bh, int group,
+				       struct ext3_group_desc *desc);
+#endif /* _LINUX_EXT3_GROUP_H */
Index: linux-2.6.9-full/fs/ext3/ialloc.c
===================================================================
--- linux-2.6.9-full.orig/fs/ext3/ialloc.c	2007-03-28 18:35:38.000000000 +0400
+++ linux-2.6.9-full/fs/ext3/ialloc.c	2007-03-28 18:36:16.000000000 +0400
@@ -28,6 +28,7 @@
 
 #include "xattr.h"
 #include "acl.h"
+#include "group.h"
 
 /*
  * ialloc.c contains the inodes allocation and deallocation routines
@@ -43,6 +44,52 @@
  * the free blocks count in the block.
  */
 
+/*
+ * To avoid calling the atomic setbit hundreds or thousands of times, we only
+ * need to use it within a single byte (to ensure we get endianness right).
+ * We can use memset for the rest of the bitmap as there are no other users.
+ */
+static void mark_bitmap_end(int start_bit, int end_bit, char *bitmap)
+{
+	int i;
+
+	if (start_bit >= end_bit)
+		return;
+
+	ext3_debug("mark end bits +%d through +%d used\n", start_bit, end_bit);
+	for (i = start_bit; i < ((start_bit + 7) & ~7UL); i++)
+		ext3_set_bit(i, bitmap);
+	if (i < end_bit)
+		memset(bitmap + (i >> 3), 0xff, (end_bit - i) >> 3);
+}
+
+/* Initializes an uninitialized inode bitmap */
+unsigned ext3_init_inode_bitmap(struct super_block *sb,
+				struct buffer_head *bh, int block_group,
+				struct ext3_group_desc *gdp)
+{
+	struct ext3_sb_info *sbi = EXT3_SB(sb);
+
+	J_ASSERT_BH(bh, buffer_locked(bh));
+
+	/* If checksum is bad mark all blocks and inodes use to prevent
+	 * allocation, essentially implementing a per-group read-only flag. */
+	if (!ext3_group_desc_csum_verify(sbi, block_group, gdp)) {
+		ext3_error(sb, __FUNCTION__, "Checksum bad for group %u\n",
+			   block_group);
+		gdp->bg_free_blocks_count = 0;
+		gdp->bg_free_inodes_count = 0;
+		gdp->bg_itable_unused = 0;
+		memset(bh->b_data, 0xff, sb->s_blocksize);
+		return 0;
+	}
+
+	memset(bh->b_data, 0, (EXT3_INODES_PER_GROUP(sb) + 7) / 8);
+	mark_bitmap_end(EXT3_INODES_PER_GROUP(sb), EXT3_BLOCKS_PER_GROUP(sb),
+			bh->b_data);
+
+	return EXT3_INODES_PER_GROUP(sb);
+}
 
 /*
  * Read the inode allocation bitmap for a given block_group, reading
@@ -59,8 +106,19 @@ read_inode_bitmap(struct super_block * s
 	desc = ext3_get_group_desc(sb, block_group, NULL);
 	if (!desc)
 		goto error_out;
-
-	bh = sb_bread(sb, le32_to_cpu(desc->bg_inode_bitmap));
+	if (desc->bg_flags & cpu_to_le16(EXT3_BG_INODE_UNINIT)) {
+		bh = sb_getblk(sb, le32_to_cpu(desc->bg_inode_bitmap));
+		if (!buffer_uptodate(bh)) {
+			lock_buffer(bh);
+			if (!buffer_uptodate(bh)) {
+				ext3_init_inode_bitmap(sb, bh,block_group,desc);
+				set_buffer_uptodate(bh);
+			}
+			unlock_buffer(bh);
+		}
+	} else {
+		bh = sb_bread(sb, le32_to_cpu(desc->bg_inode_bitmap));
+	}
 	if (!bh)
 		ext3_error(sb, "read_inode_bitmap",
 			    "Cannot read inode bitmap - "
@@ -169,6 +227,8 @@ void ext3_free_inode (handle_t *handle, 
 			if (is_directory)
 				gdp->bg_used_dirs_count = cpu_to_le16(
 				  le16_to_cpu(gdp->bg_used_dirs_count) - 1);
+			gdp->bg_checksum = ext3_group_desc_csum(sbi,block_group,
+								gdp);
 			spin_unlock(sb_bgl_lock(sbi, block_group));
 			percpu_counter_inc(&sbi->s_freeinodes_counter);
 			if (is_directory)
@@ -453,7 +513,7 @@ struct inode *ext3_new_inode(handle_t *h
 	struct ext3_sb_info *sbi;
 	int err = 0;
 	struct inode *ret;
-	int i;
+	int i, free = 0;
 
 	/* Cannot create files in a deleted directory */
 	if (!dir || !dir->i_nlink)
@@ -566,11 +626,13 @@ repeat_in_this_group:
 	goto out;