Initial bitmap support

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>

1 files changed, 315 insertions, 0 deletions

diff --git a/bitmap.c b/bitmap.c
new file mode 100644
index 0000000..57969a6
--- /dev/null
+++ b/bitmap.c
@@ -0,0 +1,315 @@
+/*
+ * mdadm - manage Linux "md" devices aka RAID arrays.
+ *
+ * Copyright (C) 2004 Paul Clements, SteelEye Technology, Inc.
+ *
+ *    This program is free software; you can redistribute it and/or modify
+ *    it under the terms of the GNU General Public License as published by
+ *    the Free Software Foundation; either version 2 of the License, or
+ *    (at your option) any later version.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *    You should have received a copy of the GNU General Public License
+ *    along with this program; if not, write to the Free Software
+ *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include "mdadm.h"
+#include <asm/byteorder.h>
+
+#define min(a,b) (((a) < (b)) ? (a) : (b))
+
+inline void sb_le_to_cpu(bitmap_super_t *sb)
+{
+	sb->magic = __le32_to_cpu(sb->magic);
+	sb->version = __le32_to_cpu(sb->version);
+	/* uuid gets no translation */
+	sb->events = __le64_to_cpu(sb->events);
+	sb->events_cleared = __le64_to_cpu(sb->events_cleared);
+	sb->state = __le32_to_cpu(sb->state);
+	sb->chunksize = __le32_to_cpu(sb->chunksize);
+	sb->daemon_sleep = __le32_to_cpu(sb->daemon_sleep);
+	sb->sync_size = __le64_to_cpu(sb->sync_size);
+}
+
+inline void sb_cpu_to_le(bitmap_super_t *sb)
+{
+	sb_le_to_cpu(sb); /* these are really the same thing */
+}
+
+mapping_t bitmap_states[] = {
+	{ "OK", 0 },
+	{ "Out of date", 2 },
+	{ NULL, -1 }
+};
+
+const char *bitmap_state(int state_num)
+{
+	char *state = map_num(bitmap_states, state_num);
+	return state ? state : "Unknown";
+}
+
+const char *human_chunksize(unsigned long bytes)
+{
+	static char buf[16];
+	char *suffixes[] = { "B", "KB", "MB", "GB", "TB", NULL };
+	int i = 0;
+
+	while (bytes >> 10) {
+		bytes >>= 10;
+		i++;
+	}
+
+	sprintf(buf, "%lu %s", bytes, suffixes[i]);
+
+	return buf;
+}
+
+typedef struct bitmap_info_s {
+	bitmap_super_t sb;
+	unsigned long long total_bits;
+	unsigned long long dirty_bits;
+} bitmap_info_t;
+
+/* count the dirty bits in the first num_bits of byte */
+inline int count_dirty_bits_byte(char byte, int num_bits)
+{
+	int num = 0;
+
+	switch (num_bits) { /* fall through... */
+		case 8:	if (byte & 128) num++;
+		case 7:	if (byte &  64) num++;
+		case 6:	if (byte &  32) num++;
+		case 5:	if (byte &  16) num++;
+		case 4:	if (byte &   8) num++;
+		case 3: if (byte &   4) num++;
+		case 2:	if (byte &   2) num++;
+		case 1:	if (byte &   1) num++;
+		default: break;
+	}
+
+	return num;
+}
+
+int count_dirty_bits(char *buf, int num_bits)
+{
+	int i, num = 0;
+
+	for (i=0; i < num_bits / 8; i++)
+		num += count_dirty_bits_byte(buf[i], 8);
+
+	if (num_bits % 8) /* not an even byte boundary */
+		num += count_dirty_bits_byte(buf[i], num_bits % 8);
+
+	return num;
+}
+
+/* calculate the size of the bitmap given the array size and bitmap chunksize */
+unsigned long long bitmap_bits(unsigned long long array_size,
+				unsigned long chunksize)
+{
+	return (array_size * 512 + chunksize - 1) / chunksize;
+}
+
+bitmap_info_t *bitmap_fd_read(int fd, int brief)
+{
+	unsigned long long total_bits = 0, read_bits = 0, dirty_bits = 0;
+	bitmap_info_t *info;
+	char buf[512];
+	int n;
+
+	info = malloc(sizeof(*info));
+	if (info == NULL) {
+		fprintf(stderr, Name ": failed to allocate %d bytes\n",
+				sizeof(*info));
+		return NULL;
+	}
+
+	if (read(fd, &info->sb, sizeof(info->sb)) != sizeof(info->sb)) {
+		fprintf(stderr, Name ": failed to read superblock of bitmap "
+			"file: %s\n", strerror(errno));
+		free(info);
+		return NULL;
+	}
+
+	sb_le_to_cpu(&info->sb); /* convert superblock to CPU byte ordering */
+	
+	if (brief || info->sb.sync_size == 0)
+		goto out;
+
+	/* read the rest of the file counting total bits and dirty bits --
+	 * we stop when either:
+	 * 1) we hit EOF, in which case we assume the rest of the bits (if any)
+	 *    are dirty
+	 * 2) we've read the full bitmap, in which case we ignore any trailing
+	 *    data in the file
+	 */
+	total_bits = bitmap_bits(info->sb.sync_size, info->sb.chunksize);
+
+	while ((n = read(fd, buf, sizeof(*buf))) > 0) {
+		unsigned long long remaining = total_bits - read_bits;
+
+		if (remaining > sizeof(*buf) * 8) /* we want the full buffer */
+			remaining = sizeof(*buf) * 8;
+		if (remaining > n * 8) /* the file is truncated */
+			remaining = n * 8;
+		dirty_bits += count_dirty_bits(buf, remaining);
+
+		read_bits += remaining;
+		if (read_bits >= total_bits) /* we've got what we want */
+			break;
+	}
+
+	if (read_bits < total_bits) { /* file truncated... */
+		fprintf(stderr, Name ": WARNING: bitmap file is not large "
+			"enough for array size %llu!\n\n", info->sb.sync_size);
+		total_bits = read_bits;
+	}
+out:
+	info->total_bits = total_bits;
+	info->dirty_bits = dirty_bits;
+	return info;
+}
+
+bitmap_info_t *bitmap_file_read(char *filename, int brief)
+{
+	int fd;
+	bitmap_info_t *info;
+
+	fd = open(filename, O_RDONLY);
+	if (fd < 0) {
+		fprintf(stderr, Name ": failed to open bitmap file %s: %s\n",
+				filename, strerror(errno));
+		return NULL;
+	}
+
+	info = bitmap_fd_read(fd, brief);
+	close(fd);
+	return info;
+}
+
+int ExamineBitmap(char *filename, int brief)
+{
+	/*
+	 * Read the bitmap file and display its contents
+	 */
+
+	bitmap_super_t *sb;
+	bitmap_info_t *info;
+	int rv = 1;
+
+	info = bitmap_file_read(filename, brief);
+	if (!info)
+		return rv;
+
+	sb = &info->sb;
+	printf("        Filename : %s\n", filename);
+	printf("           Magic : %08x\n", sb->magic);
+	if (sb->magic != BITMAP_MAGIC) {
+		fprintf(stderr, Name ": invalid bitmap magic 0x%x, the bitmap file appears to be corrupted\n", sb->magic);
+	}
+	printf("         Version : %d\n", sb->version);
+	if (sb->version != BITMAP_MAJOR) {
+		fprintf(stderr, Name ": unknown bitmap version %d, either the bitmap file is corrupted or you need to upgrade your tools\n", sb->version);
+		goto free_info;
+	}
+
+	rv = 0;
+	printf("            UUID : %08x.%08x.%08x.%08x\n",
+					*(__u32 *)(sb->uuid+0),
+					*(__u32 *)(sb->uuid+4),
+					*(__u32 *)(sb->uuid+8),
+					*(__u32 *)(sb->uuid+12));
+	printf("          Events : %llu\n", sb->events);
+	printf("  Events Cleared : %llu\n", sb->events_cleared);
+	printf("           State : %s\n", bitmap_state(sb->state));
+	printf("       Chunksize : %s\n", human_chunksize(sb->chunksize));
+	printf("          Daemon : %ds flush period\n", sb->daemon_sleep);
+	printf("       Sync Size : %llu%s\n", sb->sync_size,
+					human_size(sb->sync_size * 1024));
+	if (brief)
+		goto free_info;
+	printf("          Bitmap : %llu bits (chunks), %llu dirty (%2.1f%%)\n",
+			info->total_bits, info->dirty_bits,
+			100.0 * info->dirty_bits / (info->total_bits + 1));
+free_info:
+	free(info);
+	return rv;
+}
+
+int CreateBitmap(char *filename, int force, char uuid[16],
+		unsigned long chunksize, unsigned long daemon_sleep,
+		unsigned long long array_size)
+{
+	/*
+	 * Create a bitmap file with a superblock and (optionally) a full bitmap
+	 */
+
+	FILE *fp;
+	int rv = 1;
+	char block[512];
+	bitmap_super_t sb;
+	long long bytes, filesize;
+
+	if (!force && access(filename, F_OK) == 0) {
+		fprintf(stderr, Name ": bitmap file %s already exists, use --force to overwrite\n", filename);
+		return rv;
+	}
+
+	fp = fopen(filename, "w");
+	if (fp == NULL) {
+		fprintf(stderr, Name ": failed to open bitmap file %s: %s\n",
+			filename, strerror(errno));
+		return rv;
+	}
+
+	memset(&sb, 0, sizeof(sb));
+	sb.magic = BITMAP_MAGIC;
+	sb.version = BITMAP_MAJOR;
+	if (uuid != NULL)
+		memcpy(sb.uuid, uuid, 16);
+	sb.chunksize = chunksize;
+	sb.daemon_sleep = daemon_sleep;
+	sb.sync_size = array_size;
+
+	sb_cpu_to_le(&sb); /* convert to on-disk byte ordering */
+
+	if (fwrite(&sb, sizeof(sb), 1, fp) != 1) {
+		fprintf(stderr, Name ": failed to write superblock to bitmap file %s: %s\n", filename, strerror(errno));
+		goto out;
+	}
+
+	/* calculate the size of the bitmap and write it to disk */
+	bytes = (bitmap_bits(array_size, chunksize) + 7) / 8;
+	if (!bytes) {
+		rv = 0;
+		goto out;
+	}
+
+	filesize = bytes + sizeof(sb);
+
+	memset(block, 0xff, sizeof(block));
+
+	while (bytes > 0) {
+		if (fwrite(block, sizeof(block), 1, fp) != 1) {
+			fprintf(stderr, Name ": failed to write bitmap file %s: %s\n", filename, strerror(errno));
+			goto out;
+		}
+		bytes -= sizeof(block);
+	}
+	
+	rv = 0;
+	/* make the file be the right size (well, to the nearest byte) */
+	ftruncate(fileno(fp), filesize);
+out:
+	fclose(fp);
+	if (rv)
+		unlink(filename); /* possibly corrupted, better get rid of it */
+	return rv;
+}