Grow/bitmap: support adding bitmap via sysfs.

Adding a bitmap via ioctl can only add it at a fixed location.
That location is not suitable for 4K-block devices.

So allow setting the bitmap location via sysfs if kernel supports it
and aim to always use 4K alignments.

Signed-off-by: NeilBrown <neilb@suse.de>

Grow.c

@@ -375,12 +375,18 @@ int Grow_addbitmap(char *devname, int fd, char *file, int chunk, int delay, int
 		return 1;
 	}
 	if (strcmp(file, "internal") == 0) {
+		int rv;
 		int d;
+		int offset_setable = 0;
+		struct mdinfo *mdi;
 		if (st->ss->add_internal_bitmap == NULL) {
 			fprintf(stderr, Name ": Internal bitmaps not supported "
 				"with %s metadata\n", st->ss->name);
 			return 1;
 		}
+		mdi = sysfs_read(fd, -1, GET_BITMAP_LOCATION);
+		if (mdi)
+			offset_setable = 1;
 		for (d=0; d< st->max_devs; d++) {
 			mdu_disk_info_t disk;
 			char *dv;
@@ -401,11 +407,13 @@ int Grow_addbitmap(char *devname, int fd, char *file, int chunk, int delay, int
 					if (st->ss->add_internal_bitmap(
 						    st,
 						    &chunk, delay, write_behind,
-						    bitmapsize, 0, major)
+						    bitmapsize, offset_setable,
+						    major)
 						)
 						st->ss->write_bitmap(st, fd2);
 					else {
-						fprintf(stderr, Name ": failed to create internal bitmap - chunksize problem.\n");
+						fprintf(stderr, Name ": failed "
+				"to create internal bitmap - chunksize problem.\n");
 						close(fd2);
 						return 1;
 					}
@@ -413,8 +421,16 @@ int Grow_addbitmap(char *devname, int fd, char *file, int chunk, int delay, int
 				close(fd2);
 			}
 		}
-		array.state |= (1<<MD_SB_BITMAP_PRESENT);
-		if (ioctl(fd, SET_ARRAY_INFO, &array)!= 0) {
+		if (offset_setable) {
+			st->ss->getinfo_super(st, mdi, NULL);
+			sysfs_init(mdi, fd, -1);
+			rv = sysfs_set_num(mdi, NULL, "bitmap/location",
+					   mdi->bitmap_offset);
+		} else {
+			array.state |= (1<<MD_SB_BITMAP_PRESENT);
+			rv = ioctl(fd, SET_ARRAY_INFO, &array);
+		}
+		if (rv < 0) {
 			if (errno == EBUSY)
 				fprintf(stderr, Name
 					": Cannot add bitmap while array is"

mdadm.h

@@ -211,6 +211,7 @@ struct mdinfo {
 		unsigned long long recovery_start; /* per-device rebuild position */
 		#define MaxSector  (~0ULL) /* resync/recovery complete position */
 	};
+	unsigned long		bitmap_offset;	/* 0 == none, 1 == a file */
 	unsigned long		safe_mode_delay; /* ms delay to mark clean */
 	int			new_level, delta_disks, new_layout, new_chunk;
 	int			errors;
@@ -448,11 +449,13 @@ enum sysfs_read_flags {
 	GET_DISKS	= (1 << 7),
 	GET_DEGRADED	= (1 << 8),
 	GET_SAFEMODE	= (1 << 9),
-	GET_DEVS	= (1 << 10), /* gets role, major, minor */
-	GET_OFFSET	= (1 << 11),
-	GET_SIZE	= (1 << 12),
-	GET_STATE	= (1 << 13),
-	GET_ERROR	= (1 << 14),
+	GET_BITMAP_LOCATION = (1 << 10),
+
+	GET_DEVS	= (1 << 20), /* gets role, major, minor */
+	GET_OFFSET	= (1 << 21),
+	GET_SIZE	= (1 << 22),
+	GET_STATE	= (1 << 23),
+	GET_ERROR	= (1 << 24),
 };
 
 /* If fd >= 0, get the array it is open on,

super0.c

@@ -360,6 +360,9 @@ static void getinfo_super0(struct supertype *st, struct mdinfo *info, char *map)
 	info->array.state = sb->state;
 	info->component_size = sb->size*2;
 
+	if (sb->state & (1<<MD_SB_BITMAP_PRESENT))
+		info->bitmap_offset = 8;
+
 	info->disk.state = sb->this_disk.state;
 	info->disk.major = sb->this_disk.major;
 	info->disk.minor = sb->this_disk.minor;

super1.c

@@ -578,6 +578,8 @@ static void getinfo_super1(struct supertype *st, struct mdinfo *info, char *map)
 
 	info->data_offset = __le64_to_cpu(sb->data_offset);
 	info->component_size = __le64_to_cpu(sb->size);
+	if (sb->feature_map & __le32_to_cpu(MD_FEATURE_BITMAP_OFFSET))
+		info->bitmap_offset = __le32_to_cpu(sb->bitmap_offset);
 
 	info->disk.major = 0;
 	info->disk.minor = 0;
@@ -1384,7 +1386,8 @@ static int load_super1(struct supertype *st, int fd, char *devname)
 	return 0;
 
  no_bitmap:
-	super->feature_map = __cpu_to_le32(__le32_to_cpu(super->feature_map) & ~1);
+	super->feature_map = __cpu_to_le32(__le32_to_cpu(super->feature_map)
+					   & ~MD_FEATURE_BITMAP_OFFSET);
 	return 0;
 }
 
@@ -1486,12 +1489,10 @@ add_internal_bitmap1(struct supertype *st,
 		     int may_change, int major)
 {
 	/*
-	 * If not may_change, then this is a 'Grow', and the bitmap
-	 * must fit after the superblock.
-	 * If may_change, then this is create, and we can put the bitmap
-	 * before the superblock if we like, or may move the start.
-	 * If !may_change, the bitmap MUST live at offset of 1K, until
-	 * we get a sysfs interface.
+	 * If not may_change, then this is a 'Grow' without sysfs support for
+	 * bitmaps, and the bitmap must fit after the superblock at 1K offset.
+	 * If may_change, then this is create or a Grow with sysfs syupport,
+	 * and we can put the bitmap wherever we like.
 	 *
 	 * size is in sectors,  chunk is in bytes !!!
 	 */
@@ -1502,16 +1503,20 @@ add_internal_bitmap1(struct supertype *st,
 	long offset;
 	unsigned long long chunk = *chunkp;
 	int room = 0;
+	int creating = 0;
 	struct mdp_superblock_1 *sb = st->sb;
 	bitmap_super_t *bms = (bitmap_super_t*)(((char*)sb) + 1024);
 	int uuid[4];
 
+	if (__le64_to_cpu(sb->data_size) == 0)
+		/* Must be creating the array, else data_size would be non-zero */
+		creating = 1;
 	switch(st->minor_version) {
 	case 0:
 		/* either 3K after the superblock (when hot-add),
 		 * or some amount of space before.
 		 */
-		if (may_change) {
+		if (creating) {
 			/* We are creating array, so we *know* how much room has
 			 * been left.
 			 */
@@ -1521,8 +1526,8 @@ add_internal_bitmap1(struct supertype *st,
 			room = __le64_to_cpu(sb->super_offset)
 				- __le64_to_cpu(sb->data_offset)
 				- __le64_to_cpu(sb->data_size);
-			/* remove '1 ||' when we can set offset via sysfs */
-			if (1 || (room < 3*2 &&
+
+			if (!may_change || (room < 3*2 &&
 				  __le32_to_cpu(sb->max_dev) <= 384)) {
 				room = 3*2;
 				offset = 1*2;
@@ -1533,17 +1538,17 @@ add_internal_bitmap1(struct supertype *st,
 		break;
 	case 1:
 	case 2: /* between superblock and data */
-		if (may_change) {
+		if (creating) {
 			offset = 4*2;
 			room = choose_bm_space(__le64_to_cpu(sb->size));
 		} else {
 			room = __le64_to_cpu(sb->data_offset)
 				- __le64_to_cpu(sb->super_offset);
-			if (1 || __le32_to_cpu(sb->max_dev) <= 384) {
-				room -= 2;
+			if (!may_change) {
+				room -= 2; /* Leave 1K for superblock */
 				offset = 2;
 			} else {
-				room -= 4*2;
+				room -= 4*2; /* leave 4K for superblock */
 				offset = 4*2;
 			}
 		}
@@ -1588,7 +1593,8 @@ add_internal_bitmap1(struct supertype *st,
 
 	sb->bitmap_offset = __cpu_to_le32(offset);
 
-	sb->feature_map = __cpu_to_le32(__le32_to_cpu(sb->feature_map) | 1);
+	sb->feature_map = __cpu_to_le32(__le32_to_cpu(sb->feature_map)
+					| MD_FEATURE_BITMAP_OFFSET);
 	memset(bms, 0, sizeof(*bms));
 	bms->magic = __cpu_to_le32(BITMAP_MAGIC);
 	bms->version = __cpu_to_le32(major);
@@ -1603,7 +1609,6 @@ add_internal_bitmap1(struct supertype *st,
 	return 1;
 }
 
-
 static void locate_bitmap1(struct supertype *st, int fd)
 {
 	unsigned long long offset;

sysfs.c

@@ -217,6 +217,19 @@ struct mdinfo *sysfs_read(int fd, int devnum, unsigned long options)
 		msec = (msec * 1000) / scale;
 		sra->safe_mode_delay = msec;
 	}
+	if (options & GET_BITMAP_LOCATION) {
+		strcpy(base, "bitmap/location");
+		if (load_sys(fname, buf))
+			goto abort;
+		if (strncmp(buf, "file", 4) == 0)
+			sra->bitmap_offset = 1;
+		else if (strncmp(buf, "none", 4) == 0)
+			sra->bitmap_offset = 0;
+		else if (buf[0] == '+')
+			sra->bitmap_offset = strtoul(buf+1, NULL, 10);
+		else
+			goto abort;
+	}
 
 	if (! (options & GET_DEVS))
 		return sra;