From: NeilBrown <neilb@suse.de>
Date: Wed, 4 May 2011 07:04:36 +0000 (+1000)
Subject: FORMAT CHANGE Various changes to 'superblock' format.
X-Git-Url: http://git.neil.brown.name/?a=commitdiff_plain;h=15356cffbe96158f264be9de3ccf725d712f1fb1;p=LaFS.git

FORMAT CHANGE Various changes to 'superblock' format.

Simplify version number.
Allow reference to readonly base.
Allow arbitrary config options.

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

diff --git a/layout.h b/layout.h
index e92b8cc..8443980 100644
--- a/layout.h
+++ b/layout.h
@@ -16,10 +16,11 @@
  */
 struct lafs_dev {
 	char	idtag[16];	/* LaFS-DeviceBlock */
-	char	version[16];	/* number space options */
 	u8	uuid[16];
 	u32	checksum;
 	u32	seq;
+	u32	version;	/* Currently must be LAFS_DEV_VERS == 1 */
+	u32	pad0;
 
 	u64	ctime;
 	u64	start, size;	/* in array address space (array block)*/
@@ -34,18 +35,26 @@ struct lafs_dev {
 	u32	segment_offset;	/* offset of first segment (device byte) */
 	u32	segment_count;
 	u32	usage_inum;	/* inum of segment usage file */
-	u32	level;
+	char	options[512];	/* Space separated, nul terminated, Cap for
+				 * read-only-if-you-don't-understand
+				 */
 }  __attribute__((packed));
-#define	 LAFS_DEVBLK_SIZE	1024
+#define	LAFS_DEVBLK_SIZE	1024
+#define	LAFS_DEV_VERS		1
 
 struct lafs_state {
 	char	idtag[16];	/* LaFS-State-Block */
-	char	version[16];	/* number space options */
+	u8	uuid[16];
+	u8	alt_uuid[16];	/* allows sharing of read-only devices
+				 * between arrays
+				 */
 	u32	checksum;
+	u32	version;	/* Must be LAFS_STATE_VERS  == 1 */
 	u32	seq;
-	u8	uuid[16];
-	u32	levels;
+	u32	alt_seq;	/* seq number of the alt_uuid devices */
 	u32	devices;
+	u32	pad0;
+
 	u32	nonlog_offset;	/* offset into following segment of next non-logged
 				 * block to allocate
 				 */
@@ -54,9 +63,18 @@ struct lafs_state {
 	u16	nextyouth;
 	u32	maxsnapshot;
 
+	u64	inconsistencies;/* bit set of discovered inconsistency types.
+				 * If any unknown bits are set, an fsck is needed
+				 * for writing.
+				 * If known bits are set, behaviour is dependant
+				 * on those bits.
+				 */
+
 	u64	checkpointcluster;	/* (array block) */
+	char	options[512];	/* Space separated, nul terminated. */
 	u64	root_inodes[0];	/* (array block) */
 } __attribute__((packed));
+#define	LAFS_STATE_VERS	1
 
 struct descriptor {
 	u32	block_num;	/* (file block) */
diff --git a/state.h b/state.h
index be8b204..1ba86c7 100644
--- a/state.h
+++ b/state.h
@@ -255,7 +255,6 @@ struct fs {
 		u32	segment_stride;
 		u32	segment_count;
 		u32	usage_inum;
-		u16	level;
 
 		u32 	rows_per_table, tables_per_seg;
 
diff --git a/super.c b/super.c
index 81c32e2..0428fe6 100644
--- a/super.c
+++ b/super.c
@@ -76,7 +76,7 @@ valid_devblock(struct lafs_dev *db, sector_t addr, sector_t size)
 
 	if (strncmp(db->idtag, "LaFS-DeviceBlock", 16) != 0)
 		return 0;
-	if (strncmp(db->version, "AlphaDevel      ", 16) != 0)
+	if (le32_to_cpu(db->version) != LAFS_DEV_VERS)
 		return 0;
 	/* uuid can be anything */
 	crc = db->checksum;
@@ -156,9 +156,6 @@ valid_devblock(struct lafs_dev *db, sector_t addr, sector_t size)
 	if (le32_to_cpu(db->segment_offset) + segsize > (size << db->blockbits))
 		return 0;
 
-	if (le32_to_cpu(db->level) > 10)
-		return 0;
-
 	/* I guess it look sane enough... */
 	return 1;
 }
@@ -189,7 +186,7 @@ valid_stateblock(struct lafs_state *st, struct lafs_dev *dv)
 	u32 crc;
 	if (strncmp(st->idtag, "LaFS-State-Block", 16) != 0)
 		return 0;
-	if (strncmp(st->version, "AlphaDevel      ", 16) != 0)
+	if (le32_to_cpu(st->version) != LAFS_STATE_VERS)
 		return 0;
 	crc = st->checksum;
 	st->checksum = 0;
@@ -204,6 +201,10 @@ valid_stateblock(struct lafs_state *st, struct lafs_dev *dv)
 	    > (1<<dv->statebits))
  		return 0;
 
+	/* Don't support RO sharing yet. */
+	if (st->alt_seq)
+		return 0;
+
 	return 1;
 }
 
@@ -536,7 +537,6 @@ lafs_load(struct fs *fs, struct options *op, int newest)
 #endif
 
 	fs->seq = le32_to_cpu(st->seq);
-	fs->levels = le32_to_cpu(st->levels);
 	fs->devices = op->devcnt;
 	fs->devs_loaded = fs->devices; /* FIXME use this or lose this */
 	fs->statesize = 1 << op->statebits;
@@ -674,7 +674,6 @@ lafs_load(struct fs *fs, struct options *op, int newest)
 		dv->segment_offset = le32_to_cpu(dv->devblk->segment_offset);
 		dv->segment_count = le32_to_cpu(dv->devblk->segment_count);
 		dv->usage_inum = le32_to_cpu(dv->devblk->usage_inum);
-		dv->level = le16_to_cpu(dv->devblk->level);
 
 		if (dv->segment_size > fs->max_segment)
 			fs->max_segment = dv->segment_size;