mtd: mtdpart: implement proper partition handling

Instead of collecting partitions in a flat list, create a hierarchy
within the mtd_info structure: use a partitions list to keep track of
the partitions of an MTD device (which might be itself a partition of
another MTD device), a pointer to the parent device (NULL when the MTD
device is the root one, not a partition).

By also saving directly in mtd_info the offset of the partition, we
can get rid of the mtd_part structure.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>

drivers/mtd/mtdcore.c

@@ -426,6 +426,8 @@ int add_mtd_device(struct mtd_info *mtd)
 	mtd->index = i;
 	mtd->usecount = 0;
 
+	INIT_LIST_HEAD(&mtd->partitions);
+
 	/* default value if not set by driver */
 	if (mtd->bitflip_threshold == 0)
 		mtd->bitflip_threshold = mtd->ecc_strength;

drivers/mtd/mtdpart.c

@@ -30,29 +30,12 @@
 
 #include "mtdcore.h"
 
-/* Our partition linked list */
-static LIST_HEAD(mtd_partitions);
 #ifndef __UBOOT__
 static DEFINE_MUTEX(mtd_partitions_mutex);
 #else
 DEFINE_MUTEX(mtd_partitions_mutex);
 #endif
 
-/* Our partition node structure */
-struct mtd_part {
-	struct mtd_info mtd;
-	struct mtd_info *master;
-	uint64_t offset;
-	struct list_head list;
-};
-
-/*
- * Given a pointer to the MTD object in the mtd_part structure, we can retrieve
- * the pointer to that structure with this macro.
- */
-#define PART(x)  ((struct mtd_part *)(x))
-
-
 #ifdef __UBOOT__
 /* from mm/util.c */
 
@@ -294,19 +277,18 @@ void mtd_free_parsed_partitions(struct mtd_partition *parts,
 static int part_read(struct mtd_info *mtd, loff_t from, size_t len,
 		size_t *retlen, u_char *buf)
 {
-	struct mtd_part *part = PART(mtd);
 	struct mtd_ecc_stats stats;
 	int res;
 
-	stats = part->master->ecc_stats;
-	res = part->master->_read(part->master, from + part->offset, len,
-				  retlen, buf);
+	stats = mtd->parent->ecc_stats;
+	res = mtd->parent->_read(mtd->parent, from + mtd->offset, len,
+				 retlen, buf);
 	if (unlikely(mtd_is_eccerr(res)))
 		mtd->ecc_stats.failed +=
-			part->master->ecc_stats.failed - stats.failed;
+			mtd->parent->ecc_stats.failed - stats.failed;
 	else
 		mtd->ecc_stats.corrected +=
-			part->master->ecc_stats.corrected - stats.corrected;
+			mtd->parent->ecc_stats.corrected - stats.corrected;
 	return res;
 }
 
@@ -314,17 +296,13 @@ static int part_read(struct mtd_info *mtd, loff_t from, size_t len,
 static int part_point(struct mtd_info *mtd, loff_t from, size_t len,
 		size_t *retlen, void **virt, resource_size_t *phys)
 {
-	struct mtd_part *part = PART(mtd);
-
-	return part->master->_point(part->master, from + part->offset, len,
-				    retlen, virt, phys);
+	return mtd->parent->_point(mtd->parent, from + mtd->offset, len,
+				   retlen, virt, phys);
 }
 
 static int part_unpoint(struct mtd_info *mtd, loff_t from, size_t len)
 {
-	struct mtd_part *part = PART(mtd);
-
-	return part->master->_unpoint(part->master, from + part->offset, len);
+	return mtd->parent->_unpoint(mtd->parent, from + mtd->offset, len);
 }
 #endif
 
@@ -333,17 +311,13 @@ static unsigned long part_get_unmapped_area(struct mtd_info *mtd,
 					    unsigned long offset,
 					    unsigned long flags)
 {
-	struct mtd_part *part = PART(mtd);
-
-	offset += part->offset;
-	return part->master->_get_unmapped_area(part->master, len, offset,
-						flags);
+	offset += mtd->offset;
+	return mtd->parent->_get_unmapped_area(mtd->parent, len, offset, flags);
 }
 
 static int part_read_oob(struct mtd_info *mtd, loff_t from,
 		struct mtd_oob_ops *ops)
 {
-	struct mtd_part *part = PART(mtd);
 	int res;
 
 	if (from >= mtd->size)
@@ -368,7 +342,7 @@ static int part_read_oob(struct mtd_info *mtd, loff_t from,
 			return -EINVAL;
 	}
 
-	res = part->master->_read_oob(part->master, from + part->offset, ops);
+	res = mtd->parent->_read_oob(mtd->parent, from + mtd->offset, ops);
 	if (unlikely(res)) {
 		if (mtd_is_bitflip(res))
 			mtd->ecc_stats.corrected++;
@@ -381,99 +355,87 @@ static int part_read_oob(struct mtd_info *mtd, loff_t from,
 static int part_read_user_prot_reg(struct mtd_info *mtd, loff_t from,
 		size_t len, size_t *retlen, u_char *buf)
 {
-	struct mtd_part *part = PART(mtd);
-	return part->master->_read_user_prot_reg(part->master, from, len,
-						 retlen, buf);
+	return mtd->parent->_read_user_prot_reg(mtd->parent, from, len,
+						retlen, buf);
 }
 
 static int part_get_user_prot_info(struct mtd_info *mtd, size_t len,
 				   size_t *retlen, struct otp_info *buf)
 {
-	struct mtd_part *part = PART(mtd);
-	return part->master->_get_user_prot_info(part->master, len, retlen,
-						 buf);
+	return mtd->parent->_get_user_prot_info(mtd->parent, len, retlen,
+						buf);
 }
 
 static int part_read_fact_prot_reg(struct mtd_info *mtd, loff_t from,
 		size_t len, size_t *retlen, u_char *buf)
 {
-	struct mtd_part *part = PART(mtd);
-	return part->master->_read_fact_prot_reg(part->master, from, len,
-						 retlen, buf);
+	return mtd->parent->_read_fact_prot_reg(mtd->parent, from, len,
+						retlen, buf);
 }
 
 static int part_get_fact_prot_info(struct mtd_info *mtd, size_t len,
 				   size_t *retlen, struct otp_info *buf)
 {
-	struct mtd_part *part = PART(mtd);
-	return part->master->_get_fact_prot_info(part->master, len, retlen,
-						 buf);
+	return mtd->parent->_get_fact_prot_info(mtd->parent, len, retlen,
+						buf);
 }
 
 static int part_write(struct mtd_info *mtd, loff_t to, size_t len,
 		size_t *retlen, const u_char *buf)
 {
-	struct mtd_part *part = PART(mtd);
-	return part->master->_write(part->master, to + part->offset, len,
-				    retlen, buf);
+	return mtd->parent->_write(mtd->parent, to + mtd->offset, len,
+				   retlen, buf);
 }
 
 static int part_panic_write(struct mtd_info *mtd, loff_t to, size_t len,
 		size_t *retlen, const u_char *buf)
 {
-	struct mtd_part *part = PART(mtd);
-	return part->master->_panic_write(part->master, to + part->offset, len,
-					  retlen, buf);
+	return mtd->parent->_panic_write(mtd->parent, to + mtd->offset, len,
+					 retlen, buf);
 }
 
 static int part_write_oob(struct mtd_info *mtd, loff_t to,
 		struct mtd_oob_ops *ops)
 {
-	struct mtd_part *part = PART(mtd);
-
 	if (to >= mtd->size)
 		return -EINVAL;
 	if (ops->datbuf && to + ops->len > mtd->size)
 		return -EINVAL;
-	return part->master->_write_oob(part->master, to + part->offset, ops);
+	return mtd->parent->_write_oob(mtd->parent, to + mtd->offset, ops);
 }
 
 static int part_write_user_prot_reg(struct mtd_info *mtd, loff_t from,
 		size_t len, size_t *retlen, u_char *buf)
 {
-	struct mtd_part *part = PART(mtd);
-	return part->master->_write_user_prot_reg(part->master, from, len,
-						  retlen, buf);
+	return mtd->parent->_write_user_prot_reg(mtd->parent, from, len,
+						 retlen, buf);
 }
 
 static int part_lock_user_prot_reg(struct mtd_info *mtd, loff_t from,
 		size_t len)
 {
-	struct mtd_part *part = PART(mtd);
-	return part->master->_lock_user_prot_reg(part->master, from, len);
+	return mtd->parent->_lock_user_prot_reg(mtd->parent, from, len);
 }
 
 #ifndef __UBOOT__
 static int part_writev(struct mtd_info *mtd, const struct kvec *vecs,
 		unsigned long count, loff_t to, size_t *retlen)
 {
-	struct mtd_part *part = PART(mtd);
-	return part->master->_writev(part->master, vecs, count,
-				     to + part->offset, retlen);
+	return mtd->parent->_writev(mtd->parent, vecs, count,
+				    to + mtd->offset, retlen);
 }
 #endif
 
 static int part_erase(struct mtd_info *mtd, struct erase_info *instr)
 {
-	struct mtd_part *part = PART(mtd);
 	int ret;
 
-	instr->addr += part->offset;
-	ret = part->master->_erase(part->master, instr);
+	instr->addr += mtd->offset;
+	ret = mtd->parent->_erase(mtd->parent, instr);
 	if (ret) {
 		if (instr->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
-			instr->fail_addr -= part->offset;
-		instr->addr -= part->offset;
+			instr->fail_addr -= mtd->offset;
+		instr->addr -= mtd->offset;
 	}
 	return ret;
 }
@@ -481,11 +443,9 @@ static int part_erase(struct mtd_info *mtd, struct erase_info *instr)
 void mtd_erase_callback(struct erase_info *instr)
 {
 	if (instr->mtd->_erase == part_erase) {
-		struct mtd_part *part = PART(instr->mtd);
-
 		if (instr->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
-			instr->fail_addr -= part->offset;
-		instr->addr -= part->offset;
+			instr->fail_addr -= instr->mtd->offset;
+		instr->addr -= instr->mtd->offset;
 	}
 	if (instr->callback)
 		instr->callback(instr);
@@ -494,107 +454,112 @@ EXPORT_SYMBOL_GPL(mtd_erase_callback);
 
 static int part_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 {
-	struct mtd_part *part = PART(mtd);
-	return part->master->_lock(part->master, ofs + part->offset, len);
+	return mtd->parent->_lock(mtd->parent, ofs + mtd->offset, len);
 }
 
 static int part_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 {
-	struct mtd_part *part = PART(mtd);
-	return part->master->_unlock(part->master, ofs + part->offset, len);
+	return mtd->parent->_unlock(mtd->parent, ofs + mtd->offset, len);
 }
 
 static int part_is_locked(struct mtd_info *mtd, loff_t ofs, uint64_t len)
 {
-	struct mtd_part *part = PART(mtd);
-	return part->master->_is_locked(part->master, ofs + part->offset, len);
+	return mtd->parent->_is_locked(mtd->parent, ofs + mtd->offset, len);
 }
 
 static void part_sync(struct mtd_info *mtd)
 {
-	struct mtd_part *part = PART(mtd);
-	part->master->_sync(part->master);
+	mtd->parent->_sync(mtd->parent);
 }
 
 #ifndef __UBOOT__
 static int part_suspend(struct mtd_info *mtd)
 {
-	struct mtd_part *part = PART(mtd);
-	return part->master->_suspend(part->master);
+	return mtd->parent->_suspend(mtd->parent);
 }
 
 static void part_resume(struct mtd_info *mtd)
 {
-	struct mtd_part *part = PART(mtd);
-	part->master->_resume(part->master);
+	mtd->parent->_resume(mtd->parent);
 }
 #endif
 
 static int part_block_isreserved(struct mtd_info *mtd, loff_t ofs)
 {
-	struct mtd_part *part = PART(mtd);
-	ofs += part->offset;
-	return part->master->_block_isreserved(part->master, ofs);
+	ofs += mtd->offset;
+	return mtd->parent->_block_isreserved(mtd->parent, ofs);
 }
 
 static int part_block_isbad(struct mtd_info *mtd, loff_t ofs)
 {
-	struct mtd_part *part = PART(mtd);
-	ofs += part->offset;
-	return part->master->_block_isbad(part->master, ofs);
+	ofs += mtd->offset;
+	return mtd->parent->_block_isbad(mtd->parent, ofs);
 }
 
 static int part_block_markbad(struct mtd_info *mtd, loff_t ofs)
 {
-	struct mtd_part *part = PART(mtd);
 	int res;
 
-	ofs += part->offset;
-	res = part->master->_block_markbad(part->master, ofs);
+	ofs += mtd->offset;
+	res = mtd->parent->_block_markbad(mtd->parent, ofs);
 	if (!res)
 		mtd->ecc_stats.badblocks++;
 	return res;
 }
 
-static inline void free_partition(struct mtd_part *p)
+static inline void free_partition(struct mtd_info *p)
 {
-	kfree(p->mtd.name);
+	kfree(p->name);
 	kfree(p);
 }
 
 /*
  * This function unregisters and destroy all slave MTD objects which are
- * attached to the given master MTD object.
+ * attached to the given master MTD object, recursively.
  */
+static int do_del_mtd_partitions(struct mtd_info *master)
+{
+	struct mtd_info *slave, *next;
+	int ret, err = 0;
+
+	list_for_each_entry_safe(slave, next, &master->partitions, node) {
+		if (mtd_has_partitions(slave))
+			del_mtd_partitions(slave);
+
+		debug("Deleting %s MTD partition\n", slave->name);
+		ret = del_mtd_device(slave);
+		if (ret < 0) {
+			printf("Error when deleting partition \"%s\" (%d)\n",
+			       slave->name, ret);
+			err = ret;
+			continue;
+		}
+
+		list_del(&slave->node);
+		free_partition(slave);
+	}
+
+	return err;
+}
 
 int del_mtd_partitions(struct mtd_info *master)
 {
-	struct mtd_part *slave, *next;
-	int ret, err = 0;
+	int ret;
 
 	debug("Deleting MTD partitions on \"%s\":\n", master->name);
 
 	mutex_lock(&mtd_partitions_mutex);
-	list_for_each_entry_safe(slave, next, &mtd_partitions, list)
-		if (slave->master == master) {
-			ret = del_mtd_device(&slave->mtd);
-			if (ret < 0) {
-				err = ret;
-				continue;
-			}
-			list_del(&slave->list);
-			free_partition(slave);
-		}
+	ret = do_del_mtd_partitions(master);
 	mutex_unlock(&mtd_partitions_mutex);
 
-	return err;
+	return ret;
 }
 
-static struct mtd_part *allocate_partition(struct mtd_info *master,
-			const struct mtd_partition *part, int partno,
-			uint64_t cur_offset)
+static struct mtd_info *allocate_partition(struct mtd_info *master,
+					   const struct mtd_partition *part,
+					   int partno, uint64_t cur_offset)
 {
-	struct mtd_part *slave;
+	struct mtd_info *slave;
 	char *name;
 
 	/* allocate the partition structure */
@@ -609,85 +574,87 @@ static struct mtd_part *allocate_partition(struct mtd_info *master,
 	}
 
 	/* set up the MTD object for this partition */
-	slave->mtd.type = master->type;
-	slave->mtd.flags = master->flags & ~part->mask_flags;
-	slave->mtd.size = part->size;
-	slave->mtd.writesize = master->writesize;
-	slave->mtd.writebufsize = master->writebufsize;
-	slave->mtd.oobsize = master->oobsize;
-	slave->mtd.oobavail = master->oobavail;
-	slave->mtd.subpage_sft = master->subpage_sft;
-
-	slave->mtd.name = name;
-	slave->mtd.owner = master->owner;
+	slave->type = master->type;
+	slave->flags = master->flags & ~part->mask_flags;
+	slave->size = part->size;
+	slave->writesize = master->writesize;
+	slave->writebufsize = master->writebufsize;
+	slave->oobsize = master->oobsize;
+	slave->oobavail = master->oobavail;
+	slave->subpage_sft = master->subpage_sft;
+
+	slave->name = name;
+	slave->owner = master->owner;
 #ifndef __UBOOT__
-	slave->mtd.backing_dev_info = master->backing_dev_info;
+	slave->backing_dev_info = master->backing_dev_info;
 
 	/* NOTE:  we don't arrange MTDs as a tree; it'd be error-prone
 	 * to have the same data be in two different partitions.
 	 */
-	slave->mtd.dev.parent = master->dev.parent;
+	slave->dev.parent = master->dev.parent;
 #endif
 
 	if (master->_read)
-		slave->mtd._read = part_read;
+		slave->_read = part_read;
 	if (master->_write)
-		slave->mtd._write = part_write;
+		slave->_write = part_write;
 
 	if (master->_panic_write)
-		slave->mtd._panic_write = part_panic_write;
+		slave->_panic_write = part_panic_write;
 
 #ifndef __UBOOT__
 	if (master->_point && master->_unpoint) {
-		slave->mtd._point = part_point;
-		slave->mtd._unpoint = part_unpoint;
+		slave->_point = part_point;
+		slave->_unpoint = part_unpoint;
 	}
 #endif
 
 	if (master->_get_unmapped_area)
-		slave->mtd._get_unmapped_area = part_get_unmapped_area;
+		slave->_get_unmapped_area = part_get_unmapped_area;
 	if (master->_read_oob)
-		slave->mtd._read_oob = part_read_oob;
+		slave->_read_oob = part_read_oob;
 	if (master->_write_oob)
-		slave->mtd._write_oob = part_write_oob;
+		slave->_write_oob = part_write_oob;
 	if (master->_read_user_prot_reg)
-		slave->mtd._read_user_prot_reg = part_read_user_prot_reg;
+		slave->_read_user_prot_reg = part_read_user_prot_reg;
 	if (master->_read_fact_prot_reg)
-		slave->mtd._read_fact_prot_reg = part_read_fact_prot_reg;
+		slave->_read_fact_prot_reg = part_read_fact_prot_reg;
 	if (master->_write_user_prot_reg)
-		slave->mtd._write_user_prot_reg = part_write_user_prot_reg;
+		slave->_write_user_prot_reg = part_write_user_prot_reg;
 	if (master->_lock_user_prot_reg)
-		slave->mtd._lock_user_prot_reg = part_lock_user_prot_reg;
+		slave->_lock_user_prot_reg = part_lock_user_prot_reg;
 	if (master->_get_user_prot_info)
-		slave->mtd._get_user_prot_info = part_get_user_prot_info;
+		slave->_get_user_prot_info = part_get_user_prot_info;
 	if (master->_get_fact_prot_info)
-		slave->mtd._get_fact_prot_info = part_get_fact_prot_info;
+		slave->_get_fact_prot_info = part_get_fact_prot_info;
 	if (master->_sync)
-		slave->mtd._sync = part_sync;
+		slave->_sync = part_sync;
 #ifndef __UBOOT__
 	if (!partno && !master->dev.class && master->_suspend &&
 	    master->_resume) {
-			slave->mtd._suspend = part_suspend;
-			slave->mtd._resume = part_resume;
+		slave->_suspend = part_suspend;
+		slave->_resume = part_resume;
 	}
 	if (master->_writev)
-		slave->mtd._writev = part_writev;
+		slave->_writev = part_writev;
 #endif
 	if (master->_lock)
-		slave->mtd._lock = part_lock;
+		slave->_lock = part_lock;
 	if (master->_unlock)
-		slave->mtd._unlock = part_unlock;
+		slave->_unlock = part_unlock;
 	if (master->_is_locked)
-		slave->mtd._is_locked = part_is_locked;
+		slave->_is_locked = part_is_locked;
 	if (master->_block_isreserved)
-		slave->mtd._block_isreserved = part_block_isreserved;
+		slave->_block_isreserved = part_block_isreserved;
 	if (master->_block_isbad)
-		slave->mtd._block_isbad = part_block_isbad;
+		slave->_block_isbad = part_block_isbad;
 	if (master->_block_markbad)
-		slave->mtd._block_markbad = part_block_markbad;
-	slave->mtd._erase = part_erase;
-	slave->master = master;
+		slave->_block_markbad = part_block_markbad;
+	slave->_erase = part_erase;
+	slave->parent = master;
 	slave->offset = part->offset;
+	INIT_LIST_HEAD(&slave->partitions);
+	INIT_LIST_HEAD(&slave->node);
 
 	if (slave->offset == MTDPART_OFS_APPEND)
 		slave->offset = cur_offset;
@@ -703,41 +670,41 @@ static struct mtd_part *allocate_partition(struct mtd_info *master,
 	}
 	if (slave->offset == MTDPART_OFS_RETAIN) {
 		slave->offset = cur_offset;
-		if (master->size - slave->offset >= slave->mtd.size) {
-			slave->mtd.size = master->size - slave->offset
-							- slave->mtd.size;
+		if (master->size - slave->offset >= slave->size) {
+			slave->size = master->size - slave->offset
+							- slave->size;
 		} else {
 			debug("mtd partition \"%s\" doesn't have enough space: %#llx < %#llx, disabled\n",
 				part->name, master->size - slave->offset,
-				slave->mtd.size);
+				slave->size);
 			/* register to preserve ordering */
 			goto out_register;
 		}
 	}
-	if (slave->mtd.size == MTDPART_SIZ_FULL)
-		slave->mtd.size = master->size - slave->offset;
+	if (slave->size == MTDPART_SIZ_FULL)
+		slave->size = master->size - slave->offset;
 
 	debug("0x%012llx-0x%012llx : \"%s\"\n", (unsigned long long)slave->offset,
-		(unsigned long long)(slave->offset + slave->mtd.size), slave->mtd.name);
+		(unsigned long long)(slave->offset + slave->size), slave->name);
 
 	/* let's do some sanity checks */
 	if (slave->offset >= master->size) {
 		/* let's register it anyway to preserve ordering */
 		slave->offset = 0;
-		slave->mtd.size = 0;
+		slave->size = 0;
 		printk(KERN_ERR"mtd: partition \"%s\" is out of reach -- disabled\n",
 			part->name);
 		goto out_register;
 	}
-	if (slave->offset + slave->mtd.size > master->size) {
-		slave->mtd.size = master->size - slave->offset;
+	if (slave->offset + slave->size > master->size) {
+		slave->size = master->size - slave->offset;
 		printk(KERN_WARNING"mtd: partition \"%s\" extends beyond the end of device \"%s\" -- size truncated to %#llx\n",
-			part->name, master->name, (unsigned long long)slave->mtd.size);
+		       part->name, master->name, slave->size);
 	}
 	if (master->numeraseregions > 1) {
 		/* Deal with variable erase size stuff */
 		int i, max = master->numeraseregions;
-		u64 end = slave->offset + slave->mtd.size;
+		u64 end = slave->offset + slave->size;
 		struct mtd_erase_region_info *regions = master->eraseregions;
 
 		/* Find the first erase regions which is part of this
@@ -750,44 +717,43 @@ static struct mtd_part *allocate_partition(struct mtd_info *master,
 
 		/* Pick biggest erasesize */
 		for (; i < max && regions[i].offset < end; i++) {
-			if (slave->mtd.erasesize < regions[i].erasesize) {
-				slave->mtd.erasesize = regions[i].erasesize;
-			}
+			if (slave->erasesize < regions[i].erasesize)
+				slave->erasesize = regions[i].erasesize;
 		}
-		BUG_ON(slave->mtd.erasesize == 0);
+		WARN_ON(slave->erasesize == 0);
 	} else {
 		/* Single erase size */
-		slave->mtd.erasesize = master->erasesize;
+		slave->erasesize = master->erasesize;
 	}
 
-	if ((slave->mtd.flags & MTD_WRITEABLE) &&
-	    mtd_mod_by_eb(slave->offset, &slave->mtd)) {
+	if ((slave->flags & MTD_WRITEABLE) &&
+	    mtd_mod_by_eb(slave->offset, slave)) {
 		/* Doesn't start on a boundary of major erase size */
 		/* FIXME: Let it be writable if it is on a boundary of
 		 * _minor_ erase size though */
-		slave->mtd.flags &= ~MTD_WRITEABLE;
+		slave->flags &= ~MTD_WRITEABLE;
 		printk(KERN_WARNING"mtd: partition \"%s\" doesn't start on an erase block boundary -- force read-only\n",
 			part->name);
 	}
-	if ((slave->mtd.flags & MTD_WRITEABLE) &&
-	    mtd_mod_by_eb(slave->mtd.size, &slave->mtd)) {
-		slave->mtd.flags &= ~MTD_WRITEABLE;
+	if ((slave->flags & MTD_WRITEABLE) &&
+	    mtd_mod_by_eb(slave->size, slave)) {
+		slave->flags &= ~MTD_WRITEABLE;
 		printk(KERN_WARNING"mtd: partition \"%s\" doesn't end on an erase block -- force read-only\n",
 			part->name);
 	}
 
-	slave->mtd.ecclayout = master->ecclayout;
-	slave->mtd.ecc_step_size = master->ecc_step_size;
-	slave->mtd.ecc_strength = master->ecc_strength;
-	slave->mtd.bitflip_threshold = master->bitflip_threshold;
+	slave->ecclayout = master->ecclayout;
+	slave->ecc_step_size = master->ecc_step_size;
+	slave->ecc_strength = master->ecc_strength;
+	slave->bitflip_threshold = master->bitflip_threshold;
 
 	if (master->_block_isbad) {
 		uint64_t offs = 0;
 
-		while (offs < slave->mtd.size) {
+		while (offs < slave->size) {
 			if (mtd_block_isbad(master, offs + slave->offset))
-				slave->mtd.ecc_stats.badblocks++;
-			offs += slave->mtd.erasesize;
+				slave->ecc_stats.badblocks++;
+			offs += slave->erasesize;
 		}
 	}
 
@@ -800,7 +766,7 @@ int mtd_add_partition(struct mtd_info *master, const char *name,
 		      long long offset, long long length)
 {
 	struct mtd_partition part;
-	struct mtd_part *p, *new;
+	struct mtd_info *p, *new;
 	uint64_t start, end;
 	int ret = 0;
 
@@ -829,21 +795,20 @@ int mtd_add_partition(struct mtd_info *master, const char *name,
 	end = offset + length;
 
 	mutex_lock(&mtd_partitions_mutex);
-	list_for_each_entry(p, &mtd_partitions, list)
-		if (p->master == master) {
-			if ((start >= p->offset) &&
-			    (start < (p->offset + p->mtd.size)))
-				goto err_inv;
-
-			if ((end >= p->offset) &&
-			    (end < (p->offset + p->mtd.size)))
-				goto err_inv;
-		}
+	list_for_each_entry(p, &master->partitions, node) {
+		if (start >= p->offset &&
+		    (start < (p->offset + p->size)))
+			goto err_inv;
+
+		if (end >= p->offset &&
+		    (end < (p->offset + p->size)))
+			goto err_inv;
+	}
 
-	list_add(&new->list, &mtd_partitions);
+	list_add_tail(&new->node, &master->partitions);
 	mutex_unlock(&mtd_partitions_mutex);
 
-	add_mtd_device(&new->mtd);
+	add_mtd_device(new);
 
 	return ret;
 err_inv:
@@ -855,18 +820,17 @@ EXPORT_SYMBOL_GPL(mtd_add_partition);
 
 int mtd_del_partition(struct mtd_info *master, int partno)
 {
-	struct mtd_part *slave, *next;
+	struct mtd_info *slave, *next;
 	int ret = -EINVAL;
 
 	mutex_lock(&mtd_partitions_mutex);
-	list_for_each_entry_safe(slave, next, &mtd_partitions, list)
-		if ((slave->master == master) &&
-		    (slave->mtd.index == partno)) {
-			ret = del_mtd_device(&slave->mtd);
+	list_for_each_entry_safe(slave, next, &master->partitions, node)
+		if (slave->index == partno) {
+			ret = del_mtd_device(slave);
 			if (ret < 0)
 				break;
 
-			list_del(&slave->list);
+			list_del(&slave->node);
 			free_partition(slave);
 			break;
 		}
@@ -890,20 +854,10 @@ int add_mtd_partitions(struct mtd_info *master,
 		       const struct mtd_partition *parts,
 		       int nbparts)
 {
-	struct mtd_part *slave;
+	struct mtd_info *slave;
 	uint64_t cur_offset = 0;
 	int i;
 
-#ifdef __UBOOT__
-	/*
-	 * Need to init the list here, since LIST_INIT() does not
-	 * work on platforms where relocation has problems (like MIPS
-	 * & PPC).
-	 */
-	if (mtd_partitions.next == NULL)
-		INIT_LIST_HEAD(&mtd_partitions);
-#endif
-
 	debug("Creating %d MTD partitions on \"%s\":\n", nbparts, master->name);
 
 	for (i = 0; i < nbparts; i++) {
@@ -912,12 +866,12 @@ int add_mtd_partitions(struct mtd_info *master,
 			return PTR_ERR(slave);
 
 		mutex_lock(&mtd_partitions_mutex);
-		list_add(&slave->list, &mtd_partitions);
+		list_add_tail(&slave->node, &master->partitions);
 		mutex_unlock(&mtd_partitions_mutex);
 
-		add_mtd_device(&slave->mtd);
+		add_mtd_device(slave);
 
-		cur_offset = slave->offset + slave->mtd.size;
+		cur_offset = slave->offset + slave->size;
 	}
 
 	return 0;
@@ -1020,29 +974,12 @@ int parse_mtd_partitions(struct mtd_info *master, const char *const *types,
 }
 #endif
 
-int mtd_is_partition(const struct mtd_info *mtd)
-{
-	struct mtd_part *part;
-	int ispart = 0;
-
-	mutex_lock(&mtd_partitions_mutex);
-	list_for_each_entry(part, &mtd_partitions, list)
-		if (&part->mtd == mtd) {
-			ispart = 1;
-			break;
-		}
-	mutex_unlock(&mtd_partitions_mutex);
-
-	return ispart;
-}
-EXPORT_SYMBOL_GPL(mtd_is_partition);
-
 /* Returns the size of the entire flash chip */
 uint64_t mtd_get_device_size(const struct mtd_info *mtd)
 {
-	if (!mtd_is_partition(mtd))
-		return mtd->size;
+	if (mtd_is_partition(mtd))
+		return mtd->parent->size;
 
-	return PART(mtd)->master->size;
+	return mtd->size;
 }
 EXPORT_SYMBOL_GPL(mtd_get_device_size);

include/linux/mtd/mtd.h

@@ -20,6 +20,7 @@
 #include <linux/compat.h>
 #include <mtd/mtd-abi.h>
 #include <linux/errno.h>
+#include <linux/list.h>
 #include <div64.h>
 #if IS_ENABLED(CONFIG_DM)
 #include <dm/device.h>
@@ -307,6 +308,27 @@ struct mtd_info {
 	struct udevice *dev;
 #endif
 	int usecount;
+
+	/* MTD devices do not have any parent. MTD partitions do. */
+	struct mtd_info *parent;
+
+	/*
+	 * Offset of the partition relatively to the parent offset.
+	 * Is 0 for real MTD devices (ie. not partitions).
+	 */
+	u64 offset;
+
+	/*
+	 * List node used to add an MTD partition to the parent
+	 * partition list.
+	 */
+	struct list_head node;
+
+	/*
+	 * List of partitions attached to this MTD device (the parent
+	 * MTD device can itself be a partition).
+	 */
+	struct list_head partitions;
 };
 
 #if IS_ENABLED(CONFIG_DM)
@@ -334,6 +356,16 @@ static inline const struct device_node *mtd_get_of_node(struct mtd_info *mtd)
 }
 #endif
 
+static inline bool mtd_is_partition(const struct mtd_info *mtd)
+{
+	return mtd->parent;
+}
+
+static inline bool mtd_has_partitions(const struct mtd_info *mtd)
+{
+	return !list_empty(&mtd->partitions);
+}
+
 int mtd_ooblayout_ecc(struct mtd_info *mtd, int section,
 		      struct mtd_oob_region *oobecc);
 int mtd_ooblayout_find_eccregion(struct mtd_info *mtd, int eccbyte,

include/linux/mtd/partitions.h

@@ -81,7 +81,6 @@ extern void register_mtd_parser(struct mtd_part_parser *parser);
 extern void deregister_mtd_parser(struct mtd_part_parser *parser);
 #endif
 
-int mtd_is_partition(const struct mtd_info *mtd);
 int mtd_add_partition(struct mtd_info *master, const char *name,
 		      long long offset, long long length);
 int mtd_del_partition(struct mtd_info *master, int partno);