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- From: Felix Fietkau <nbd@nbd.name>
- Subject: mtd: implement write support for partitions covering only a part of an eraseblock (buffer data that would otherwise be erased)
- lede-commit: 87a8e8ac1067f58ba831c4aae443f3655c31cd80
- Signed-off-by: Felix Fietkau <nbd@nbd.name>
- ---
- drivers/mtd/mtdpart.c | 90 ++++++++++++++++++++++++++++++++++++++++++++-----
- include/linux/mtd/mtd.h | 4 +++
- 2 files changed, 85 insertions(+), 9 deletions(-)
- --- a/drivers/mtd/mtdpart.c
- +++ b/drivers/mtd/mtdpart.c
- @@ -37,6 +37,8 @@
- #include "mtdcore.h"
- #include "mtdsplit/mtdsplit.h"
-
- +#define MTD_ERASE_PARTIAL 0x8000 /* partition only covers parts of an erase block */
- +
- /* Our partition linked list */
- static LIST_HEAD(mtd_partitions);
- static DEFINE_MUTEX(mtd_partitions_mutex);
- @@ -242,13 +244,61 @@ static int part_erase(struct mtd_info *m
- struct mtd_part *part = mtd_to_part(mtd);
- int ret;
-
- +
- + instr->partial_start = false;
- + if (mtd->flags & MTD_ERASE_PARTIAL) {
- + size_t readlen = 0;
- + u64 mtd_ofs;
- +
- + instr->erase_buf = kmalloc(part->parent->erasesize, GFP_ATOMIC);
- + if (!instr->erase_buf)
- + return -ENOMEM;
- +
- + mtd_ofs = part->offset + instr->addr;
- + instr->erase_buf_ofs = do_div(mtd_ofs, part->parent->erasesize);
- +
- + if (instr->erase_buf_ofs > 0) {
- + instr->addr -= instr->erase_buf_ofs;
- + ret = mtd_read(part->parent,
- + instr->addr + part->offset,
- + part->parent->erasesize,
- + &readlen, instr->erase_buf);
- +
- + instr->len += instr->erase_buf_ofs;
- + instr->partial_start = true;
- + } else {
- + mtd_ofs = part->offset + part->mtd.size;
- + instr->erase_buf_ofs = part->parent->erasesize -
- + do_div(mtd_ofs, part->parent->erasesize);
- +
- + if (instr->erase_buf_ofs > 0) {
- + instr->len += instr->erase_buf_ofs;
- + ret = mtd_read(part->parent,
- + part->offset + instr->addr +
- + instr->len - part->parent->erasesize,
- + part->parent->erasesize, &readlen,
- + instr->erase_buf);
- + } else {
- + ret = 0;
- + }
- + }
- + if (ret < 0) {
- + kfree(instr->erase_buf);
- + return ret;
- + }
- +
- + }
- +
- instr->addr += part->offset;
- ret = part->parent->_erase(part->parent, instr);
- if (ret) {
- if (instr->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
- instr->fail_addr -= part->offset;
- instr->addr -= part->offset;
- + if (mtd->flags & MTD_ERASE_PARTIAL)
- + kfree(instr->erase_buf);
- }
- +
- return ret;
- }
-
- @@ -256,6 +306,25 @@ void mtd_erase_callback(struct erase_inf
- {
- if (instr->mtd->_erase == part_erase) {
- struct mtd_part *part = mtd_to_part(instr->mtd);
- + size_t wrlen = 0;
- +
- + if (instr->mtd->flags & MTD_ERASE_PARTIAL) {
- + if (instr->partial_start) {
- + part->parent->_write(part->parent,
- + instr->addr, instr->erase_buf_ofs,
- + &wrlen, instr->erase_buf);
- + instr->addr += instr->erase_buf_ofs;
- + } else {
- + instr->len -= instr->erase_buf_ofs;
- + part->parent->_write(part->parent,
- + instr->addr + instr->len,
- + instr->erase_buf_ofs, &wrlen,
- + instr->erase_buf +
- + part->parent->erasesize -
- + instr->erase_buf_ofs);
- + }
- + kfree(instr->erase_buf);
- + }
-
- if (instr->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
- instr->fail_addr -= part->offset;
- @@ -562,19 +631,22 @@ static struct mtd_part *allocate_partiti
- remainder = do_div(tmp, wr_alignment);
- if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
- /* 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;
- - printk(KERN_WARNING"mtd: partition \"%s\" doesn't start on an erase/write block boundary -- force read-only\n",
- - part->name);
- + slave->mtd.flags |= MTD_ERASE_PARTIAL;
- + if (((u32)slave->mtd.size) > parent->erasesize)
- + slave->mtd.flags &= ~MTD_WRITEABLE;
- + else
- + slave->mtd.erasesize = slave->mtd.size;
- }
-
- - tmp = slave->mtd.size;
- + tmp = slave->offset + slave->mtd.size;
- remainder = do_div(tmp, wr_alignment);
- if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
- - slave->mtd.flags &= ~MTD_WRITEABLE;
- - printk(KERN_WARNING"mtd: partition \"%s\" doesn't end on an erase/write block -- force read-only\n",
- - part->name);
- + slave->mtd.flags |= MTD_ERASE_PARTIAL;
- +
- + if ((u32)slave->mtd.size > parent->erasesize)
- + slave->mtd.flags &= ~MTD_WRITEABLE;
- + else
- + slave->mtd.erasesize = slave->mtd.size;
- }
-
- mtd_set_ooblayout(&slave->mtd, &part_ooblayout_ops);
- --- a/include/linux/mtd/mtd.h
- +++ b/include/linux/mtd/mtd.h
- @@ -55,6 +55,10 @@ struct erase_info {
- u_long priv;
- u_char state;
- struct erase_info *next;
- +
- + u8 *erase_buf;
- + u32 erase_buf_ofs;
- + bool partial_start;
- };
-
- struct mtd_erase_region_info {
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