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132 lines
3.8 KiB
Diff
132 lines
3.8 KiB
Diff
From: Felix Fietkau <nbd@nbd.name>
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Subject: mtd: implement write support for partitions covering only a part of an eraseblock (buffer data that would otherwise be erased)
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lede-commit: 87a8e8ac1067f58ba831c4aae443f3655c31cd80
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Signed-off-by: Felix Fietkau <nbd@nbd.name>
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---
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drivers/mtd/mtdpart.c | 90 ++++++++++++++++++++++++++++++++++++++++++++-----
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include/linux/mtd/mtd.h | 4 +++
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2 files changed, 85 insertions(+), 9 deletions(-)
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--- a/drivers/mtd/mtdpart.c
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+++ b/drivers/mtd/mtdpart.c
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@@ -22,6 +22,8 @@
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#include "mtdcore.h"
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#include "mtdsplit/mtdsplit.h"
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+#define MTD_ERASE_PARTIAL 0x8000 /* partition only covers parts of an erase block */
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+
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/* Our partition linked list */
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static LIST_HEAD(mtd_partitions);
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static DEFINE_MUTEX(mtd_partitions_mutex);
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@@ -206,6 +208,53 @@ static int part_erase(struct mtd_info *m
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{
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struct mtd_part *part = mtd_to_part(mtd);
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int ret;
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+ size_t wrlen = 0;
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+ u8 *erase_buf = NULL;
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+ u32 erase_buf_ofs = 0;
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+ bool partial_start = false;
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+
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+ if (mtd->flags & MTD_ERASE_PARTIAL) {
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+ size_t readlen = 0;
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+ u64 mtd_ofs;
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+
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+ erase_buf = kmalloc(part->parent->erasesize, GFP_ATOMIC);
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+ if (!erase_buf)
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+ return -ENOMEM;
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+
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+ mtd_ofs = part->offset + instr->addr;
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+ erase_buf_ofs = do_div(mtd_ofs, part->parent->erasesize);
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+
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+ if (erase_buf_ofs > 0) {
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+ instr->addr -= erase_buf_ofs;
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+ ret = mtd_read(part->parent,
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+ instr->addr + part->offset,
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+ part->parent->erasesize,
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+ &readlen, erase_buf);
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+
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+ instr->len += erase_buf_ofs;
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+ partial_start = true;
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+ } else {
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+ mtd_ofs = part->offset + part->mtd.size;
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+ erase_buf_ofs = part->parent->erasesize -
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+ do_div(mtd_ofs, part->parent->erasesize);
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+
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+ if (erase_buf_ofs > 0) {
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+ instr->len += erase_buf_ofs;
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+ ret = mtd_read(part->parent,
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+ part->offset + instr->addr +
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+ instr->len - part->parent->erasesize,
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+ part->parent->erasesize, &readlen,
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+ erase_buf);
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+ } else {
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+ ret = 0;
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+ }
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+ }
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+ if (ret < 0) {
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+ kfree(erase_buf);
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+ return ret;
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+ }
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+
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+ }
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instr->addr += part->offset;
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ret = part->parent->_erase(part->parent, instr);
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@@ -213,6 +262,24 @@ static int part_erase(struct mtd_info *m
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instr->fail_addr -= part->offset;
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instr->addr -= part->offset;
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+ if (mtd->flags & MTD_ERASE_PARTIAL) {
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+ if (partial_start) {
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+ part->parent->_write(part->parent,
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+ instr->addr, erase_buf_ofs,
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+ &wrlen, erase_buf);
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+ instr->addr += erase_buf_ofs;
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+ } else {
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+ instr->len -= erase_buf_ofs;
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+ part->parent->_write(part->parent,
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+ instr->addr + instr->len,
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+ erase_buf_ofs, &wrlen,
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+ erase_buf +
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+ part->parent->erasesize -
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+ erase_buf_ofs);
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+ }
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+ kfree(erase_buf);
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+ }
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+
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return ret;
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}
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@@ -525,19 +592,22 @@ static struct mtd_part *allocate_partiti
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remainder = do_div(tmp, wr_alignment);
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if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
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/* Doesn't start on a boundary of major erase size */
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- /* FIXME: Let it be writable if it is on a boundary of
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- * _minor_ erase size though */
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- slave->mtd.flags &= ~MTD_WRITEABLE;
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- printk(KERN_WARNING"mtd: partition \"%s\" doesn't start on an erase/write block boundary -- force read-only\n",
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- part->name);
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+ slave->mtd.flags |= MTD_ERASE_PARTIAL;
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+ if (((u32)slave->mtd.size) > parent->erasesize)
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+ slave->mtd.flags &= ~MTD_WRITEABLE;
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+ else
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+ slave->mtd.erasesize = slave->mtd.size;
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}
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tmp = part_absolute_offset(parent) + slave->offset + slave->mtd.size;
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remainder = do_div(tmp, wr_alignment);
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if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
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- slave->mtd.flags &= ~MTD_WRITEABLE;
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- printk(KERN_WARNING"mtd: partition \"%s\" doesn't end on an erase/write block -- force read-only\n",
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- part->name);
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+ slave->mtd.flags |= MTD_ERASE_PARTIAL;
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+
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+ if ((u32)slave->mtd.size > parent->erasesize)
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+ slave->mtd.flags &= ~MTD_WRITEABLE;
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+ else
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+ slave->mtd.erasesize = slave->mtd.size;
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}
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mtd_set_ooblayout(&slave->mtd, &part_ooblayout_ops);
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