1 From: Felix Fietkau <nbd@nbd.name>
2 Subject: mtd: implement write support for partitions covering only a part of an eraseblock (buffer data that would otherwise be erased)
4 lede-commit: 87a8e8ac1067f58ba831c4aae443f3655c31cd80
5 Signed-off-by: Felix Fietkau <nbd@nbd.name>
7 drivers/mtd/mtdpart.c | 90 ++++++++++++++++++++++++++++++++++++++++++++-----
8 include/linux/mtd/mtd.h | 4 +++
9 2 files changed, 85 insertions(+), 9 deletions(-)
11 diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
12 index fce83882fd4e..0238b0babe2f 100644
13 --- a/drivers/mtd/mtdpart.c
14 +++ b/drivers/mtd/mtdpart.c
17 #include "mtdsplit/mtdsplit.h"
19 +#define MTD_ERASE_PARTIAL 0x8000 /* partition only covers parts of an erase block */
21 /* Our partition linked list */
22 static LIST_HEAD(mtd_partitions);
23 static DEFINE_MUTEX(mtd_partitions_mutex);
24 @@ -241,13 +243,61 @@ static int part_erase(struct mtd_info *mtd, struct erase_info *instr)
25 struct mtd_part *part = mtd_to_part(mtd);
29 + instr->partial_start = false;
30 + if (mtd->flags & MTD_ERASE_PARTIAL) {
34 + instr->erase_buf = kmalloc(part->parent->erasesize, GFP_ATOMIC);
35 + if (!instr->erase_buf)
38 + mtd_ofs = part->offset + instr->addr;
39 + instr->erase_buf_ofs = do_div(mtd_ofs, part->parent->erasesize);
41 + if (instr->erase_buf_ofs > 0) {
42 + instr->addr -= instr->erase_buf_ofs;
43 + ret = mtd_read(part->parent,
44 + instr->addr + part->offset,
45 + part->parent->erasesize,
46 + &readlen, instr->erase_buf);
48 + instr->len += instr->erase_buf_ofs;
49 + instr->partial_start = true;
51 + mtd_ofs = part->offset + part->mtd.size;
52 + instr->erase_buf_ofs = part->parent->erasesize -
53 + do_div(mtd_ofs, part->parent->erasesize);
55 + if (instr->erase_buf_ofs > 0) {
56 + instr->len += instr->erase_buf_ofs;
57 + ret = mtd_read(part->parent,
58 + part->offset + instr->addr +
59 + instr->len - part->parent->erasesize,
60 + part->parent->erasesize, &readlen,
67 + kfree(instr->erase_buf);
73 instr->addr += part->offset;
74 ret = part->parent->_erase(part->parent, instr);
76 if (instr->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
77 instr->fail_addr -= part->offset;
78 instr->addr -= part->offset;
79 + if (mtd->flags & MTD_ERASE_PARTIAL)
80 + kfree(instr->erase_buf);
86 @@ -255,6 +305,25 @@ void mtd_erase_callback(struct erase_info *instr)
88 if (instr->mtd->_erase == part_erase) {
89 struct mtd_part *part = mtd_to_part(instr->mtd);
92 + if (instr->mtd->flags & MTD_ERASE_PARTIAL) {
93 + if (instr->partial_start) {
94 + part->parent->_write(part->parent,
95 + instr->addr, instr->erase_buf_ofs,
96 + &wrlen, instr->erase_buf);
97 + instr->addr += instr->erase_buf_ofs;
99 + instr->len -= instr->erase_buf_ofs;
100 + part->parent->_write(part->parent,
101 + instr->addr + instr->len,
102 + instr->erase_buf_ofs, &wrlen,
104 + part->parent->erasesize -
105 + instr->erase_buf_ofs);
107 + kfree(instr->erase_buf);
110 if (instr->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
111 instr->fail_addr -= part->offset;
112 @@ -590,19 +659,22 @@ static struct mtd_part *allocate_partition(struct mtd_info *parent,
113 remainder = do_div(tmp, wr_alignment);
114 if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
115 /* Doesn't start on a boundary of major erase size */
116 - /* FIXME: Let it be writable if it is on a boundary of
117 - * _minor_ erase size though */
118 - slave->mtd.flags &= ~MTD_WRITEABLE;
119 - printk(KERN_WARNING"mtd: partition \"%s\" doesn't start on an erase/write block boundary -- force read-only\n",
121 + slave->mtd.flags |= MTD_ERASE_PARTIAL;
122 + if (((u32)slave->mtd.size) > parent->erasesize)
123 + slave->mtd.flags &= ~MTD_WRITEABLE;
125 + slave->mtd.erasesize = slave->mtd.size;
128 - tmp = slave->mtd.size;
129 + tmp = slave->offset + slave->mtd.size;
130 remainder = do_div(tmp, wr_alignment);
131 if ((slave->mtd.flags & MTD_WRITEABLE) && remainder) {
132 - slave->mtd.flags &= ~MTD_WRITEABLE;
133 - printk(KERN_WARNING"mtd: partition \"%s\" doesn't end on an erase/write block -- force read-only\n",
135 + slave->mtd.flags |= MTD_ERASE_PARTIAL;
137 + if ((u32)slave->mtd.size > parent->erasesize)
138 + slave->mtd.flags &= ~MTD_WRITEABLE;
140 + slave->mtd.erasesize = slave->mtd.size;
143 mtd_set_ooblayout(&slave->mtd, &part_ooblayout_ops);
144 diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
145 index e7d5091bb447..0db85491f085 100644
146 --- a/include/linux/mtd/mtd.h
147 +++ b/include/linux/mtd/mtd.h
148 @@ -55,6 +55,10 @@ struct erase_info {
151 struct erase_info *next;
155 + bool partial_start;
158 struct mtd_erase_region_info {