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 --- a/drivers/mtd/mtdpart.c
12 +++ b/drivers/mtd/mtdpart.c
15 #include "mtdsplit/mtdsplit.h"
17 +#define MTD_ERASE_PARTIAL 0x8000 /* partition only covers parts of an erase block */
19 /* Our partition linked list */
20 static LIST_HEAD(mtd_partitions);
21 static DEFINE_MUTEX(mtd_partitions_mutex);
22 @@ -235,13 +237,60 @@ static int part_erase(struct mtd_info *m
23 struct mtd_part *part = mtd_to_part(mtd);
26 + instr->partial_start = false;
27 + if (mtd->flags & MTD_ERASE_PARTIAL) {
31 + instr->erase_buf = kmalloc(part->master->erasesize, GFP_ATOMIC);
32 + if (!instr->erase_buf)
35 + mtd_ofs = part->offset + instr->addr;
36 + instr->erase_buf_ofs = do_div(mtd_ofs, part->master->erasesize);
38 + if (instr->erase_buf_ofs > 0) {
39 + instr->addr -= instr->erase_buf_ofs;
40 + ret = mtd_read(part->master,
41 + instr->addr + part->offset,
42 + part->master->erasesize,
43 + &readlen, instr->erase_buf);
45 + instr->len += instr->erase_buf_ofs;
46 + instr->partial_start = true;
48 + mtd_ofs = part->offset + part->mtd.size;
49 + instr->erase_buf_ofs = part->master->erasesize -
50 + do_div(mtd_ofs, part->master->erasesize);
52 + if (instr->erase_buf_ofs > 0) {
53 + instr->len += instr->erase_buf_ofs;
54 + ret = mtd_read(part->master,
55 + part->offset + instr->addr +
56 + instr->len - part->master->erasesize,
57 + part->master->erasesize, &readlen,
64 + kfree(instr->erase_buf);
70 instr->addr += part->offset;
71 ret = part->master->_erase(part->master, instr);
73 if (instr->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
74 instr->fail_addr -= part->offset;
75 instr->addr -= part->offset;
76 + if (mtd->flags & MTD_ERASE_PARTIAL)
77 + kfree(instr->erase_buf);
83 @@ -249,6 +298,25 @@ void mtd_erase_callback(struct erase_inf
85 if (instr->mtd->_erase == part_erase) {
86 struct mtd_part *part = mtd_to_part(instr->mtd);
89 + if (instr->mtd->flags & MTD_ERASE_PARTIAL) {
90 + if (instr->partial_start) {
91 + part->master->_write(part->master,
92 + instr->addr, instr->erase_buf_ofs,
93 + &wrlen, instr->erase_buf);
94 + instr->addr += instr->erase_buf_ofs;
96 + instr->len -= instr->erase_buf_ofs;
97 + part->master->_write(part->master,
98 + instr->addr + instr->len,
99 + instr->erase_buf_ofs, &wrlen,
101 + part->master->erasesize -
102 + instr->erase_buf_ofs);
104 + kfree(instr->erase_buf);
107 if (instr->fail_addr != MTD_FAIL_ADDR_UNKNOWN)
108 instr->fail_addr -= part->offset;
109 @@ -564,17 +632,20 @@ static struct mtd_part *allocate_partiti
110 if ((slave->mtd.flags & MTD_WRITEABLE) &&
111 mtd_mod_by_eb(slave->offset, &slave->mtd)) {
112 /* Doesn't start on a boundary of major erase size */
113 - /* FIXME: Let it be writable if it is on a boundary of
114 - * _minor_ erase size though */
115 - slave->mtd.flags &= ~MTD_WRITEABLE;
116 - printk(KERN_WARNING"mtd: partition \"%s\" doesn't start on an erase block boundary -- force read-only\n",
118 + slave->mtd.flags |= MTD_ERASE_PARTIAL;
119 + if (((u32)slave->mtd.size) > master->erasesize)
120 + slave->mtd.flags &= ~MTD_WRITEABLE;
122 + slave->mtd.erasesize = slave->mtd.size;
124 if ((slave->mtd.flags & MTD_WRITEABLE) &&
125 - mtd_mod_by_eb(slave->mtd.size, &slave->mtd)) {
126 - slave->mtd.flags &= ~MTD_WRITEABLE;
127 - printk(KERN_WARNING"mtd: partition \"%s\" doesn't end on an erase block -- force read-only\n",
129 + mtd_mod_by_eb(slave->offset + slave->mtd.size, &slave->mtd)) {
130 + slave->mtd.flags |= MTD_ERASE_PARTIAL;
132 + if ((u32) slave->mtd.size > master->erasesize)
133 + slave->mtd.flags &= ~MTD_WRITEABLE;
135 + slave->mtd.erasesize = slave->mtd.size;
138 mtd_set_ooblayout(&slave->mtd, &part_ooblayout_ops);
139 --- a/include/linux/mtd/mtd.h
140 +++ b/include/linux/mtd/mtd.h
141 @@ -55,6 +55,10 @@ struct erase_info {
144 struct erase_info *next;
148 + bool partial_start;
151 struct mtd_erase_region_info {