// SPDX-License-Identifier: GPL-2.0
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#define dev_fmt(fmt) "mtdoops-pstore: " fmt
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/pstore_blk.h>
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#include <linux/mtd/mtd.h>
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#include <linux/bitops.h>
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#include <linux/slab.h>
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static struct mtdpstore_context {
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int index;
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struct pstore_blk_config info;
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struct pstore_device_info dev;
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struct mtd_info *mtd;
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unsigned long *rmmap; /* removed bit map */
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unsigned long *usedmap; /* used bit map */
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/*
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* used for panic write
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* As there are no block_isbad for panic case, we should keep this
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* status before panic to ensure panic_write not failed.
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*/
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unsigned long *badmap; /* bad block bit map */
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} oops_cxt;
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static int mtdpstore_block_isbad(struct mtdpstore_context *cxt, loff_t off)
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{
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int ret;
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struct mtd_info *mtd = cxt->mtd;
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u64 blknum;
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off = ALIGN_DOWN(off, mtd->erasesize);
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blknum = div_u64(off, mtd->erasesize);
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if (test_bit(blknum, cxt->badmap))
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return true;
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ret = mtd_block_isbad(mtd, off);
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if (ret < 0) {
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dev_err(&mtd->dev, "mtd_block_isbad failed, aborting\n");
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return ret;
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} else if (ret > 0) {
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set_bit(blknum, cxt->badmap);
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return true;
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}
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return false;
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}
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static inline int mtdpstore_panic_block_isbad(struct mtdpstore_context *cxt,
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loff_t off)
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{
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struct mtd_info *mtd = cxt->mtd;
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u64 blknum;
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off = ALIGN_DOWN(off, mtd->erasesize);
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blknum = div_u64(off, mtd->erasesize);
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return test_bit(blknum, cxt->badmap);
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}
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static inline void mtdpstore_mark_used(struct mtdpstore_context *cxt,
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loff_t off)
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{
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struct mtd_info *mtd = cxt->mtd;
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u64 zonenum = div_u64(off, cxt->info.kmsg_size);
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dev_dbg(&mtd->dev, "mark zone %llu used\n", zonenum);
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set_bit(zonenum, cxt->usedmap);
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}
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static inline void mtdpstore_mark_unused(struct mtdpstore_context *cxt,
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loff_t off)
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{
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struct mtd_info *mtd = cxt->mtd;
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u64 zonenum = div_u64(off, cxt->info.kmsg_size);
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dev_dbg(&mtd->dev, "mark zone %llu unused\n", zonenum);
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clear_bit(zonenum, cxt->usedmap);
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}
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static inline void mtdpstore_block_mark_unused(struct mtdpstore_context *cxt,
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loff_t off)
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{
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struct mtd_info *mtd = cxt->mtd;
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u32 zonecnt = mtd->erasesize / cxt->info.kmsg_size;
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u64 zonenum;
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off = ALIGN_DOWN(off, mtd->erasesize);
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zonenum = div_u64(off, cxt->info.kmsg_size);
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while (zonecnt > 0) {
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dev_dbg(&mtd->dev, "mark zone %llu unused\n", zonenum);
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clear_bit(zonenum, cxt->usedmap);
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zonenum++;
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zonecnt--;
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}
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}
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static inline int mtdpstore_is_used(struct mtdpstore_context *cxt, loff_t off)
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{
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u64 zonenum = div_u64(off, cxt->info.kmsg_size);
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u64 blknum = div_u64(off, cxt->mtd->erasesize);
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if (test_bit(blknum, cxt->badmap))
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return true;
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return test_bit(zonenum, cxt->usedmap);
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}
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static int mtdpstore_block_is_used(struct mtdpstore_context *cxt,
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loff_t off)
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{
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struct mtd_info *mtd = cxt->mtd;
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u32 zonecnt = mtd->erasesize / cxt->info.kmsg_size;
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u64 zonenum;
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off = ALIGN_DOWN(off, mtd->erasesize);
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zonenum = div_u64(off, cxt->info.kmsg_size);
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while (zonecnt > 0) {
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if (test_bit(zonenum, cxt->usedmap))
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return true;
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zonenum++;
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zonecnt--;
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}
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return false;
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}
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static int mtdpstore_is_empty(struct mtdpstore_context *cxt, char *buf,
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size_t size)
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{
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struct mtd_info *mtd = cxt->mtd;
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size_t sz;
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int i;
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sz = min_t(uint32_t, size, mtd->writesize / 4);
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for (i = 0; i < sz; i++) {
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if (buf[i] != (char)0xFF)
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return false;
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}
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return true;
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}
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static void mtdpstore_mark_removed(struct mtdpstore_context *cxt, loff_t off)
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{
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struct mtd_info *mtd = cxt->mtd;
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u64 zonenum = div_u64(off, cxt->info.kmsg_size);
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dev_dbg(&mtd->dev, "mark zone %llu removed\n", zonenum);
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set_bit(zonenum, cxt->rmmap);
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}
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static void mtdpstore_block_clear_removed(struct mtdpstore_context *cxt,
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loff_t off)
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{
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struct mtd_info *mtd = cxt->mtd;
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u32 zonecnt = mtd->erasesize / cxt->info.kmsg_size;
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u64 zonenum;
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off = ALIGN_DOWN(off, mtd->erasesize);
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zonenum = div_u64(off, cxt->info.kmsg_size);
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while (zonecnt > 0) {
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clear_bit(zonenum, cxt->rmmap);
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zonenum++;
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zonecnt--;
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}
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}
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static int mtdpstore_block_is_removed(struct mtdpstore_context *cxt,
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loff_t off)
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{
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struct mtd_info *mtd = cxt->mtd;
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u32 zonecnt = mtd->erasesize / cxt->info.kmsg_size;
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u64 zonenum;
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off = ALIGN_DOWN(off, mtd->erasesize);
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zonenum = div_u64(off, cxt->info.kmsg_size);
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while (zonecnt > 0) {
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if (test_bit(zonenum, cxt->rmmap))
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return true;
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zonenum++;
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zonecnt--;
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}
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return false;
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}
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static int mtdpstore_erase_do(struct mtdpstore_context *cxt, loff_t off)
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{
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struct mtd_info *mtd = cxt->mtd;
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struct erase_info erase;
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int ret;
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off = ALIGN_DOWN(off, cxt->mtd->erasesize);
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dev_dbg(&mtd->dev, "try to erase off 0x%llx\n", off);
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erase.len = cxt->mtd->erasesize;
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erase.addr = off;
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ret = mtd_erase(cxt->mtd, &erase);
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if (!ret)
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mtdpstore_block_clear_removed(cxt, off);
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else
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dev_err(&mtd->dev, "erase of region [0x%llx, 0x%llx] on \"%s\" failed\n",
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(unsigned long long)erase.addr,
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(unsigned long long)erase.len, cxt->info.device);
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return ret;
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}
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/*
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* called while removing file
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*
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* Avoiding over erasing, do erase block only when the whole block is unused.
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* If the block contains valid log, do erase lazily on flush_removed() when
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* unregister.
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*/
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static ssize_t mtdpstore_erase(size_t size, loff_t off)
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{
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struct mtdpstore_context *cxt = &oops_cxt;
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if (mtdpstore_block_isbad(cxt, off))
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return -EIO;
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mtdpstore_mark_unused(cxt, off);
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/* If the block still has valid data, mtdpstore do erase lazily */
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if (likely(mtdpstore_block_is_used(cxt, off))) {
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mtdpstore_mark_removed(cxt, off);
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return 0;
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}
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/* all zones are unused, erase it */
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return mtdpstore_erase_do(cxt, off);
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}
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/*
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* What is security for mtdpstore?
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* As there is no erase for panic case, we should ensure at least one zone
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* is writable. Otherwise, panic write will fail.
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* If zone is used, write operation will return -ENOMSG, which means that
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* pstore/blk will try one by one until gets an empty zone. So, it is not
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* needed to ensure the next zone is empty, but at least one.
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*/
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static int mtdpstore_security(struct mtdpstore_context *cxt, loff_t off)
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{
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int ret = 0, i;
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struct mtd_info *mtd = cxt->mtd;
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u32 zonenum = (u32)div_u64(off, cxt->info.kmsg_size);
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u32 zonecnt = (u32)div_u64(cxt->mtd->size, cxt->info.kmsg_size);
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u32 blkcnt = (u32)div_u64(cxt->mtd->size, cxt->mtd->erasesize);
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u32 erasesize = cxt->mtd->erasesize;
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for (i = 0; i < zonecnt; i++) {
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u32 num = (zonenum + i) % zonecnt;
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/* found empty zone */
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if (!test_bit(num, cxt->usedmap))
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return 0;
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}
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/* If there is no any empty zone, we have no way but to do erase */
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while (blkcnt--) {
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div64_u64_rem(off + erasesize, cxt->mtd->size, (u64 *)&off);
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if (mtdpstore_block_isbad(cxt, off))
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continue;
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ret = mtdpstore_erase_do(cxt, off);
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if (!ret) {
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mtdpstore_block_mark_unused(cxt, off);
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break;
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}
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}
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if (ret)
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dev_err(&mtd->dev, "all blocks bad!\n");
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dev_dbg(&mtd->dev, "end security\n");
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return ret;
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}
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static ssize_t mtdpstore_write(const char *buf, size_t size, loff_t off)
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{
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struct mtdpstore_context *cxt = &oops_cxt;
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struct mtd_info *mtd = cxt->mtd;
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size_t retlen;
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int ret;
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if (mtdpstore_block_isbad(cxt, off))
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return -ENOMSG;
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/* zone is used, please try next one */
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if (mtdpstore_is_used(cxt, off))
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return -ENOMSG;
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dev_dbg(&mtd->dev, "try to write off 0x%llx size %zu\n", off, size);
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ret = mtd_write(cxt->mtd, off, size, &retlen, (u_char *)buf);
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if (ret < 0 || retlen != size) {
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dev_err(&mtd->dev, "write failure at %lld (%zu of %zu written), err %d\n",
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off, retlen, size, ret);
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return -EIO;
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}
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mtdpstore_mark_used(cxt, off);
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mtdpstore_security(cxt, off);
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return retlen;
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}
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static inline bool mtdpstore_is_io_error(int ret)
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{
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return ret < 0 && !mtd_is_bitflip(ret) && !mtd_is_eccerr(ret);
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}
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/*
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* All zones will be read as pstore/blk will read zone one by one when do
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* recover.
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*/
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static ssize_t mtdpstore_read(char *buf, size_t size, loff_t off)
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{
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struct mtdpstore_context *cxt = &oops_cxt;
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struct mtd_info *mtd = cxt->mtd;
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size_t retlen, done;
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int ret;
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if (mtdpstore_block_isbad(cxt, off))
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return -ENOMSG;
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dev_dbg(&mtd->dev, "try to read off 0x%llx size %zu\n", off, size);
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for (done = 0, retlen = 0; done < size; done += retlen) {
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retlen = 0;
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ret = mtd_read(cxt->mtd, off + done, size - done, &retlen,
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(u_char *)buf + done);
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if (mtdpstore_is_io_error(ret)) {
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dev_err(&mtd->dev, "read failure at %lld (%zu of %zu read), err %d\n",
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off + done, retlen, size - done, ret);
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/* the zone may be broken, try next one */
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return -ENOMSG;
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}
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/*
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* ECC error. The impact on log data is so small. Maybe we can
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* still read it and try to understand. So mtdpstore just hands
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* over what it gets and user can judge whether the data is
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* valid or not.
|
*/
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if (mtd_is_eccerr(ret)) {
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dev_err(&mtd->dev, "ecc error at %lld (%zu of %zu read), err %d\n",
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off + done, retlen, size - done, ret);
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/* driver may not set retlen when ecc error */
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retlen = retlen == 0 ? size - done : retlen;
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}
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}
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if (mtdpstore_is_empty(cxt, buf, size))
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mtdpstore_mark_unused(cxt, off);
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else
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mtdpstore_mark_used(cxt, off);
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mtdpstore_security(cxt, off);
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return retlen;
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}
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static ssize_t mtdpstore_panic_write(const char *buf, size_t size, loff_t off)
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{
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struct mtdpstore_context *cxt = &oops_cxt;
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struct mtd_info *mtd = cxt->mtd;
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size_t retlen;
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int ret;
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if (mtdpstore_panic_block_isbad(cxt, off))
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return -ENOMSG;
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/* zone is used, please try next one */
|
if (mtdpstore_is_used(cxt, off))
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return -ENOMSG;
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ret = mtd_panic_write(cxt->mtd, off, size, &retlen, (u_char *)buf);
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if (ret < 0 || size != retlen) {
|
dev_err(&mtd->dev, "panic write failure at %lld (%zu of %zu read), err %d\n",
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off, retlen, size, ret);
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return -EIO;
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}
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mtdpstore_mark_used(cxt, off);
|
|
return retlen;
|
}
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static void mtdpstore_notify_add(struct mtd_info *mtd)
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{
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int ret;
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struct mtdpstore_context *cxt = &oops_cxt;
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struct pstore_blk_config *info = &cxt->info;
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unsigned long longcnt;
|
|
if (!strcmp(mtd->name, info->device))
|
cxt->index = mtd->index;
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|
if (mtd->index != cxt->index || cxt->index < 0)
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return;
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|
dev_dbg(&mtd->dev, "found matching MTD device %s\n", mtd->name);
|
|
if (mtd->size < info->kmsg_size * 2) {
|
dev_err(&mtd->dev, "MTD partition %d not big enough\n",
|
mtd->index);
|
return;
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}
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/*
|
* kmsg_size must be aligned to 4096 Bytes, which is limited by
|
* psblk. The default value of kmsg_size is 64KB. If kmsg_size
|
* is larger than erasesize, some errors will occur since mtdpsotre
|
* is designed on it.
|
*/
|
if (mtd->erasesize < info->kmsg_size) {
|
dev_err(&mtd->dev, "eraseblock size of MTD partition %d too small\n",
|
mtd->index);
|
return;
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}
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if (unlikely(info->kmsg_size % mtd->writesize)) {
|
dev_err(&mtd->dev, "record size %lu KB must align to write size %d KB\n",
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info->kmsg_size / 1024,
|
mtd->writesize / 1024);
|
return;
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}
|
|
longcnt = BITS_TO_LONGS(div_u64(mtd->size, info->kmsg_size));
|
cxt->rmmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL);
|
cxt->usedmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL);
|
|
longcnt = BITS_TO_LONGS(div_u64(mtd->size, mtd->erasesize));
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cxt->badmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL);
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|
cxt->dev.total_size = mtd->size;
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/* just support dmesg right now */
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cxt->dev.flags = PSTORE_FLAGS_DMESG;
|
cxt->dev.read = mtdpstore_read;
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cxt->dev.write = mtdpstore_write;
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cxt->dev.erase = mtdpstore_erase;
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cxt->dev.panic_write = mtdpstore_panic_write;
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ret = register_pstore_device(&cxt->dev);
|
if (ret) {
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dev_err(&mtd->dev, "mtd%d register to psblk failed\n",
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mtd->index);
|
return;
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}
|
cxt->mtd = mtd;
|
dev_info(&mtd->dev, "Attached to MTD device %d\n", mtd->index);
|
}
|
|
static int mtdpstore_flush_removed_do(struct mtdpstore_context *cxt,
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loff_t off, size_t size)
|
{
|
struct mtd_info *mtd = cxt->mtd;
|
u_char *buf;
|
int ret;
|
size_t retlen;
|
struct erase_info erase;
|
|
buf = kmalloc(mtd->erasesize, GFP_KERNEL);
|
if (!buf)
|
return -ENOMEM;
|
|
/* 1st. read to cache */
|
ret = mtd_read(mtd, off, mtd->erasesize, &retlen, buf);
|
if (mtdpstore_is_io_error(ret))
|
goto free;
|
|
/* 2nd. erase block */
|
erase.len = mtd->erasesize;
|
erase.addr = off;
|
ret = mtd_erase(mtd, &erase);
|
if (ret)
|
goto free;
|
|
/* 3rd. write back */
|
while (size) {
|
unsigned int zonesize = cxt->info.kmsg_size;
|
|
/* there is valid data on block, write back */
|
if (mtdpstore_is_used(cxt, off)) {
|
ret = mtd_write(mtd, off, zonesize, &retlen, buf);
|
if (ret)
|
dev_err(&mtd->dev, "write failure at %lld (%zu of %u written), err %d\n",
|
off, retlen, zonesize, ret);
|
}
|
|
off += zonesize;
|
size -= min_t(unsigned int, zonesize, size);
|
}
|
|
free:
|
kfree(buf);
|
return ret;
|
}
|
|
/*
|
* What does mtdpstore_flush_removed() do?
|
* When user remove any log file on pstore filesystem, mtdpstore should do
|
* something to ensure log file removed. If the whole block is no longer used,
|
* it's nice to erase the block. However if the block still contains valid log,
|
* what mtdpstore can do is to erase and write the valid log back.
|
*/
|
static int mtdpstore_flush_removed(struct mtdpstore_context *cxt)
|
{
|
struct mtd_info *mtd = cxt->mtd;
|
int ret;
|
loff_t off;
|
u32 blkcnt = (u32)div_u64(mtd->size, mtd->erasesize);
|
|
for (off = 0; blkcnt > 0; blkcnt--, off += mtd->erasesize) {
|
ret = mtdpstore_block_isbad(cxt, off);
|
if (ret)
|
continue;
|
|
ret = mtdpstore_block_is_removed(cxt, off);
|
if (!ret)
|
continue;
|
|
ret = mtdpstore_flush_removed_do(cxt, off, mtd->erasesize);
|
if (ret)
|
return ret;
|
}
|
return 0;
|
}
|
|
static void mtdpstore_notify_remove(struct mtd_info *mtd)
|
{
|
struct mtdpstore_context *cxt = &oops_cxt;
|
|
if (mtd->index != cxt->index || cxt->index < 0)
|
return;
|
|
mtdpstore_flush_removed(cxt);
|
|
unregister_pstore_device(&cxt->dev);
|
kfree(cxt->badmap);
|
kfree(cxt->usedmap);
|
kfree(cxt->rmmap);
|
cxt->mtd = NULL;
|
cxt->index = -1;
|
}
|
|
static struct mtd_notifier mtdpstore_notifier = {
|
.add = mtdpstore_notify_add,
|
.remove = mtdpstore_notify_remove,
|
};
|
|
static int __init mtdpstore_init(void)
|
{
|
int ret;
|
struct mtdpstore_context *cxt = &oops_cxt;
|
struct pstore_blk_config *info = &cxt->info;
|
|
ret = pstore_blk_get_config(info);
|
if (unlikely(ret))
|
return ret;
|
|
if (strlen(info->device) == 0) {
|
pr_err("mtd device must be supplied (device name is empty)\n");
|
return -EINVAL;
|
}
|
if (!info->kmsg_size) {
|
pr_err("no backend enabled (kmsg_size is 0)\n");
|
return -EINVAL;
|
}
|
|
/* Setup the MTD device to use */
|
ret = kstrtoint((char *)info->device, 0, &cxt->index);
|
if (ret)
|
cxt->index = -1;
|
|
register_mtd_user(&mtdpstore_notifier);
|
return 0;
|
}
|
module_init(mtdpstore_init);
|
|
static void __exit mtdpstore_exit(void)
|
{
|
unregister_mtd_user(&mtdpstore_notifier);
|
}
|
module_exit(mtdpstore_exit);
|
|
MODULE_LICENSE("GPL");
|
MODULE_AUTHOR("WeiXiong Liao <liaoweixiong@allwinnertech.com>");
|
MODULE_DESCRIPTION("MTD backend for pstore/blk");
|
