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579 lines
14 KiB
579 lines
14 KiB
// 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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/* |
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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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*/ |
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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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|
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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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|
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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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|
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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) { |
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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); |
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|
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return retlen; |
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} |
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|
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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; |
|
|
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if (!strcmp(mtd->name, info->device)) |
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cxt->index = mtd->index; |
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|
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if (mtd->index != cxt->index || cxt->index < 0) |
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return; |
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|
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dev_dbg(&mtd->dev, "found matching MTD device %s\n", mtd->name); |
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|
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if (mtd->size < info->kmsg_size * 2) { |
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dev_err(&mtd->dev, "MTD partition %d not big enough\n", |
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mtd->index); |
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return; |
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} |
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/* |
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* kmsg_size must be aligned to 4096 Bytes, which is limited by |
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* psblk. The default value of kmsg_size is 64KB. If kmsg_size |
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* is larger than erasesize, some errors will occur since mtdpsotre |
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* is designed on it. |
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*/ |
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if (mtd->erasesize < info->kmsg_size) { |
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dev_err(&mtd->dev, "eraseblock size of MTD partition %d too small\n", |
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mtd->index); |
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return; |
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} |
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if (unlikely(info->kmsg_size % mtd->writesize)) { |
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dev_err(&mtd->dev, "record size %lu KB must align to write size %d KB\n", |
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info->kmsg_size / 1024, |
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mtd->writesize / 1024); |
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return; |
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} |
|
|
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longcnt = BITS_TO_LONGS(div_u64(mtd->size, info->kmsg_size)); |
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cxt->rmmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL); |
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cxt->usedmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL); |
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|
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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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/* just support dmesg right now */ |
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cxt->dev.flags = PSTORE_FLAGS_DMESG; |
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cxt->dev.zone.read = mtdpstore_read; |
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cxt->dev.zone.write = mtdpstore_write; |
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cxt->dev.zone.erase = mtdpstore_erase; |
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cxt->dev.zone.panic_write = mtdpstore_panic_write; |
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cxt->dev.zone.total_size = mtd->size; |
|
|
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ret = register_pstore_device(&cxt->dev); |
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if (ret) { |
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dev_err(&mtd->dev, "mtd%d register to psblk failed\n", |
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mtd->index); |
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return; |
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} |
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cxt->mtd = mtd; |
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dev_info(&mtd->dev, "Attached to MTD device %d\n", mtd->index); |
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} |
|
|
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static int mtdpstore_flush_removed_do(struct mtdpstore_context *cxt, |
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loff_t off, size_t size) |
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{ |
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struct mtd_info *mtd = cxt->mtd; |
|
u_char *buf; |
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int ret; |
|
size_t retlen; |
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struct erase_info erase; |
|
|
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buf = kmalloc(mtd->erasesize, GFP_KERNEL); |
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if (!buf) |
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return -ENOMEM; |
|
|
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/* 1st. read to cache */ |
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ret = mtd_read(mtd, off, mtd->erasesize, &retlen, buf); |
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if (mtdpstore_is_io_error(ret)) |
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goto free; |
|
|
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/* 2nd. erase block */ |
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erase.len = mtd->erasesize; |
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erase.addr = off; |
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ret = mtd_erase(mtd, &erase); |
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if (ret) |
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goto free; |
|
|
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/* 3rd. write back */ |
|
while (size) { |
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unsigned int zonesize = cxt->info.kmsg_size; |
|
|
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/* there is valid data on block, write back */ |
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if (mtdpstore_is_used(cxt, off)) { |
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ret = mtd_write(mtd, off, zonesize, &retlen, buf); |
|
if (ret) |
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dev_err(&mtd->dev, "write failure at %lld (%zu of %u written), err %d\n", |
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off, retlen, zonesize, ret); |
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} |
|
|
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off += zonesize; |
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size -= min_t(unsigned int, zonesize, size); |
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} |
|
|
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free: |
|
kfree(buf); |
|
return ret; |
|
} |
|
|
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/* |
|
* 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, |
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* what mtdpstore can do is to erase and write the valid log back. |
|
*/ |
|
static int mtdpstore_flush_removed(struct mtdpstore_context *cxt) |
|
{ |
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struct mtd_info *mtd = cxt->mtd; |
|
int ret; |
|
loff_t off; |
|
u32 blkcnt = (u32)div_u64(mtd->size, mtd->erasesize); |
|
|
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for (off = 0; blkcnt > 0; blkcnt--, off += mtd->erasesize) { |
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ret = mtdpstore_block_isbad(cxt, off); |
|
if (ret) |
|
continue; |
|
|
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ret = mtdpstore_block_is_removed(cxt, off); |
|
if (!ret) |
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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; |
|
|
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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 <[email protected]>"); |
|
MODULE_DESCRIPTION("MTD backend for pstore/blk");
|
|
|