[resend to proper CC list...] On Tue, May 12, 2020 at 11:12:42AM +0800, WeiXiong Liao wrote: > hi Kees Cook, > > The off parameter on mtdpsore_block*() does not align to block size, > which makes some bugs. For example, a block contains 4 dmesg zones > and it's expected to erase this block when user remove all files on > these zones. However it work failed since it get wrongly zonenum from > misaligned off. Ah, okay. I haven't touched any of this logic. Did something change in pstore/blk or /zone that I broke? Regardless, can you send a regular patch for what you have below and I'll fold it into the mtdpstore commit. Thanks! -Kees > On 2020/5/12 AM 7:32, Kees Cook wrote: > > From: WeiXiong Liao <liaoweixiong@xxxxxxxxxxxxxxxxx> > > > > This introduces mtdpstore, which is similar to mtdoops but more > > powerful. It uses pstore/blk, and aims to store panic and oops logs to > > a flash partition, where pstore can later read back and present as files > > in the mounted pstore filesystem. > > > > To make mtdpstore work, the "blkdev" of pstore/blk should be set > > as MTD device name or MTD device number. For more details, see > > Documentation/admin-guide/pstore-blk.rst > > > > This solves a number of issues: > > - Work duplication: both of pstore and mtdoops do the same job storing > > panic/oops log. They have very similar logic, registering to kmsg > > dumper and storing logs to several chunks one by one. > > - Layer violations: drivers should provides methods instead of polices. > > MTD should provide read/write/erase operations, and allow a higher > > level drivers to provide the chunk management, kmsg dump > > configuration, etc. > > - Missing features: pstore provides many additional features, including > > presenting the logs as files, logging dump time and count, and > > supporting other frontends like pmsg, console, etc. > > > > Signed-off-by: WeiXiong Liao <liaoweixiong@xxxxxxxxxxxxxxxxx> > > Link: https://lore.kernel.org/r/1585126506-18635-12-git-send-email-liaoweixiong@xxxxxxxxxxxxxxxxx > > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > > --- > > Documentation/admin-guide/pstore-blk.rst | 9 +- > > drivers/mtd/Kconfig | 10 + > > drivers/mtd/Makefile | 1 + > > drivers/mtd/mtdpstore.c | 563 +++++++++++++++++++++++ > > 4 files changed, 581 insertions(+), 2 deletions(-) > > create mode 100644 drivers/mtd/mtdpstore.c > > > > diff --git a/Documentation/admin-guide/pstore-blk.rst b/Documentation/admin-guide/pstore-blk.rst > > index d45341e55e82..296d5027787a 100644 > > --- a/Documentation/admin-guide/pstore-blk.rst > > +++ b/Documentation/admin-guide/pstore-blk.rst > > @@ -43,9 +43,9 @@ blkdev > > ~~~~~~ > > > > The block device to use. Most of the time, it is a partition of block device. > > -It's required for pstore/blk. > > +It's required for pstore/blk. It is also used for MTD device. > > > > -It accepts the following variants: > > +It accepts the following variants for block device: > > > > 1. <hex_major><hex_minor> device number in hexadecimal represents itself; no > > leading 0x, for example b302. > > @@ -64,6 +64,11 @@ It accepts the following variants: > > partition with a known unique id. > > #. <major>:<minor> major and minor number of the device separated by a colon. > > > > +It accepts the following variants for MTD device: > > + > > +1. <device name> MTD device name. "pstore" is recommended. > > +#. <device number> MTD device number. > > + > > kmsg_size > > ~~~~~~~~~ > > > > diff --git a/drivers/mtd/Kconfig b/drivers/mtd/Kconfig > > index 42d401ea60ee..6ddab796216d 100644 > > --- a/drivers/mtd/Kconfig > > +++ b/drivers/mtd/Kconfig > > @@ -170,6 +170,16 @@ config MTD_OOPS > > buffer in a flash partition where it can be read back at some > > later point. > > > > +config MTD_PSTORE > > + tristate "Log panic/oops to an MTD buffer based on pstore" > > + depends on PSTORE_BLK > > + help > > + This enables panic and oops messages to be logged to a circular > > + buffer in a flash partition where it can be read back as files after > > + mounting pstore filesystem. > > + > > + If unsure, say N. > > + > > config MTD_SWAP > > tristate "Swap on MTD device support" > > depends on MTD && SWAP > > diff --git a/drivers/mtd/Makefile b/drivers/mtd/Makefile > > index 56cc60ccc477..593d0593a038 100644 > > --- a/drivers/mtd/Makefile > > +++ b/drivers/mtd/Makefile > > @@ -20,6 +20,7 @@ obj-$(CONFIG_RFD_FTL) += rfd_ftl.o > > obj-$(CONFIG_SSFDC) += ssfdc.o > > obj-$(CONFIG_SM_FTL) += sm_ftl.o > > obj-$(CONFIG_MTD_OOPS) += mtdoops.o > > +obj-$(CONFIG_MTD_PSTORE) += mtdpstore.o > > obj-$(CONFIG_MTD_SWAP) += mtdswap.o > > > > nftl-objs := nftlcore.o nftlmount.o > > diff --git a/drivers/mtd/mtdpstore.c b/drivers/mtd/mtdpstore.c > > new file mode 100644 > > index 000000000000..06084eff1004 > > --- /dev/null > > +++ b/drivers/mtd/mtdpstore.c > > @@ -0,0 +1,563 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > + > > +#define dev_fmt(fmt) "mtdoops-pstore: " fmt > > + > > +#include <linux/kernel.h> > > +#include <linux/module.h> > > +#include <linux/pstore_blk.h> > > +#include <linux/mtd/mtd.h> > > +#include <linux/bitops.h> > > + > > +static struct mtdpstore_context { > > + int index; > > + struct pstore_blk_config info; > > + struct pstore_device_info dev; > > + struct mtd_info *mtd; > > + unsigned long *rmmap; /* removed bit map */ > > + unsigned long *usedmap; /* used bit map */ > > + /* > > + * used for panic write > > + * As there are no block_isbad for panic case, we should keep this > > + * status before panic to ensure panic_write not failed. > > + */ > > + unsigned long *badmap; /* bad block bit map */ > > +} oops_cxt; > > + > > +static int mtdpstore_block_isbad(struct mtdpstore_context *cxt, loff_t off) > > +{ > > + int ret; > > + struct mtd_info *mtd = cxt->mtd; > > + u64 blknum = div_u64(off, mtd->erasesize); > > - u64 blknum = div_u64(off, mtd->erasesize); > + u64 blknum; > + > + off = ALIGN_DOWN(off, mtd->erasesize); > + blknum = div_u64(off, mtd->erasesize); > > > + > > + if (test_bit(blknum, cxt->badmap)) > > + return true; > > + ret = mtd_block_isbad(mtd, off); > > + if (ret < 0) { > > + dev_err(&mtd->dev, "mtd_block_isbad failed, aborting\n"); > > + return ret; > > + } else if (ret > 0) { > > + set_bit(blknum, cxt->badmap); > > + return true; > > + } > > + return false; > > +} > > + > > +static inline int mtdpstore_panic_block_isbad(struct mtdpstore_context *cxt, > > + loff_t off) > > +{ > > + struct mtd_info *mtd = cxt->mtd; > > + u64 blknum = div_u64(off, mtd->erasesize); > > + > > - u64 blknum = div_u64(off, mtd->erasesize); > + u64 blknum; > > + off = ALIGN_DOWN(off, mtd->erasesize); > + blknum = div_u64(off, mtd->erasesize); > > > + return test_bit(blknum, cxt->badmap); > > +} > > + > > +static inline void mtdpstore_mark_used(struct mtdpstore_context *cxt, > > + loff_t off) > > +{ > > + struct mtd_info *mtd = cxt->mtd; > > + u64 zonenum = div_u64(off, cxt->info.kmsg_size); > > + > > + dev_dbg(&mtd->dev, "mark zone %llu used\n", zonenum); > > + set_bit(zonenum, cxt->usedmap); > > +} > > + > > +static inline void mtdpstore_mark_unused(struct mtdpstore_context *cxt, > > + loff_t off) > > +{ > > + struct mtd_info *mtd = cxt->mtd; > > + u64 zonenum = div_u64(off, cxt->info.kmsg_size); > > + > > + dev_dbg(&mtd->dev, "mark zone %llu unused\n", zonenum); > > + clear_bit(zonenum, cxt->usedmap); > > +} > > + > > +static inline void mtdpstore_block_mark_unused(struct mtdpstore_context *cxt, > > + loff_t off) > > +{ > > + struct mtd_info *mtd = cxt->mtd; > > + u64 zonenum = div_u64(off, cxt->info.kmsg_size); > > + u32 zonecnt = cxt->mtd->erasesize / cxt->info.kmsg_size; > > + > > - u64 zonenum = div_u64(off, cxt->info.kmsg_size); > - u32 zonecnt = cxt->mtd->erasesize / cxt->info.kmsg_size; > + u32 zonecnt = mtd->erasesize / cxt->info.kmsg_size; > + u64 zonenum; > > + off = ALIGN_DOWN(off, mtd->erasesize); > + zonenum = div_u64(off, cxt->info.kmsg_size); > > > + while (zonecnt > 0) { > > + dev_dbg(&mtd->dev, "mark zone %llu unused\n", zonenum); > > + clear_bit(zonenum, cxt->usedmap); > > + zonenum++; > > + zonecnt--; > > + } > > +} > > + > > +static inline int mtdpstore_is_used(struct mtdpstore_context *cxt, loff_t off) > > +{ > > + u64 zonenum = div_u64(off, cxt->info.kmsg_size); > > + u64 blknum = div_u64(off, cxt->mtd->erasesize); > > + > > + if (test_bit(blknum, cxt->badmap)) > > + return true; > > + return test_bit(zonenum, cxt->usedmap); > > +} > > + > > +static int mtdpstore_block_is_used(struct mtdpstore_context *cxt, > > + loff_t off) > > +{ > > + u64 zonenum = div_u64(off, cxt->info.kmsg_size); > > + u32 zonecnt = cxt->mtd->erasesize / cxt->info.kmsg_size; > > + > > - u64 zonenum = div_u64(off, cxt->info.kmsg_size); > - u32 zonecnt = cxt->mtd->erasesize / cxt->info.kmsg_size; > + struct mtd_info *mtd = cxt->mtd; > + u32 zonecnt = mtd->erasesize / cxt->info.kmsg_size; > + u64 zonenum; > > + off = ALIGN_DOWN(off, mtd->erasesize); > + zonenum = div_u64(off, cxt->info.kmsg_size); > > > + while (zonecnt > 0) { > > + if (test_bit(zonenum, cxt->usedmap)) > > + return true; > > + zonenum++; > > + zonecnt--; > > + } > > + return false; > > +} > > + > > +static int mtdpstore_is_empty(struct mtdpstore_context *cxt, char *buf, > > + size_t size) > > +{ > > + struct mtd_info *mtd = cxt->mtd; > > + size_t sz; > > + int i; > > + > > + sz = min_t(uint32_t, size, mtd->writesize / 4); > > + for (i = 0; i < sz; i++) { > > + if (buf[i] != (char)0xFF) > > + return false; > > + } > > + return true; > > +} > > + > > +static void mtdpstore_mark_removed(struct mtdpstore_context *cxt, loff_t off) > > +{ > > + struct mtd_info *mtd = cxt->mtd; > > + u64 zonenum = div_u64(off, cxt->info.kmsg_size); > > + > > + dev_dbg(&mtd->dev, "mark zone %llu removed\n", zonenum); > > + set_bit(zonenum, cxt->rmmap); > > +} > > + > > +static void mtdpstore_block_clear_removed(struct mtdpstore_context *cxt, > > + loff_t off) > > +{ > > + u64 zonenum = div_u64(off, cxt->info.kmsg_size); > > + u32 zonecnt = cxt->mtd->erasesize / cxt->info.kmsg_size; > > + > > - u64 zonenum = div_u64(off, cxt->info.kmsg_size); > - u32 zonecnt = cxt->mtd->erasesize / cxt->info.kmsg_size; > + struct mtd_info *mtd = cxt->mtd; > + u32 zonecnt = mtd->erasesize / cxt->info.kmsg_size; > + u64 zonenum; > > + off = ALIGN_DOWN(off, mtd->erasesize); > + zonenum = div_u64(off, cxt->info.kmsg_size); > > > + while (zonecnt > 0) { > > + clear_bit(zonenum, cxt->rmmap); > > + zonenum++; > > + zonecnt--; > > + } > > +} > > + > > +static int mtdpstore_block_is_removed(struct mtdpstore_context *cxt, > > + loff_t off) > > +{ > > + u64 zonenum = div_u64(off, cxt->info.kmsg_size); > > + u32 zonecnt = cxt->mtd->erasesize / cxt->info.kmsg_size; > > + > > - u64 zonenum = div_u64(off, cxt->info.kmsg_size); > - u32 zonecnt = cxt->mtd->erasesize / cxt->info.kmsg_size; > + struct mtd_info *mtd = cxt->mtd; > + u32 zonecnt = mtd->erasesize / cxt->info.kmsg_size; > + u64 zonenum; > > + off = ALIGN_DOWN(off, mtd->erasesize); > + zonenum = div_u64(off, cxt->info.kmsg_size); > > > + while (zonecnt > 0) { > > + if (test_bit(zonenum, cxt->rmmap)) > > + return true; > > + zonenum++; > > + zonecnt--; > > + } > > + return false; > > +} > > + > > +static int mtdpstore_erase_do(struct mtdpstore_context *cxt, loff_t off) > > +{ > > + struct mtd_info *mtd = cxt->mtd; > > + struct erase_info erase; > > + int ret; > > + > > int ret; > > + off = ALIGN_DOWN(off, cxt->mtd->erasesize); > dev_dbg(&mtd->dev, "try to erase off 0x%llx\n", off); > > > + dev_dbg(&mtd->dev, "try to erase off 0x%llx\n", off); > > + erase.len = cxt->mtd->erasesize; > > + erase.addr = off; > > + ret = mtd_erase(cxt->mtd, &erase); > > + if (!ret) > > + mtdpstore_block_clear_removed(cxt, off); > > + else > > + dev_err(&mtd->dev, "erase of region [0x%llx, 0x%llx] on \"%s\" failed\n", > > + (unsigned long long)erase.addr, > > + (unsigned long long)erase.len, cxt->info.device); > > + return ret; > > +} > > + > > +/* > > + * called while removing file > > + * > > + * Avoiding over erasing, do erase block only when the whole block is unused. > > + * If the block contains valid log, do erase lazily on flush_removed() when > > + * unregister. > > + */ > > +static ssize_t mtdpstore_erase(size_t size, loff_t off) > > +{ > > + struct mtdpstore_context *cxt = &oops_cxt; > > + > > + if (mtdpstore_block_isbad(cxt, off)) > > + return -EIO; > > + > > + mtdpstore_mark_unused(cxt, off); > > + > > + /* If the block still has valid data, mtdpstore do erase lazily */ > > + if (likely(mtdpstore_block_is_used(cxt, off))) { > > + mtdpstore_mark_removed(cxt, off); > > + return 0; > > + } > > + > > + /* all zones are unused, erase it */ > > + off = ALIGN_DOWN(off, cxt->mtd->erasesize); > > /* all zones are unused, erase it */ > - off = ALIGN_DOWN(off, cxt->mtd->erasesize); > return mtdpstore_erase_do(cxt, off); > > > + return mtdpstore_erase_do(cxt, off); > > +} > > + > > +/* > > + * What is security for mtdpstore? > > + * As there is no erase for panic case, we should ensure at least one zone > > + * is writable. Otherwise, panic write will fail. > > + * If zone is used, write operation will return -ENOMSG, which means that > > + * pstore/blk will try one by one until gets an empty zone. So, it is not > > + * needed to ensure the next zone is empty, but at least one. > > + */ > > +static int mtdpstore_security(struct mtdpstore_context *cxt, loff_t off) > > +{ > > + int ret = 0, i; > > + struct mtd_info *mtd = cxt->mtd; > > + u32 zonenum = (u32)div_u64(off, cxt->info.kmsg_size); > > + u32 zonecnt = (u32)div_u64(cxt->mtd->size, cxt->info.kmsg_size); > > + u32 blkcnt = (u32)div_u64(cxt->mtd->size, cxt->mtd->erasesize); > > + u32 erasesize = cxt->mtd->erasesize; > > + > > + for (i = 0; i < zonecnt; i++) { > > + u32 num = (zonenum + i) % zonecnt; > > + > > + /* found empty zone */ > > + if (!test_bit(num, cxt->usedmap)) > > + return 0; > > + } > > + > > + /* If there is no any empty zone, we have no way but to do erase */ > > + off = ALIGN_DOWN(off, erasesize); > > + while (blkcnt--) { > > + div64_u64_rem(off + erasesize, cxt->mtd->size, (u64 *)&off); > > + > > + if (mtdpstore_block_isbad(cxt, off)) > > + continue; > > + > > + ret = mtdpstore_erase_do(cxt, off); > > + if (!ret) { > > + mtdpstore_block_mark_unused(cxt, off); > > + break; > > + } > > + } > > + > > + if (ret) > > + dev_err(&mtd->dev, "all blocks bad!\n"); > > + dev_dbg(&mtd->dev, "end security\n"); > > + return ret; > > +} > > + > > +static ssize_t mtdpstore_write(const char *buf, size_t size, loff_t off) > > +{ > > + struct mtdpstore_context *cxt = &oops_cxt; > > + struct mtd_info *mtd = cxt->mtd; > > + size_t retlen; > > + int ret; > > + > > + if (mtdpstore_block_isbad(cxt, off)) > > + return -ENOMSG; > > + > > + /* zone is used, please try next one */ > > + if (mtdpstore_is_used(cxt, off)) > > + return -ENOMSG; > > + > > + dev_dbg(&mtd->dev, "try to write off 0x%llx size %zu\n", off, size); > > + ret = mtd_write(cxt->mtd, off, size, &retlen, (u_char *)buf); > > + if (ret < 0 || retlen != size) { > > + dev_err(&mtd->dev, "write failure at %lld (%zu of %zu written), err %d\n", > > + off, retlen, size, ret); > > + return -EIO; > > + } > > + mtdpstore_mark_used(cxt, off); > > + > > + mtdpstore_security(cxt, off); > > + return retlen; > > +} > > + > > +static inline bool mtdpstore_is_io_error(int ret) > > +{ > > + return ret < 0 && !mtd_is_bitflip(ret) && !mtd_is_eccerr(ret); > > +} > > + > > +/* > > + * All zones will be read as pstore/blk will read zone one by one when do > > + * recover. > > + */ > > +static ssize_t mtdpstore_read(char *buf, size_t size, loff_t off) > > +{ > > + struct mtdpstore_context *cxt = &oops_cxt; > > + struct mtd_info *mtd = cxt->mtd; > > + size_t retlen, done; > > + int ret; > > + > > + if (mtdpstore_block_isbad(cxt, off)) > > + return -ENOMSG; > > + > > + dev_dbg(&mtd->dev, "try to read off 0x%llx size %zu\n", off, size); > > + for (done = 0, retlen = 0; done < size; done += retlen) { > > + retlen = 0; > > + > > + ret = mtd_read(cxt->mtd, off + done, size - done, &retlen, > > + (u_char *)buf + done); > > + if (mtdpstore_is_io_error(ret)) { > > + dev_err(&mtd->dev, "read failure at %lld (%zu of %zu read), err %d\n", > > + off + done, retlen, size - done, ret); > > + /* the zone may be broken, try next one */ > > + return -ENOMSG; > > + } > > + > > + /* > > + * ECC error. The impact on log data is so small. Maybe we can > > + * still read it and try to understand. So mtdpstore just hands > > + * over what it gets and user can judge whether the data is > > + * valid or not. > > + */ > > + if (mtd_is_eccerr(ret)) { > > + dev_err(&mtd->dev, "ecc error at %lld (%zu of %zu read), err %d\n", > > + off + done, retlen, size - done, ret); > > + /* driver may not set retlen when ecc error */ > > + retlen = retlen == 0 ? size - done : retlen; > > + } > > + } > > + > > + if (mtdpstore_is_empty(cxt, buf, size)) > > + mtdpstore_mark_unused(cxt, off); > > + else > > + mtdpstore_mark_used(cxt, off); > > + > > + mtdpstore_security(cxt, off); > > + return retlen; > > +} > > + > > +static ssize_t mtdpstore_panic_write(const char *buf, size_t size, loff_t off) > > +{ > > + struct mtdpstore_context *cxt = &oops_cxt; > > + struct mtd_info *mtd = cxt->mtd; > > + size_t retlen; > > + int ret; > > + > > + if (mtdpstore_panic_block_isbad(cxt, off)) > > + return -ENOMSG; > > + > > + /* zone is used, please try next one */ > > + if (mtdpstore_is_used(cxt, off)) > > + return -ENOMSG; > > + > > + ret = mtd_panic_write(cxt->mtd, off, size, &retlen, (u_char *)buf); > > + if (ret < 0 || size != retlen) { > > + dev_err(&mtd->dev, "panic write failure at %lld (%zu of %zu read), err %d\n", > > + off, retlen, size, ret); > > + return -EIO; > > + } > > + mtdpstore_mark_used(cxt, off); > > + > > + return retlen; > > +} > > + > > +static void mtdpstore_notify_add(struct mtd_info *mtd) > > +{ > > + int ret; > > + struct mtdpstore_context *cxt = &oops_cxt; > > + struct pstore_blk_config *info = &cxt->info; > > + unsigned long longcnt; > > + > > + if (!strcmp(mtd->name, info->device)) > > + cxt->index = mtd->index; > > + > > + if (mtd->index != cxt->index || cxt->index < 0) > > + return; > > + > > + 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; > > + } > > + /* > > + * 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; > > + } > > + if (unlikely(info->kmsg_size % mtd->writesize)) { > > + dev_err(&mtd->dev, "record size %lu KB must align to write size %d KB\n", > > + info->kmsg_size / 1024, > > + mtd->writesize / 1024); > > + return; > > + } > > + > > + 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)); > > + cxt->badmap = kcalloc(longcnt, sizeof(long), GFP_KERNEL); > > + > > + cxt->dev.total_size = mtd->size; > > + /* just support dmesg right now */ > > + cxt->dev.flags = PSTORE_FLAGS_DMESG; > > + cxt->dev.read = mtdpstore_read; > > + cxt->dev.write = mtdpstore_write; > > + cxt->dev.erase = mtdpstore_erase; > > + cxt->dev.panic_write = mtdpstore_panic_write; > > + > > + ret = register_pstore_device(&cxt->dev); > > + if (ret) { > > + dev_err(&mtd->dev, "mtd%d register to psblk failed\n", > > + mtd->index); > > + return; > > + } > > + 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, > > + 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@xxxxxxxxxxxxxxxxx>"); > > +MODULE_DESCRIPTION("MTD backend for pstore/blk"); > > > > -- > WeiXiong Liao -- Kees Cook
