One requirement to support MTD devices in pstore/zone is having a way to declare certain regions as broken. Add this support to pstore/zone. The MTD driver should return -ENOMSG when encountering a bad region, which tells pstore/zone to skip and try the next one. Signed-off-by: WeiXiong Liao <liaoweixiong@xxxxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/1585126506-18635-9-git-send-email-liaoweixiong@xxxxxxxxxxxxxxxxx Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> --- fs/pstore/blk.c | 10 +++++-- fs/pstore/zone.c | 65 ++++++++++++++++++++++++++++++++++++--------- include/linux/pstore_blk.h | 3 ++- include/linux/pstore_zone.h | 12 ++++++--- 4 files changed, 71 insertions(+), 19 deletions(-) diff --git a/fs/pstore/blk.c b/fs/pstore/blk.c index 84ca98923d8a..bf27dbd18db2 100644 --- a/fs/pstore/blk.c +++ b/fs/pstore/blk.c @@ -101,9 +101,12 @@ * means error. * @write: The same as @read, but the following error number: * -EBUSY means try to write again later. + * -ENOMSG means to try next zone. * @panic_write:The write operation only used for panic case. It's optional - * if you do not care panic log. The parameters and return value - * are the same as @read. + * if you do not care panic log. The parameters are relative + * value to storage. + * On success, the number of bytes should be returned, others + * excluding -ENOMSG mean error. -ENOMSG means to try next zone. */ struct psblk_device { unsigned long total_size; @@ -315,6 +318,9 @@ static ssize_t psblk_blk_panic_write(const char *buf, size_t size, /* size and off must align to SECTOR_SIZE for block device */ ret = blkdev_panic_write(buf, off >> SECTOR_SHIFT, size >> SECTOR_SHIFT); + /* try next zone */ + if (ret == -ENOMSG) + return ret; return ret ? -EIO : size; } diff --git a/fs/pstore/zone.c b/fs/pstore/zone.c index a51594f95347..9a9a4a7134d0 100644 --- a/fs/pstore/zone.c +++ b/fs/pstore/zone.c @@ -247,6 +247,9 @@ static int psz_zone_write(struct pstore_zone *zone, return 0; dirty: + /* no need to mark dirty if going to try next zone */ + if (wcnt == -ENOMSG) + return -ENOMSG; atomic_set(&zone->dirty, true); /* flush dirty zones nicely */ if (wcnt == -EBUSY && !is_on_panic()) @@ -389,7 +392,11 @@ static int psz_recover_oops_meta(struct psz_context *cxt) return -EINVAL; rcnt = info->read((char *)buf, len, zone->off); - if (rcnt != len) { + if (rcnt == -ENOMSG) { + pr_debug("%s with id %lu may be broken, skip\n", + zone->name, i); + continue; + } else if (rcnt != len) { pr_err("read %s with id %lu failed\n", zone->name, i); return (int)rcnt < 0 ? (int)rcnt : -EIO; } @@ -724,24 +731,58 @@ static void psz_write_kmsg_hdr(struct pstore_zone *zone, hdr->counter = 0; } +/* + * In case zone is broken, which may occur to MTD device, we try each zones, + * start at cxt->oops_write_cnt. + */ static inline int notrace psz_oops_write_record(struct psz_context *cxt, struct pstore_record *record) { + int ret = -EBUSY; size_t size, hlen; struct pstore_zone *zone; - unsigned int zonenum; + unsigned int i; - zonenum = cxt->oops_write_cnt; - zone = cxt->opszs[zonenum]; - if (unlikely(!zone)) - return -ENOSPC; - cxt->oops_write_cnt = (zonenum + 1) % cxt->oops_max_cnt; + for (i = 0; i < cxt->oops_max_cnt; i++) { + unsigned int zonenum, len; - pr_debug("write %s to zone id %d\n", zone->name, zonenum); - psz_write_kmsg_hdr(zone, record); - hlen = sizeof(struct psz_oops_header); - size = min_t(size_t, record->size, zone->buffer_size - hlen); - return psz_zone_write(zone, FLUSH_ALL, record->buf, size, hlen); + zonenum = (cxt->oops_write_cnt + i) % cxt->oops_max_cnt; + zone = cxt->opszs[zonenum]; + if (unlikely(!zone)) + return -ENOSPC; + + /* avoid destorying old data, allocate a new one */ + len = zone->buffer_size + sizeof(*zone->buffer); + zone->oldbuf = zone->buffer; + zone->buffer = kzalloc(len, GFP_KERNEL); + if (!zone->buffer) { + zone->buffer = zone->oldbuf; + return -ENOMEM; + } + zone->buffer->sig = zone->oldbuf->sig; + + pr_debug("write %s to zone id %d\n", zone->name, zonenum); + psz_write_kmsg_hdr(zone, record); + hlen = sizeof(struct psz_oops_header); + size = min_t(size_t, record->size, zone->buffer_size - hlen); + ret = psz_zone_write(zone, FLUSH_ALL, record->buf, size, hlen); + if (likely(!ret || ret != -ENOMSG)) { + cxt->oops_write_cnt = zonenum + 1; + cxt->oops_write_cnt %= cxt->oops_max_cnt; + /* no need to try next zone, free last zone buffer */ + kfree(zone->oldbuf); + zone->oldbuf = NULL; + return ret; + } + + pr_debug("zone %u may be broken, try next dmesg zone\n", + zonenum); + kfree(zone->buffer); + zone->buffer = zone->oldbuf; + zone->oldbuf = NULL; + } + + return -EBUSY; } static int notrace psz_oops_write(struct psz_context *cxt, diff --git a/include/linux/pstore_blk.h b/include/linux/pstore_blk.h index d8f609e60288..828b0763d477 100644 --- a/include/linux/pstore_blk.h +++ b/include/linux/pstore_blk.h @@ -14,7 +14,8 @@ * @start_sect: start sector to block device * @sects: sectors count on buf * - * Return: On success, zero should be returned. Others mean error. + * Return: On success, zero should be returned. Others excluding -ENOMSG + * mean error. -ENOMSG means to try next zone. * * Panic write to block device must be aligned to SECTOR_SIZE. */ diff --git a/include/linux/pstore_zone.h b/include/linux/pstore_zone.h index 94f441b8b616..ddb3dfea4ea6 100644 --- a/include/linux/pstore_zone.h +++ b/include/linux/pstore_zone.h @@ -23,11 +23,15 @@ * @read: The general read operation. Both of the function parameters * @size and @offset are relative value to storage. * On success, the number of bytes should be returned, others - * means error. - * @write: The same as @read, but -EBUSY means try to write again later. + * mean error. + * @write: The same as @read, but the following error number: + * -EBUSY means try to write again later. + * -ENOMSG means to try next zone. * @panic_write:The write operation only used for panic case. It's optional - * if you do not care panic log. The parameters and return value - * are the same as @read. + * if you do not care panic log. The parameters are relative + * value to storage. + * On success, the number of bytes should be returned, others + * excluding -ENOMSG mean error. -ENOMSG means to try next zone. */ struct pstore_zone_info { struct module *owner; -- 1.9.1
