[PATCH] cpukit/jffs2: Handle used empty file system

[Joel Sherrill]

Ignoring any specific technical comments from others.

(1) Should this have a ticket? Seems impactful and odd enough to since that
shows up in release notes.

(2) Should it also be applied to 5.x with a separate ticket?

--joel

On Fri, Feb 2, 2024 at 4:40 PM Kinsey Moore <kinsey.moore at oarcorp.com>
wrote:

> On JFFS2 file systems on NOR flash or dataflash that does not have spare
> area for metadata and thus does not invoke delayed writes, it is
> possible to put the file system into a state where all blocks have been
> written to and all files have been deleted from the filesystem. There is
> a bug in the JFFS2 file system scan routine that detects this situation
> as a corrupted file system since the scan routine relies on "used" space
> to discriminate a valid file system when there are blocks that need to
> be erased. The correct fix would require a partial rewrite of the scan
> routine, so instead this patch tracks the space marked as obsolete along
> with space at the end of each block that is otherwise too small to
> contain a JFFS2 node so that it can me compared with the dirty space.
> Corrupted data (or otherwise non-JFFS2 blocks) will still cause this
> check to fail as corrupted data isn't recognized as obsoleted (deleted)
> nodes.
> ---
>  cpukit/libfs/src/jffs2/src/jffs2_fs_sb.h |  3 +++
>  cpukit/libfs/src/jffs2/src/scan.c        | 24 ++++++++++++++++++++++++
>  2 files changed, 27 insertions(+)
>
> diff --git a/cpukit/libfs/src/jffs2/src/jffs2_fs_sb.h
> b/cpukit/libfs/src/jffs2/src/jffs2_fs_sb.h
> index 4ee43a6f30..7960f92f85 100644
> --- a/cpukit/libfs/src/jffs2/src/jffs2_fs_sb.h
> +++ b/cpukit/libfs/src/jffs2/src/jffs2_fs_sb.h
> @@ -75,6 +75,9 @@ struct jffs2_sb_info {
>         uint32_t bad_size;
>         uint32_t sector_size;
>         uint32_t unchecked_size;
> +#ifdef __rtems__
> +       uint32_t obsolete_size;
> +#endif
>
>         uint32_t nr_free_blocks;
>         uint32_t nr_erasing_blocks;
> diff --git a/cpukit/libfs/src/jffs2/src/scan.c
> b/cpukit/libfs/src/jffs2/src/scan.c
> index 10663feb1f..8ac4a40414 100644
> --- a/cpukit/libfs/src/jffs2/src/scan.c
> +++ b/cpukit/libfs/src/jffs2/src/scan.c
> @@ -264,14 +264,32 @@ int jffs2_scan_medium(struct jffs2_sb_info *c)
>         }
>  #endif
>         if (c->nr_erasing_blocks) {
> +#ifdef __rtems__
> +               if (c->obsolete_size != c->dirty_size) {
> +#endif
>                 if (!c->used_size && !c->unchecked_size &&
>                         ((c->nr_free_blocks+empty_blocks+bad_blocks) !=
> c->nr_blocks || bad_blocks == c->nr_blocks)) {
>                         pr_notice("Cowardly refusing to erase blocks on
> filesystem with no valid JFFS2 nodes\n");
>                         pr_notice("empty_blocks %d, bad_blocks %d,
> c->nr_blocks %d\n",
>                                   empty_blocks, bad_blocks, c->nr_blocks);
> +#ifdef __rtems__
> +                       pr_notice("nr_erasing_blocks %d, used 0x%x, dirty
> 0x%x, wasted 0x%x, free 0x%x, erasing 0x%x, bad 0x%x, obsolete 0x%x,
> unchecked 0x%x\n",
> +                                 c->nr_erasing_blocks,
> +                                 c->used_size,
> +                                 c->dirty_size,
> +                                 c->wasted_size,
> +                                 c->free_size,
> +                                 c->erasing_size,
> +                                 c->bad_size,
> +                                 c->obsolete_size,
> +                                 c->unchecked_size);
> +#endif
>                         ret = -EIO;
>                         goto out;
>                 }
> +#ifdef __rtems__
> +               }
> +#endif
>                 spin_lock(&c->erase_completion_lock);
>                 jffs2_garbage_collect_trigger(c);
>                 spin_unlock(&c->erase_completion_lock);
> @@ -646,6 +664,9 @@ scan_more:
>                                   sizeof(struct jffs2_unknown_node),
>                                   jeb->offset, c->sector_size, ofs,
>                                   sizeof(*node));
> +#ifdef __rtems__
> +                       c->obsolete_size += (jeb->offset + c->sector_size
> - ofs);
> +#endif
>                         if ((err = jffs2_scan_dirty_space(c, jeb,
> (jeb->offset + c->sector_size)-ofs)))
>                                 return err;
>                         break;
> @@ -796,6 +817,9 @@ scan_more:
>                         if ((err = jffs2_scan_dirty_space(c, jeb,
> PAD(je32_to_cpu(node->totlen)))))
>                                 return err;
>                         ofs += PAD(je32_to_cpu(node->totlen));
> +#ifdef __rtems__
> +                       c->obsolete_size += PAD(je32_to_cpu(node->totlen));
> +#endif
>                         continue;
>                 }
>
> --
> 2.39.2
>
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