Re: [PATCH] UBIFS: endian handling fixes and annotations

Sebastian Andrzej Siewior
2008-11-22T19:28:00Z

* Artem Bityutskiy | 2008-11-21 19:19:24 [+0200]:

>index 9ee6508..3f1f16b 100644
>--- a/fs/ubifs/key.h
>+++ b/fs/ubifs/key.h
>@@ -345,7 +345,7 @@ static inline int key_type_flash(const struct ubifs_info *c, const void *k)
> {
> const union ubifs_key *key = k;
>
>- return le32_to_cpu(key->u32[1]) >> UBIFS_S_KEY_BLOCK_BITS;
>+ return le32_to_cpu(key->j32[1]) >> UBIFS_S_KEY_BLOCK_BITS;

If you would change such references to something like
|return le32_to_cpup(&key->j32[1]) >> UBIFS_S_KEY_BLOCK_BITS;
then on powerpc

text data bss dec hex filename
155384 1284 24 156692 26414 ubifs-b4.ko
155372 1284 24 156680 26408 ubifs-after.ko

because now it is possible to load the value as LE from memory instead
of loading it BE and swapping it afterwads.

> }
>
> /**
>@@ -416,7 +416,7 @@ static inline unsigned int key_block_flash(const struct ubifs_info *c,
> {
> const union ubifs_key *key = k;
>
>- return le32_to_cpu(key->u32[1]) & UBIFS_S_KEY_BLOCK_MASK;
>+ return le32_to_cpu(key->j32[1]) & UBIFS_S_KEY_BLOCK_MASK;
> }

This and the previous change look like a bugfix for something that
should trigger during recovery or something? Shouldn't I fail in
ubifs_validate_entry() during recovery?

> /**
>diff --git a/fs/ubifs/recovery.c b/fs/ubifs/recovery.c
>index 77d26c1..bed9742 100644
>--- a/fs/ubifs/recovery.c
>+++ b/fs/ubifs/recovery.c
>@@ -168,12 +168,12 @@ static int write_rcvrd_mst_node(struct ubifs_info *c,
> struct ubifs_mst_node *mst)
> {
> int err = 0, lnum = UBIFS_MST_LNUM, sz = c->mst_node_alsz;
>- uint32_t save_flags;
>+ __le32 save_flags;
>
> dbg_rcvry("recovery");
>
> save_flags = mst->flags;
>- mst->flags = cpu_to_le32(le32_to_cpu(mst->flags) | UBIFS_MST_RCVRY);
>+ mst->flags |= cpu_to_le32(UBIFS_MST_RCVRY);

another micro optimisation would be to use __constant_cpu_to_le32()

Sebastian