RE: ubifs: read bad node type in ubifs_tnc_read_wbuf

[李傲傲 (Carson Li1/9542) <Carson.Li1@xxxxxxxxxx>]

Hi，

>@@ -1482,12 +1489,6 @@ again:
>        gc_seq1 = c->gc_seq;
>        mutex_unlock(&c->tnc_mutex);
>
>-       if (ubifs_get_wbuf(c, zbr.lnum)) {
>-               /* We do not GC journal heads */
>-               err = ubifs_tnc_read_node(c, &zbr, node);
>-               return err;
>-       }
>-
>        err = fallible_read_node(c, key, &zbr, node);
>        if (err <= 0 || maybe_leb_gced(c, zbr.lnum, gc_seq1)) {

That is what I do now. and can you please have a check at what I post before:
------------------------------------temporary solution--------------------------------
--- a/fs/ubifs/tnc.c
+++ b/fs/ubifs/tnc.c
@@ -1482,12 +1482,6 @@ again:
 gc_seq1 = c->gc_seq;
 mutex_unlock(&c->tnc_mutex);

-if (ubifs_get_wbuf(c, zbr.lnum)) {
-/* We do not GC journal heads */
-err = ubifs_tnc_read_node(c, &zbr, node);
-return err;
-}
-
Actually, compared to that solution described above, I more suggest to modify the
ubifs_get_wbuf.ubifs_get_wbuf is to check if the LEB is on the jhead, but
ubifs_tnc_read_wbuf only read node from wbuf when the lnum is equal to wbuf.lnum
and the others still need to read on flash. It seems to be better to just make
ubifs_get_wbuf to check if the LEB is equal to the wbufs.lnum, and then there is
no need to have a double check in ubifs_tnc_read_wbuf.
-----------------------------more suggested but not tested solution---------------------
--- a/fs/ubifs/log.c
+++ b/fs/ubifs/log.c
@@ -70,28 +70,16 @@ struct ubifs_bud *ubifs_search_bud(struct ubifs_info *c, int lnum)
  */
 struct ubifs_wbuf *ubifs_get_wbuf(struct ubifs_info *c, int lnum)  {
-struct rb_node *p;
-struct ubifs_bud *bud;
 int jhead;

 if (!c->jheads)
 return NULL;

-spin_lock(&c->buds_lock);
-p = c->buds.rb_node;
-while (p) {
-bud = rb_entry(p, struct ubifs_bud, rb);
-if (lnum < bud->lnum)
-p = p->rb_left;
-else if (lnum > bud->lnum)
-p = p->rb_right;
-else {
-jhead = bud->jhead;
-spin_unlock(&c->buds_lock);
+for(jhead = 0; jhead < c->jhead_cnt; jhead++){
+if(lnum == c->jheads[jhead].wbuf.lnum)
 return &c->jheads[jhead].wbuf;
-}
 }
-spin_unlock(&c->buds_lock);
+
 return NULL;
 }

--- a/fs/ubifs/io.c
+++ b/fs/ubifs/io.c
@@ -906,9 +906,10 @@ int ubifs_read_node_wbuf(struct ubifs_wbuf *wbuf, void *buf, int type, int len,
 ubifs_assert(wbuf && lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
 ubifs_assert(!(offs & 7) && offs < c->leb_size);
 ubifs_assert(type >= 0 && type < UBIFS_NODE_TYPES_CNT);
+ubifs_assert(wbuf->lnum == lnum);

 spin_lock(&wbuf->lock);
-overlap = (lnum == wbuf->lnum && offs + len > wbuf->offs);
+overlap = (offs + len > wbuf->offs);
 if (!overlap) {
 /* We may safely unlock the write-buffer and read the data */
 spin_unlock(&wbuf->lock);

after the modification, the LEB contains node will not be GCed since even though
there is a commit, the wbuf.lnum is still on the bud rbtree as a journal head leb.



Thanks.
Carson

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