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Subject[PATCH] Reduce nr of ptr derefs in fs/jffs2/summary.c
Date
Here's a small patch to reduce the nr. of pointer dereferences in
fs/jffs2/summary.c

Benefits:
- micro speed optimization due to fewer pointer derefs
- generated code is slightly smaller
- better readability

Please consider applying...


Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
---

fs/jffs2/summary.c | 38 +++++++++++++++++++-------------------
1 files changed, 19 insertions(+), 19 deletions(-)

orig:
text data bss dec hex filename
5033 0 0 5033 13a9 fs/jffs2/summary.o
patched:
text data bss dec hex filename
4935 0 0 4935 1347 fs/jffs2/summary.o

--- linux-2.6.15-rc5-git1-orig/fs/jffs2/summary.c 2005-12-04 18:48:38.000000000 +0100
+++ linux-2.6.15-rc5-git1/fs/jffs2/summary.c 2005-12-11 06:01:51.000000000 +0100
@@ -581,16 +581,17 @@ static int jffs2_sum_write_data(struct j
wpage = c->summary->sum_buf;

while (c->summary->sum_num) {
+ temp = c->summary->sum_list_head;

- switch (je16_to_cpu(c->summary->sum_list_head->u.nodetype)) {
+ switch (je16_to_cpu(temp->u.nodetype)) {
case JFFS2_NODETYPE_INODE: {
struct jffs2_sum_inode_flash *sino_ptr = wpage;

- sino_ptr->nodetype = c->summary->sum_list_head->i.nodetype;
- sino_ptr->inode = c->summary->sum_list_head->i.inode;
- sino_ptr->version = c->summary->sum_list_head->i.version;
- sino_ptr->offset = c->summary->sum_list_head->i.offset;
- sino_ptr->totlen = c->summary->sum_list_head->i.totlen;
+ sino_ptr->nodetype = temp->i.nodetype;
+ sino_ptr->inode = temp->i.inode;
+ sino_ptr->version = temp->i.version;
+ sino_ptr->offset = temp->i.offset;
+ sino_ptr->totlen = temp->i.totlen;

wpage += JFFS2_SUMMARY_INODE_SIZE;

@@ -600,19 +601,19 @@ static int jffs2_sum_write_data(struct j
case JFFS2_NODETYPE_DIRENT: {
struct jffs2_sum_dirent_flash *sdrnt_ptr = wpage;

- sdrnt_ptr->nodetype = c->summary->sum_list_head->d.nodetype;
- sdrnt_ptr->totlen = c->summary->sum_list_head->d.totlen;
- sdrnt_ptr->offset = c->summary->sum_list_head->d.offset;
- sdrnt_ptr->pino = c->summary->sum_list_head->d.pino;
- sdrnt_ptr->version = c->summary->sum_list_head->d.version;
- sdrnt_ptr->ino = c->summary->sum_list_head->d.ino;
- sdrnt_ptr->nsize = c->summary->sum_list_head->d.nsize;
- sdrnt_ptr->type = c->summary->sum_list_head->d.type;
+ sdrnt_ptr->nodetype = temp->d.nodetype;
+ sdrnt_ptr->totlen = temp->d.totlen;
+ sdrnt_ptr->offset = temp->d.offset;
+ sdrnt_ptr->pino = temp->d.pino;
+ sdrnt_ptr->version = temp->d.version;
+ sdrnt_ptr->ino = temp->d.ino;
+ sdrnt_ptr->nsize = temp->d.nsize;
+ sdrnt_ptr->type = temp->d.type;

- memcpy(sdrnt_ptr->name, c->summary->sum_list_head->d.name,
- c->summary->sum_list_head->d.nsize);
+ memcpy(sdrnt_ptr->name, temp->d.name,
+ temp->d.nsize);

- wpage += JFFS2_SUMMARY_DIRENT_SIZE(c->summary->sum_list_head->d.nsize);
+ wpage += JFFS2_SUMMARY_DIRENT_SIZE(temp->d.nsize);

break;
}
@@ -622,8 +623,7 @@ static int jffs2_sum_write_data(struct j
}
}

- temp = c->summary->sum_list_head;
- c->summary->sum_list_head = c->summary->sum_list_head->u.next;
+ c->summary->sum_list_head = temp->u.next;
kfree(temp);

c->summary->sum_num--;


-
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