Summary improvement
David Woodhouse
dwmw2 at infradead.org
Fri May 19 16:23:26 EDT 2006
Any comments before I pull this into the main tree? Could someone test
it on NOR flash with and without ->point() (i.e. XIP-style reads)? Would
be interesting to know (a) if it works, and (b) how much of a difference
it makes...
From: David Woodhouse <dwmw2 at infradead.org>
Date: Fri, 19 May 2006 20:15:08 +0000 (+0100)
Subject: [JFFS2] Optimise reading of eraseblock summary nodes
X-Git-Url: http://git.infradead.org/?p=users/dwmw2/jffs2-play-2.6.git;a=commitdiff;h=13364d291299216beccc8fe9d838c1945b0e8292
[JFFS2] Optimise reading of eraseblock summary nodes
This improves the time to mount 512MiB of NAND flash on my OLPC prototype
by about 4%. We used to read the last page of the eraseblock twice -- once
to find the offset of the summary node, and again to actually _read_ the
summary node. Now we read the last page only once, and read more only if
we need to.
We also don't allocate a new buffer just for the summary code -- we use
the buffer which was already allocated for the scan. Better still, if the
'buffer' for the scan is actually just a pointer directly into NOR flash,
we use that too, avoiding the memcpy() which we used to do.
Signed-off-by: David Woodhouse <dwmw2 at infradead.org>
---
--- a/fs/jffs2/scan.c
+++ b/fs/jffs2/scan.c
@@ -306,11 +306,12 @@ int jffs2_scan_classify_jeb(struct jffs2
return BLK_STATE_ALLDIRTY;
}
+/* Called with 'buf_size == 0' if buf is in fact a pointer _directly_ into
+ the flash, XIP-style */
static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
- unsigned char *buf, uint32_t buf_size, struct jffs2_summary *s) {
+ unsigned char *buf, uint32_t buf_size, struct jffs2_summary *s) {
struct jffs2_unknown_node *node;
struct jffs2_unknown_node crcnode;
- struct jffs2_sum_marker *sm;
uint32_t ofs, prevofs;
uint32_t hdr_crc, buf_ofs, buf_len;
int err;
@@ -344,32 +345,69 @@ static int jffs2_scan_eraseblock (struct
#endif
if (jffs2_sum_active()) {
- sm = kmalloc(sizeof(struct jffs2_sum_marker), GFP_KERNEL);
- if (!sm) {
- return -ENOMEM;
- }
+ struct jffs2_sum_marker *sm;
+ void *sumptr = NULL;
+ uint32_t sumlen;
+
+ if (!buf_size) {
+ /* XIP case. Just look, point at the summary if it's there */
+ sm = (void *)buf + jeb->offset - sizeof(*sm);
+ if (je32_to_cpu(sm->magic) == JFFS2_SUM_MAGIC) {
+ sumptr = buf + je32_to_cpu(sm->offset);
+ sumlen = c->sector_size - je32_to_cpu(sm->offset);
+ }
+ } else {
+ /* If NAND flash, read a whole page of it. Else just the end */
+ if (c->wbuf_pagesize)
+ buf_len = c->wbuf_pagesize;
+ else
+ buf_len = sizeof(*sm);
+
+ /* Read as much as we want into the _end_ of the preallocated buffer */
+ err = jffs2_fill_scan_buf(c, buf + buf_size - buf_len,
+ jeb->offset + c->sector_size - buf_len,
+ buf_len);
+ if (err)
+ return err;
+
+ sm = (void *)buf + buf_size - sizeof(*sm);
+ if (je32_to_cpu(sm->magic) == JFFS2_SUM_MAGIC) {
+ sumlen = c->sector_size - je32_to_cpu(sm->offset);
+ sumptr = buf + buf_size - sumlen;
+
+ /* Now, make sure the summary itself is available */
+ if (sumlen > buf_size) {
+ /* Need to kmalloc for this. */
+ sumptr = kmalloc(sumlen, GFP_KERNEL);
+ if (!sumptr)
+ return -ENOMEM;
+ memcpy(sumptr + sumlen - buf_len, buf + buf_size - buf_len, buf_len);
+ }
+ if (buf_len < sumlen) {
+ /* Need to read more so that the entire summary node is present */
+ err = jffs2_fill_scan_buf(c, sumptr,
+ jeb->offset + c->sector_size - sumlen,
+ sumlen - buf_len);
+ if (err)
+ return err;
+ }
+ }
- err = jffs2_fill_scan_buf(c, (unsigned char *) sm, jeb->offset + c->sector_size -
- sizeof(struct jffs2_sum_marker), sizeof(struct jffs2_sum_marker));
- if (err) {
- kfree(sm);
- return err;
}
- if (je32_to_cpu(sm->magic) == JFFS2_SUM_MAGIC ) {
- err = jffs2_sum_scan_sumnode(c, jeb, je32_to_cpu(sm->offset), &pseudo_random);
- if (err) {
- kfree(sm);
+ if (sumptr) {
+ err = jffs2_sum_scan_sumnode(c, jeb, sumptr, sumlen, &pseudo_random);
+ if (err)
return err;
- }
+ if (buf_size && sumlen > buf_size)
+ kfree(sumptr);
}
-
- kfree(sm);
}
buf_ofs = jeb->offset;
if (!buf_size) {
+ /* This is the XIP case -- we're reading _directly_ from the flash chip */
buf_len = c->sector_size;
} else {
buf_len = EMPTY_SCAN_SIZE(c->sector_size);
--- a/fs/jffs2/summary.c
+++ b/fs/jffs2/summary.c
@@ -417,39 +417,23 @@ static int jffs2_sum_process_sum_data(st
}
}
- kfree(summary);
return 0;
}
/* Process the summary node - called from jffs2_scan_eraseblock() */
-
int jffs2_sum_scan_sumnode(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
- uint32_t ofs, uint32_t *pseudo_random)
+ struct jffs2_raw_summary *summary, uint32_t sumsize,
+ uint32_t *pseudo_random)
{
struct jffs2_unknown_node crcnode;
struct jffs2_raw_node_ref *cache_ref;
- struct jffs2_raw_summary *summary;
- int ret, sumsize;
+ int ret, ofs;
uint32_t crc;
- sumsize = c->sector_size - ofs;
- ofs += jeb->offset;
+ ofs = jeb->offset + c->sector_size - sumsize;
dbg_summary("summary found for 0x%08x at 0x%08x (0x%x bytes)\n",
- jeb->offset, ofs, sumsize);
-
- summary = kmalloc(sumsize, GFP_KERNEL);
-
- if (!summary) {
- return -ENOMEM;
- }
-
- ret = jffs2_fill_scan_buf(c, (unsigned char *)summary, ofs, sumsize);
-
- if (ret) {
- kfree(summary);
- return ret;
- }
+ jeb->offset, ofs, sumsize);
/* OK, now check for node validity and CRC */
crcnode.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
@@ -499,7 +483,6 @@ int jffs2_sum_scan_sumnode(struct jffs2_
if (!marker_ref) {
JFFS2_NOTICE("Failed to allocate node ref for clean marker\n");
- kfree(summary);
return -ENOMEM;
}
--- a/fs/jffs2/summary.h
+++ b/fs/jffs2/summary.h
@@ -160,7 +160,8 @@ int jffs2_sum_add_padding_mem(struct jff
int jffs2_sum_add_inode_mem(struct jffs2_summary *s, struct jffs2_raw_inode *ri, uint32_t ofs);
int jffs2_sum_add_dirent_mem(struct jffs2_summary *s, struct jffs2_raw_dirent *rd, uint32_t ofs);
int jffs2_sum_scan_sumnode(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb,
- uint32_t ofs, uint32_t *pseudo_random);
+ struct jffs2_raw_summary *summary, uint32_t sumlen,
+ uint32_t *pseudo_random);
#else /* SUMMARY DISABLED */
--
dwmw2
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