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[JFFS2] Optimise reading of eraseblock summary nodes

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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@infradead.org>
This commit is contained in:
David Woodhouse
2006-05-20 16:13:34 +01:00
parent 6c8b44abc8
commit 9641b784ff
3 changed files with 66 additions and 51 deletions
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36
fs/jffs2/summary.c
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@@ -318,7 +318,6 @@ static int jffs2_sum_process_sum_data(struct jffs2_sb_info *c, struct jffs2_eras
raw = jffs2_alloc_raw_node_ref();
if (!raw) {
JFFS2_NOTICE("allocation of node reference failed\n");
kfree(summary);
return -ENOMEM;
}
@@ -326,7 +325,6 @@ static int jffs2_sum_process_sum_data(struct jffs2_sb_info *c, struct jffs2_eras
if (!ic) {
JFFS2_NOTICE("scan_make_ino_cache failed\n");
jffs2_free_raw_node_ref(raw);
kfree(summary);
return -ENOMEM;
}
@@ -358,10 +356,8 @@ static int jffs2_sum_process_sum_data(struct jffs2_sb_info *c, struct jffs2_eras
jeb->offset + je32_to_cpu(spd->offset));
fd = jffs2_alloc_full_dirent(spd->nsize+1);
if (!fd) {
kfree(summary);
if (!fd)
return -ENOMEM;
}
memcpy(&fd->name, spd->name, spd->nsize);
fd->name[spd->nsize] = 0;
@@ -370,7 +366,6 @@ static int jffs2_sum_process_sum_data(struct jffs2_sb_info *c, struct jffs2_eras
if (!raw) {
jffs2_free_full_dirent(fd);
JFFS2_NOTICE("allocation of node reference failed\n");
kfree(summary);
return -ENOMEM;
}
@@ -378,7 +373,6 @@ static int jffs2_sum_process_sum_data(struct jffs2_sb_info *c, struct jffs2_eras
if (!ic) {
jffs2_free_full_dirent(fd);
jffs2_free_raw_node_ref(raw);
kfree(summary);
return -ENOMEM;
}
@@ -411,45 +405,28 @@ static int jffs2_sum_process_sum_data(struct jffs2_sb_info *c, struct jffs2_eras
default : {
JFFS2_WARNING("Unsupported node type found in summary! Exiting...");
kfree(summary);
return -EIO;
}
}
}
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 +476,6 @@ int jffs2_sum_scan_sumnode(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb
if (!marker_ref) {
JFFS2_NOTICE("Failed to allocate node ref for clean marker\n");
kfree(summary);
return -ENOMEM;
}