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Commit 9641b784 authored by David Woodhouse's avatar David Woodhouse
Browse files

[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: default avatarDavid Woodhouse <dwmw2@infradead.org>
parent 6c8b44ab

fs/jffs2/scan.c

+56 −18
Original line number Diff line number Diff line
@@ -306,11 +306,12 @@ int jffs2_scan_classify_jeb(struct jffs2_sb_info *c, struct jffs2_eraseblock *je 
		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) {

	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 jffs2_sb_info *c, struct jffs2_eraseblo 
#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);



		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);

			/* 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) {

			err = jffs2_sum_scan_sumnode(c, jeb, je32_to_cpu(sm->offset), &pseudo_random);

			if (err) {

				kfree(sm);

				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;

				}

			}



		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);

		}

	}



	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);

fs/jffs2/summary.c

+6 −30
Original line number Diff line number Diff line
@@ -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;

				}
@@ -411,46 +405,29 @@ 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;

	}



	/* OK, now check for node validity and CRC */

	crcnode.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);

	crcnode.nodetype = cpu_to_je16(JFFS2_NODETYPE_SUMMARY);
@@ -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;

			}

fs/jffs2/summary.h

+2 −1
Original line number Diff line number Diff line
@@ -160,7 +160,8 @@ int jffs2_sum_add_padding_mem(struct jffs2_summary *s, uint32_t size); 
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 */