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Commit 6554a657 authored by Matthew L. Creech's avatar Matthew L. Creech Committed by Artem Bityutskiy
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UBIFS: add the fixup function 



This patch adds the 'ubifs_fixup_free_space()' function which scans all
LEBs in the filesystem for those that are in-use but have one or more
empty pages, then re-maps the LEBs in order to erase the empty portions.
Afterward it removes the "space_fixup" flag from the UBIFS superblock.

Artem: massaged the patch

Signed-off-by: default avatarMatthew L. Creech <mlcreech@gmail.com>
Signed-off-by: default avatarArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
parent 9f58d350

fs/ubifs/sb.c

+149 −0
Original line number Diff line number Diff line
@@ -652,3 +652,152 @@ out: 
	kfree(sup);

	return err;

}



/**

 * fixup_leb - fixup/unmap an LEB containing free space.

 * @c: UBIFS file-system description object

 * @lnum: the LEB number to fix up

 * @len: number of used bytes in LEB (starting at offset 0)

 *

 * This function reads the contents of the given LEB number @lnum, then fixes

 * it up, so that empty min. I/O units in the end of LEB are actually erased on

 * flash (rather than being just all-0xff real data). If the LEB is completely

 * empty, it is simply unmapped.

 */

static int fixup_leb(struct ubifs_info *c, int lnum, int len)

{

	int err;



	ubifs_assert(len >= 0);

	ubifs_assert(len % c->min_io_size == 0);

	ubifs_assert(len < c->leb_size);



	if (len == 0) {

		dbg_mnt("unmap empty LEB %d", lnum);

		return ubi_leb_unmap(c->ubi, lnum);

	}



	dbg_mnt("fixup LEB %d, data len %d", lnum, len);

	err = ubi_read(c->ubi, lnum, c->sbuf, 0, len);

	if (err)

		return err;



	return ubi_leb_change(c->ubi, lnum, c->sbuf, len, UBI_UNKNOWN);

}



/**

 * fixup_free_space - find & remap all LEBs containing free space.

 * @c: UBIFS file-system description object

 *

 * This function walks through all LEBs in the filesystem and fiexes up those

 * containing free/empty space.

 */

static int fixup_free_space(struct ubifs_info *c)

{

	int lnum, err = 0;

	struct ubifs_lprops *lprops;



	ubifs_get_lprops(c);



	/* Fixup LEBs in the master area */

	for (lnum = UBIFS_MST_LNUM; lnum < UBIFS_LOG_LNUM; lnum++) {

		err = fixup_leb(c, lnum, c->mst_offs + c->mst_node_alsz);

		if (err)

			goto out;

	}



	/* Unmap unused log LEBs */

	lnum = ubifs_next_log_lnum(c, c->lhead_lnum);

	while (lnum != c->ltail_lnum) {

		err = fixup_leb(c, lnum, 0);

		if (err)

			goto out;

		lnum = ubifs_next_log_lnum(c, lnum);

	}



	/* Fixup the current log head */

	err = fixup_leb(c, c->lhead_lnum, c->lhead_offs);

	if (err)

		goto out;



	/* Fixup LEBs in the LPT area */

	for (lnum = c->lpt_first; lnum <= c->lpt_last; lnum++) {

		int free = c->ltab[lnum - c->lpt_first].free;



		if (free > 0) {

			err = fixup_leb(c, lnum, c->leb_size - free);

			if (err)

				goto out;

		}

	}



	/* Unmap LEBs in the orphans area */

	for (lnum = c->orph_first; lnum <= c->orph_last; lnum++) {

		err = fixup_leb(c, lnum, 0);

		if (err)

			goto out;

	}



	/* Fixup LEBs in the main area */

	for (lnum = c->main_first; lnum < c->leb_cnt; lnum++) {

		lprops = ubifs_lpt_lookup(c, lnum);

		if (IS_ERR(lprops)) {

			err = PTR_ERR(lprops);

			goto out;

		}



		if (lprops->free > 0) {

			err = fixup_leb(c, lnum, c->leb_size - lprops->free);

			if (err)

				goto out;

		}

	}



out:

	ubifs_release_lprops(c);

	return err;

}



/**

 * ubifs_fixup_free_space - find & fix all LEBs with free space.

 * @c: UBIFS file-system description object

 *

 * This function fixes up LEBs containing free space on first mount, if the

 * appropriate flag was set when the FS was created. Each LEB with one or more

 * empty min. I/O unit (i.e. free-space-count > 0) is re-written, to make sure

 * the free space is actually erased. E.g., this is necessary for some NAND

 * chips, since the free space may have been programmed like real "0xff" data

 * (generating a non-0xff ECC), causing future writes to the not-really-erased

 * NAND pages to behave badly. After the space is fixed up, the superblock flag

 * is cleared, so that this is skipped for all future mounts.

 */

int ubifs_fixup_free_space(struct ubifs_info *c)

{

	int err;

	struct ubifs_sb_node *sup;



	ubifs_assert(c->space_fixup);

	ubifs_assert(!c->ro_mount);



	ubifs_msg("start fixing up free space");



	err = fixup_free_space(c);

	if (err)

		return err;



	sup = ubifs_read_sb_node(c);

	if (IS_ERR(sup))

		return PTR_ERR(sup);



	/* Free-space fixup is no longer required */

	c->space_fixup = 0;

	sup->flags &= cpu_to_le32(~UBIFS_FLG_SPACE_FIXUP);



	err = ubifs_write_sb_node(c, sup);

	kfree(sup);

	if (err)

		return err;



	ubifs_msg("free space fixup complete");

	return err;

}

fs/ubifs/ubifs.h

+1 −0
Original line number Diff line number Diff line
@@ -1633,6 +1633,7 @@ int ubifs_write_master(struct ubifs_info *c); 
int ubifs_read_superblock(struct ubifs_info *c);

struct ubifs_sb_node *ubifs_read_sb_node(struct ubifs_info *c);

int ubifs_write_sb_node(struct ubifs_info *c, struct ubifs_sb_node *sup);

int ubifs_fixup_free_space(struct ubifs_info *c);



/* replay.c */

int ubifs_validate_entry(struct ubifs_info *c,