[PATCH 1/2] UBIFS: add the fixup function
Matthew L. Creech
mlcreech at gmail.com
Fri May 6 18:58:22 EDT 2011
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.
Signed-off-by: Matthew L. Creech <mlcreech at gmail.com>
---
fs/ubifs/sb.c | 152 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
fs/ubifs/ubifs.h | 1 +
2 files changed, 153 insertions(+), 0 deletions(-)
diff --git a/fs/ubifs/sb.c b/fs/ubifs/sb.c
index 93d6928..3f61a5d 100644
--- a/fs/ubifs/sb.c
+++ b/fs/ubifs/sb.c
@@ -652,3 +652,155 @@ out:
kfree(sup);
return err;
}
+
+/**
+ * fixup_leb_free_space - fixup/unmap an LEB containing free space.
+ * @c: UBIFS file-system description object
+ * @lnum: LEB number
+ * @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 any empty min. I/O units 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_free_space(struct ubifs_info *c, int lnum, int len)
+{
+ int err;
+ void *sbuf = c->sbuf;
+
+ 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, sbuf, 0, len);
+ if (err && err != -EBADMSG)
+ return err;
+
+ return ubi_leb_change(c->ubi, lnum, 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_free_space(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_free_space(c, lnum, 0);
+ if (err)
+ goto out;
+ lnum = ubifs_next_log_lnum(c, lnum);
+ }
+
+ /* Fixup the current log head */
+ err = fixup_leb_free_space(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_free_space(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_free_space(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_free_space(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 fixup, the superblock space fixup 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;
+}
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index 6f0bfa9..43b3195 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -1635,6 +1635,7 @@ 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,
--
1.6.3.3
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