}
/**
- * drop_incomplete_group - drop nodes from an incomplete group.
+ * drop_last_node - drop the last node or group of nodes.
* @sleb: scanned LEB information
* @offs: offset of dropped nodes is returned here
+ * @grouped: non-zero if whole group of nodes have to be dropped
*
- * This function returns %1 if nodes are dropped and %0 otherwise.
+ * This is a helper function for 'ubifs_recover_leb()' which drops the last
+ * node of the scanned LEB or the last group of nodes if @grouped is not zero.
+ * This function returns %1 if a node was dropped and %0 otherwise.
*/
-static int drop_incomplete_group(struct ubifs_scan_leb *sleb, int *offs)
+static int drop_last_node(struct ubifs_scan_leb *sleb, int *offs, int grouped)
{
int dropped = 0;
kfree(snod);
sleb->nodes_cnt -= 1;
dropped = 1;
+ if (!grouped)
+ break;
}
return dropped;
}
struct ubifs_scan_leb *ubifs_recover_leb(struct ubifs_info *c, int lnum,
int offs, void *sbuf, int grouped)
{
- int err, len = c->leb_size - offs, need_clean = 0, quiet = 1;
- int empty_chkd = 0, start = offs;
+ int ret = 0, err, len = c->leb_size - offs, start = offs, min_io_unit;
struct ubifs_scan_leb *sleb;
void *buf = sbuf + offs;
if (IS_ERR(sleb))
return sleb;
- if (sleb->ecc)
- need_clean = 1;
-
+ ubifs_assert(len >= 8);
while (len >= 8) {
- int ret;
-
dbg_scan("look at LEB %d:%d (%d bytes left)",
lnum, offs, len);
* Scan quietly until there is an error from which we cannot
* recover
*/
- ret = ubifs_scan_a_node(c, buf, len, lnum, offs, quiet);
-
+ ret = ubifs_scan_a_node(c, buf, len, lnum, offs, 0);
if (ret == SCANNED_A_NODE) {
/* A valid node, and not a padding node */
struct ubifs_ch *ch = buf;
offs += node_len;
buf += node_len;
len -= node_len;
- continue;
- }
-
- if (ret > 0) {
+ } else if (ret > 0) {
/* Padding bytes or a valid padding node */
offs += ret;
buf += ret;
len -= ret;
- continue;
- }
-
- if (ret == SCANNED_EMPTY_SPACE) {
- if (!is_empty(buf, len)) {
- if (!is_last_write(c, buf, offs))
- break;
- clean_buf(c, &buf, lnum, &offs, &len);
- need_clean = 1;
- }
- empty_chkd = 1;
+ } else if (ret == SCANNED_EMPTY_SPACE ||
+ ret == SCANNED_GARBAGE ||
+ ret == SCANNED_A_BAD_PAD_NODE ||
+ ret == SCANNED_A_CORRUPT_NODE) {
+ dbg_rcvry("found corruption - %d", ret);
break;
- }
-
- if (ret == SCANNED_GARBAGE || ret == SCANNED_A_BAD_PAD_NODE)
- if (is_last_write(c, buf, offs)) {
- clean_buf(c, &buf, lnum, &offs, &len);
- need_clean = 1;
- empty_chkd = 1;
- break;
- }
-
- if (ret == SCANNED_A_CORRUPT_NODE)
- if (no_more_nodes(c, buf, len, lnum, offs)) {
- clean_buf(c, &buf, lnum, &offs, &len);
- need_clean = 1;
- empty_chkd = 1;
- break;
- }
-
- if (quiet) {
- /* Redo the last scan but noisily */
- quiet = 0;
- continue;
- }
-
- switch (ret) {
- case SCANNED_GARBAGE:
- dbg_err("garbage");
- goto corrupted;
- case SCANNED_A_CORRUPT_NODE:
- case SCANNED_A_BAD_PAD_NODE:
- dbg_err("bad node");
- goto corrupted;
- default:
- dbg_err("unknown");
+ } else {
+ dbg_err("unexpected return value %d", ret);
err = -EINVAL;
goto error;
}
}
- if (!empty_chkd && !is_empty(buf, len)) {
- if (is_last_write(c, buf, offs)) {
- clean_buf(c, &buf, lnum, &offs, &len);
- need_clean = 1;
- } else {
+ if (ret == SCANNED_GARBAGE || ret == SCANNED_A_BAD_PAD_NODE) {
+ if (!is_last_write(c, buf, offs))
+ goto corrupted_rescan;
+ } else if (ret == SCANNED_A_CORRUPT_NODE) {
+ if (!no_more_nodes(c, buf, len, lnum, offs))
+ goto corrupted_rescan;
+ } else if (!is_empty(buf, len)) {
+ if (!is_last_write(c, buf, offs)) {
int corruption = first_non_ff(buf, len);
/*
}
}
- /* Drop nodes from incomplete group */
- if (grouped && drop_incomplete_group(sleb, &offs)) {
- buf = sbuf + offs;
- len = c->leb_size - offs;
- clean_buf(c, &buf, lnum, &offs, &len);
- need_clean = 1;
- }
+ min_io_unit = round_down(offs, c->min_io_size);
+ if (grouped)
+ /*
+ * If nodes are grouped, always drop the incomplete group at
+ * the end.
+ */
+ drop_last_node(sleb, &offs, 1);
- if (offs % c->min_io_size) {
- clean_buf(c, &buf, lnum, &offs, &len);
- need_clean = 1;
- }
+ /*
+ * While we are in the middle of the same min. I/O unit keep dropping
+ * nodes. So basically, what we want is to make sure that the last min.
+ * I/O unit where we saw the corruption is dropped completely with all
+ * the uncorrupted node which may possibly sit there.
+ *
+ * In other words, let's name the min. I/O unit where the corruption
+ * starts B, and the previous min. I/O unit A. The below code tries to
+ * deal with a situation when half of B contains valid nodes or the end
+ * of a valid node, and the second half of B contains corrupted data or
+ * garbage. This means that UBIFS had been writing to B just before the
+ * power cut happened. I do not know how realistic is this scenario
+ * that half of the min. I/O unit had been written successfully and the
+ * other half not, but this is possible in our 'failure mode emulation'
+ * infrastructure at least.
+ *
+ * So what is the problem, why we need to drop those nodes? Whey can't
+ * we just clean-up the second half of B by putting a padding node
+ * there? We can, and this works fine with one exception which was
+ * reproduced with power cut emulation testing and happens extremely
+ * rarely. The description follows, but it is worth noting that that is
+ * only about the GC head, so we could do this trick only if the bud
+ * belongs to the GC head, but it does not seem to be worth an
+ * additional "if" statement.
+ *
+ * So, imagine the file-system is full, we run GC which is moving valid
+ * nodes from LEB X to LEB Y (obviously, LEB Y is the current GC head
+ * LEB). The @c->gc_lnum is -1, which means that GC will retain LEB X
+ * and will try to continue. Imagine that LEB X is currently the
+ * dirtiest LEB, and the amount of used space in LEB Y is exactly the
+ * same as amount of free space in LEB X.
+ *
+ * And a power cut happens when nodes are moved from LEB X to LEB Y. We
+ * are here trying to recover LEB Y which is the GC head LEB. We find
+ * the min. I/O unit B as described above. Then we clean-up LEB Y by
+ * padding min. I/O unit. And later 'ubifs_rcvry_gc_commit()' function
+ * fails, because it cannot find a dirty LEB which could be GC'd into
+ * LEB Y! Even LEB X does not match because the amount of valid nodes
+ * there does not fit the free space in LEB Y any more! And this is
+ * because of the padding node which we added to LEB Y. The
+ * user-visible effect of this which I once observed and analysed is
+ * that we cannot mount the file-system with -ENOSPC error.
+ *
+ * So obviously, to make sure that situation does not happen we should
+ * free min. I/O unit B in LEB Y completely and the last used min. I/O
+ * unit in LEB Y should be A. This is basically what the below code
+ * tries to do.
+ */
+ while (min_io_unit == round_down(offs, c->min_io_size) &&
+ min_io_unit != offs &&
+ drop_last_node(sleb, &offs, grouped));
+
+ buf = sbuf + offs;
+ len = c->leb_size - offs;
+ clean_buf(c, &buf, lnum, &offs, &len);
ubifs_end_scan(c, sleb, lnum, offs);
- if (need_clean) {
- err = fix_unclean_leb(c, sleb, start);
- if (err)
- goto error;
- }
+ err = fix_unclean_leb(c, sleb, start);
+ if (err)
+ goto error;
return sleb;
+corrupted_rescan:
+ /* Re-scan the corrupted data with verbose messages */
+ dbg_err("corruptio %d", ret);
+ ubifs_scan_a_node(c, buf, len, lnum, offs, 1);
corrupted:
ubifs_scanned_corruption(c, lnum, offs, buf);
err = -EUCLEAN;
return 0;
}
+/**
+ * grab_empty_leb - grab an empty LEB to use as GC LEB and run commit.
+ * @c: UBIFS file-system description object
+ *
+ * This is a helper function for 'ubifs_rcvry_gc_commit()' which grabs an empty
+ * LEB to be used as GC LEB (@c->gc_lnum), and then runs the commit. Returns
+ * zero in case of success and a negative error code in case of failure.
+ */
+static int grab_empty_leb(struct ubifs_info *c)
+{
+ int lnum, err;
+
+ /*
+ * Note, it is very important to first search for an empty LEB and then
+ * run the commit, not vice-versa. The reason is that there might be
+ * only one empty LEB at the moment, the one which has been the
+ * @c->gc_lnum just before the power cut happened. During the regular
+ * UBIFS operation (not now) @c->gc_lnum is marked as "taken", so no
+ * one but GC can grab it. But at this moment this single empty LEB is
+ * not marked as taken, so if we run commit - what happens? Right, the
+ * commit will grab it and write the index there. Remember that the
+ * index always expands as long as there is free space, and it only
+ * starts consolidating when we run out of space.
+ *
+ * IOW, if we run commit now, we might not be able to find a free LEB
+ * after this.
+ */
+ lnum = ubifs_find_free_leb_for_idx(c);
+ if (lnum < 0) {
+ dbg_err("could not find an empty LEB");
+ dbg_dump_lprops(c);
+ dbg_dump_budg(c, &c->bi);
+ return lnum;
+ }
+
+ /* Reset the index flag */
+ err = ubifs_change_one_lp(c, lnum, LPROPS_NC, LPROPS_NC, 0,
+ LPROPS_INDEX, 0);
+ if (err)
+ return err;
+
+ c->gc_lnum = lnum;
+ dbg_rcvry("found empty LEB %d, run commit", lnum);
+
+ return ubifs_run_commit(c);
+}
+
/**
* ubifs_rcvry_gc_commit - recover the GC LEB number and run the commit.
* @c: UBIFS file-system description object
{
struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;
struct ubifs_lprops lp;
- int lnum, err;
+ int err;
+
+ dbg_rcvry("GC head LEB %d, offs %d", wbuf->lnum, wbuf->offs);
c->gc_lnum = -1;
- if (wbuf->lnum == -1) {
- dbg_rcvry("no GC head LEB");
- goto find_free;
- }
- /*
- * See whether the used space in the dirtiest LEB fits in the GC head
- * LEB.
- */
- if (wbuf->offs == c->leb_size) {
- dbg_rcvry("no room in GC head LEB");
- goto find_free;
- }
+ if (wbuf->lnum == -1 || wbuf->offs == c->leb_size)
+ return grab_empty_leb(c);
+
err = ubifs_find_dirty_leb(c, &lp, wbuf->offs, 2);
if (err) {
- /*
- * There are no dirty or empty LEBs subject to here being
- * enough for the index. Try to use
- * 'ubifs_find_free_leb_for_idx()', which will return any empty
- * LEBs (ignoring index requirements). If the index then
- * doesn't have enough LEBs the recovery commit will fail -
- * which is the same result anyway i.e. recovery fails. So
- * there is no problem ignoring index requirements and just
- * grabbing a free LEB since we have already established there
- * is not a dirty LEB we could have used instead.
- */
- if (err == -ENOSPC) {
- dbg_rcvry("could not find a dirty LEB");
- goto find_free;
- }
- return err;
- }
- ubifs_assert(!(lp.flags & LPROPS_INDEX));
- lnum = lp.lnum;
- if (lp.free + lp.dirty == c->leb_size) {
- /* An empty LEB was returned */
- if (lp.free != c->leb_size) {
- err = ubifs_change_one_lp(c, lnum, c->leb_size,
- 0, 0, 0, 0);
- if (err)
- return err;
- }
- err = ubifs_leb_unmap(c, lnum);
- if (err)
+ if (err != -ENOSPC)
return err;
- c->gc_lnum = lnum;
- dbg_rcvry("allocated LEB %d for GC", lnum);
- /* Run the commit */
- dbg_rcvry("committing");
- return ubifs_run_commit(c);
- }
- /*
- * There was no empty LEB so the used space in the dirtiest LEB must fit
- * in the GC head LEB.
- */
- if (lp.free + lp.dirty < wbuf->offs) {
- dbg_rcvry("LEB %d doesn't fit in GC head LEB %d:%d",
- lnum, wbuf->lnum, wbuf->offs);
- err = ubifs_return_leb(c, lnum);
- if (err)
- return err;
- goto find_free;
+
+ dbg_rcvry("could not find a dirty LEB");
+ return grab_empty_leb(c);
}
+
+ ubifs_assert(!(lp.flags & LPROPS_INDEX));
+ ubifs_assert(lp.free + lp.dirty >= wbuf->offs);
+
/*
* We run the commit before garbage collection otherwise subsequent
* mounts will see the GC and orphan deletion in a different order.
err = ubifs_run_commit(c);
if (err)
return err;
- /*
- * The data in the dirtiest LEB fits in the GC head LEB, so do the GC
- * - use locking to keep 'ubifs_assert()' happy.
- */
- dbg_rcvry("GC'ing LEB %d", lnum);
+
+ dbg_rcvry("GC'ing LEB %d", lp.lnum);
mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
err = ubifs_garbage_collect_leb(c, &lp);
if (err >= 0) {
err = -EINVAL;
return err;
}
- if (err != LEB_RETAINED) {
- dbg_err("GC returned %d", err);
+
+ ubifs_assert(err == LEB_RETAINED);
+ if (err != LEB_RETAINED)
return -EINVAL;
- }
+
err = ubifs_leb_unmap(c, c->gc_lnum);
if (err)
return err;
- dbg_rcvry("allocated LEB %d for GC", lnum);
- return 0;
-find_free:
- /*
- * There is no GC head LEB or the free space in the GC head LEB is too
- * small, or there are not dirty LEBs. Allocate gc_lnum by calling
- * 'ubifs_find_free_leb_for_idx()' so GC is not run.
- */
- lnum = ubifs_find_free_leb_for_idx(c);
- if (lnum < 0) {
- dbg_err("could not find an empty LEB");
- return lnum;
- }
- /* And reset the index flag */
- err = ubifs_change_one_lp(c, lnum, LPROPS_NC, LPROPS_NC, 0,
- LPROPS_INDEX, 0);
- if (err)
- return err;
- c->gc_lnum = lnum;
- dbg_rcvry("allocated LEB %d for GC", lnum);
- /* Run the commit */
- dbg_rcvry("committing");
- return ubifs_run_commit(c);
+ dbg_rcvry("allocated LEB %d for GC", lp.lnum);
+ return 0;
}
/**
err = ubi_leb_change(c->ubi, lnum, c->sbuf, len, UBI_UNKNOWN);
if (err)
goto out;
- dbg_rcvry("inode %lu at %d:%d size %lld -> %lld ",
+ dbg_rcvry("inode %lu at %d:%d size %lld -> %lld",
(unsigned long)e->inum, lnum, offs, i_size, e->d_size);
return 0;
e->i_size = le64_to_cpu(ino->size);
}
}
+
if (e->exists && e->i_size < e->d_size) {
- if (!e->inode && c->ro_mount) {
+ if (c->ro_mount) {
/* Fix the inode size and pin it in memory */
struct inode *inode;
+ struct ubifs_inode *ui;
+
+ ubifs_assert(!e->inode);
inode = ubifs_iget(c->vfs_sb, e->inum);
if (IS_ERR(inode))
return PTR_ERR(inode);
+
+ ui = ubifs_inode(inode);
if (inode->i_size < e->d_size) {
dbg_rcvry("ino %lu size %lld -> %lld",
(unsigned long)e->inum,
- e->d_size, inode->i_size);
+ inode->i_size, e->d_size);
inode->i_size = e->d_size;
- ubifs_inode(inode)->ui_size = e->d_size;
+ ui->ui_size = e->d_size;
+ ui->synced_i_size = e->d_size;
e->inode = inode;
this = rb_next(this);
continue;
iput(e->inode);
}
}
+
this = rb_next(this);
rb_erase(&e->rb, &c->size_tree);
kfree(e);
}
+
return 0;
}
git.openpandora.org / pandora-kernel.git / blobdiff