1 files changed, 283 insertions, 0 deletions

diff --git a/fs/ubifs/tnc.c b/fs/ubifs/tnc.c
index ba13c92fdf6a..d279012d8dd5 100644
--- a/fs/ubifs/tnc.c
+++ b/fs/ubifs/tnc.c
@@ -1492,6 +1492,289 @@ out:
 }
 
 /**
+ * ubifs_tnc_get_bu_keys - lookup keys for bulk-read.
+ * @c: UBIFS file-system description object
+ * @bu: bulk-read parameters and results
+ *
+ * Lookup consecutive data node keys for the same inode that reside
+ * consecutively in the same LEB.
+ */
+int ubifs_tnc_get_bu_keys(struct ubifs_info *c, struct bu_info *bu)
+{
+        int n, err = 0, lnum = -1, uninitialized_var(offs);
+        int uninitialized_var(len);
+        unsigned int block = key_block(c, &bu->key);
+        struct ubifs_znode *znode;
+
+        bu->cnt = 0;
+        bu->blk_cnt = 0;
+        bu->eof = 0;
+
+        mutex_lock(&c->tnc_mutex);
+        /* Find first key */
+        err = ubifs_lookup_level0(c, &bu->key, &znode, &n);
+        if (err < 0)
+                goto out;
+        if (err) {
+                /* Key found */
+                len = znode->zbranch[n].len;
+                /* The buffer must be big enough for at least 1 node */
+                if (len > bu->buf_len) {
+                        err = -EINVAL;
+                        goto out;
+                }
+                /* Add this key */
+                bu->zbranch[bu->cnt++] = znode->zbranch[n];
+                bu->blk_cnt += 1;
+                lnum = znode->zbranch[n].lnum;
+                offs = ALIGN(znode->zbranch[n].offs + len, 8);
+        }
+        while (1) {
+                struct ubifs_zbranch *zbr;
+                union ubifs_key *key;
+                unsigned int next_block;
+
+                /* Find next key */
+                err = tnc_next(c, &znode, &n);
+                if (err)
+                        goto out;
+                zbr = &znode->zbranch[n];
+                key = &zbr->key;
+                /* See if there is another data key for this file */
+                if (key_inum(c, key) != key_inum(c, &bu->key) ||
+                    key_type(c, key) != UBIFS_DATA_KEY) {
+                        err = -ENOENT;
+                        goto out;
+                }
+                if (lnum < 0) {
+                        /* First key found */
+                        lnum = zbr->lnum;
+                        offs = ALIGN(zbr->offs + zbr->len, 8);
+                        len = zbr->len;
+                        if (len > bu->buf_len) {
+                                err = -EINVAL;
+                                goto out;
+                        }
+                } else {
+                        /*
+                         * The data nodes must be in consecutive positions in
+                         * the same LEB.
+                         */
+                        if (zbr->lnum != lnum || zbr->offs != offs)
+                                goto out;
+                        offs += ALIGN(zbr->len, 8);
+                        len = ALIGN(len, 8) + zbr->len;
+                        /* Must not exceed buffer length */
+                        if (len > bu->buf_len)
+                                goto out;
+                }
+                /* Allow for holes */
+                next_block = key_block(c, key);
+                bu->blk_cnt += (next_block - block - 1);
+                if (bu->blk_cnt >= UBIFS_MAX_BULK_READ)
+                        goto out;
+                block = next_block;
+                /* Add this key */
+                bu->zbranch[bu->cnt++] = *zbr;
+                bu->blk_cnt += 1;
+                /* See if we have room for more */
+                if (bu->cnt >= UBIFS_MAX_BULK_READ)
+                        goto out;
+                if (bu->blk_cnt >= UBIFS_MAX_BULK_READ)
+                        goto out;
+        }
+out:
+        if (err == -ENOENT) {
+                bu->eof = 1;
+                err = 0;
+        }
+        bu->gc_seq = c->gc_seq;
+        mutex_unlock(&c->tnc_mutex);
+        if (err)
+                return err;
+        /*
+         * An enormous hole could cause bulk-read to encompass too many
+         * page cache pages, so limit the number here.
+         */
+        if (bu->blk_cnt >= UBIFS_MAX_BULK_READ)
+                bu->blk_cnt = UBIFS_MAX_BULK_READ;
+        /*
+         * Ensure that bulk-read covers a whole number of page cache
+         * pages.
+         */
+        if (UBIFS_BLOCKS_PER_PAGE == 1 ||
+            !(bu->blk_cnt & (UBIFS_BLOCKS_PER_PAGE - 1)))
+                return 0;
+        if (bu->eof) {
+                /* At the end of file we can round up */
+                bu->blk_cnt += UBIFS_BLOCKS_PER_PAGE - 1;
+                return 0;
+        }
+        /* Exclude data nodes that do not make up a whole page cache page */
+        block = key_block(c, &bu->key) + bu->blk_cnt;
+        block &= ~(UBIFS_BLOCKS_PER_PAGE - 1);
+        while (bu->cnt) {
+                if (key_block(c, &bu->zbranch[bu->cnt - 1].key) < block)
+                        break;
+                bu->cnt -= 1;
+        }
+        return 0;
+}
+
+/**
+ * read_wbuf - bulk-read from a LEB with a wbuf.
+ * @wbuf: wbuf that may overlap the read
+ * @buf: buffer into which to read
+ * @len: read length
+ * @lnum: LEB number from which to read
+ * @offs: offset from which to read
+ *
+ * This functions returns %0 on success or a negative error code on failure.
+ */
+static int read_wbuf(struct ubifs_wbuf *wbuf, void *buf, int len, int lnum,
+                     int offs)
+{
+        const struct ubifs_info *c = wbuf->c;
+        int rlen, overlap;
+
+        dbg_io("LEB %d:%d, length %d", lnum, offs, len);
+        ubifs_assert(wbuf && lnum >= 0 && lnum < c->leb_cnt && offs >= 0);
+        ubifs_assert(!(offs & 7) && offs < c->leb_size);
+        ubifs_assert(offs + len <= c->leb_size);
+
+        spin_lock(&wbuf->lock);
+        overlap = (lnum == wbuf->lnum && offs + len > wbuf->offs);
+        if (!overlap) {
+                /* We may safely unlock the write-buffer and read the data */
+                spin_unlock(&wbuf->lock);
+                return ubi_read(c->ubi, lnum, buf, offs, len);
+        }
+
+        /* Don't read under wbuf */
+        rlen = wbuf->offs - offs;
+        if (rlen < 0)
+                rlen = 0;
+
+        /* Copy the rest from the write-buffer */
+        memcpy(buf + rlen, wbuf->buf + offs + rlen - wbuf->offs, len - rlen);
+        spin_unlock(&wbuf->lock);
+
+        if (rlen > 0)
+                /* Read everything that goes before write-buffer */
+                return ubi_read(c->ubi, lnum, buf, offs, rlen);
+
+        return 0;
+}
+
+/**
+ * validate_data_node - validate data nodes for bulk-read.
+ * @c: UBIFS file-system description object
+ * @buf: buffer containing data node to validate
+ * @zbr: zbranch of data node to validate
+ *
+ * This functions returns %0 on success or a negative error code on failure.
+ */
+static int validate_data_node(struct ubifs_info *c, void *buf,
+                              struct ubifs_zbranch *zbr)
+{
+        union ubifs_key key1;
+        struct ubifs_ch *ch = buf;
+        int err, len;
+
+        if (ch->node_type != UBIFS_DATA_NODE) {
+                ubifs_err("bad node type (%d but expected %d)",
+                          ch->node_type, UBIFS_DATA_NODE);
+                goto out_err;
+        }
+
+        err = ubifs_check_node(c, buf, zbr->lnum, zbr->offs, 0);
+        if (err) {
+                ubifs_err("expected node type %d", UBIFS_DATA_NODE);
+                goto out;
+        }
+
+        len = le32_to_cpu(ch->len);
+        if (len != zbr->len) {
+                ubifs_err("bad node length %d, expected %d", len, zbr->len);
+                goto out_err;
+        }
+
+        /* Make sure the key of the read node is correct */
+        key_read(c, buf + UBIFS_KEY_OFFSET, &key1);
+        if (!keys_eq(c, &zbr->key, &key1)) {
+                ubifs_err("bad key in node at LEB %d:%d",
+                          zbr->lnum, zbr->offs);
+                dbg_tnc("looked for key %s found node's key %s",
+                        DBGKEY(&zbr->key), DBGKEY1(&key1));
+                goto out_err;
+        }
+
+        return 0;
+
+out_err:
+        err = -EINVAL;
+out:
+        ubifs_err("bad node at LEB %d:%d", zbr->lnum, zbr->offs);
+        dbg_dump_node(c, buf);
+        dbg_dump_stack();
+        return err;
+}
+
+/**
+ * ubifs_tnc_bulk_read - read a number of data nodes in one go.
+ * @c: UBIFS file-system description object
+ * @bu: bulk-read parameters and results
+ *
+ * This functions reads and validates the data nodes that were identified by the
+ * 'ubifs_tnc_get_bu_keys()' function. This functions returns %0 on success,
+ * -EAGAIN to indicate a race with GC, or another negative error code on
+ * failure.
+ */
+int ubifs_tnc_bulk_read(struct ubifs_info *c, struct bu_info *bu)
+{
+        int lnum = bu->zbranch[0].lnum, offs = bu->zbranch[0].offs, len, err, i;
+        struct ubifs_wbuf *wbuf;
+        void *buf;
+
+        len = bu->zbranch[bu->cnt - 1].offs;
+        len += bu->zbranch[bu->cnt - 1].len - offs;
+        if (len > bu->buf_len) {
+                ubifs_err("buffer too small %d vs %d", bu->buf_len, len);
+                return -EINVAL;
+        }
+
+        /* Do the read */
+        wbuf = ubifs_get_wbuf(c, lnum);
+        if (wbuf)
+                err = read_wbuf(wbuf, bu->buf, len, lnum, offs);
+        else
+                err = ubi_read(c->ubi, lnum, bu->buf, offs, len);
+
+        /* Check for a race with GC */
+        if (maybe_leb_gced(c, lnum, bu->gc_seq))
+                return -EAGAIN;
+
+        if (err && err != -EBADMSG) {
+                ubifs_err("failed to read from LEB %d:%d, error %d",
+                          lnum, offs, err);
+                dbg_dump_stack();
+                dbg_tnc("key %s", DBGKEY(&bu->key));
+                return err;
+        }
+
+        /* Validate the nodes read */
+        buf = bu->buf;
+        for (i = 0; i < bu->cnt; i++) {
+                err = validate_data_node(c, buf, &bu->zbranch[i]);
+                if (err)
+                        return err;
+                buf = buf + ALIGN(bu->zbranch[i].len, 8);
+        }
+
+        return 0;
+}
+
+/**
  * do_lookup_nm- look up a "hashed" node.
  * @c: UBIFS file-system description object
  * @key: node key to lookup