1 files changed, 73 insertions, 17 deletions

diff --git a/fs/ubifs/commit.c b/fs/ubifs/commit.c
index 02429d81ca33..ff8229340cd5 100644
--- a/fs/ubifs/commit.c
+++ b/fs/ubifs/commit.c
@@ -48,6 +48,56 @@
 #include <linux/slab.h>
 #include "ubifs.h"
 
+/*
+ * nothing_to_commit - check if there is nothing to commit.
+ * @c: UBIFS file-system description object
+ *
+ * This is a helper function which checks if there is anything to commit. It is
+ * used as an optimization to avoid starting the commit if it is not really
+ * necessary. Indeed, the commit operation always assumes flash I/O (e.g.,
+ * writing the commit start node to the log), and it is better to avoid doing
+ * this unnecessarily. E.g., 'ubifs_sync_fs()' runs the commit, but if there is
+ * nothing to commit, it is more optimal to avoid any flash I/O.
+ *
+ * This function has to be called with @c->commit_sem locked for writing -
+ * this function does not take LPT/TNC locks because the @c->commit_sem
+ * guarantees that we have exclusive access to the TNC and LPT data structures.
+ *
+ * This function returns %1 if there is nothing to commit and %0 otherwise.
+ */
+static int nothing_to_commit(struct ubifs_info *c)
+{
+	/*
+	 * During mounting or remounting from R/O mode to R/W mode we may
+	 * commit for various recovery-related reasons.
+	 */
+	if (c->mounting || c->remounting_rw)
+		return 0;
+
+	/*
+	 * If the root TNC node is dirty, we definitely have something to
+	 * commit.
+	 */
+	if (c->zroot.znode && ubifs_zn_dirty(c->zroot.znode))
+		return 0;
+
+	/*
+	 * Even though the TNC is clean, the LPT tree may have dirty nodes. For
+	 * example, this may happen if the budgeting subsystem invoked GC to
+	 * make some free space, and the GC found an LEB with only dirty and
+	 * free space. In this case GC would just change the lprops of this
+	 * LEB (by turning all space into free space) and unmap it.
+	 */
+	if (c->nroot && test_bit(DIRTY_CNODE, &c->nroot->flags))
+		return 0;
+
+	ubifs_assert(atomic_long_read(&c->dirty_zn_cnt) == 0);
+	ubifs_assert(c->dirty_pn_cnt == 0);
+	ubifs_assert(c->dirty_nn_cnt == 0);
+
+	return 1;
+}
+
 /**
  * do_commit - commit the journal.
  * @c: UBIFS file-system description object
@@ -70,6 +120,12 @@ static int do_commit(struct ubifs_info *c)
 		goto out_up;
 	}
 
+	if (nothing_to_commit(c)) {
+		up_write(&c->commit_sem);
+		err = 0;
+		goto out_cancel;
+	}
+
 	/* Sync all write buffers (necessary for recovery) */
 	for (i = 0; i < c->jhead_cnt; i++) {
 		err = ubifs_wbuf_sync(&c->jheads[i].wbuf);
@@ -126,7 +182,7 @@ static int do_commit(struct ubifs_info *c)
 	c->mst_node->root_len    = cpu_to_le32(zroot.len);
 	c->mst_node->ihead_lnum  = cpu_to_le32(c->ihead_lnum);
 	c->mst_node->ihead_offs  = cpu_to_le32(c->ihead_offs);
-	c->mst_node->index_size  = cpu_to_le64(c->old_idx_sz);
+	c->mst_node->index_size  = cpu_to_le64(c->bi.old_idx_sz);
 	c->mst_node->lpt_lnum    = cpu_to_le32(c->lpt_lnum);
 	c->mst_node->lpt_offs    = cpu_to_le32(c->lpt_offs);
 	c->mst_node->nhead_lnum  = cpu_to_le32(c->nhead_lnum);
@@ -162,12 +218,12 @@ static int do_commit(struct ubifs_info *c)
 	if (err)
 		goto out;
 
+out_cancel:
 	spin_lock(&c->cs_lock);
 	c->cmt_state = COMMIT_RESTING;
 	wake_up(&c->cmt_wq);
 	dbg_cmt("commit end");
 	spin_unlock(&c->cs_lock);
-
 	return 0;
 
 out_up:
@@ -237,8 +293,8 @@ int ubifs_bg_thread(void *info)
 	int err;
 	struct ubifs_info *c = info;
 
-	dbg_msg("background thread \"%s\" started, PID %d",
-		c->bgt_name, current->pid);
+	ubifs_msg("background thread \"%s\" started, PID %d",
+		  c->bgt_name, current->pid);
 	set_freezable();
 
 	while (1) {
@@ -272,7 +328,7 @@ int ubifs_bg_thread(void *info)
 		cond_resched();
 	}
 
-	dbg_msg("background thread \"%s\" stops", c->bgt_name);
+	ubifs_msg("background thread \"%s\" stops", c->bgt_name);
 	return 0;
 }
 
@@ -362,7 +418,7 @@ int ubifs_run_commit(struct ubifs_info *c)
 
 	spin_lock(&c->cs_lock);
 	if (c->cmt_state == COMMIT_BROKEN) {
-		err = -EINVAL;
+		err = -EROFS;
 		goto out;
 	}
 
@@ -388,7 +444,7 @@ int ubifs_run_commit(struct ubifs_info *c)
 	 * re-check it.
 	 */
 	if (c->cmt_state == COMMIT_BROKEN) {
-		err = -EINVAL;
+		err = -EROFS;
 		goto out_cmt_unlock;
 	}
 
@@ -440,7 +496,9 @@ int ubifs_gc_should_commit(struct ubifs_info *c)
 	return ret;
 }
 
-#ifdef CONFIG_UBIFS_FS_DEBUG
+/*
+ * Everything below is related to debugging.
+ */
 
 /**
  * struct idx_node - hold index nodes during index tree traversal.
@@ -456,7 +514,7 @@ struct idx_node {
 	struct list_head list;
 	int iip;
 	union ubifs_key upper_key;
-	struct ubifs_idx_node idx __attribute__((aligned(8)));
+	struct ubifs_idx_node idx __aligned(8);
 };
 
 /**
@@ -520,8 +578,8 @@ int dbg_check_old_index(struct ubifs_info *c, struct ubifs_zbranch *zroot)
 	struct idx_node *i;
 	size_t sz;
 
-	if (!(ubifs_chk_flags & UBIFS_CHK_OLD_IDX))
-		goto out;
+	if (!dbg_is_chk_index(c))
+		return 0;
 
 	INIT_LIST_HEAD(&list);
 
@@ -658,14 +716,14 @@ out:
 	return 0;
 
 out_dump:
-	dbg_err("dumping index node (iip=%d)", i->iip);
-	dbg_dump_node(c, idx);
+	ubifs_err("dumping index node (iip=%d)", i->iip);
+	ubifs_dump_node(c, idx);
 	list_del(&i->list);
 	kfree(i);
 	if (!list_empty(&list)) {
 		i = list_entry(list.prev, struct idx_node, list);
-		dbg_err("dumping parent index node");
-		dbg_dump_node(c, &i->idx);
+		ubifs_err("dumping parent index node");
+		ubifs_dump_node(c, &i->idx);
 	}
 out_free:
 	while (!list_empty(&list)) {
@@ -678,5 +736,3 @@ out_free:
 		err = -EINVAL;
 	return err;
 }
-
-#endif /* CONFIG_UBIFS_FS_DEBUG */