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authorArtem Bityutskiy <Artem.Bityutskiy@nokia.com>2011-05-15 12:05:54 +0300
committerArtem Bityutskiy <Artem.Bityutskiy@nokia.com>2011-05-16 10:31:40 +0300
commitdebf12d54182b324a01c4276b003669c94b7b531 (patch)
tree972640a41690e8946bd89636765cbaa6a5aa63f5 /fs/ubifs/replay.c
parent074bcb9b5ce698bd7b02ddb469da9cba21fe83fd (diff)
UBIFS: substitute the replay tree with a replay list
This patch simplifies replay even further - it removes the replay tree and adds the replay list instead. Indeed, we just do not need to use a tree here - all we need to do is to add all nodes to the list and then sort it. Using RB-tree is an overkill - more code and slower. And since we replay buds in order, we expect the nodes to follow in _mostly_ sorted order, so the merge sort becomes much cheaper in average than an RB-tree. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Diffstat (limited to 'fs/ubifs/replay.c')
-rw-r--r--fs/ubifs/replay.c172
1 files changed, 74 insertions, 98 deletions
diff --git a/fs/ubifs/replay.c b/fs/ubifs/replay.c
index 08f5036a905..47915a78992 100644
--- a/fs/ubifs/replay.c
+++ b/fs/ubifs/replay.c
@@ -33,22 +33,24 @@
*/
#include "ubifs.h"
+#include <linux/list_sort.h>
/**
- * struct replay_entry - replay tree entry.
+ * struct replay_entry - replay list entry.
* @lnum: logical eraseblock number of the node
* @offs: node offset
* @len: node length
* @deletion: non-zero if this entry corresponds to a node deletion
* @sqnum: node sequence number
- * @rb: links the replay tree
+ * @list: links the replay list
* @key: node key
* @nm: directory entry name
* @old_size: truncation old size
* @new_size: truncation new size
*
- * UBIFS journal replay must compare node sequence numbers, which means it must
- * build a tree of node information to insert into the TNC.
+ * The replay process first scans all buds and builds the replay list, then
+ * sorts the replay list in nodes sequence number order, and then inserts all
+ * the replay entries to the TNC.
*/
struct replay_entry {
int lnum;
@@ -56,7 +58,7 @@ struct replay_entry {
int len;
unsigned int deletion:1;
unsigned long long sqnum;
- struct rb_node rb;
+ struct list_head list;
union ubifs_key key;
union {
struct qstr nm;
@@ -263,68 +265,77 @@ static int apply_replay_entry(struct ubifs_info *c, struct replay_entry *r)
}
/**
- * destroy_replay_tree - destroy the replay.
- * @c: UBIFS file-system description object
+ * replay_entries_cmp - compare 2 replay entries.
+ * @priv: UBIFS file-system description object
+ * @a: first replay entry
+ * @a: second replay entry
*
- * Destroy the replay tree.
+ * This is a comparios function for 'list_sort()' which compares 2 replay
+ * entries @a and @b by comparing their sequence numer. Returns %1 if @a has
+ * greater sequence number and %-1 otherwise.
*/
-static void destroy_replay_tree(struct ubifs_info *c)
+static int replay_entries_cmp(void *priv, struct list_head *a,
+ struct list_head *b)
{
- struct rb_node *this = c->replay_tree.rb_node;
- struct replay_entry *r;
-
- while (this) {
- if (this->rb_left) {
- this = this->rb_left;
- continue;
- } else if (this->rb_right) {
- this = this->rb_right;
- continue;
- }
- r = rb_entry(this, struct replay_entry, rb);
- this = rb_parent(this);
- if (this) {
- if (this->rb_left == &r->rb)
- this->rb_left = NULL;
- else
- this->rb_right = NULL;
- }
- if (is_hash_key(c, &r->key))
- kfree(r->nm.name);
- kfree(r);
- }
- c->replay_tree = RB_ROOT;
+ struct replay_entry *ra, *rb;
+
+ cond_resched();
+ if (a == b)
+ return 0;
+
+ ra = list_entry(a, struct replay_entry, list);
+ rb = list_entry(b, struct replay_entry, list);
+ ubifs_assert(ra->sqnum != rb->sqnum);
+ if (ra->sqnum > rb->sqnum)
+ return 1;
+ return -1;
}
/**
- * apply_replay_tree - apply the replay tree to the TNC.
+ * apply_replay_list - apply the replay list to the TNC.
* @c: UBIFS file-system description object
*
- * Apply the replay tree.
- * Returns zero in case of success and a negative error code in case of
- * failure.
+ * Apply all entries in the replay list to the TNC. Returns zero in case of
+ * success and a negative error code in case of failure.
*/
-static int apply_replay_tree(struct ubifs_info *c)
+static int apply_replay_list(struct ubifs_info *c)
{
- struct rb_node *this = rb_first(&c->replay_tree);
+ struct replay_entry *r;
+ int err;
- while (this) {
- struct replay_entry *r;
- int err;
+ list_sort(c, &c->replay_list, &replay_entries_cmp);
+ list_for_each_entry(r, &c->replay_list, list) {
cond_resched();
- r = rb_entry(this, struct replay_entry, rb);
err = apply_replay_entry(c, r);
if (err)
return err;
- this = rb_next(this);
}
+
return 0;
}
/**
- * insert_node - insert a node to the replay tree.
+ * destroy_replay_list - destroy the replay.
+ * @c: UBIFS file-system description object
+ *
+ * Destroy the replay list.
+ */
+static void destroy_replay_list(struct ubifs_info *c)
+{
+ struct replay_entry *r, *tmp;
+
+ list_for_each_entry_safe(r, tmp, &c->replay_list, list) {
+ if (is_hash_key(c, &r->key))
+ kfree(r->nm.name);
+ list_del(&r->list);
+ kfree(r);
+ }
+}
+
+/**
+ * insert_node - insert a node to the replay list
* @c: UBIFS file-system description object
* @lnum: node logical eraseblock number
* @offs: node offset
@@ -336,39 +347,25 @@ static int apply_replay_tree(struct ubifs_info *c)
* @old_size: truncation old size
* @new_size: truncation new size
*
- * This function inserts a scanned non-direntry node to the replay tree. The
- * replay tree is an RB-tree containing @struct replay_entry elements which are
- * indexed by the sequence number. The replay tree is applied at the very end
- * of the replay process. Since the tree is sorted in sequence number order,
- * the older modifications are applied first. This function returns zero in
- * case of success and a negative error code in case of failure.
+ * This function inserts a scanned non-direntry node to the replay list. The
+ * replay list contains @struct replay_entry elements, and we sort this list in
+ * sequence number order before applying it. The replay list is applied at the
+ * very end of the replay process. Since the list is sorted in sequence number
+ * order, the older modifications are applied first. This function returns zero
+ * in case of success and a negative error code in case of failure.
*/
static int insert_node(struct ubifs_info *c, int lnum, int offs, int len,
union ubifs_key *key, unsigned long long sqnum,
int deletion, int *used, loff_t old_size,
loff_t new_size)
{
- struct rb_node **p = &c->replay_tree.rb_node, *parent = NULL;
struct replay_entry *r;
+ dbg_mnt("add LEB %d:%d, key %s", lnum, offs, DBGKEY(key));
+
if (key_inum(c, key) >= c->highest_inum)
c->highest_inum = key_inum(c, key);
- dbg_mnt("add LEB %d:%d, key %s", lnum, offs, DBGKEY(key));
- while (*p) {
- parent = *p;
- r = rb_entry(parent, struct replay_entry, rb);
- if (sqnum < r->sqnum) {
- p = &(*p)->rb_left;
- continue;
- } else if (sqnum > r->sqnum) {
- p = &(*p)->rb_right;
- continue;
- }
- ubifs_err("duplicate sqnum in replay");
- return -EINVAL;
- }
-
r = kzalloc(sizeof(struct replay_entry), GFP_KERNEL);
if (!r)
return -ENOMEM;
@@ -384,13 +381,12 @@ static int insert_node(struct ubifs_info *c, int lnum, int offs, int len,
r->old_size = old_size;
r->new_size = new_size;
- rb_link_node(&r->rb, parent, p);
- rb_insert_color(&r->rb, &c->replay_tree);
+ list_add_tail(&r->list, &c->replay_list);
return 0;
}
/**
- * insert_dent - insert a directory entry node into the replay tree.
+ * insert_dent - insert a directory entry node into the replay list.
* @c: UBIFS file-system description object
* @lnum: node logical eraseblock number
* @offs: node offset
@@ -402,43 +398,25 @@ static int insert_node(struct ubifs_info *c, int lnum, int offs, int len,
* @deletion: non-zero if this is a deletion
* @used: number of bytes in use in a LEB
*
- * This function inserts a scanned directory entry node to the replay tree.
- * Returns zero in case of success and a negative error code in case of
- * failure.
- *
- * This function is also used for extended attribute entries because they are
- * implemented as directory entry nodes.
+ * This function inserts a scanned directory entry node or an extended
+ * attribute entry to the replay list. Returns zero in case of success and a
+ * negative error code in case of failure.
*/
static int insert_dent(struct ubifs_info *c, int lnum, int offs, int len,
union ubifs_key *key, const char *name, int nlen,
unsigned long long sqnum, int deletion, int *used)
{
- struct rb_node **p = &c->replay_tree.rb_node, *parent = NULL;
struct replay_entry *r;
char *nbuf;
+ dbg_mnt("add LEB %d:%d, key %s", lnum, offs, DBGKEY(key));
if (key_inum(c, key) >= c->highest_inum)
c->highest_inum = key_inum(c, key);
- dbg_mnt("add LEB %d:%d, key %s", lnum, offs, DBGKEY(key));
- while (*p) {
- parent = *p;
- r = rb_entry(parent, struct replay_entry, rb);
- if (sqnum < r->sqnum) {
- p = &(*p)->rb_left;
- continue;
- }
- if (sqnum > r->sqnum) {
- p = &(*p)->rb_right;
- continue;
- }
- ubifs_err("duplicate sqnum in replay");
- return -EINVAL;
- }
-
r = kzalloc(sizeof(struct replay_entry), GFP_KERNEL);
if (!r)
return -ENOMEM;
+
nbuf = kmalloc(nlen + 1, GFP_KERNEL);
if (!nbuf) {
kfree(r);
@@ -458,9 +436,7 @@ static int insert_dent(struct ubifs_info *c, int lnum, int offs, int len,
nbuf[nlen] = '\0';
r->nm.name = nbuf;
- ubifs_assert(!*p);
- rb_link_node(&r->rb, parent, p);
- rb_insert_color(&r->rb, &c->replay_tree);
+ list_add_tail(&r->list, &c->replay_list);
return 0;
}
@@ -1017,7 +993,7 @@ int ubifs_replay_journal(struct ubifs_info *c)
if (err)
goto out;
- err = apply_replay_tree(c);
+ err = apply_replay_list(c);
if (err)
goto out;
@@ -1039,7 +1015,7 @@ int ubifs_replay_journal(struct ubifs_info *c)
"highest_inum %lu", c->lhead_lnum, c->lhead_offs, c->max_sqnum,
(unsigned long)c->highest_inum);
out:
- destroy_replay_tree(c);
+ destroy_replay_list(c);
destroy_bud_list(c);
c->replaying = 0;
return err;