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Commit debf12d5 authored by Artem Bityutskiy's avatar Artem Bityutskiy
Browse files

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: default avatarArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
parent 074bcb9b

fs/ubifs/replay.c

+74 −98
Original line number Diff line number Diff line
@@ -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;

	struct replay_entry *ra, *rb;



	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;

	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);



	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;

fs/ubifs/ubifs.h

+0 −2
Original line number Diff line number Diff line
@@ -1205,7 +1205,6 @@ struct ubifs_debug_info; 
 * @replaying: %1 during journal replay

 * @mounting: %1 while mounting

 * @remounting_rw: %1 while re-mounting from R/O mode to R/W mode

 * @replay_tree: temporary tree used during journal replay

 * @replay_list: temporary list used during journal replay

 * @replay_buds: list of buds to replay

 * @cs_sqnum: sequence number of first node in the log (commit start node)
@@ -1435,7 +1434,6 @@ struct ubifs_info { 
	unsigned int replaying:1;

	unsigned int mounting:1;

	unsigned int remounting_rw:1;

	struct rb_root replay_tree;

	struct list_head replay_list;

	struct list_head replay_buds;

	unsigned long long cs_sqnum;