nilfs2: add bmap function to seek a valid key

Add a new bmap function, nilfs_bmap_seek_key(), which seeks a valid
entry and returns its key starting from a given key.  This function
can be used to skip hole blocks efficiently.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/nilfs2/bmap.c b/fs/nilfs2/bmap.c
index c82f4361c1f94aded36c15358e209dd3d7b23363..27f75bcbeb30d78e63321831eb39e7339cf714ce 100644 (file)
--- a/fs/nilfs2/bmap.c
+++ b/fs/nilfs2/bmap.c
@@ -189,6 +189,37 @@ static int nilfs_bmap_do_delete(struct nilfs_bmap *bmap, __u64 key)
        return bmap->b_ops->bop_delete(bmap, key);
 }
 
+/**
+ * nilfs_bmap_seek_key - seek a valid entry and return its key
+ * @bmap: bmap struct
+ * @start: start key number
+ * @keyp: place to store valid key
+ *
+ * Description: nilfs_bmap_seek_key() seeks a valid key on @bmap
+ * starting from @start, and stores it to @keyp if found.
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOENT - No valid entry was found
+ */
+int nilfs_bmap_seek_key(struct nilfs_bmap *bmap, __u64 start, __u64 *keyp)
+{
+       int ret;
+
+       down_read(&bmap->b_sem);
+       ret = bmap->b_ops->bop_seek_key(bmap, start, keyp);
+       up_read(&bmap->b_sem);
+
+       if (ret < 0)
+               ret = nilfs_bmap_convert_error(bmap, __func__, ret);
+       return ret;
+}
+
 int nilfs_bmap_last_key(struct nilfs_bmap *bmap, __u64 *keyp)
 {
        int ret;

diff --git a/fs/nilfs2/bmap.h b/fs/nilfs2/bmap.h
index 9230d3335001f5c5b554dfe9448dc1891b9742d3..bfa817ce40b3ad6f66faf296bf3b7e1033904435 100644 (file)
--- a/fs/nilfs2/bmap.h
+++ b/fs/nilfs2/bmap.h
@@ -76,8 +76,10 @@ struct nilfs_bmap_operations {
                          union nilfs_binfo *);
        int (*bop_mark)(struct nilfs_bmap *, __u64, int);
 
-       /* The following functions are internal use only. */
+       int (*bop_seek_key)(const struct nilfs_bmap *, __u64, __u64 *);
        int (*bop_last_key)(const struct nilfs_bmap *, __u64 *);
+
+       /* The following functions are internal use only. */
        int (*bop_check_insert)(const struct nilfs_bmap *, __u64);
        int (*bop_check_delete)(struct nilfs_bmap *, __u64);
        int (*bop_gather_data)(struct nilfs_bmap *, __u64 *, __u64 *, int);
@@ -155,6 +157,7 @@ void nilfs_bmap_write(struct nilfs_bmap *, struct nilfs_inode *);
 int nilfs_bmap_lookup_contig(struct nilfs_bmap *, __u64, __u64 *, unsigned);
 int nilfs_bmap_insert(struct nilfs_bmap *bmap, __u64 key, unsigned long rec);
 int nilfs_bmap_delete(struct nilfs_bmap *bmap, __u64 key);
+int nilfs_bmap_seek_key(struct nilfs_bmap *bmap, __u64 start, __u64 *keyp);
 int nilfs_bmap_last_key(struct nilfs_bmap *bmap, __u64 *keyp);
 int nilfs_bmap_truncate(struct nilfs_bmap *bmap, __u64 key);
 void nilfs_bmap_clear(struct nilfs_bmap *);

diff --git a/fs/nilfs2/btree.c b/fs/nilfs2/btree.c
index ecdbae19a766d914e7d68c005c14356455dc83af..059f37137f9ad7b55b6dc0c3f34fa6c0fea6160b 100644 (file)
--- a/fs/nilfs2/btree.c
+++ b/fs/nilfs2/btree.c
@@ -633,6 +633,44 @@ static int nilfs_btree_do_lookup_last(const struct nilfs_bmap *btree,
        return 0;
 }
 
+/**
+ * nilfs_btree_get_next_key - get next valid key from btree path array
+ * @btree: bmap struct of btree
+ * @path: array of nilfs_btree_path struct
+ * @minlevel: start level
+ * @nextkey: place to store the next valid key
+ *
+ * Return Value: If a next key was found, 0 is returned. Otherwise,
+ * -ENOENT is returned.
+ */
+static int nilfs_btree_get_next_key(const struct nilfs_bmap *btree,
+                                   const struct nilfs_btree_path *path,
+                                   int minlevel, __u64 *nextkey)
+{
+       struct nilfs_btree_node *node;
+       int maxlevel = nilfs_btree_height(btree) - 1;
+       int index, next_adj, level;
+
+       /* Next index is already set to bp_index for leaf nodes. */
+       next_adj = 0;
+       for (level = minlevel; level <= maxlevel; level++) {
+               if (level == maxlevel)
+                       node = nilfs_btree_get_root(btree);
+               else
+                       node = nilfs_btree_get_nonroot_node(path, level);
+
+               index = path[level].bp_index + next_adj;
+               if (index < nilfs_btree_node_get_nchildren(node)) {
+                       /* Next key is in this node */
+                       *nextkey = nilfs_btree_node_get_key(node, index);
+                       return 0;
+               }
+               /* For non-leaf nodes, next index is stored at bp_index + 1. */
+               next_adj = 1;
+       }
+       return -ENOENT;
+}
+
 static int nilfs_btree_lookup(const struct nilfs_bmap *btree,
                              __u64 key, int level, __u64 *ptrp)
 {
@@ -1563,6 +1601,27 @@ out:
        return ret;
 }
 
+static int nilfs_btree_seek_key(const struct nilfs_bmap *btree, __u64 start,
+                               __u64 *keyp)
+{
+       struct nilfs_btree_path *path;
+       const int minlevel = NILFS_BTREE_LEVEL_NODE_MIN;
+       int ret;
+
+       path = nilfs_btree_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       ret = nilfs_btree_do_lookup(btree, path, start, NULL, minlevel, 0);
+       if (!ret)
+               *keyp = start;
+       else if (ret == -ENOENT)
+               ret = nilfs_btree_get_next_key(btree, path, minlevel, keyp);
+
+       nilfs_btree_free_path(path);
+       return ret;
+}
+
 static int nilfs_btree_last_key(const struct nilfs_bmap *btree, __u64 *keyp)
 {
        struct nilfs_btree_path *path;
@@ -2298,7 +2357,9 @@ static const struct nilfs_bmap_operations nilfs_btree_ops = {
        .bop_assign             =       nilfs_btree_assign,
        .bop_mark               =       nilfs_btree_mark,
 
+       .bop_seek_key           =       nilfs_btree_seek_key,
        .bop_last_key           =       nilfs_btree_last_key,
+
        .bop_check_insert       =       NULL,
        .bop_check_delete       =       nilfs_btree_check_delete,
        .bop_gather_data        =       nilfs_btree_gather_data,
@@ -2318,7 +2379,9 @@ static const struct nilfs_bmap_operations nilfs_btree_ops_gc = {
        .bop_assign             =       nilfs_btree_assign_gc,
        .bop_mark               =       NULL,
 
+       .bop_seek_key           =       NULL,
        .bop_last_key           =       NULL,
+
        .bop_check_insert       =       NULL,
        .bop_check_delete       =       NULL,
        .bop_gather_data        =       NULL,

diff --git a/fs/nilfs2/direct.c b/fs/nilfs2/direct.c
index 82f4865e86dd5de3b33570be200a205c87d95ccf..ebf89fd8ac1a10bc7b5a1fd8f8208f6ed73306f1 100644 (file)
--- a/fs/nilfs2/direct.c
+++ b/fs/nilfs2/direct.c
@@ -173,6 +173,21 @@ static int nilfs_direct_delete(struct nilfs_bmap *bmap, __u64 key)
        return ret;
 }
 
+static int nilfs_direct_seek_key(const struct nilfs_bmap *direct, __u64 start,
+                                __u64 *keyp)
+{
+       __u64 key;
+
+       for (key = start; key <= NILFS_DIRECT_KEY_MAX; key++) {
+               if (nilfs_direct_get_ptr(direct, key) !=
+                   NILFS_BMAP_INVALID_PTR) {
+                       *keyp = key;
+                       return 0;
+               }
+       }
+       return -ENOENT;
+}
+
 static int nilfs_direct_last_key(const struct nilfs_bmap *direct, __u64 *keyp)
 {
        __u64 key, lastkey;
@@ -355,7 +370,9 @@ static const struct nilfs_bmap_operations nilfs_direct_ops = {
        .bop_assign             =       nilfs_direct_assign,
        .bop_mark               =       NULL,
 
+       .bop_seek_key           =       nilfs_direct_seek_key,
        .bop_last_key           =       nilfs_direct_last_key,
+
        .bop_check_insert       =       nilfs_direct_check_insert,
        .bop_check_delete       =       NULL,
        .bop_gather_data        =       nilfs_direct_gather_data,