nilfs2: add checkpoint tree to nilfs object

To hold multiple versions of a filesystem in one sb instance, a new
on-memory structure is necessary to handle one or more checkpoints.

This adds a red-black tree of checkpoints to nilfs object, and adds
lookup and create functions for them.

Each checkpoint is represented by "nilfs_root" structure, and this
structure has rb_node to configure the rb-tree.

The nilfs_root object is identified with a checkpoint number.  For
each snapshot, a nilfs_root object is allocated and the checkpoint
number of snapshot is assigned to it.  For a regular mount
(i.e. current mode mount), NILFS_CPTREE_CURRENT_CNO constant is
assigned to the corresponding nilfs_root object.

Each nilfs_root object has an ifile inode and some counters.  These
items will displace those of nilfs_sb_info structure in successive
patches.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
This commit is contained in:
Ryusuke Konishi 2010-08-14 12:59:15 +09:00
parent 263d90cefc
commit ba65ae4729
2 changed files with 134 additions and 0 deletions

View file

@ -89,6 +89,8 @@ static struct the_nilfs *alloc_nilfs(struct block_device *bdev)
INIT_LIST_HEAD(&nilfs->ns_supers);
INIT_LIST_HEAD(&nilfs->ns_gc_inodes);
spin_lock_init(&nilfs->ns_last_segment_lock);
nilfs->ns_cptree = RB_ROOT;
spin_lock_init(&nilfs->ns_cptree_lock);
init_rwsem(&nilfs->ns_segctor_sem);
return nilfs;
@ -809,6 +811,96 @@ int nilfs_near_disk_full(struct the_nilfs *nilfs)
return ncleansegs <= nilfs->ns_nrsvsegs + nincsegs;
}
struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno)
{
struct rb_node *n;
struct nilfs_root *root;
spin_lock(&nilfs->ns_cptree_lock);
n = nilfs->ns_cptree.rb_node;
while (n) {
root = rb_entry(n, struct nilfs_root, rb_node);
if (cno < root->cno) {
n = n->rb_left;
} else if (cno > root->cno) {
n = n->rb_right;
} else {
atomic_inc(&root->count);
spin_unlock(&nilfs->ns_cptree_lock);
return root;
}
}
spin_unlock(&nilfs->ns_cptree_lock);
return NULL;
}
struct nilfs_root *
nilfs_find_or_create_root(struct the_nilfs *nilfs, __u64 cno)
{
struct rb_node **p, *parent;
struct nilfs_root *root, *new;
root = nilfs_lookup_root(nilfs, cno);
if (root)
return root;
new = kmalloc(sizeof(*root), GFP_KERNEL);
if (!new)
return NULL;
spin_lock(&nilfs->ns_cptree_lock);
p = &nilfs->ns_cptree.rb_node;
parent = NULL;
while (*p) {
parent = *p;
root = rb_entry(parent, struct nilfs_root, rb_node);
if (cno < root->cno) {
p = &(*p)->rb_left;
} else if (cno > root->cno) {
p = &(*p)->rb_right;
} else {
atomic_inc(&root->count);
spin_unlock(&nilfs->ns_cptree_lock);
kfree(new);
return root;
}
}
new->cno = cno;
new->ifile = NULL;
new->nilfs = nilfs;
atomic_set(&new->count, 1);
atomic_set(&new->inodes_count, 0);
atomic_set(&new->blocks_count, 0);
rb_link_node(&new->rb_node, parent, p);
rb_insert_color(&new->rb_node, &nilfs->ns_cptree);
spin_unlock(&nilfs->ns_cptree_lock);
return new;
}
void nilfs_put_root(struct nilfs_root *root)
{
if (atomic_dec_and_test(&root->count)) {
struct the_nilfs *nilfs = root->nilfs;
spin_lock(&nilfs->ns_cptree_lock);
rb_erase(&root->rb_node, &nilfs->ns_cptree);
spin_unlock(&nilfs->ns_cptree_lock);
if (root->ifile)
nilfs_mdt_destroy(root->ifile);
kfree(root);
}
}
/**
* nilfs_find_sbinfo - find existing nilfs_sb_info structure
* @nilfs: nilfs object

View file

@ -26,6 +26,7 @@
#include <linux/types.h>
#include <linux/buffer_head.h>
#include <linux/rbtree.h>
#include <linux/fs.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
@ -80,6 +81,8 @@ enum {
* @ns_cpfile: checkpoint file inode
* @ns_sufile: segusage file inode
* @ns_gc_dat: shadow inode of the DAT file inode for GC
* @ns_cptree: rb-tree of all mounted checkpoints (nilfs_root)
* @ns_cptree_lock: lock protecting @ns_cptree
* @ns_gc_inodes: dummy inodes to keep live blocks
* @ns_blocksize_bits: bit length of block size
* @ns_blocksize: block size
@ -164,6 +167,10 @@ struct the_nilfs {
struct inode *ns_sufile;
struct inode *ns_gc_dat;
/* Checkpoint tree */
struct rb_root ns_cptree;
spinlock_t ns_cptree_lock;
/* GC inode list */
struct list_head ns_gc_inodes;
@ -200,6 +207,32 @@ THE_NILFS_FNS(DISCONTINUED, discontinued)
THE_NILFS_FNS(GC_RUNNING, gc_running)
THE_NILFS_FNS(SB_DIRTY, sb_dirty)
/**
* struct nilfs_root - nilfs root object
* @cno: checkpoint number
* @rb_node: red-black tree node
* @count: refcount of this structure
* @nilfs: nilfs object
* @ifile: inode file
* @root: root inode
* @inodes_count: number of inodes
* @blocks_count: number of blocks (Reserved)
*/
struct nilfs_root {
__u64 cno;
struct rb_node rb_node;
atomic_t count;
struct the_nilfs *nilfs;
struct inode *ifile;
atomic_t inodes_count;
atomic_t blocks_count;
};
/* Special checkpoint number */
#define NILFS_CPTREE_CURRENT_CNO 0
/* Minimum interval of periodical update of superblocks (in seconds) */
#define NILFS_SB_FREQ 10
@ -222,6 +255,10 @@ int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *);
int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *);
int nilfs_discard_segments(struct the_nilfs *, __u64 *, size_t);
int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno);
struct nilfs_root *nilfs_find_or_create_root(struct the_nilfs *nilfs,
__u64 cno);
void nilfs_put_root(struct nilfs_root *root);
struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *, int, __u64);
int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int);
int nilfs_near_disk_full(struct the_nilfs *);
@ -235,6 +272,11 @@ static inline void get_nilfs(struct the_nilfs *nilfs)
atomic_inc(&nilfs->ns_count);
}
static inline void nilfs_get_root(struct nilfs_root *root)
{
atomic_inc(&root->count);
}
static inline void
nilfs_attach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
{