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nilfs2: add btree get block function with readahead option 

This adds __nilfs_btree_get_block() function that can issue a series
of read-ahead requests for sibling btree nodes.

This read-ahead needs parent node block, so nilfs_btree_readahead_info
structure is added to pass the information that
__nilfs_btree_get_block() needs.

This also replaces the previous nilfs_btree_get_block() implementation
with a wrapper function of __nilfs_btree_get_block().

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
This commit is contained in:
Ryusuke Konishi 2010-07-18 10:42:24 +09:00
parent 26dfdd8e29
commit 464ece8863
1 changed files with 68 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

94
fs/nilfs2/btree.c
View File

@ -66,32 +66,6 @@ static void nilfs_btree_free_path(struct nilfs_btree_path *path)
/*
* B-tree node operations
*/
static int nilfs_btree_get_block(const struct nilfs_bmap *btree, __u64 ptr,
struct buffer_head **bhp)
{
struct address_space *btnc = &NILFS_BMAP_I(btree)->i_btnode_cache;
struct buffer_head *bh;
sector_t pbn = 0;
int err;
err = nilfs_btnode_submit_block(btnc, ptr, pbn, READ, bhp, &pbn);
if (err)
return err == -EEXIST ? 0 : err;
bh = *bhp;
wait_on_buffer(bh);
if (!buffer_uptodate(bh)) {
brelse(bh);
return -EIO;
}
if (nilfs_btree_broken_node_block(bh)) {
clear_buffer_uptodate(bh);
brelse(bh);
return -EINVAL;
}
return 0;
}
static int nilfs_btree_get_new_block(const struct nilfs_bmap *btree,
__u64 ptr, struct buffer_head **bhp)
{
@ -452,6 +426,74 @@ nilfs_btree_bad_node(struct nilfs_btree_node *node, int level)
return 0;
}
struct nilfs_btree_readahead_info {
struct nilfs_btree_node *node; /* parent node */
int max_ra_blocks; /* max nof blocks to read ahead */
int index; /* current index on the parent node */
int ncmax; /* nof children in the parent node */
};
static int __nilfs_btree_get_block(const struct nilfs_bmap *btree, __u64 ptr,
struct buffer_head **bhp,
const struct nilfs_btree_readahead_info *ra)
{
struct address_space *btnc = &NILFS_BMAP_I(btree)->i_btnode_cache;
struct buffer_head *bh, *ra_bh;
sector_t submit_ptr = 0;
int ret;
ret = nilfs_btnode_submit_block(btnc, ptr, 0, READ, &bh, &submit_ptr);
if (ret) {
if (ret != -EEXIST)
return ret;
goto out_check;
}
if (ra) {
int i, n;
__u64 ptr2;
/* read ahead sibling nodes */
for (n = ra->max_ra_blocks, i = ra->index + 1;
n > 0 && i < ra->ncmax; n--, i++) {
ptr2 = nilfs_btree_node_get_ptr(ra->node, i, ra->ncmax);
ret = nilfs_btnode_submit_block(btnc, ptr2, 0, READA,
&ra_bh, &submit_ptr);
if (likely(!ret || ret == -EEXIST))
brelse(ra_bh);
else if (ret != -EBUSY)
break;
if (!buffer_locked(bh))
goto out_no_wait;
}
}
wait_on_buffer(bh);
out_no_wait:
if (!buffer_uptodate(bh)) {
brelse(bh);
return -EIO;
}
out_check:
if (nilfs_btree_broken_node_block(bh)) {
clear_buffer_uptodate(bh);
brelse(bh);
return -EINVAL;
}
*bhp = bh;
return 0;
}
static int nilfs_btree_get_block(const struct nilfs_bmap *btree, __u64 ptr,
struct buffer_head **bhp)
{
return __nilfs_btree_get_block(btree, ptr, bhp, NULL);
}
static int nilfs_btree_do_lookup(const struct nilfs_bmap *btree,
struct nilfs_btree_path *path,
__u64 key, __u64 *ptrp, int minlevel)