nilfs2: add read ahead mode to nilfs_btnode_submit_block
This adds mode argument to nilfs_btnode_submit_block() function and
allows it to issue a read-ahead request.
An optional submit_ptr argument is also added to store the actual
block address for which bio is sent. submit_ptr is used for a series
of read-ahead requests, and helps to decide if each requested block is
continous to the previous one on disk.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/fs/nilfs2/btnode.c b/fs/nilfs2/btnode.c
index 0a6834b..f78ab10 100644
--- a/fs/nilfs2/btnode.c
+++ b/fs/nilfs2/btnode.c
@@ -96,7 +96,8 @@
}
int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
- sector_t pblocknr, struct buffer_head **pbh)
+ sector_t pblocknr, int mode,
+ struct buffer_head **pbh, sector_t *submit_ptr)
{
struct buffer_head *bh;
struct inode *inode = NILFS_BTNC_I(btnc);
@@ -127,7 +128,16 @@
}
}
}
- lock_buffer(bh);
+
+ if (mode == READA) {
+ if (pblocknr != *submit_ptr + 1 || !trylock_buffer(bh)) {
+ err = -EBUSY; /* internal code */
+ brelse(bh);
+ goto out_locked;
+ }
+ } else { /* mode == READ */
+ lock_buffer(bh);
+ }
if (buffer_uptodate(bh)) {
unlock_buffer(bh);
err = -EEXIST; /* internal code */
@@ -138,8 +148,9 @@
bh->b_blocknr = pblocknr; /* set block address for read */
bh->b_end_io = end_buffer_read_sync;
get_bh(bh);
- submit_bh(READ, bh);
+ submit_bh(mode, bh);
bh->b_blocknr = blocknr; /* set back to the given block address */
+ *submit_ptr = pblocknr;
err = 0;
found:
*pbh = bh;