nilfs2: add helper to find existent block on metadata file

Add a new metadata file function, nilfs_mdt_find_block(), which finds
an existent block on a metadata file in a given range of blocks.  This
function skips continuous hole blocks efficiently by using
nilfs_bmap_seek_key().

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/nilfs2/mdt.h b/fs/nilfs2/mdt.h
index a294ea38e4c7..fe529a87a208 100644
--- a/fs/nilfs2/mdt.h
+++ b/fs/nilfs2/mdt.h
@@ -78,6 +78,9 @@ int nilfs_mdt_get_block(struct inode *, unsigned long, int,
                         void (*init_block)(struct inode *,
                                            struct buffer_head *, void *),
                         struct buffer_head **);
+int nilfs_mdt_find_block(struct inode *inode, unsigned long start,
+                         unsigned long end, unsigned long *blkoff,
+                         struct buffer_head **out_bh);
 int nilfs_mdt_delete_block(struct inode *, unsigned long);
 int nilfs_mdt_forget_block(struct inode *, unsigned long);
 int nilfs_mdt_mark_block_dirty(struct inode *, unsigned long);