From fa33915c92b43f5a4e95649f81303cc089b10dc6 Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi Date: Thu, 16 Apr 2015 12:46:39 -0700 Subject: [PATCH] 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/nilfs2/mdt.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++ fs/nilfs2/mdt.h | 3 +++ 2 files changed, 57 insertions(+) diff --git a/fs/nilfs2/mdt.c b/fs/nilfs2/mdt.c index 892cf5ffdb8e..dee34d990281 100644 --- a/fs/nilfs2/mdt.c +++ b/fs/nilfs2/mdt.c @@ -260,6 +260,60 @@ int nilfs_mdt_get_block(struct inode *inode, unsigned long blkoff, int create, return ret; } +/** + * nilfs_mdt_find_block - find and get a buffer on meta data file. + * @inode: inode of the meta data file + * @start: start block offset (inclusive) + * @end: end block offset (inclusive) + * @blkoff: block offset + * @out_bh: place to store a pointer to buffer_head struct + * + * nilfs_mdt_find_block() looks up an existing block in range of + * [@start, @end] and stores pointer to a buffer head of the block to + * @out_bh, and block offset to @blkoff, respectively. @out_bh and + * @blkoff are substituted only when zero is returned. + * + * Return Value: On success, it returns 0. On error, the following negative + * error code is returned. + * + * %-ENOMEM - Insufficient memory available. + * + * %-EIO - I/O error + * + * %-ENOENT - no block was found in the range + */ +int nilfs_mdt_find_block(struct inode *inode, unsigned long start, + unsigned long end, unsigned long *blkoff, + struct buffer_head **out_bh) +{ + __u64 next; + int ret; + + if (unlikely(start > end)) + return -ENOENT; + + ret = nilfs_mdt_read_block(inode, start, true, out_bh); + if (!ret) { + *blkoff = start; + goto out; + } + if (unlikely(ret != -ENOENT || start == ULONG_MAX)) + goto out; + + ret = nilfs_bmap_seek_key(NILFS_I(inode)->i_bmap, start + 1, &next); + if (!ret) { + if (next <= end) { + ret = nilfs_mdt_read_block(inode, next, true, out_bh); + if (!ret) + *blkoff = next; + } else { + ret = -ENOENT; + } + } +out: + return ret; +} + /** * nilfs_mdt_delete_block - make a hole on the meta data file. * @inode: inode of the meta data file 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); -- 2.20.1