On Mon, Dec 13, 2010 at 3:22 PM, Shaohua Li <shaohua.li@xxxxxxxxx> wrote:
> Implementation btrfs .metadata_readahead. In btrfs, all metadata pages are in a
> special btree_inode. We do readahead in it.
>
> Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx>
>
> ---
> fs/btrfs/disk-io.c | 10 ++++++++++
> fs/btrfs/super.c | 13 +++++++++++++
> mm/readahead.c | 1 +
> 3 files changed, 24 insertions(+)
>
> Index: linux/fs/btrfs/disk-io.c
> ===================================================================
> --- linux.orig/fs/btrfs/disk-io.c 2010-12-07 13:32:24.000000000 +0800
> +++ linux/fs/btrfs/disk-io.c 2010-12-07 13:33:08.000000000 +0800
> @@ -776,6 +776,15 @@ static int btree_readpage(struct file *f
> return extent_read_full_page(tree, page, btree_get_extent);
> }
>
> +static int btree_readpages(struct file *file, struct address_space *mapping,
> + struct list_head *pages, unsigned nr_pages)
> +{
> + struct extent_io_tree *tree;
> + tree = &BTRFS_I(mapping->host)->io_tree;
> + return extent_readpages(tree, mapping, pages, nr_pages,
> + btree_get_extent);
> +}
> +
> static int btree_releasepage(struct page *page, gfp_t gfp_flags)
> {
> struct extent_io_tree *tree;
> @@ -819,6 +828,7 @@ static void btree_invalidatepage(struct
>
> static const struct address_space_operations btree_aops = {
> .readpage = btree_readpage,
> + .readpages = btree_readpages,
> .writepage = btree_writepage,
> .writepages = btree_writepages,
> .releasepage = btree_releasepage,
> Index: linux/fs/btrfs/super.c
> ===================================================================
> --- linux.orig/fs/btrfs/super.c 2010-12-07 13:32:24.000000000 +0800
> +++ linux/fs/btrfs/super.c 2010-12-07 13:33:08.000000000 +0800
> @@ -892,6 +892,18 @@ out:
> return -ENOENT;
> }
>
> +static int btrfs_metadata_readahead(struct super_block *sb, loff_t offset,
> + ssize_t size)
> +{
> + struct btrfs_root *tree_root = btrfs_sb(sb);
> + struct inode *btree_inode = tree_root->fs_info->btree_inode;
> + struct address_space *mapping = btree_inode->i_mapping;
> +
> + force_page_cache_readahead(mapping, NULL, offset >> PAGE_CACHE_SHIFT,
> + size >> PAGE_CACHE_SHIFT);
> + return 0;
> +}
> +
> static const struct super_operations btrfs_super_ops = {
> .drop_inode = btrfs_drop_inode,
> .evict_inode = btrfs_evict_inode,
> @@ -907,6 +919,7 @@ static const struct super_operations btr
> .freeze_fs = btrfs_freeze,
> .unfreeze_fs = btrfs_unfreeze,
> .metadata_incore = btrfs_metadata_incore,
> + .metadata_readahead = btrfs_metadata_readahead,
> };
>
> static const struct file_operations btrfs_ctl_fops = {
> Index: linux/mm/readahead.c
> ===================================================================
> --- linux.orig/mm/readahead.c 2010-12-07 13:32:24.000000000 +0800
> +++ linux/mm/readahead.c 2010-12-07 13:33:08.000000000 +0800
> @@ -228,6 +228,7 @@ int force_page_cache_readahead(struct ad
> }
> return ret;
> }
> +EXPORT_SYMBOL_GPL(force_page_cache_readahead);
>
> /*
> * Given a desired number of PAGE_CACHE_SIZE readahead pages, return a
>
>
btrfs will crash If the read-ahead range falls into unallocated chunk.
need code to check validity of the user input.
Yan, Zheng
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