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@intel.com>
---
fs/btrfs/disk-io.c | 10 ++++++++++
fs/btrfs/super.c | 1 +
fs/btrfs/volumes.c | 38 ++++++++++++++++++++++++++++++++++++++
fs/btrfs/volumes.h | 2 ++
mm/readahead.c | 1 +
5 files changed, 52 insertions(+)
Index: linux/fs/btrfs/disk-io.c
==================================================================---
linux.orig/fs/btrfs/disk-io.c 2011-01-18 10:15:17.000000000 +0800
+++ linux/fs/btrfs/disk-io.c 2011-01-18 10:42:20.000000000 +0800
@@ -796,6 +796,15 @@ 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;
@@ -839,6 +848,7 @@ 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 2011-01-18 10:41:15.000000000 +0800
+++ linux/fs/btrfs/super.c 2011-01-18 10:42:20.000000000 +0800
@@ -1162,6 +1162,7 @@ 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 2011-01-17 14:47:11.000000000 +0800
+++ linux/mm/readahead.c 2011-01-18 10:42:20.000000000 +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
Index: linux/fs/btrfs/volumes.c
==================================================================---
linux.orig/fs/btrfs/volumes.c 2011-01-18 10:15:17.000000000 +0800
+++ linux/fs/btrfs/volumes.c 2011-01-18 10:42:20.000000000 +0800
@@ -3744,3 +3744,41 @@ error:
btrfs_free_path(path);
return ret;
}
+
+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;
+ struct btrfs_fs_info *info = tree_root->fs_info;
+ struct btrfs_block_group_cache *cache = NULL;
+ u64 bytenr = offset;
+ int retval = -EINVAL;
+
+ lock_chunks(tree_root);
+ /* Make sure readahead range is in valid chunk */
+ while (1) {
+ cache = btrfs_lookup_block_group(info, bytenr);
+ if (!cache)
+ break;
+
+ if (cache->key.objectid + cache->key.offset >+ offset + size) {
+ retval = 0;
+ break;
+ }
+ bytenr = cache->key.objectid + cache->key.offset;
+ btrfs_put_block_group(cache);
+ cache = NULL;
+ }
+ if (cache)
+ btrfs_put_block_group(cache);
+
+ if (!retval)
+ force_page_cache_readahead(mapping, NULL,
+ offset >> PAGE_CACHE_SHIFT,
+ size >> PAGE_CACHE_SHIFT);
+ unlock_chunks(tree_root);
+ return retval;
+}
Index: linux/fs/btrfs/volumes.h
==================================================================---
linux.orig/fs/btrfs/volumes.h 2011-01-18 10:15:17.000000000 +0800
+++ linux/fs/btrfs/volumes.h 2011-01-18 10:42:20.000000000 +0800
@@ -212,4 +212,6 @@ int btrfs_chunk_readonly(struct btrfs_ro
int find_free_dev_extent(struct btrfs_trans_handle *trans,
struct btrfs_device *device, u64 num_bytes,
u64 *start, u64 *max_avail);
+int btrfs_metadata_readahead(struct super_block *sb, loff_t offset,
+ ssize_t size);
#endif
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