Btrfs: Do more optimal file RA during shrinking and defrag

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index a589912fdd51..fe4fe709c312 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2263,6 +2263,12 @@ int btrfs_free_block_groups(struct btrfs_fs_info *info)
         return 0;
 }
 
+static unsigned long calc_ra(unsigned long start, unsigned long last,
+                             unsigned long nr)
+{
+        return min(last, start + nr - 1);
+}
+
 static int noinline relocate_inode_pages(struct inode *inode, u64 start,
                                          u64 len)
 {
@@ -2275,6 +2281,8 @@ static int noinline relocate_inode_pages(struct inode *inode, u64 start,
         struct page *page;
         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
         struct file_ra_state *ra;
+        unsigned long total_read = 0;
+        unsigned long ra_pages;
 
         ra = kzalloc(sizeof(*ra), GFP_NOFS);
 
@@ -2282,11 +2290,17 @@ static int noinline relocate_inode_pages(struct inode *inode, u64 start,
         i = start >> PAGE_CACHE_SHIFT;
         last_index = (start + len - 1) >> PAGE_CACHE_SHIFT;
 
+        ra_pages = BTRFS_I(inode)->root->fs_info->bdi.ra_pages;
+
         file_ra_state_init(ra, inode->i_mapping);
-        btrfs_force_ra(inode->i_mapping, ra, NULL, i, last_index);
         kfree(ra);
 
         for (; i <= last_index; i++) {
+                if (total_read % ra_pages == 0) {
+                        btrfs_force_ra(inode->i_mapping, ra, NULL, i,
+                                       calc_ra(i, last_index, ra_pages));
+                }
+                total_read++;
                 page = grab_cache_page(inode->i_mapping, i);
                 if (!page)
                         goto out_unlock;