Btrfs: Do more optimal file RA during shrinking and defrag

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

2 files changed, 22 insertions, 9 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;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 4d12aa532c5b..ab707c0930df 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2814,14 +2814,12 @@ unsigned long btrfs_force_ra(struct address_space *mapping,
                               struct file_ra_state *ra, struct file *file,
                               pgoff_t offset, pgoff_t last_index)
 {
-        pgoff_t req_size;
+        pgoff_t req_size = last_index - offset + 1;
 
 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
-        req_size = last_index - offset + 1;
         offset = page_cache_readahead(mapping, ra, file, offset, req_size);
         return offset;
 #else
-        req_size = min(last_index - offset + 1, (pgoff_t)128);
         page_cache_sync_readahead(mapping, ra, file, offset, req_size);
         return offset + req_size;
 #endif
@@ -2833,7 +2831,8 @@ int btrfs_defrag_file(struct file *file) {
         struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
         struct page *page;
         unsigned long last_index;
-        unsigned long ra_index = 0;
+        unsigned long ra_pages = root->fs_info->bdi.ra_pages;
+        unsigned long total_read = 0;
         u64 page_start;
         u64 page_end;
         unsigned long i;
@@ -2848,11 +2847,11 @@ int btrfs_defrag_file(struct file *file) {
         mutex_lock(&inode->i_mutex);
         last_index = inode->i_size >> PAGE_CACHE_SHIFT;
         for (i = 0; i <= last_index; i++) {
-                if (i == ra_index) {
-                        ra_index = btrfs_force_ra(inode->i_mapping,
-                                                  &file->f_ra,
-                                                  file, ra_index, last_index);
+                if (total_read % ra_pages == 0) {
+                        btrfs_force_ra(inode->i_mapping, &file->f_ra, file, i,
+                                       min(last_index, i + ra_pages - 1));
                 }
+                total_read++;
                 page = grab_cache_page(inode->i_mapping, i);
                 if (!page)
                         goto out_unlock;