1 files changed, 23 insertions, 10 deletions

diff --git a/mm/readahead.c b/mm/readahead.c
index 4a58befbde4a..fd588ffc5086 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -380,6 +380,29 @@ ondemand_readahead(struct address_space *mapping,
         }
 
         /*
+         * Hit a marked page without valid readahead state.
+         * E.g. interleaved reads.
+         * Query the pagecache for async_size, which normally equals to
+         * readahead size. Ramp it up and use it as the new readahead size.
+         */
+        if (hit_readahead_marker) {
+                pgoff_t start;
+
+                read_lock_irq(&mapping->tree_lock);
+                start = radix_tree_next_hole(&mapping->page_tree, offset, max+1);
+                read_unlock_irq(&mapping->tree_lock);
+
+                if (!start || start - offset > max)
+                        return 0;
+
+                ra->start = start;
+                ra->size = start - offset;      /* old async_size */
+                ra->size = get_next_ra_size(ra, max);
+                ra->async_size = ra->size;
+                goto readit;
+        }
+
+        /*
          * It may be one of
          *      - first read on start of file
          *      - sequential cache miss
@@ -390,16 +413,6 @@ ondemand_readahead(struct address_space *mapping,
         ra->size = get_init_ra_size(req_size, max);
         ra->async_size = ra->size > req_size ? ra->size - req_size : ra->size;
 
-        /*
-         * Hit on a marked page without valid readahead state.
-         * E.g. interleaved reads.
-         * Not knowing its readahead pos/size, bet on the minimal possible one.
-         */
-        if (hit_readahead_marker) {
-                ra->start++;
-                ra->size = get_next_ra_size(ra, max);
-        }
-
 readit:
         return ra_submit(ra, mapping, filp);
 }