1 files changed, 25 insertions, 21 deletions

diff --git a/mm/readahead.c b/mm/readahead.c
index a7f01fcce9e7..ceed7e4790bd 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -339,33 +339,25 @@ ondemand_readahead(struct address_space *mapping,
                    unsigned long req_size)
 {
         unsigned long max = max_sane_readahead(ra->ra_pages);
-        pgoff_t prev_offset;
-        int     sequential;
+
+        /*
+         * start of file
+         */
+        if (!offset)
+                goto initial_readahead;
 
         /*
          * It's the expected callback offset, assume sequential access.
          * Ramp up sizes, and push forward the readahead window.
          */
-        if (offset && (offset == (ra->start + ra->size - ra->async_size) ||
-                        offset == (ra->start + ra->size))) {
+        if ((offset == (ra->start + ra->size - ra->async_size) ||
+             offset == (ra->start + ra->size))) {
                 ra->start += ra->size;
                 ra->size = get_next_ra_size(ra, max);
                 ra->async_size = ra->size;
                 goto readit;
         }
 
-        prev_offset = ra->prev_pos >> PAGE_CACHE_SHIFT;
-        sequential = offset - prev_offset <= 1UL || req_size > max;
-
-        /*
-         * Standalone, small read.
-         * Read as is, and do not pollute the readahead state.
-         */
-        if (!hit_readahead_marker && !sequential) {
-                return __do_page_cache_readahead(mapping, filp,
-                                                offset, req_size, 0);
-        }
-
         /*
          * Hit a marked page without valid readahead state.
          * E.g. interleaved reads.
@@ -391,12 +383,24 @@ ondemand_readahead(struct address_space *mapping,
         }
 
         /*
-         * It may be one of
-         *      - first read on start of file
-         *      - sequential cache miss
-         *      - oversize random read
-         * Start readahead for it.
+         * oversize read
          */
+        if (req_size > max)
+                goto initial_readahead;
+
+        /*
+         * sequential cache miss
+         */
+        if (offset - (ra->prev_pos >> PAGE_CACHE_SHIFT) <= 1UL)
+                goto initial_readahead;
+
+        /*
+         * standalone, small random read
+         * Read as is, and do not pollute the readahead state.
+         */
+        return __do_page_cache_readahead(mapping, filp, offset, req_size, 0);
+
+initial_readahead:
         ra->start = offset;
         ra->size = get_init_ra_size(req_size, max);
         ra->async_size = ra->size > req_size ? ra->size - req_size : ra->size;