Move the call to thrashing_recovery_readahead() before state_based_readahead().
That catches the rare case where thrashing happened on the time we are to read
the page at ra->lookahead_index. Obviously this case should be handled by
thrashing_recovery_readahead() instead of state_based_readahead().
Signed-off-by: Fengguang Wu <[EMAIL PROTECTED]>
---
mm/readahead.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
--- linux-2.6.21-rc3-mm2.orig/mm/readahead.c
+++ linux-2.6.21-rc3-mm2/mm/readahead.c
@@ -1638,6 +1638,13 @@ page_cache_readahead_adaptive(struct add
return initial_readahead(mapping, filp, ra, req_size);
/*
+ * Recover from possible thrashing.
+ */
+ if (!page && offset - ra->prev_page <= 1 && ra_has_index(ra, offset))
+ return thrashing_recovery_readahead(mapping, filp, ra,
+ offset, ra_max);
+
+ /*
* State based sequential read-ahead.
*/
if (offset == ra->prev_page + 1 &&
@@ -1647,13 +1654,6 @@ page_cache_readahead_adaptive(struct add
offset, req_size, ra_max);
/*
- * Recover from possible thrashing.
- */
- if (!page && offset - ra->prev_page <= 1 && ra_has_index(ra, offset))
- return thrashing_recovery_readahead(mapping, filp, ra,
- offset, ra_max);
-
- /*
* Backward read-ahead.
*/
if (!page && try_backward_prefetching(ra, offset, req_size, ra_max))
--
-
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