LU-14778 readahead: fix to reserve min pages

@pages_min might be larger than @pages which indicate
more pages should be read, and it will cause a warning
later.

Lustre-change: https://review.whamcloud.com/44050
Lustre-commit: 4fc127428f00d6a3b179a143a61ddc78e5d8ca7c

Signed-off-by: Wang Shilong <wshilong@ddn.com>
Change-Id: Ifd82f709c3877172f08b87ab0551da735a0613e0
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Reviewed-on: https://review.whamcloud.com/44287
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>

diff --git a/lustre/llite/rw.c b/lustre/llite/rw.c
index 530a59e..1e460f0 100644 (file)
--- a/lustre/llite/rw.c
+++ b/lustre/llite/rw.c
@@ -90,8 +90,9 @@ static unsigned long ll_ra_count_get(struct ll_sb_info *sbi,
 
         ENTRY;
 
+       WARN_ON_ONCE(pages_min > pages);
        /**
-        * Don't try readahead agreesively if we are limited
+        * Don't try readahead aggresively if we are limited
         * LRU pages, otherwise, it could cause deadlock.
         */
        pages = min(sbi->ll_cache->ccc_lru_max >> 2, pages);
@@ -100,7 +101,7 @@ static unsigned long ll_ra_count_get(struct ll_sb_info *sbi,
         * this will make us leak @ra_cur_pages, because
         * ll_ra_count_put() acutally freed @pages.
         */
-       if (WARN_ON_ONCE(pages_min > pages))
+       if (unlikely(pages_min > pages))
                pages_min = pages;
 
        /*
@@ -816,7 +817,8 @@ static int ll_readahead(const struct lu_env *env, struct cl_io *io,
        /* don't over reserved for mmap range read */
        if (skip_index)
                pages_min = 0;
-
+       if (pages_min > pages)
+               pages = pages_min;
        ria->ria_reserved = ll_ra_count_get(ll_i2sbi(inode), ria, pages,
                                            pages_min);
        if (ria->ria_reserved < pages)