On Wed, Mar 17, 2010 at 05:20:53PM +1100, Nick Piggin wrote:
> btrfs: use add_to_page_cache_lru, use __page_cache_alloc
> 
> Pagecache pages should be allocated with __page_cache_alloc, so they
> obey pagecache memory policies.
> 
> add_to_page_cache_lru is exported, so it should be used. Benefits over
> using a private pagevec: neater code, 128 bytes fewer stack used, percpu
> lru ordering is preserved, and finally don't need to flush pagevec
> before returning so batching may be shared with other LRU insertions.
> 
> Signed-off-by: Nick Piggin <npig...@suse.de>:

Missed a rediff.
---
 fs/btrfs/compression.c |   20 ++------------------
 fs/btrfs/extent_io.c   |   22 +++++-----------------
 2 files changed, 7 insertions(+), 35 deletions(-)

Index: linux-2.6/fs/btrfs/compression.c
===================================================================
--- linux-2.6.orig/fs/btrfs/compression.c
+++ linux-2.6/fs/btrfs/compression.c
@@ -31,7 +31,6 @@
 #include <linux/swap.h>
 #include <linux/writeback.h>
 #include <linux/bit_spinlock.h>
-#include <linux/pagevec.h>
 #include "compat.h"
 #include "ctree.h"
 #include "disk-io.h"
@@ -445,7 +444,6 @@ static noinline int add_ra_bio_pages(str
        unsigned long nr_pages = 0;
        struct extent_map *em;
        struct address_space *mapping = inode->i_mapping;
-       struct pagevec pvec;
        struct extent_map_tree *em_tree;
        struct extent_io_tree *tree;
        u64 end;
@@ -461,7 +459,6 @@ static noinline int add_ra_bio_pages(str
 
        end_index = (i_size_read(inode) - 1) >> PAGE_CACHE_SHIFT;
 
-       pagevec_init(&pvec, 0);
        while (last_offset < compressed_end) {
                page_index = last_offset >> PAGE_CACHE_SHIFT;
 
@@ -478,26 +475,17 @@ static noinline int add_ra_bio_pages(str
                        goto next;
                }
 
-               page = alloc_page(mapping_gfp_mask(mapping) & ~__GFP_FS);
+               page = __page_cache_alloc(mapping_gfp_mask(mapping) &
+                                                               ~__GFP_FS);
                if (!page)
                        break;
 
-               page->index = page_index;
-               /*
-                * what we want to do here is call add_to_page_cache_lru,
-                * but that isn't exported, so we reproduce it here
-                */
-               if (add_to_page_cache(page, mapping,
-                                     page->index, GFP_NOFS)) {
+               if (add_to_page_cache_lru(page, mapping, page_index,
+                                                               GFP_NOFS)) {
                        page_cache_release(page);
                        goto next;
                }
 
-               /* open coding of lru_cache_add, also not exported */
-               page_cache_get(page);
-               if (!pagevec_add(&pvec, page))
-                       __pagevec_lru_add_file(&pvec);
-
                end = last_offset + PAGE_CACHE_SIZE - 1;
                /*
                 * at this point, we have a locked page in the page cache
@@ -551,8 +539,6 @@ static noinline int add_ra_bio_pages(str
 next:
                last_offset += PAGE_CACHE_SIZE;
        }
-       if (pagevec_count(&pvec))
-               __pagevec_lru_add_file(&pvec);
        return 0;
 }
 
Index: linux-2.6/fs/btrfs/extent_io.c
===================================================================
--- linux-2.6.orig/fs/btrfs/extent_io.c
+++ linux-2.6/fs/btrfs/extent_io.c
@@ -2663,33 +2663,21 @@ int extent_readpages(struct extent_io_tr
 {
        struct bio *bio = NULL;
        unsigned page_idx;
-       struct pagevec pvec;
        unsigned long bio_flags = 0;
 
-       pagevec_init(&pvec, 0);
        for (page_idx = 0; page_idx < nr_pages; page_idx++) {
                struct page *page = list_entry(pages->prev, struct page, lru);
 
                prefetchw(&page->flags);
                list_del(&page->lru);
-               /*
-                * what we want to do here is call add_to_page_cache_lru,
-                * but that isn't exported, so we reproduce it here
-                */
-               if (!add_to_page_cache(page, mapping,
+               if (add_to_page_cache_lru(page, mapping,
                                        page->index, GFP_KERNEL)) {
-
-                       /* open coding of lru_cache_add, also not exported */
-                       page_cache_get(page);
-                       if (!pagevec_add(&pvec, page))
-                               __pagevec_lru_add_file(&pvec);
-                       __extent_read_full_page(tree, page, get_extent,
-                                               &bio, 0, &bio_flags);
+                       page_cache_release(page);
+                       continue;
                }
-               page_cache_release(page);
+               __extent_read_full_page(tree, page, get_extent,
+                                               &bio, 0, &bio_flags);
        }
-       if (pagevec_count(&pvec))
-               __pagevec_lru_add_file(&pvec);
        BUG_ON(!list_empty(pages));
        if (bio)
                submit_one_bio(READ, bio, 0, bio_flags);
--
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