[PATCH V3 4/8] Cleancache: VFS hooks for cleancache

Implement core hooks in VFS for: initializing cleancache
per filesystem; capturing clean pages evicted by page cache;
attempting to get pages from cleancache before filesystem
read; and ensuring coherency between pagecache, disk,
and cleancache.  All hooks become no-ops if CONFIG_CLEANCACHE
is unset, or become compare-function-pointer-to-NULL if
CONFIG_CLEANCACHE is set but no cleancache "backend" has
claimed cleancache_ops.

Signed-off-by: Chris Mason <[email protected]>
Signed-off-by: Dan Magenheimer <[email protected]>

Diffstat:
 fs/buffer.c                              |    5 +++++
 fs/mpage.c                               |    7 +++++++
 fs/super.c                               |    7 +++++++
 mm/filemap.c                             |   11 +++++++++++
 mm/truncate.c                            |   10 ++++++++++
 5 files changed, 40 insertions(+)

--- linux-2.6.35-rc2/fs/super.c 2010-06-05 21:43:24.000000000 -0600
+++ linux-2.6.35-rc2-cleancache/fs/super.c      2010-06-11 09:06:41.000000000 
-0600
@@ -30,6 +30,7 @@
 #include <linux/idr.h>
 #include <linux/mutex.h>
 #include <linux/backing-dev.h>
+#include <linux/cleancache.h>
 #include "internal.h"
 
 
@@ -95,6 +96,7 @@ static struct super_block *alloc_super(s
                s->s_maxbytes = MAX_NON_LFS;
                s->s_op = &default_op;
                s->s_time_gran = 1000000000;
+               s->cleancache_poolid = -1;
        }
 out:
        return s;
@@ -158,6 +160,11 @@ void deactivate_locked_super(struct supe
        struct file_system_type *fs = s->s_type;
        if (atomic_dec_and_test(&s->s_active)) {
                fs->kill_sb(s);
+               if (s->cleancache_poolid >= 0) {
+                       int cleancache_poolid = s->cleancache_poolid;
+                       s->cleancache_poolid = -1; /* avoid races */
+                       cleancache_flush_fs(cleancache_poolid);
+               }
                put_filesystem(fs);
                put_super(s);
        } else {
--- linux-2.6.35-rc2/fs/buffer.c        2010-06-05 21:43:24.000000000 -0600
+++ linux-2.6.35-rc2-cleancache/fs/buffer.c     2010-06-11 09:01:37.000000000 
-0600
@@ -41,6 +41,7 @@
 #include <linux/bitops.h>
 #include <linux/mpage.h>
 #include <linux/bit_spinlock.h>
+#include <linux/cleancache.h>
 
 static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
 
@@ -277,6 +278,10 @@ void invalidate_bdev(struct block_device
        invalidate_bh_lrus();
        lru_add_drain_all();    /* make sure all lru add caches are flushed */
        invalidate_mapping_pages(mapping, 0, -1);
+       /* 99% of the time, we don't need to flush the cleancache on the bdev.
+        * But, for the strange corners, lets be cautious
+        */
+       cleancache_flush_inode(mapping);
 }
 EXPORT_SYMBOL(invalidate_bdev);
 
--- linux-2.6.35-rc2/fs/mpage.c 2010-06-05 21:43:24.000000000 -0600
+++ linux-2.6.35-rc2-cleancache/fs/mpage.c      2010-06-11 10:29:15.000000000 
-0600
@@ -27,6 +27,7 @@
 #include <linux/writeback.h>
 #include <linux/backing-dev.h>
 #include <linux/pagevec.h>
+#include <linux/cleancache.h>
 
 /*
  * I/O completion handler for multipage BIOs.
@@ -286,6 +287,12 @@ do_mpage_readpage(struct bio *bio, struc
                SetPageMappedToDisk(page);
        }
 
+       if (fully_mapped && blocks_per_page == 1 && !PageUptodate(page) &&
+           cleancache_get_page(page) == 0) {
+               SetPageUptodate(page);
+               goto confused;
+       }
+
        /*
         * This page will go to BIO.  Do we need to send this BIO off first?
         */
--- linux-2.6.35-rc2/mm/filemap.c       2010-06-05 21:43:24.000000000 -0600
+++ linux-2.6.35-rc2-cleancache/mm/filemap.c    2010-06-11 09:01:37.000000000 
-0600
@@ -34,6 +34,7 @@
 #include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
 #include <linux/memcontrol.h>
 #include <linux/mm_inline.h> /* for page_is_file_cache() */
+#include <linux/cleancache.h>
 #include "internal.h"
 
 /*
@@ -119,6 +120,16 @@ void __remove_from_page_cache(struct pag
 {
        struct address_space *mapping = page->mapping;
 
+       /*
+        * if we're uptodate, flush out into the cleancache, otherwise
+        * invalidate any existing cleancache entries.  We can't leave
+        * stale data around in the cleancache once our page is gone
+        */
+       if (PageUptodate(page))
+               cleancache_put_page(page);
+       else
+               cleancache_flush_page(mapping, page);
+
        radix_tree_delete(&mapping->page_tree, page->index);
        page->mapping = NULL;
        mapping->nrpages--;
--- linux-2.6.35-rc2/mm/truncate.c      2010-06-05 21:43:24.000000000 -0600
+++ linux-2.6.35-rc2-cleancache/mm/truncate.c   2010-06-11 09:01:37.000000000 
-0600
@@ -19,6 +19,7 @@
 #include <linux/task_io_accounting_ops.h>
 #include <linux/buffer_head.h> /* grr. try_to_release_page,
                                   do_invalidatepage */
+#include <linux/cleancache.h>
 #include "internal.h"
 
 
@@ -51,6 +52,7 @@ void do_invalidatepage(struct page *page
 static inline void truncate_partial_page(struct page *page, unsigned partial)
 {
        zero_user_segment(page, partial, PAGE_CACHE_SIZE);
+       cleancache_flush_page(page->mapping, page);
        if (page_has_private(page))
                do_invalidatepage(page, partial);
 }
@@ -108,6 +110,10 @@ truncate_complete_page(struct address_sp
        clear_page_mlock(page);
        remove_from_page_cache(page);
        ClearPageMappedToDisk(page);
+       /* this must be after the remove_from_page_cache which
+        * calls cleancache_put_page (and note page->mapping is now NULL)
+        */
+       cleancache_flush_page(mapping, page);
        page_cache_release(page);       /* pagecache ref */
        return 0;
 }
@@ -215,6 +221,7 @@ void truncate_inode_pages_range(struct a
        pgoff_t next;
        int i;
 
+       cleancache_flush_inode(mapping);
        if (mapping->nrpages == 0)
                return;
 
@@ -290,6 +297,7 @@ void truncate_inode_pages_range(struct a
                pagevec_release(&pvec);
                mem_cgroup_uncharge_end();
        }
+       cleancache_flush_inode(mapping);
 }
 EXPORT_SYMBOL(truncate_inode_pages_range);
 
@@ -428,6 +436,7 @@ int invalidate_inode_pages2_range(struct
        int did_range_unmap = 0;
        int wrapped = 0;
 
+       cleancache_flush_inode(mapping);
        pagevec_init(&pvec, 0);
        next = start;
        while (next <= end && !wrapped &&
@@ -486,6 +495,7 @@ int invalidate_inode_pages2_range(struct
                mem_cgroup_uncharge_end();
                cond_resched();
        }
+       cleancache_flush_inode(mapping);
        return ret;
 }
 EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);

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