Dan Magenheimer
2010-May-28 17:36 UTC
[PATCH V2 3/7] Cleancache (was Transcendent Memory): VFS hooks
[PATCH V2 3/7] Cleancache (was Transcendent Memory): VFS hooks
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-pointer-to-NULL if
CONFIG_CLEANCACHE is set but no cleancache "backend" has
claimed cleancache_ops.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Diffstat:
fs/buffer.c | 5 +++++
fs/mpage.c | 7 +++++++
fs/super.c | 8 ++++++++
mm/filemap.c | 11 +++++++++++
mm/truncate.c | 10 ++++++++++
5 files changed, 41 insertions(+)
--- linux-2.6.34/fs/super.c 2010-05-16 15:17:36.000000000 -0600
+++ linux-2.6.34-cleancache/fs/super.c 2010-05-24 12:15:20.000000000 -0600
@@ -38,6 +38,7 @@
#include <linux/mutex.h>
#include <linux/file.h>
#include <linux/backing-dev.h>
+#include <linux/cleancache.h>
#include <asm/uaccess.h>
#include "internal.h"
@@ -105,6 +106,7 @@ static struct super_block *alloc_super(s
s->s_qcop = sb_quotactl_ops;
s->s_op = &default_op;
s->s_time_gran = 1000000000;
+ s->cleancache_poolid = -1;
}
out:
return s;
@@ -195,6 +197,11 @@ void deactivate_super(struct super_block
vfs_dq_off(s, 0);
down_write(&s->s_umount);
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);
}
@@ -221,6 +228,7 @@ void deactivate_locked_super(struct supe
spin_unlock(&sb_lock);
vfs_dq_off(s, 0);
fs->kill_sb(s);
+ cleancache_flush_fs(s->cleancache_poolid);
put_filesystem(fs);
put_super(s);
} else {
--- linux-2.6.34/fs/buffer.c 2010-05-16 15:17:36.000000000 -0600
+++ linux-2.6.34-cleancache/fs/buffer.c 2010-05-24 12:14:44.000000000 -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);
@@ -276,6 +277,10 @@ void invalidate_bdev(struct block_device
invalidate_bh_lrus();
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-2.6.34/fs/mpage.c 2010-05-16 15:17:36.000000000 -0600
+++ linux-2.6.34-cleancache/fs/mpage.c 2010-05-24 12:29:28.000000000 -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) == CLEANCACHE_GET_PAGE_SUCCESS) {
+ SetPageUptodate(page);
+ goto confused;
+ }
+
/*
* This page will go to BIO. Do we need to send this BIO off first?
*/
--- linux-2.6.34/mm/filemap.c 2010-05-16 15:17:36.000000000 -0600
+++ linux-2.6.34-cleancache/mm/filemap.c 2010-05-24 12:14:44.000000000 -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-2.6.34/mm/truncate.c 2010-05-16 15:17:36.000000000 -0600
+++ linux-2.6.34-cleancache/mm/truncate.c 2010-05-24 12:14:44.000000000 -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);
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs"
in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Dan Magenheimer
2010-May-28 17:36 UTC
[Ocfs2-devel] [PATCH V2 3/7] Cleancache (was Transcendent Memory): VFS hooks
[PATCH V2 3/7] Cleancache (was Transcendent Memory): VFS hooks
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-pointer-to-NULL if
CONFIG_CLEANCACHE is set but no cleancache "backend" has
claimed cleancache_ops.
Signed-off-by: Chris Mason <chris.mason at oracle.com>
Signed-off-by: Dan Magenheimer <dan.magenheimer at oracle.com>
Diffstat:
fs/buffer.c | 5 +++++
fs/mpage.c | 7 +++++++
fs/super.c | 8 ++++++++
mm/filemap.c | 11 +++++++++++
mm/truncate.c | 10 ++++++++++
5 files changed, 41 insertions(+)
--- linux-2.6.34/fs/super.c 2010-05-16 15:17:36.000000000 -0600
+++ linux-2.6.34-cleancache/fs/super.c 2010-05-24 12:15:20.000000000 -0600
@@ -38,6 +38,7 @@
#include <linux/mutex.h>
#include <linux/file.h>
#include <linux/backing-dev.h>
+#include <linux/cleancache.h>
#include <asm/uaccess.h>
#include "internal.h"
@@ -105,6 +106,7 @@ static struct super_block *alloc_super(s
s->s_qcop = sb_quotactl_ops;
s->s_op = &default_op;
s->s_time_gran = 1000000000;
+ s->cleancache_poolid = -1;
}
out:
return s;
@@ -195,6 +197,11 @@ void deactivate_super(struct super_block
vfs_dq_off(s, 0);
down_write(&s->s_umount);
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);
}
@@ -221,6 +228,7 @@ void deactivate_locked_super(struct supe
spin_unlock(&sb_lock);
vfs_dq_off(s, 0);
fs->kill_sb(s);
+ cleancache_flush_fs(s->cleancache_poolid);
put_filesystem(fs);
put_super(s);
} else {
--- linux-2.6.34/fs/buffer.c 2010-05-16 15:17:36.000000000 -0600
+++ linux-2.6.34-cleancache/fs/buffer.c 2010-05-24 12:14:44.000000000 -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);
@@ -276,6 +277,10 @@ void invalidate_bdev(struct block_device
invalidate_bh_lrus();
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-2.6.34/fs/mpage.c 2010-05-16 15:17:36.000000000 -0600
+++ linux-2.6.34-cleancache/fs/mpage.c 2010-05-24 12:29:28.000000000 -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) == CLEANCACHE_GET_PAGE_SUCCESS) {
+ SetPageUptodate(page);
+ goto confused;
+ }
+
/*
* This page will go to BIO. Do we need to send this BIO off first?
*/
--- linux-2.6.34/mm/filemap.c 2010-05-16 15:17:36.000000000 -0600
+++ linux-2.6.34-cleancache/mm/filemap.c 2010-05-24 12:14:44.000000000 -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-2.6.34/mm/truncate.c 2010-05-16 15:17:36.000000000 -0600
+++ linux-2.6.34-cleancache/mm/truncate.c 2010-05-24 12:14:44.000000000 -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);
Dan Magenheimer
2010-Jun-04 15:13 UTC
[Ocfs2-devel] [PATCH V2 3/7] Cleancache (was Transcendent Memory): VFS hooks
> Hi, Dan. > I reviewed quickly. So I may be wrong. :)Hi Minchan -- Thanks for your thorough review! I don't think anyone else yet has examined the semantics of the cleancache patch as deeply as you have. Excellent!> > + /* > > + * 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); > > I doubt it's right place related to PFRA.I agree it doesn't seem to be the right place, but it does work and there doesn't seem to be a better place.> 1) > You mentiond PFRA in you description and I understood cleancache has > a cold clean page which is evicted by reclaimer. > But __remove_from_page_cache can be called by other call sites. > > For example, shmem_write page calls it for moving the page from page > cache > to swap cache. Although there isn't the page in page cache, it is in > swap cache. > So next read/write of shmem until swapout happens can be read/write in > swap cache. > > I didn't looked into whole of callsites. But please review again them.I think the "if (PageUptodate(page))" eliminates all the cases where bad things can happen. Note that there may be cases where some unnecessary puts/flushes occur. The focus of the patch is on correctness first; it may be possible to increase performance (marginally) in the future by reducing unnecessary cases.> 3) Please consider system memory pressure. > And I hope Nitin consider this, too.This is definitely very important but remember that cleancache provides a great deal of flexibility: Any page in cleancache can be thrown away at any time as every page is clean! It can even accept a page and throw it away immediately. Clearly the backend needs to do this intelligently so this will take some policy work. Since I saw you sent a separate response to Nitin, I'll let him answer for his in-kernel page cache compression work. The solution to the similar problem for Xen is described in the tmem internals document that I think I pointed to earlier here: http://oss.oracle.com/projects/tmem/documentation/internals/ Thanks, Dan