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Message-ID: <20121102182945.GC30100@konrad-lan.dumpdata.com>
Date: Fri, 2 Nov 2012 11:29:45 -0700 (PDT)
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: Dan Magenheimer <dan.magenheimer@...cle.com>
Cc: devel@...uxdriverproject.org, linux-kernel@...r.kernel.org,
gregkh@...uxfoundation.org, linux-mm@...ck.org, ngupta@...are.org,
sjenning@...ux.vnet.ibm.com, minchan@...nel.org,
fschmaus@...il.com, andor.damm@...glemail.com,
ilendir@...glemail.com, akpm@...ux-foundation.org, mgorman@...e.de
Subject: Re: [PATCH 1/5] mm: cleancache: lazy initialization to allow tmem
backends to build/run as modules
On Wed, Oct 31, 2012 at 08:07:50AM -0700, Dan Magenheimer wrote:
> With the goal of allowing tmem backends (zcache, ramster, Xen tmem) to be
> built/loaded as modules rather than built-in and enabled by a boot parameter,
> this patch provides "lazy initialization", allowing backends to register to
> cleancache even after filesystems were mounted. Calls to init_fs and
> init_shared_fs are remembered as fake poolids but no real tmem_pools created.
> On backend registration the fake poolids are mapped to real poolids and
> respective tmem_pools.
>
> Signed-off-by: Stefan Hengelein <ilendir@...glemail.com>
> Signed-off-by: Florian Schmaus <fschmaus@...il.com>
> Signed-off-by: Andor Daam <andor.daam@...glemail.com>
> Signed-off-by: Dan Magenheimer <dan.magenheimer@...cle.com>
> ---
> include/linux/cleancache.h | 1 +
> mm/cleancache.c | 157 +++++++++++++++++++++++++++++++++++++++-----
> 2 files changed, 141 insertions(+), 17 deletions(-)
>
> diff --git a/include/linux/cleancache.h b/include/linux/cleancache.h
> index 42e55de..f7e32f0 100644
> --- a/include/linux/cleancache.h
> +++ b/include/linux/cleancache.h
> @@ -37,6 +37,7 @@ extern struct cleancache_ops
> cleancache_register_ops(struct cleancache_ops *ops);
> extern void __cleancache_init_fs(struct super_block *);
> extern void __cleancache_init_shared_fs(char *, struct super_block *);
> +#define CLEANCACHE_HAS_LAZY_INIT
> extern int __cleancache_get_page(struct page *);
> extern void __cleancache_put_page(struct page *);
> extern void __cleancache_invalidate_page(struct address_space *, struct page *);
> diff --git a/mm/cleancache.c b/mm/cleancache.c
> index 32e6f41..29430b7 100644
> --- a/mm/cleancache.c
> +++ b/mm/cleancache.c
> @@ -45,15 +45,42 @@ static u64 cleancache_puts;
> static u64 cleancache_invalidates;
>
> /*
> + * When no backend is registered all calls to init_fs and init_shard_fs
> + * are registered and fake poolids are given to the respective
> + * super block but no tmem_pools are created. When a backend
> + * registers with cleancache the previous calls to init_fs and
> + * init_shared_fs are executed to create tmem_pools and set the
> + * respective poolids. While no backend is registered all "puts",
> + * "gets" and "flushes" are ignored or fail.
> + */
> +#define MAX_INITIALIZABLE_FS 32
> +#define FAKE_FS_POOLID_OFFSET 1000
> +#define FAKE_SHARED_FS_POOLID_OFFSET 2000
> +static int fs_poolid_map[MAX_INITIALIZABLE_FS];
> +static int shared_fs_poolid_map[MAX_INITIALIZABLE_FS];
> +static char *uuids[MAX_INITIALIZABLE_FS];
> +static int backend_registered;
Those could use some #define's and bool, so please see attached
patch which does this.
>From a89c1224ec1957f1afaf4fbc1de349124bed6c67 Mon Sep 17 00:00:00 2001
From: Dan Magenheimer <dan.magenheimer@...cle.com>
Date: Wed, 31 Oct 2012 08:07:50 -0700
Subject: [PATCH 1/2] mm: cleancache: lazy initialization to allow tmem
backends to build/run as modules
With the goal of allowing tmem backends (zcache, ramster, Xen tmem) to be
built/loaded as modules rather than built-in and enabled by a boot parameter,
this patch provides "lazy initialization", allowing backends to register to
cleancache even after filesystems were mounted. Calls to init_fs and
init_shared_fs are remembered as fake poolids but no real tmem_pools created.
On backend registration the fake poolids are mapped to real poolids and
respective tmem_pools.
Signed-off-by: Stefan Hengelein <ilendir@...glemail.com>
Signed-off-by: Florian Schmaus <fschmaus@...il.com>
Signed-off-by: Andor Daam <andor.daam@...glemail.com>
Signed-off-by: Dan Magenheimer <dan.magenheimer@...cle.com>
[v1: Minor fixes: used #define for some values and bools]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
---
include/linux/cleancache.h | 1 +
mm/cleancache.c | 156 ++++++++++++++++++++++++++++++++++++++++-----
2 files changed, 140 insertions(+), 17 deletions(-)
diff --git a/include/linux/cleancache.h b/include/linux/cleancache.h
index 42e55de..f7e32f0 100644
--- a/include/linux/cleancache.h
+++ b/include/linux/cleancache.h
@@ -37,6 +37,7 @@ extern struct cleancache_ops
cleancache_register_ops(struct cleancache_ops *ops);
extern void __cleancache_init_fs(struct super_block *);
extern void __cleancache_init_shared_fs(char *, struct super_block *);
+#define CLEANCACHE_HAS_LAZY_INIT
extern int __cleancache_get_page(struct page *);
extern void __cleancache_put_page(struct page *);
extern void __cleancache_invalidate_page(struct address_space *, struct page *);
diff --git a/mm/cleancache.c b/mm/cleancache.c
index 32e6f41..318a0ad 100644
--- a/mm/cleancache.c
+++ b/mm/cleancache.c
@@ -45,15 +45,45 @@ static u64 cleancache_puts;
static u64 cleancache_invalidates;
/*
+ * When no backend is registered all calls to init_fs and init_shard_fs
+ * are registered and fake poolids are given to the respective
+ * super block but no tmem_pools are created. When a backend
+ * registers with cleancache the previous calls to init_fs and
+ * init_shared_fs are executed to create tmem_pools and set the
+ * respective poolids. While no backend is registered all "puts",
+ * "gets" and "flushes" are ignored or fail.
+ */
+#define MAX_INITIALIZABLE_FS 32
+#define FAKE_FS_POOLID_OFFSET 1000
+#define FAKE_SHARED_FS_POOLID_OFFSET 2000
+
+#define FS_NO_BACKEND (-1)
+#define FS_UNKNOWN (-2)
+static int fs_poolid_map[MAX_INITIALIZABLE_FS];
+static int shared_fs_poolid_map[MAX_INITIALIZABLE_FS];
+
+static char *uuids[MAX_INITIALIZABLE_FS];
+static bool __read_mostly backend_registered;
+
+/*
* register operations for cleancache, returning previous thus allowing
* detection of multiple backends and possible nesting
*/
struct cleancache_ops cleancache_register_ops(struct cleancache_ops *ops)
{
struct cleancache_ops old = cleancache_ops;
+ int i;
cleancache_ops = *ops;
- cleancache_enabled = 1;
+
+ backend_registered = true;
+ for (i = 0; i < MAX_INITIALIZABLE_FS; i++) {
+ if (fs_poolid_map[i] == FS_NO_BACKEND)
+ fs_poolid_map[i] = (*cleancache_ops.init_fs)(PAGE_SIZE);
+ if (shared_fs_poolid_map[i] == FS_NO_BACKEND)
+ shared_fs_poolid_map[i] = (*cleancache_ops.init_shared_fs)
+ (uuids[i], PAGE_SIZE);
+ }
return old;
}
EXPORT_SYMBOL(cleancache_register_ops);
@@ -61,15 +91,38 @@ EXPORT_SYMBOL(cleancache_register_ops);
/* Called by a cleancache-enabled filesystem at time of mount */
void __cleancache_init_fs(struct super_block *sb)
{
- sb->cleancache_poolid = (*cleancache_ops.init_fs)(PAGE_SIZE);
+ int i;
+
+ for (i = 0; i < MAX_INITIALIZABLE_FS; i++) {
+ if (fs_poolid_map[i] == FS_UNKNOWN) {
+ sb->cleancache_poolid = i + FAKE_FS_POOLID_OFFSET;
+ if (backend_registered)
+ fs_poolid_map[i] = (*cleancache_ops.init_fs)(PAGE_SIZE);
+ else
+ fs_poolid_map[i] = FS_NO_BACKEND;
+ break;
+ }
+ }
}
EXPORT_SYMBOL(__cleancache_init_fs);
/* Called by a cleancache-enabled clustered filesystem at time of mount */
void __cleancache_init_shared_fs(char *uuid, struct super_block *sb)
{
- sb->cleancache_poolid =
- (*cleancache_ops.init_shared_fs)(uuid, PAGE_SIZE);
+ int i;
+
+ for (i = 0; i < MAX_INITIALIZABLE_FS; i++) {
+ if (shared_fs_poolid_map[i] == FS_UNKNOWN) {
+ sb->cleancache_poolid = i + FAKE_SHARED_FS_POOLID_OFFSET;
+ uuids[i] = uuid;
+ if (backend_registered)
+ shared_fs_poolid_map[i] = (*cleancache_ops.init_shared_fs)
+ (uuid, PAGE_SIZE);
+ else
+ shared_fs_poolid_map[i] = FS_NO_BACKEND;
+ break;
+ }
+ }
}
EXPORT_SYMBOL(__cleancache_init_shared_fs);
@@ -99,6 +152,19 @@ static int cleancache_get_key(struct inode *inode,
}
/*
+ * Returns a pool_id that is associated with a given fake poolid.
+ */
+static int get_poolid_from_fake(int fake_pool_id)
+{
+ if (fake_pool_id >= FAKE_SHARED_FS_POOLID_OFFSET)
+ return shared_fs_poolid_map[fake_pool_id -
+ FAKE_SHARED_FS_POOLID_OFFSET];
+ else if (fake_pool_id >= FAKE_FS_POOLID_OFFSET)
+ return fs_poolid_map[fake_pool_id - FAKE_FS_POOLID_OFFSET];
+ return FS_NO_BACKEND;
+}
+
+/*
* "Get" data from cleancache associated with the poolid/inode/index
* that were specified when the data was put to cleanache and, if
* successful, use it to fill the specified page with data and return 0.
@@ -109,17 +175,26 @@ int __cleancache_get_page(struct page *page)
{
int ret = -1;
int pool_id;
+ int fake_pool_id;
struct cleancache_filekey key = { .u.key = { 0 } };
+ if (!backend_registered) {
+ cleancache_failed_gets++;
+ goto out;
+ }
+
VM_BUG_ON(!PageLocked(page));
- pool_id = page->mapping->host->i_sb->cleancache_poolid;
- if (pool_id < 0)
+ fake_pool_id = page->mapping->host->i_sb->cleancache_poolid;
+ if (fake_pool_id < 0)
goto out;
+ pool_id = get_poolid_from_fake(fake_pool_id);
if (cleancache_get_key(page->mapping->host, &key) < 0)
goto out;
- ret = (*cleancache_ops.get_page)(pool_id, key, page->index, page);
+ if (pool_id >= 0)
+ ret = (*cleancache_ops.get_page)(pool_id,
+ key, page->index, page);
if (ret == 0)
cleancache_succ_gets++;
else
@@ -138,12 +213,23 @@ EXPORT_SYMBOL(__cleancache_get_page);
void __cleancache_put_page(struct page *page)
{
int pool_id;
+ int fake_pool_id;
struct cleancache_filekey key = { .u.key = { 0 } };
+ if (!backend_registered) {
+ cleancache_puts++;
+ return;
+ }
+
VM_BUG_ON(!PageLocked(page));
- pool_id = page->mapping->host->i_sb->cleancache_poolid;
+ fake_pool_id = page->mapping->host->i_sb->cleancache_poolid;
+ if (fake_pool_id < 0)
+ return;
+
+ pool_id = get_poolid_from_fake(fake_pool_id);
+
if (pool_id >= 0 &&
- cleancache_get_key(page->mapping->host, &key) >= 0) {
+ cleancache_get_key(page->mapping->host, &key) >= 0) {
(*cleancache_ops.put_page)(pool_id, key, page->index, page);
cleancache_puts++;
}
@@ -158,14 +244,22 @@ void __cleancache_invalidate_page(struct address_space *mapping,
struct page *page)
{
/* careful... page->mapping is NULL sometimes when this is called */
- int pool_id = mapping->host->i_sb->cleancache_poolid;
+ int pool_id;
+ int fake_pool_id = mapping->host->i_sb->cleancache_poolid;
struct cleancache_filekey key = { .u.key = { 0 } };
- if (pool_id >= 0) {
+ if (!backend_registered)
+ return;
+
+ if (fake_pool_id >= 0) {
+ pool_id = get_poolid_from_fake(fake_pool_id);
+ if (pool_id < 0)
+ return;
+
VM_BUG_ON(!PageLocked(page));
if (cleancache_get_key(mapping->host, &key) >= 0) {
(*cleancache_ops.invalidate_page)(pool_id,
- key, page->index);
+ key, page->index);
cleancache_invalidates++;
}
}
@@ -179,9 +273,18 @@ EXPORT_SYMBOL(__cleancache_invalidate_page);
*/
void __cleancache_invalidate_inode(struct address_space *mapping)
{
- int pool_id = mapping->host->i_sb->cleancache_poolid;
+ int pool_id;
+ int fake_pool_id = mapping->host->i_sb->cleancache_poolid;
struct cleancache_filekey key = { .u.key = { 0 } };
+ if (!backend_registered)
+ return;
+
+ if (fake_pool_id < 0)
+ return;
+
+ pool_id = get_poolid_from_fake(fake_pool_id);
+
if (pool_id >= 0 && cleancache_get_key(mapping->host, &key) >= 0)
(*cleancache_ops.invalidate_inode)(pool_id, key);
}
@@ -194,16 +297,30 @@ EXPORT_SYMBOL(__cleancache_invalidate_inode);
*/
void __cleancache_invalidate_fs(struct super_block *sb)
{
- if (sb->cleancache_poolid >= 0) {
- int old_poolid = sb->cleancache_poolid;
- sb->cleancache_poolid = -1;
- (*cleancache_ops.invalidate_fs)(old_poolid);
+ int index;
+ int fake_pool_id = sb->cleancache_poolid;
+ int old_poolid = fake_pool_id;
+
+ if (fake_pool_id >= FAKE_SHARED_FS_POOLID_OFFSET) {
+ index = fake_pool_id - FAKE_SHARED_FS_POOLID_OFFSET;
+ old_poolid = shared_fs_poolid_map[index];
+ shared_fs_poolid_map[index] = FS_UNKNOWN;
+ uuids[index] = NULL;
+ } else if (fake_pool_id >= FAKE_FS_POOLID_OFFSET) {
+ index = fake_pool_id - FAKE_FS_POOLID_OFFSET;
+ old_poolid = fs_poolid_map[index];
+ fs_poolid_map[index] = FS_UNKNOWN;
}
+ sb->cleancache_poolid = -1;
+ if (backend_registered)
+ (*cleancache_ops.invalidate_fs)(old_poolid);
}
EXPORT_SYMBOL(__cleancache_invalidate_fs);
static int __init init_cleancache(void)
{
+ int i;
+
#ifdef CONFIG_DEBUG_FS
struct dentry *root = debugfs_create_dir("cleancache", NULL);
if (root == NULL)
@@ -215,6 +332,11 @@ static int __init init_cleancache(void)
debugfs_create_u64("invalidates", S_IRUGO,
root, &cleancache_invalidates);
#endif
+ for (i = 0; i < MAX_INITIALIZABLE_FS; i++) {
+ fs_poolid_map[i] = FS_UNKNOWN;
+ shared_fs_poolid_map[i] = FS_UNKNOWN;
+ }
+ cleancache_enabled = 1;
return 0;
}
module_init(init_cleancache)
--
1.7.11.7
--
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