9p: Add fscache support to 9p
This patch adds a persistent, read-only caching facility for
9p clients using the FS-Cache caching backend.
When the fscache facility is enabled, each inode is associated
with a corresponding vcookie which is an index into the FS-Cache
indexing tree. The FS-Cache indexing tree is indexed at 3 levels:
- session object associated with each mount.
- inode/vcookie
- actual data (pages)
A cache tag is chosen randomly for each session. These tags can
be read off /sys/fs/9p/caches and can be passed as a mount-time
parameter to re-attach to the specified caching session.
Signed-off-by: Abhishek Kulkarni <adkulkar@umail.iu.edu>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
index f7003cf..cf62b05 100644
--- a/fs/9p/v9fs.c
+++ b/fs/9p/v9fs.c
@@ -34,21 +34,25 @@
#include <net/9p/transport.h>
#include "v9fs.h"
#include "v9fs_vfs.h"
+#include "cache.h"
+
+static DEFINE_SPINLOCK(v9fs_sessionlist_lock);
+static LIST_HEAD(v9fs_sessionlist);
/*
- * Option Parsing (code inspired by NFS code)
- * NOTE: each transport will parse its own options
- */
+ * Option Parsing (code inspired by NFS code)
+ * NOTE: each transport will parse its own options
+ */
enum {
/* Options that take integer arguments */
Opt_debug, Opt_dfltuid, Opt_dfltgid, Opt_afid,
/* String options */
- Opt_uname, Opt_remotename, Opt_trans,
+ Opt_uname, Opt_remotename, Opt_trans, Opt_cache, Opt_cachetag,
/* Options that take no arguments */
Opt_nodevmap,
/* Cache options */
- Opt_cache_loose,
+ Opt_cache_loose, Opt_fscache,
/* Access options */
Opt_access,
/* Error token */
@@ -63,8 +67,10 @@
{Opt_uname, "uname=%s"},
{Opt_remotename, "aname=%s"},
{Opt_nodevmap, "nodevmap"},
- {Opt_cache_loose, "cache=loose"},
+ {Opt_cache, "cache=%s"},
{Opt_cache_loose, "loose"},
+ {Opt_fscache, "fscache"},
+ {Opt_cachetag, "cachetag=%s"},
{Opt_access, "access=%s"},
{Opt_err, NULL}
};
@@ -89,16 +95,16 @@
v9ses->afid = ~0;
v9ses->debug = 0;
v9ses->cache = 0;
+#ifdef CONFIG_9P_FSCACHE
+ v9ses->cachetag = NULL;
+#endif
if (!opts)
return 0;
options = kstrdup(opts, GFP_KERNEL);
- if (!options) {
- P9_DPRINTK(P9_DEBUG_ERROR,
- "failed to allocate copy of option string\n");
- return -ENOMEM;
- }
+ if (!options)
+ goto fail_option_alloc;
while ((p = strsep(&options, ",")) != NULL) {
int token;
@@ -143,16 +149,33 @@
case Opt_cache_loose:
v9ses->cache = CACHE_LOOSE;
break;
+ case Opt_fscache:
+ v9ses->cache = CACHE_FSCACHE;
+ break;
+ case Opt_cachetag:
+#ifdef CONFIG_9P_FSCACHE
+ v9ses->cachetag = match_strdup(&args[0]);
+#endif
+ break;
+ case Opt_cache:
+ s = match_strdup(&args[0]);
+ if (!s)
+ goto fail_option_alloc;
+
+ if (strcmp(s, "loose") == 0)
+ v9ses->cache = CACHE_LOOSE;
+ else if (strcmp(s, "fscache") == 0)
+ v9ses->cache = CACHE_FSCACHE;
+ else
+ v9ses->cache = CACHE_NONE;
+ kfree(s);
+ break;
case Opt_access:
s = match_strdup(&args[0]);
- if (!s) {
- P9_DPRINTK(P9_DEBUG_ERROR,
- "failed to allocate copy"
- " of option argument\n");
- ret = -ENOMEM;
- break;
- }
+ if (!s)
+ goto fail_option_alloc;
+
v9ses->flags &= ~V9FS_ACCESS_MASK;
if (strcmp(s, "user") == 0)
v9ses->flags |= V9FS_ACCESS_USER;
@@ -173,6 +196,11 @@
}
kfree(options);
return ret;
+
+fail_option_alloc:
+ P9_DPRINTK(P9_DEBUG_ERROR,
+ "failed to allocate copy of option argument\n");
+ return -ENOMEM;
}
/**
@@ -200,6 +228,10 @@
return ERR_PTR(-ENOMEM);
}
+ spin_lock(&v9fs_sessionlist_lock);
+ list_add(&v9ses->slist, &v9fs_sessionlist);
+ spin_unlock(&v9fs_sessionlist_lock);
+
v9ses->flags = V9FS_EXTENDED | V9FS_ACCESS_USER;
strcpy(v9ses->uname, V9FS_DEFUSER);
strcpy(v9ses->aname, V9FS_DEFANAME);
@@ -249,6 +281,11 @@
else
fid->uid = ~0;
+#ifdef CONFIG_9P_FSCACHE
+ /* register the session for caching */
+ v9fs_cache_session_get_cookie(v9ses);
+#endif
+
return fid;
error:
@@ -268,8 +305,18 @@
v9ses->clnt = NULL;
}
+#ifdef CONFIG_9P_FSCACHE
+ if (v9ses->fscache) {
+ v9fs_cache_session_put_cookie(v9ses);
+ kfree(v9ses->cachetag);
+ }
+#endif
__putname(v9ses->uname);
__putname(v9ses->aname);
+
+ spin_lock(&v9fs_sessionlist_lock);
+ list_del(&v9ses->slist);
+ spin_unlock(&v9fs_sessionlist_lock);
}
/**
@@ -286,25 +333,132 @@
extern int v9fs_error_init(void);
+static struct kobject *v9fs_kobj;
+
+#ifdef CONFIG_9P_FSCACHE
/**
- * v9fs_init - Initialize module
+ * caches_show - list caches associated with a session
+ *
+ * Returns the size of buffer written.
+ */
+
+static ssize_t caches_show(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ char *buf)
+{
+ ssize_t n = 0, count = 0, limit = PAGE_SIZE;
+ struct v9fs_session_info *v9ses;
+
+ spin_lock(&v9fs_sessionlist_lock);
+ list_for_each_entry(v9ses, &v9fs_sessionlist, slist) {
+ if (v9ses->cachetag) {
+ n = snprintf(buf, limit, "%s\n", v9ses->cachetag);
+ if (n < 0) {
+ count = n;
+ break;
+ }
+
+ count += n;
+ limit -= n;
+ }
+ }
+
+ spin_unlock(&v9fs_sessionlist_lock);
+ return count;
+}
+
+static struct kobj_attribute v9fs_attr_cache = __ATTR_RO(caches);
+#endif /* CONFIG_9P_FSCACHE */
+
+static struct attribute *v9fs_attrs[] = {
+#ifdef CONFIG_9P_FSCACHE
+ &v9fs_attr_cache.attr,
+#endif
+ NULL,
+};
+
+static struct attribute_group v9fs_attr_group = {
+ .attrs = v9fs_attrs,
+};
+
+/**
+ * v9fs_sysfs_init - Initialize the v9fs sysfs interface
+ *
+ */
+
+static int v9fs_sysfs_init(void)
+{
+ v9fs_kobj = kobject_create_and_add("9p", fs_kobj);
+ if (!v9fs_kobj)
+ return -ENOMEM;
+
+ if (sysfs_create_group(v9fs_kobj, &v9fs_attr_group)) {
+ kobject_put(v9fs_kobj);
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+/**
+ * v9fs_sysfs_cleanup - Unregister the v9fs sysfs interface
+ *
+ */
+
+static void v9fs_sysfs_cleanup(void)
+{
+ sysfs_remove_group(v9fs_kobj, &v9fs_attr_group);
+ kobject_put(v9fs_kobj);
+}
+
+/**
+ * init_v9fs - Initialize module
*
*/
static int __init init_v9fs(void)
{
+ int err;
printk(KERN_INFO "Installing v9fs 9p2000 file system support\n");
/* TODO: Setup list of registered trasnport modules */
- return register_filesystem(&v9fs_fs_type);
+ err = register_filesystem(&v9fs_fs_type);
+ if (err < 0) {
+ printk(KERN_ERR "Failed to register filesystem\n");
+ return err;
+ }
+
+ err = v9fs_cache_register();
+ if (err < 0) {
+ printk(KERN_ERR "Failed to register v9fs for caching\n");
+ goto out_fs_unreg;
+ }
+
+ err = v9fs_sysfs_init();
+ if (err < 0) {
+ printk(KERN_ERR "Failed to register with sysfs\n");
+ goto out_sysfs_cleanup;
+ }
+
+ return 0;
+
+out_sysfs_cleanup:
+ v9fs_sysfs_cleanup();
+
+out_fs_unreg:
+ unregister_filesystem(&v9fs_fs_type);
+
+ return err;
}
/**
- * v9fs_init - shutdown module
+ * exit_v9fs - shutdown module
*
*/
static void __exit exit_v9fs(void)
{
+ v9fs_sysfs_cleanup();
+ v9fs_cache_unregister();
unregister_filesystem(&v9fs_fs_type);
}