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/vfs_inode.c b/fs/9p/vfs_inode.c
index f3bfa87..5947628 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -40,6 +40,7 @@
#include "v9fs.h"
#include "v9fs_vfs.h"
#include "fid.h"
+#include "cache.h"
static const struct inode_operations v9fs_dir_inode_operations;
static const struct inode_operations v9fs_dir_inode_operations_ext;
@@ -197,6 +198,39 @@
wstat->extension = NULL;
}
+#ifdef CONFIG_9P_FSCACHE
+/**
+ * v9fs_alloc_inode - helper function to allocate an inode
+ * This callback is executed before setting up the inode so that we
+ * can associate a vcookie with each inode.
+ *
+ */
+
+struct inode *v9fs_alloc_inode(struct super_block *sb)
+{
+ struct v9fs_cookie *vcookie;
+ vcookie = (struct v9fs_cookie *)kmem_cache_alloc(vcookie_cache,
+ GFP_KERNEL);
+ if (!vcookie)
+ return NULL;
+
+ vcookie->fscache = NULL;
+ vcookie->qid = NULL;
+ spin_lock_init(&vcookie->lock);
+ return &vcookie->inode;
+}
+
+/**
+ * v9fs_destroy_inode - destroy an inode
+ *
+ */
+
+void v9fs_destroy_inode(struct inode *inode)
+{
+ kmem_cache_free(vcookie_cache, v9fs_inode2cookie(inode));
+}
+#endif
+
/**
* v9fs_get_inode - helper function to setup an inode
* @sb: superblock
@@ -326,6 +360,21 @@
}
*/
+
+/**
+ * v9fs_clear_inode - release an inode
+ * @inode: inode to release
+ *
+ */
+void v9fs_clear_inode(struct inode *inode)
+{
+ filemap_fdatawrite(inode->i_mapping);
+
+#ifdef CONFIG_9P_FSCACHE
+ v9fs_cache_inode_put_cookie(inode);
+#endif
+}
+
/**
* v9fs_inode_from_fid - populate an inode by issuing a attribute request
* @v9ses: session information
@@ -356,8 +405,14 @@
v9fs_stat2inode(st, ret, sb);
ret->i_ino = v9fs_qid2ino(&st->qid);
+
+#ifdef CONFIG_9P_FSCACHE
+ v9fs_vcookie_set_qid(ret, &st->qid);
+ v9fs_cache_inode_get_cookie(ret);
+#endif
p9stat_free(st);
kfree(st);
+
return ret;
error:
@@ -751,7 +806,7 @@
P9_DPRINTK(P9_DEBUG_VFS, "dentry: %p\n", dentry);
err = -EPERM;
v9ses = v9fs_inode2v9ses(dentry->d_inode);
- if (v9ses->cache == CACHE_LOOSE)
+ if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
return simple_getattr(mnt, dentry, stat);
fid = v9fs_fid_lookup(dentry);