fuse: invalidation reverse calls

Add notification messages that allow the filesystem to invalidate VFS
caches.

Two notifications are added:

 1) inode invalidation

   - invalidate cached attributes
   - invalidate a range of pages in the page cache (this is optional)

 2) dentry invalidation

   - try to invalidate a subtree in the dentry cache

Care must be taken while accessing the 'struct super_block' for the
mount, as it can go away while an invalidation is in progress.  To
prevent this, introduce a rw-semaphore, that is taken for read during
the invalidation and taken for write in the ->kill_sb callback.

Cc: Csaba Henk <csaba@gluster.com>
Cc: Anand Avati <avati@zresearch.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

1 files changed, 81 insertions, 0 deletions

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 8a11a8c67c42..f58ecbc416c8 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -849,6 +849,81 @@ err:
         return err;
 }
 
+static int fuse_notify_inval_inode(struct fuse_conn *fc, unsigned int size,
+                                   struct fuse_copy_state *cs)
+{
+        struct fuse_notify_inval_inode_out outarg;
+        int err = -EINVAL;
+
+        if (size != sizeof(outarg))
+                goto err;
+
+        err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+        if (err)
+                goto err;
+        fuse_copy_finish(cs);
+
+        down_read(&fc->killsb);
+        err = -ENOENT;
+        if (!fc->sb)
+                goto err_unlock;
+
+        err = fuse_reverse_inval_inode(fc->sb, outarg.ino,
+                                       outarg.off, outarg.len);
+
+err_unlock:
+        up_read(&fc->killsb);
+        return err;
+
+err:
+        fuse_copy_finish(cs);
+        return err;
+}
+
+static int fuse_notify_inval_entry(struct fuse_conn *fc, unsigned int size,
+                                   struct fuse_copy_state *cs)
+{
+        struct fuse_notify_inval_entry_out outarg;
+        int err = -EINVAL;
+        char buf[FUSE_NAME_MAX+1];
+        struct qstr name;
+
+        if (size < sizeof(outarg))
+                goto err;
+
+        err = fuse_copy_one(cs, &outarg, sizeof(outarg));
+        if (err)
+                goto err;
+
+        err = -ENAMETOOLONG;
+        if (outarg.namelen > FUSE_NAME_MAX)
+                goto err;
+
+        name.name = buf;
+        name.len = outarg.namelen;
+        err = fuse_copy_one(cs, buf, outarg.namelen + 1);
+        if (err)
+                goto err;
+        fuse_copy_finish(cs);
+        buf[outarg.namelen] = 0;
+        name.hash = full_name_hash(name.name, name.len);
+
+        down_read(&fc->killsb);
+        err = -ENOENT;
+        if (!fc->sb)
+                goto err_unlock;
+
+        err = fuse_reverse_inval_entry(fc->sb, outarg.parent, &name);
+
+err_unlock:
+        up_read(&fc->killsb);
+        return err;
+
+err:
+        fuse_copy_finish(cs);
+        return err;
+}
+
 static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
                        unsigned int size, struct fuse_copy_state *cs)
 {
@@ -856,6 +931,12 @@ static int fuse_notify(struct fuse_conn *fc, enum fuse_notify_code code,
         case FUSE_NOTIFY_POLL:
                 return fuse_notify_poll(fc, size, cs);
 
+        case FUSE_NOTIFY_INVAL_INODE:
+                return fuse_notify_inval_inode(fc, size, cs);
+
+        case FUSE_NOTIFY_INVAL_ENTRY:
+                return fuse_notify_inval_entry(fc, size, cs);
+
         default:
                 fuse_copy_finish(cs);
                 return -EINVAL;