Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse

Pull fuse update from Miklos Szeredi:
 "This series adds cached writeback support to fuse, improving write
  throughput"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
  fuse: fix "uninitialized variable" warning
  fuse: Turn writeback cache on
  fuse: Fix O_DIRECT operations vs cached writeback misorder
  fuse: fuse_flush() should wait on writeback
  fuse: Implement write_begin/write_end callbacks
  fuse: restructure fuse_readpage()
  fuse: Flush files on wb close
  fuse: Trust kernel i_mtime only
  fuse: Trust kernel i_size only
  fuse: Connection bit for enabling writeback
  fuse: Prepare to handle short reads
  fuse: Linking file to inode helper

6 files changed, 384 insertions, 84 deletions

diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c
index b96a49b37d66..23e363f38302 100644
--- a/fs/fuse/cuse.c
+++ b/fs/fuse/cuse.c
@@ -95,7 +95,7 @@ static ssize_t cuse_read(struct file *file, char __user *buf, size_t count,
         struct iovec iov = { .iov_base = buf, .iov_len = count };
         struct fuse_io_priv io = { .async = 0, .file = file };
 
-        return fuse_direct_io(&io, &iov, 1, count, &pos, 0);
+        return fuse_direct_io(&io, &iov, 1, count, &pos, FUSE_DIO_CUSE);
 }
 
 static ssize_t cuse_write(struct file *file, const char __user *buf,
@@ -109,7 +109,8 @@ static ssize_t cuse_write(struct file *file, const char __user *buf,
          * No locking or generic_write_checks(), the server is
          * responsible for locking and sanity checks.
          */
-        return fuse_direct_io(&io, &iov, 1, count, &pos, 1);
+        return fuse_direct_io(&io, &iov, 1, count, &pos,
+                              FUSE_DIO_WRITE | FUSE_DIO_CUSE);
 }
 
 static int cuse_open(struct inode *inode, struct file *file)
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 1d1292c581c3..5b4e035b364c 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -839,6 +839,14 @@ static void fuse_fillattr(struct inode *inode, struct fuse_attr *attr,
                           struct kstat *stat)
 {
         unsigned int blkbits;
+        struct fuse_conn *fc = get_fuse_conn(inode);
+
+        /* see the comment in fuse_change_attributes() */
+        if (fc->writeback_cache && S_ISREG(inode->i_mode)) {
+                attr->size = i_size_read(inode);
+                attr->mtime = inode->i_mtime.tv_sec;
+                attr->mtimensec = inode->i_mtime.tv_nsec;
+        }
 
         stat->dev = inode->i_sb->s_dev;
         stat->ino = attr->ino;
@@ -1477,12 +1485,16 @@ static long fuse_dir_compat_ioctl(struct file *file, unsigned int cmd,
                                  FUSE_IOCTL_COMPAT | FUSE_IOCTL_DIR);
 }
 
-static bool update_mtime(unsigned ivalid)
+static bool update_mtime(unsigned ivalid, bool trust_local_mtime)
 {
         /* Always update if mtime is explicitly set  */
         if (ivalid & ATTR_MTIME_SET)
                 return true;
 
+        /* Or if kernel i_mtime is the official one */
+        if (trust_local_mtime)
+                return true;
+
         /* If it's an open(O_TRUNC) or an ftruncate(), don't update */
         if ((ivalid & ATTR_SIZE) && (ivalid & (ATTR_OPEN | ATTR_FILE)))
                 return false;
@@ -1491,7 +1503,8 @@ static bool update_mtime(unsigned ivalid)
         return true;
 }
 
-static void iattr_to_fattr(struct iattr *iattr, struct fuse_setattr_in *arg)
+static void iattr_to_fattr(struct iattr *iattr, struct fuse_setattr_in *arg,
+                           bool trust_local_mtime)
 {
         unsigned ivalid = iattr->ia_valid;
 
@@ -1510,11 +1523,11 @@ static void iattr_to_fattr(struct iattr *iattr, struct fuse_setattr_in *arg)
                 if (!(ivalid & ATTR_ATIME_SET))
                         arg->valid |= FATTR_ATIME_NOW;
         }
-        if ((ivalid & ATTR_MTIME) && update_mtime(ivalid)) {
+        if ((ivalid & ATTR_MTIME) && update_mtime(ivalid, trust_local_mtime)) {
                 arg->valid |= FATTR_MTIME;
                 arg->mtime = iattr->ia_mtime.tv_sec;
                 arg->mtimensec = iattr->ia_mtime.tv_nsec;
-                if (!(ivalid & ATTR_MTIME_SET))
+                if (!(ivalid & ATTR_MTIME_SET) && !trust_local_mtime)
                         arg->valid |= FATTR_MTIME_NOW;
         }
 }
@@ -1563,6 +1576,63 @@ void fuse_release_nowrite(struct inode *inode)
         spin_unlock(&fc->lock);
 }
 
+static void fuse_setattr_fill(struct fuse_conn *fc, struct fuse_req *req,
+                              struct inode *inode,
+                              struct fuse_setattr_in *inarg_p,
+                              struct fuse_attr_out *outarg_p)
+{
+        req->in.h.opcode = FUSE_SETATTR;
+        req->in.h.nodeid = get_node_id(inode);
+        req->in.numargs = 1;
+        req->in.args[0].size = sizeof(*inarg_p);
+        req->in.args[0].value = inarg_p;
+        req->out.numargs = 1;
+        if (fc->minor < 9)
+                req->out.args[0].size = FUSE_COMPAT_ATTR_OUT_SIZE;
+        else
+                req->out.args[0].size = sizeof(*outarg_p);
+        req->out.args[0].value = outarg_p;
+}
+
+/*
+ * Flush inode->i_mtime to the server
+ */
+int fuse_flush_mtime(struct file *file, bool nofail)
+{
+        struct inode *inode = file->f_mapping->host;
+        struct fuse_inode *fi = get_fuse_inode(inode);
+        struct fuse_conn *fc = get_fuse_conn(inode);
+        struct fuse_req *req = NULL;
+        struct fuse_setattr_in inarg;
+        struct fuse_attr_out outarg;
+        int err;
+
+        if (nofail) {
+                req = fuse_get_req_nofail_nopages(fc, file);
+        } else {
+                req = fuse_get_req_nopages(fc);
+                if (IS_ERR(req))
+                        return PTR_ERR(req);
+        }
+
+        memset(&inarg, 0, sizeof(inarg));
+        memset(&outarg, 0, sizeof(outarg));
+
+        inarg.valid |= FATTR_MTIME;
+        inarg.mtime = inode->i_mtime.tv_sec;
+        inarg.mtimensec = inode->i_mtime.tv_nsec;
+
+        fuse_setattr_fill(fc, req, inode, &inarg, &outarg);
+        fuse_request_send(fc, req);
+        err = req->out.h.error;
+        fuse_put_request(fc, req);
+
+        if (!err)
+                clear_bit(FUSE_I_MTIME_DIRTY, &fi->state);
+
+        return err;
+}
+
 /*
  * Set attributes, and at the same time refresh them.
  *
@@ -1580,8 +1650,10 @@ int fuse_do_setattr(struct inode *inode, struct iattr *attr,
         struct fuse_setattr_in inarg;
         struct fuse_attr_out outarg;
         bool is_truncate = false;
+        bool is_wb = fc->writeback_cache;
         loff_t oldsize;
         int err;
+        bool trust_local_mtime = is_wb && S_ISREG(inode->i_mode);
 
         if (!(fc->flags & FUSE_DEFAULT_PERMISSIONS))
                 attr->ia_valid |= ATTR_FORCE;
@@ -1610,7 +1682,7 @@ int fuse_do_setattr(struct inode *inode, struct iattr *attr,
 
         memset(&inarg, 0, sizeof(inarg));
         memset(&outarg, 0, sizeof(outarg));
-        iattr_to_fattr(attr, &inarg);
+        iattr_to_fattr(attr, &inarg, trust_local_mtime);
         if (file) {
                 struct fuse_file *ff = file->private_data;
                 inarg.valid |= FATTR_FH;
@@ -1621,17 +1693,7 @@ int fuse_do_setattr(struct inode *inode, struct iattr *attr,
                 inarg.valid |= FATTR_LOCKOWNER;