fuse: Introduce fi->lock to protect write related fields

To minimize contention of fc->lock, this patch introduces a new spinlock
for protection fuse_inode metadata:

fuse_inode:
	writectr
	writepages
	write_files
	queued_writes
	attr_version

inode:
	i_size
	i_nlink
	i_mtime
	i_ctime

Also, it protects the fields changed in fuse_change_attributes_common()
(too many to list).

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

1 files changed, 12 insertions, 13 deletions

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 10106f23e9e8..eb7dfb0d9513 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -658,7 +658,7 @@ static int fuse_unlink(struct inode *dir, struct dentry *entry)
 		struct inode *inode = d_inode(entry);
 		struct fuse_inode *fi = get_fuse_inode(inode);
 
-		spin_lock(&fc->lock);
+		spin_lock(&fi->lock);
 		fi->attr_version = atomic64_inc_return(&fc->attr_version);
 		/*
 		 * If i_nlink == 0 then unlink doesn't make sense, yet this can
@@ -668,7 +668,7 @@ static int fuse_unlink(struct inode *dir, struct dentry *entry)
 		 */
 		if (inode->i_nlink > 0)
 			drop_nlink(inode);
-		spin_unlock(&fc->lock);
+		spin_unlock(&fi->lock);
 		fuse_invalidate_attr(inode);
 		fuse_dir_changed(dir);
 		fuse_invalidate_entry_cache(entry);
@@ -812,10 +812,10 @@ static int fuse_link(struct dentry *entry, struct inode *newdir,
 	if (!err) {
 		struct fuse_inode *fi = get_fuse_inode(inode);
 
-		spin_lock(&fc->lock);
+		spin_lock(&fi->lock);
 		fi->attr_version = atomic64_inc_return(&fc->attr_version);
 		inc_nlink(inode);
-		spin_unlock(&fc->lock);
+		spin_unlock(&fi->lock);
 		fuse_invalidate_attr(inode);
 		fuse_update_ctime(inode);
 	} else if (err == -EINTR) {
@@ -1343,15 +1343,14 @@ static void iattr_to_fattr(struct fuse_conn *fc, struct iattr *iattr,
  */
 void fuse_set_nowrite(struct inode *inode)
 {
-	struct fuse_conn *fc = get_fuse_conn(inode);
 	struct fuse_inode *fi = get_fuse_inode(inode);
 
 	BUG_ON(!inode_is_locked(inode));
 
-	spin_lock(&fc->lock);
+	spin_lock(&fi->lock);
 	BUG_ON(fi->writectr < 0);
 	fi->writectr += FUSE_NOWRITE;
-	spin_unlock(&fc->lock);
+	spin_unlock(&fi->lock);
 	wait_event(fi->page_waitq, fi->writectr == FUSE_NOWRITE);
 }
 
@@ -1372,11 +1371,11 @@ static void __fuse_release_nowrite(struct inode *inode)
 
 void fuse_release_nowrite(struct inode *inode)
 {
-	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct fuse_inode *fi = get_fuse_inode(inode);
 
-	spin_lock(&fc->lock);
+	spin_lock(&fi->lock);
 	__fuse_release_nowrite(inode);
-	spin_unlock(&fc->lock);
+	spin_unlock(&fi->lock);
 }
 
 static void fuse_setattr_fill(struct fuse_conn *fc, struct fuse_args *args,
@@ -1511,7 +1510,7 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr,
 		goto error;
 	}
 
-	spin_lock(&fc->lock);
+	spin_lock(&fi->lock);
 	/* the kernel maintains i_mtime locally */
 	if (trust_local_cmtime) {
 		if (attr->ia_valid & ATTR_MTIME)
@@ -1529,10 +1528,10 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr,
 		i_size_write(inode, outarg.attr.size);
 
 	if (is_truncate) {
-		/* NOTE: this may release/reacquire fc->lock */
+		/* NOTE: this may release/reacquire fi->lock */
 		__fuse_release_nowrite(inode);
 	}
-	spin_unlock(&fc->lock);
+	spin_unlock(&fi->lock);
 
 	/*
 	 * Only call invalidate_inode_pages2() after removing