fs: add sync_inode_metadata

Add a new helper to write out the inode using the writeback code,
that is including the correct dirty bit and list manipulation.  A few
of filesystems already opencode this, and a lot of others should be
using it instead of using write_inode_now which also writes out the
data.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

8 files changed, 28 insertions, 36 deletions

diff --git a/fs/exofs/file.c b/fs/exofs/file.c
index 68cb23e3bb98..b905c79b4f0a 100644
--- a/fs/exofs/file.c
+++ b/fs/exofs/file.c
@@ -46,10 +46,6 @@ static int exofs_file_fsync(struct file *filp, int datasync)
 {
         int ret;
         struct inode *inode = filp->f_mapping->host;
-        struct writeback_control wbc = {
-                .sync_mode = WB_SYNC_ALL,
-                .nr_to_write = 0, /* metadata-only; caller takes care of data */
-        };
         struct super_block *sb;
 
         if (!(inode->i_state & I_DIRTY))
@@ -57,7 +53,7 @@ static int exofs_file_fsync(struct file *filp, int datasync)
         if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
                 return 0;
 
-        ret = sync_inode(inode, &wbc);
+        ret = sync_inode_metadata(inode, 1);
 
         /* This is a good place to write the sb */
         /* TODO: Sechedule an sb-sync on create */
diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
index 764109886ec0..2709b34206ab 100644
--- a/fs/ext2/dir.c
+++ b/fs/ext2/dir.c
@@ -98,7 +98,7 @@ static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
         if (IS_DIRSYNC(dir)) {
                 err = write_one_page(page, 1);
                 if (!err)
-                        err = ext2_sync_inode(dir);
+                        err = sync_inode_metadata(dir, 1);
         } else {
                 unlock_page(page);
         }
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 416daa62242c..6346a2acf326 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -120,7 +120,6 @@ extern unsigned long ext2_count_free (struct buffer_head *, unsigned);
 extern struct inode *ext2_iget (struct super_block *, unsigned long);
 extern int ext2_write_inode (struct inode *, struct writeback_control *);
 extern void ext2_evict_inode(struct inode *);
-extern int ext2_sync_inode (struct inode *);
 extern int ext2_get_block(struct inode *, sector_t, struct buffer_head *, int);
 extern int ext2_setattr (struct dentry *, struct iattr *);
 extern void ext2_set_inode_flags(struct inode *inode);
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 533699c16040..40ad210a5049 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -1203,7 +1203,7 @@ static int ext2_setsize(struct inode *inode, loff_t newsize)
         inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
         if (inode_needs_sync(inode)) {
                 sync_mapping_buffers(inode->i_mapping);
-                ext2_sync_inode (inode);
+                sync_inode_metadata(inode, 1);
         } else {
                 mark_inode_dirty(inode);
         }
@@ -1523,15 +1523,6 @@ int ext2_write_inode(struct inode *inode, struct writeback_control *wbc)
         return __ext2_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
 }
 
-int ext2_sync_inode(struct inode *inode)
-{
-        struct writeback_control wbc = {
-                .sync_mode = WB_SYNC_ALL,
-                .nr_to_write = 0,       /* sys_fsync did this */
-        };
-        return sync_inode(inode, &wbc);
-}
-
 int ext2_setattr(struct dentry *dentry, struct iattr *iattr)
 {
         struct inode *inode = dentry->d_inode;
diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
index 8c29ae15129e..f84700be3274 100644
--- a/fs/ext2/xattr.c
+++ b/fs/ext2/xattr.c
@@ -699,7 +699,7 @@ ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh,
         EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0;
         inode->i_ctime = CURRENT_TIME_SEC;
         if (IS_SYNC(inode)) {
-                error = ext2_sync_inode (inode);
+                error = sync_inode_metadata(inode, 1);
                 /* In case sync failed due to ENOSPC the inode was actually
                  * written (only some dirty data were not) so we just proceed
                  * as if nothing happened and cleanup the unused block */
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index ab38fef1c9a1..29e3f409bbd0 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1198,3 +1198,23 @@ int sync_inode(struct inode *inode, struct writeback_control *wbc)
         return ret;
 }
 EXPORT_SYMBOL(sync_inode);
+
+/**
+ * sync_inode - write an inode to disk
+ * @inode: the inode to sync
+ * @wait: wait for I/O to complete.
+ *
+ * Write an inode to disk and adjust it's dirty state after completion.
+ *
+ * Note: only writes the actual inode, no associated data or other metadata.
+ */
+int sync_inode_metadata(struct inode *inode, int wait)
+{
+        struct writeback_control wbc = {
+                .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_NONE,
+                .nr_to_write = 0, /* metadata-only */
+        };
+
+        return sync_inode(inode, &wbc);
+}
+EXPORT_SYMBOL(sync_inode_metadata);
diff --git a/fs/libfs.c b/fs/libfs.c
index 62baa0387d6e..2dbf4877d7ef 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -892,10 +892,6 @@ EXPORT_SYMBOL_GPL(generic_fh_to_parent);
  */
 int generic_file_fsync(struct file *file, int datasync)
 {
-        struct writeback_control wbc = {
-                .sync_mode = WB_SYNC_ALL,
-                .nr_to_write = 0, /* metadata-only; caller takes care of data */
-        };
         struct inode *inode = file->f_mapping->host;
         int err;
         int ret;
@@ -906,7 +902,7 @@ int generic_file_fsync(struct file *file, int datasync)
         if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
                 return ret;
 
-        err = sync_inode(inode, &wbc);
+        err = sync_inode_metadata(inode, 1);
         if (ret == 0)
                 ret = err;
         return ret;
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 661a6cf8e826..184938fcff04 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -281,23 +281,13 @@ commit_metadata(struct svc_fh *fhp)
 {
         struct inode *inode = fhp->fh_dentry->d_inode;
         const struct export_operations *export_ops = inode->i_sb->s_export_op;
-        int error = 0;
 
         if (!EX_ISSYNC(fhp->fh_export))
                 return 0;
 
-        if (export_ops->commit_metadata) {
-                error = export_ops->commit_metadata(inode);
-        } else {
-                struct writeback_control wbc = {
-                        .sync_mode = WB_SYNC_ALL,
-                        .nr_to_write = 0, /* metadata only */
-                };
-
-                error = sync_inode(inode, &wbc);
-        }
-
-        return error;
+        if (export_ops->commit_metadata)
+                return export_ops->commit_metadata(inode);
+        return sync_inode_metadata(inode, 1);
 }
 
 /*