fs: push i_mutex and filemap_write_and_wait down into ->fsync() handlers

Btrfs needs to be able to control how filemap_write_and_wait_range() is called
in fsync to make it less of a painful operation, so push down taking i_mutex and
the calling of filemap_write_and_wait() down into the ->fsync() handlers.  Some
file systems can drop taking the i_mutex altogether it seems, like ext3 and
ocfs2.  For correctness sake I just pushed everything down in all cases to make
sure that we keep the current behavior the same for everybody, and then each
individual fs maintainer can make up their mind about what to do from there.
Thanks,

Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

2 files changed, 11 insertions, 2 deletions

diff --git a/fs/logfs/file.c b/fs/logfs/file.c
index c2ad7028def..b548c87a86f 100644
--- a/fs/logfs/file.c
+++ b/fs/logfs/file.c
@@ -219,11 +219,20 @@ long logfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
         }
 }
 
-int logfs_fsync(struct file *file, int datasync)
+int logfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 {
         struct super_block *sb = file->f_mapping->host->i_sb;
+        struct inode *inode = file->f_mapping->host;
+        int ret;
+
+        ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
+        if (ret)
+                return ret;
 
+        mutex_lock(&inode->i_mutex);
         logfs_write_anchor(sb);
+        mutex_unlock(&inode->i_mutex);
+
         return 0;
 }
 
diff --git a/fs/logfs/logfs.h b/fs/logfs/logfs.h
index 57afd4a6fab..f22d108bfa5 100644
--- a/fs/logfs/logfs.h
+++ b/fs/logfs/logfs.h
@@ -506,7 +506,7 @@ extern const struct file_operations logfs_reg_fops;
 extern const struct address_space_operations logfs_reg_aops;
 int logfs_readpage(struct file *file, struct page *page);
 long logfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
-int logfs_fsync(struct file *file, int datasync);
+int logfs_fsync(struct file *file, loff_t start, loff_t end, int datasync);
 
 /* gc.c */
 u32 get_best_cand(struct super_block *sb, struct candidate_list *list, u32 *ec);