btrfs: make reflinks respect O_SYNC O_DSYNC and S_SYNC flags

[mirror_ubuntu-jammy-kernel.git] / fs / btrfs / reflink.c

diff --git a/fs/btrfs/reflink.c b/fs/btrfs/reflink.c
index 6746460fd2194677d3181d91e52a96d04af1f6bc..f4ec06b53aa039ff434ffb14161d190909c104da 100644 (file)
--- a/fs/btrfs/reflink.c
+++ b/fs/btrfs/reflink.c
@@ -834,6 +834,16 @@ static int btrfs_remap_file_range_prep(struct file *file_in, loff_t pos_in,
                                            len, remap_flags);
 }
 
+static bool file_sync_write(const struct file *file)
+{
+       if (file->f_flags & (__O_SYNC | O_DSYNC))
+               return true;
+       if (IS_SYNC(file_inode(file)))
+               return true;
+
+       return false;
+}
+
 loff_t btrfs_remap_file_range(struct file *src_file, loff_t off,
                struct file *dst_file, loff_t destoff, loff_t len,
                unsigned int remap_flags)
@@ -871,5 +881,20 @@ out_unlock:
                unlock_two_nondirectories(src_inode, dst_inode);
        }
 
+       /*
+        * If either the source or the destination file was opened with O_SYNC,
+        * O_DSYNC or has the S_SYNC attribute, fsync both the destination and
+        * source files/ranges, so that after a successful return (0) followed
+        * by a power failure results in the reflinked data to be readable from
+        * both files/ranges.
+        */
+       if (ret == 0 && len > 0 &&
+           (file_sync_write(src_file) || file_sync_write(dst_file))) {
+               ret = btrfs_sync_file(src_file, off, off + len - 1, 0);
+               if (ret == 0)
+                       ret = btrfs_sync_file(dst_file, destoff,
+                                             destoff + len - 1, 0);
+       }
+
        return ret < 0 ? ret : len;
 }