fs/libfs.c: add generic data flush to fsync

Description by Jan Kara:
 "A lot of older filesystems don't properly flush volatile disk caches
  on fsync(2) which can lead to loss of fsynced data after power failure.

This patch makes generic_file_fsync() issue proper cache flush to fix the
problem.  Sysadmin can use /sys/devices/.../cache_type to tell the system
it should not send the cache flush."

[akpm@linux-foundation.org: nuke ifdef]
[akpm@linux-foundation.org: fix warning]
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Suggested-by: Jan Kara <jack@suse.cz>
Suggested-by: Christoph Hellwig <hch@infradead.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 8aba35f46f87..45cf6e537c83 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1607,6 +1607,9 @@ struct block_device_operations {
 extern int __blkdev_driver_ioctl(struct block_device *, fmode_t, unsigned int,
                                  unsigned long);
 #else /* CONFIG_BLOCK */
+
+struct block_device;
+
 /*
  * stubs for when the block layer is configured out
  */
@@ -1642,6 +1645,12 @@ static inline bool blk_needs_flush_plug(struct task_struct *tsk)
         return false;
 }
 
+static inline int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
+                                     sector_t *error_sector)
+{
+        return 0;
+}
+
 #endif /* CONFIG_BLOCK */
 
 #endif