fs: move code out of buffer.c

Move invalidate_bdev, block_sync_page into fs/block_dev.c.  Export
kill_bdev as well, so brd doesn't have to open code it.  Reduce
buffer_head.h requirement accordingly.

Removed a rather large comment from invalidate_bdev, as it looked a bit
obsolete to bother moving.  The small comment replacing it says enough.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 0 insertions, 50 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index 19d8eb7fdc81..1a30db77af32 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -41,7 +41,6 @@
 #include <linux/bitops.h>
 #include <linux/mpage.h>
 #include <linux/bit_spinlock.h>
-#include <linux/cleancache.h>
 
 static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
 
@@ -231,55 +230,6 @@ out:
         return ret;
 }
 
-/* If invalidate_buffers() will trash dirty buffers, it means some kind
-   of fs corruption is going on. Trashing dirty data always imply losing
-   information that was supposed to be just stored on the physical layer
-   by the user.
-
-   Thus invalidate_buffers in general usage is not allwowed to trash
-   dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to
-   be preserved.  These buffers are simply skipped.
-  
-   We also skip buffers which are still in use.  For example this can
-   happen if a userspace program is reading the block device.
-
-   NOTE: In the case where the user removed a removable-media-disk even if
-   there's still dirty data not synced on disk (due a bug in the device driver
-   or due an error of the user), by not destroying the dirty buffers we could
-   generate corruption also on the next media inserted, thus a parameter is
-   necessary to handle this case in the most safe way possible (trying
-   to not corrupt also the new disk inserted with the data belonging to
-   the old now corrupted disk). Also for the ramdisk the natural thing
-   to do in order to release the ramdisk memory is to destroy dirty buffers.
-
-   These are two special cases. Normal usage imply the device driver
-   to issue a sync on the device (without waiting I/O completion) and
-   then an invalidate_buffers call that doesn't trash dirty buffers.
-
-   For handling cache coherency with the blkdev pagecache the 'update' case
-   is been introduced. It is needed to re-read from disk any pinned
-   buffer. NOTE: re-reading from disk is destructive so we can do it only
-   when we assume nobody is changing the buffercache under our I/O and when
-   we think the disk contains more recent information than the buffercache.
-   The update == 1 pass marks the buffers we need to update, the update == 2
-   pass does the actual I/O. */
-void invalidate_bdev(struct block_device *bdev)
-{
-        struct address_space *mapping = bdev->bd_inode->i_mapping;
-
-        if (mapping->nrpages == 0)
-                return;
-
-        invalidate_bh_lrus();
-        lru_add_drain_all();    /* make sure all lru add caches are flushed */
-        invalidate_mapping_pages(mapping, 0, -1);
-        /* 99% of the time, we don't need to flush the cleancache on the bdev.
-         * But, for the strange corners, lets be cautious
-         */
-        cleancache_flush_inode(mapping);
-}
-EXPORT_SYMBOL(invalidate_bdev);
-
 /*
  * Kick the writeback threads then try to free up some ZONE_NORMAL memory.
  */