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fs: move code out of buffer.c

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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>
This commit is contained in:
Al Viro 2011-09-16 02:31:11 -04:00
parent 94ea4158f1
commit ff01bb4832
28 changed files with 40 additions and 83 deletions
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50
fs/buffer.c
View file

@ -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.
*/