linux/drivers/md/bitmap.c, branch v3.5

md/bitmap: record the space available for the bitmap in the superblock.

2012-05-22T03:55:34Z

Now that bitmaps can grow and shrink it is best if we record how much space is available. This means that when we reduce the size of the bitmap we won't "lose" the space for late when we might want to increase the size of the bitmap again. Signed-off-by: NeilBrown

md/bitmap: make sure reshape request are reflected in superblock.

2012-05-22T03:55:26Z

As a reshape may change the sync_size and/or chunk_size, we need to update these whenever we write out the bitmap superblock. Signed-off-by: NeilBrown

md/bitmap: add bitmap_resize function to allow bitmap resizing.

2012-05-22T03:55:25Z

This function will allocate the new data structures and copy bits across from old to new, allowing for the possibility that the chunksize has changed. Use the same function for performing the initial allocation of the structures. This improves test coverage. When bitmap_resize is used to resize an existing bitmap, it only copies '1' bits in, not '0' bits. So when allocating the bitmap, ensure everything is initialised to ZERO. Signed-off-by: NeilBrown

md/bitmap: use DIV_ROUND_UP instead of open-code

2012-05-22T03:55:25Z

Also take the opportunity to simplify CHUNK_BLOCK_RATIO. Signed-off-by: NeilBrown

md/bitmap: create a 'struct bitmap_counts' substructure of 'struct bitmap'

2012-05-22T03:55:24Z

The new "struct bitmap_counts" contains all the fields that are related to counting the number of active writes in each bitmap chunk. Having this separate will make it easier to change the chunksize or overall size of a bitmap atomically. Signed-off-by: NeilBrown

md/bitmap: make bitmap bitops atomic.

2012-05-22T03:55:23Z

This allows us to remove spinlock protection which is more heavy-weight than simple atomics. Signed-off-by: NeilBrown

md/bitmap: make _page_attr bitops atomic.

2012-05-22T03:55:22Z

Using e.g. set_bit instead of __set_bit and using test_and_clear_bit allow us to remove some locking and contract other locked ranges. It is rare that we set or clear a lot of these bits, so gain should outweigh any cost. Signed-off-by: NeilBrown

md/bitmap: merge bitmap_file_unmap and bitmap_file_put.

2012-05-22T03:55:21Z

There functions really do one thing together: release the 'bitmap_storage'. So make them just one function. Since we removed the locking (previous patch), we don't need to zero any fields before freeing them, so it all becomes a bit simpler. Signed-off-by: NeilBrown

md/bitmap: remove async freeing of bitmap file.

2012-05-22T03:55:21Z

There is no real value in freeing things the moment there is an error. It is just as good to free the bitmap file and pages when the bitmap is explicitly removed (and replaced?) or at shutdown. With this gone, the bitmap will only disappear when the array is quiescent, so we can remove some locking. As the 'filemap' doesn't disappear now, include extra checks before trying to write any of it out. Also remove the check for "has it disappeared" in bitmap_daemon_write(). Signed-off-by: NeilBrown

md/bitmap: convert some spin_lock_irqsave to spin_lock_irq

2012-05-22T03:55:19Z

All of these sites can only be called from process context with irqs enabled, so using irqsave/irqrestore just adds noise. Remove it. Signed-off-by: NeilBrown