Re: [PATCH 04/12] mm: Add support for a filesystem to activate swap files and use direct_IO for writing swap pages

On 06/20/2012 05:37 AM, Mel Gorman wrote:

Currently swapfiles are managed entirely by the core VM by using ->bmap
to allocate space and write to the blocks directly. This effectively
ensures that the underlying blocks are allocated and avoids the need
for the swap subsystem to locate what physical blocks store offsets
within a file.

If the swap subsystem is to use the filesystem information to locate
the blocks, it is critical that information such as block groups,
block bitmaps and the block descriptor table that map the swap file
were resident in memory. This patch adds address_space_operations that
the VM can call when activating or deactivating swap backed by a file.

   int swap_activate(struct file *);
   int swap_deactivate(struct file *);

Acked-by: Rik van Riel<redacted>

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