Re: [PATCH -mm 1/6] swsusp: Use device and offset to intentify swap areas

Pavel Machek
2006-09-21T21:27:16Z

Hi!

> The Linux kernel handles swap files almost in the same way as it handles swap
> partitions and there are only two differences between these two types of swap
> areas:
> (1) swap files need not be contiguous,
> (2) the header of a swap file is not in the first block of the partition that
> holds it. From the swsusp's point of view (1) is not a problem, because it is
> already taken care of by the swap-handling code, but (2) has to be taken into
> consideration.
>
> In principle the location of a swap file's header may be determined with the
> help of appropriate filesystem driver. Unfortunately, however, it requires the
> filesystem holding the swap file to be mounted, and if this filesystem is
> journaled, it cannot be mounted during a resume from disk. For this reason
> we need some other means by which swap areas can be identified.
>
> For example, to identify a swap area we can use the partition that holds the
> area and the offset from the beginning of this partition at which the swap
> header is located.
>
> The following patch allows swsusp to identify swap areas this way. It changes
> swap_type_of() so that it takes an additional argument representing an offset
> of the swap header within the partition represented by its first argument.
>
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

ACK.

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