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We can use paddr -1 as an indicator for unset/uninitialized paddr. We can not use 0 paddr, unlike virtual address 0 which is never mapped thus will always trigger a page fault, physical address 0 may be a valid page. So here we follow swiotlb to use (paddr)-1 as a special indicator for invalid/unset physical address. Even if the PFN may still be valid, our usage of the physical address should always be aligned to fs block size (or page size for bs > ps cases), thus such -1 paddr should never be a valid one. With this special -1 paddr, we can get rid of has_paddr member and save 1 byte for sector_ptr structure. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.