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For encoded writes in send v2, we will get the encoded data with btrfs_encoded_read_regular_fill_pages(), which expects a list of raw pages. To avoid extra buffers and copies, we should read directly into the send buffer. Therefore, we need the raw pages for the send buffer. We currently allocate the send buffer with kvmalloc(), which may return a kmalloc'd buffer or a vmalloc'd buffer. For vmalloc, we can get the pages with vmalloc_to_page(). For kmalloc, we could use virt_to_page(). However, the buffer size we use (144K) is not a power of two, which in theory is not guaranteed to return a page-aligned buffer, and in practice would waste a lot of memory due to rounding up to the next power of two. 144K is large enough that it usually gets allocated with vmalloc(), anyways. So, for send v2, replace kvmalloc() with vmalloc() and save the pages in an array. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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 Restructured Text 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.