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Unlike reservation calculation used in inode rsv for metadata, qgroup doesn't really need to care about things like csum size or extent usage for the whole tree COW. Qgroups care more about net change of the extent usage. That's to say, if we're going to insert one file extent, it will mostly find its place in COWed tree block, leaving no change in extent usage. Or causing a leaf split, resulting in one new net extent and increasing qgroup number by nodesize. Or in an even more rare case, increase the tree level, increasing qgroup number by 2 * nodesize. So here instead of using the complicated calculation for extent allocator, which cares more about accuracy and no error, qgroup doesn't need that over-estimated reservation. This patch will maintain 2 new members in btrfs_block_rsv structure for qgroup, using much smaller calculation for qgroup rsv, reducing false EDQUOT. Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Qu Wenruo <wqu@suse.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.