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When mounting, we handle deleted subvolume and orphan items. First, find add orphan roots, then add them to fs_root radix tree. Second, in tree-root, process each orphan item, skip if it is dead root. The original algorithm is based on the list of dead_roots, one by one to visit and check whether the objectid is consistent, the time complexity is O (n ^ 2). When processing 50000 deleted subvols, it takes about 120s. Because btrfs_find_orphan_roots has already ran before us, and added deleted subvol to fs_roots radix tree. The fs root will only be removed from the fs_roots radix tree after the cleaner process is started, and the cleaner will only start execution after the mount is complete. btrfs_orphan_cleanup can be called during the whole filesystem mount lifetime, but only "tree root" will be used in this section of code, and only mount time will be brought into tree root. So we can quickly check whether the orphan item is dead root through the fs_roots radix tree. Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Robbie Ko <robbieko@synology.com> Signed-off-by: David Sterba <dsterba@suse.com> |
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| block | ||
| 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 | ||
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| COPYING | ||
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| 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.