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A new fs state EMERGENCY_SHUTDOWN is introduced, which is btrfs' equivalent of XFS_IOC_GOINGDOWN or EXT4_IOC_SHUTDOWN, after entering emergency shutdown state, all operations will return errors (-EIO), and can not be bring back to normal state until unmouont. The new state will reject the following file operations: - read_iter() - write_iter() - mmap() - open() - remap_file_range() - uring_cmd() - splice_read() This requires a small wrapper to do the extra shutdown check, then call the regular filemap_splice_read() function This should reject most of the file operations on a shutdown btrfs. And for the existing dirty folios, extra shutdown checks are introduced to the following functions: - run_delalloc_nocow() - run_delalloc_compressed() - cow_file_range() So that dirty ranges will still be properly cleaned without being submitted. Finally the shutdown state will also set the fs error, so that no new transaction will be committed, protecting the metadata from any possible further corruption. And when the fs entered shutdown mode for the first time, a critical level kernel message will show up to indicate the incident. That message will be important for end users as rejected delalloc ranges will output error messages, hopefully that shutdown message and the fact that all fs operations are returning error will prevent end users from getting too confused about the delalloc error messages. Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Anand Jain <asj@kernel.org> Tested-by: Anand Jain <asj@kernel.org> 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.