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ffa8fc603d
For fallocate() we have this loop that checks if we have ordered extents after locking the file range, and if so unlock the range, wait for ordered extents, and retry until we don't find more ordered extents. This logic was needed in the past because: 1) Direct IO writes within the i_size boundary did not take the inode's VFS lock. This was because that lock used to be a mutex, then some years ago it was switched to a rw semaphore (commit9902af79c0("parallel lookups: actual switch to rwsem")), and then btrfs was changed to take the VFS inode's lock in shared mode for writes that don't cross the i_size boundary (commite9adabb971("btrfs: use shared lock for direct writes within EOF")); 2) We could race with memory mapped writes, because memory mapped writes don't acquire the inode's VFS lock. We don't have that race anymore, as we have a rw semaphore to synchronize memory mapped writes with fallocate (and reflinking too). That change happened with commit8d9b4a162a("btrfs: exclude mmap from happening during all fallocate operations"). So stop looking for ordered extents after locking the file range when doing a plain fallocate. Signed-off-by: Filipe Manana <fdmanana@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 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.