mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-05-04 00:15:49 -04:00
5909440344
If we are doing a NOWAIT direct IO read/write, we can block when locking the file range at btrfs_dio_iomap_begin(), as it's possible the range (or a part of it) is already locked by another task (mmap writes, another direct IO read/write racing with us, fiemap, etc). We are also waiting for completion of any ordered extent we find in the range, which also can block us for a significant amount of time. There's also the incorrect fallback to buffered IO (returning -ENOTBLK) when we are dealing with a NOWAIT request and we can't proceed. In this case we should be returning -EAGAIN, as falling back to buffered IO can result in blocking for many different reasons, so that the caller can delegate a retry to a context where blocking is more acceptable. Fix these cases by: 1) Doing a try lock on the file range and failing with -EAGAIN if we can not lock right away; 2) Fail with -EAGAIN if we find an ordered extent; 3) Return -EAGAIN instead of -ENOTBLK when we need to fallback to buffered IO and we have a NOWAIT request. This will also allow us to avoid a duplicated check that verifies if we are able to do a NOCOW write for NOWAIT direct IO writes, done in the next patch. 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.