302167c50b
Previously callers to btrfs_end_transaction_throttle() would commit the
transaction if there wasn't enough delayed refs space. This happens in
relocation, and if the fs is relatively empty we'll run out of delayed
refs space basically immediately, so we'll just be stuck in this loop of
committing the transaction over and over again.
This code existed because we didn't have a good feedback mechanism for
running delayed refs, but with the delayed refs rsv we do now. Delete
this throttling code and let the btrfs_start_transaction() in relocation
deal with putting pressure on the delayed refs infrastructure. With
this patch we no longer take 5 minutes to balance a metadata only fs.
Qu has submitted a fstest to catch slow balance or excessive transaction
commits. Steps to reproduce:
* create subvolume
* create many (eg. 16000) inlined files, of size 2KiB
* iteratively snapshot and touch several files to trigger metadata
updates
* start balance -m
Reported-by: Qu Wenruo <wqu@suse.com>
Fixes: 64403612b73a ("btrfs: rework btrfs_check_space_for_delayed_refs")
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ add tags and steps to reproduce ]
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.