mainlining shenanigans
0096420adb
We ran into a problem in production where a box with plenty of space was getting wedged doing ENOSPC flushing. These boxes only had 20% of the disk allocated, but their metadata space + global reserve was right at the size of their metadata chunk. In this case can_overcommit should be allowing allocations without problem, but there's logic in can_overcommit that doesn't allow us to overcommit if there's not enough real space to satisfy the global reserve. This is for historical reasons. Before there were only certain places we could allocate chunks. We could go to commit the transaction and not have enough space for our pending delayed refs and such and be unable to allocate a new chunk. This would result in a abort because of ENOSPC. This code was added to solve this problem. However since then we've gained the ability to always be able to allocate a chunk. So we can easily overcommit in these cases without risking a transaction abort because of ENOSPC. Also prior to now the global reserve really would be used because that's the space we relied on for delayed refs. With delayed refs being tracked separately we no longer have to worry about running out of delayed refs space while committing. We are much less likely to exhaust our global reserve space during transaction commit. Fix the can_overcommit code to simply see if our current usage + what we want is less than our current free space plus whatever slack space we have in the disk is. This solves the problem we were seeing in production and keeps us from flushing as aggressively as we approach our actual metadata size usage. Reviewed-by: Nikolay Borisov <nborisov@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: David Sterba <dsterba@suse.com> |
||
|---|---|---|
| arch | ||
| 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 | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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.