Sun YangKai 80cf22e7ff btrfs: fix periodic reclaim condition
[ Upstream commit 19eff93dc7 ]

Problems with current implementation:

1. reclaimable_bytes is signed while chunk_sz is unsigned, causing
   negative reclaimable_bytes to trigger reclaim unexpectedly

2. The "space must be freed between scans" assumption breaks the
   two-scan requirement: first scan marks block groups, second scan
   reclaims them. Without the second scan, no reclamation occurs.

Instead, track actual reclaim progress: pause reclaim when block groups
will be reclaimed, and resume only when progress is made. This ensures
reclaim continues until no further progress can be made. And resume
periodic reclaim when there's enough free space.

And we take care if reclaim is making any progress now, so it's
unnecessary to set periodic_reclaim_ready to false when failed to reclaim
a block group.

Fixes: 813d4c6422 ("btrfs: prevent pathological periodic reclaim loops")
CC: stable@vger.kernel.org # 6.12+
Suggested-by: Boris Burkov <boris@bur.io>
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Sun YangKai <sunk67188@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2026-03-13 17:20:28 +01:00
2026-03-13 17:20:28 +01:00
2026-03-05 10:04:32 -05:00

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.
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