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A mirror of the official Linux kernel repository just in case
ce85a1e046
If the fscounters scrubber notices incorrect summary counters, it's entirely possible that scrub is simply racing with other threads that are updating the incore counters. There isn't a good way to stabilize percpu counters or set ourselves up to observe live updates with hooks like we do for the quotacheck or nlinks scanners, so we instead choose to freeze the filesystem long enough to walk the incore per-AG structures. Past me thought that it was going to be commonplace to have to freeze the filesystem to perform some kind of repair and set up a whole separate infrastructure to freeze the filesystem in such a way that userspace could not unfreeze while we were running. This involved adding a mutex and freeze_super/thaw_super functions and dealing with the fact that the VFS freeze/thaw functions can free the VFS superblock references on return. This was all very overwrought, since fscounters turned out to be the only user of scrub freezes, and it doesn't require the log to quiesce, only the incore superblock counters. We prevent other threads from changing the freeze level by calling freeze_super_excl with a custom freeze cookie to keep everyone else out of the filesystem. The end result is that fscounters should be much more efficient. When we're checking a busy system and we can't stabilize the counters, the custom freeze will do less work, which should result in less downtime. Repair should be similarly speedy, but that's in a later patch. Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> |
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| fs | ||
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| kernel | ||
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| samples | ||
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| .get_maintainer.ignore | ||
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| COPYING | ||
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| 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.