xfs: improve handling of busy extents in the low-level allocator

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Currently we force the log and simply try again if we hit a busy extent,
but especially with online discard enabled it might take a while after
the log force for the busy extents to disappear, and we might have
already completed our second pass.

So instead we add a new waitqueue and a generation counter to the pag
structure so that we can do wakeups once we've removed busy extents,
and we replace the single retry with an unconditional one - after
all we hold the AGF buffer lock, so no other allocations or frees
can be racing with us in this AG.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

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This commit is contained in:

Christoph Hellwig 2017-02-07 14:06:57 -08:00 • committed by Darrick J. Wong

parent 5e30c23d13

commit ebf5587261

5 changed files with 166 additions and 73 deletions

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93

fs/xfs/libxfs/xfs_alloc.c

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125

fs/xfs/xfs_extent_busy.c

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11

fs/xfs/xfs_extent_busy.h

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8

fs/xfs/xfs_mount.c

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2

fs/xfs/xfs_mount.h

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