https://github.com/torvalds/linux
Revision f2a459565b02b60408f3f2e5ca992a031319712b authored by Dave Chinner on 21 January 2013, 12:53:54 UTC, committed by Ben Myers on 28 January 2013, 18:50:50 UTC
There is a window on small filesytsems where specualtive
preallocation can be larger than that ENOSPC throttling thresholds,
resulting in specualtive preallocation trying to reserve more space
than there is space available. This causes immediate ENOSPC to be
triggered, prealloc to be turned off and flushing to occur. One the
next write (i.e. next 4k page), we do exactly the same thing, and so
effective drive into synchronous 4k writes by triggering ENOSPC
flushing on every page while in the window between the prealloc size
and the ENOSPC prealloc throttle threshold.

Fix this by checking to see if the prealloc size would consume all
free space, and throttle it appropriately to avoid premature
ENOSPC...

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
1 parent eb17861
History
Tip revision: f2a459565b02b60408f3f2e5ca992a031319712b authored by Dave Chinner on 21 January 2013, 12:53:54 UTC
xfs: limit speculative prealloc near ENOSPC thresholds
Tip revision: f2a4595
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