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e04426b xfs: move allocation stack switch up to xfs_bmapi_allocate
2455881 xfs: introduce XFS_BMAPI_STACK_SWITCH
a004168 xfs: zero allocation_args on the kernel stack
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commit e04426b9202bccd4cfcbc70b2fa2aeca1c86d8f5
Author: Dave Chinner <dchinner@xxxxxxxxxx>
Date: Fri Oct 5 11:06:59 2012 +1000
xfs: move allocation stack switch up to xfs_bmapi_allocate
Switching stacks are xfs_alloc_vextent can cause deadlocks when we
run out of worker threads on the allocation workqueue. This can
occur because xfs_bmap_btalloc can make multiple calls to
xfs_alloc_vextent() and even if xfs_alloc_vextent() fails it can
return with the AGF locked in the current allocation transaction.
If we then need to make another allocation, and all the allocation
worker contexts are exhausted because the are blocked waiting for
the AGF lock, holder of the AGF cannot get it's xfs-alloc_vextent
work completed to release the AGF. Hence allocation effectively
deadlocks.
To avoid this, move the stack switch one layer up to
xfs_bmapi_allocate() so that all of the allocation attempts in a
single switched stack transaction occur in a single worker context.
This avoids the problem of an allocation being blocked waiting for
a worker thread whilst holding the AGF.
Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
Reviewed-by: Mark Tinguely <tinguely@xxxxxxx>
Signed-off-by: Ben Myers <bpm@xxxxxxx>
commit 2455881c0b52f87be539c4c7deab1afff4d8a560
Author: Dave Chinner <dchinner@xxxxxxxxxx>
Date: Fri Oct 5 11:06:58 2012 +1000
xfs: introduce XFS_BMAPI_STACK_SWITCH
Certain allocation paths through xfs_bmapi_write() are in situations
where we have limited stack available. These are almost always in
the buffered IO writeback path when convertion delayed allocation
extents to real extents.
The current stack switch occurs for userdata allocations, which
means we also do stack switches for preallocation, direct IO and
unwritten extent conversion, even those these call chains have never
been implicated in a stack overrun.
Hence, let's target just the single stack overun offended for stack
switches. To do that, introduce a XFS_BMAPI_STACK_SWITCH flag that
the caller can pass xfs_bmapi_write() to indicate it should switch
stacks if it needs to do allocation.
Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
Reviewed-by: Mark Tinguely <tinguely@xxxxxxx>
Signed-off-by: Ben Myers <bpm@xxxxxxx>
commit a00416844b8f4b0106344bdfd90fe45a854b1d05
Author: Mark Tinguely <tinguely@xxxxxxx>
Date: Thu Sep 20 13:16:45 2012 -0500
xfs: zero allocation_args on the kernel stack
Zero the kernel stack space that makes up the xfs_alloc_arg structures.
Signed-off-by: Mark Tinguely <tinguely@xxxxxxx>
Reviewed-by: Ben Myers <bpm@xxxxxxx>
Signed-off-by: Ben Myers <bpm@xxxxxxx>
-----------------------------------------------------------------------
Summary of changes:
fs/xfs/xfs_alloc.c | 43 ++---------------------------------
fs/xfs/xfs_alloc.h | 3 ---
fs/xfs/xfs_bmap.c | 63 +++++++++++++++++++++++++++++++++++++++++++--------
fs/xfs/xfs_bmap.h | 9 +++++++-
fs/xfs/xfs_ialloc.c | 1 +
fs/xfs/xfs_iomap.c | 4 +++-
6 files changed, 68 insertions(+), 55 deletions(-)
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