tree 65354bb8abe5c9ab63ce0a6d36cf9b957f9a1353
parent 408cc4e97a3ccd172d2d676e4b585badf439271b
author Dave Chinner <dchinner@redhat.com> 1349399218 +1000
committer Ben Myers <bpm@sgi.com> 1352394507 -0600

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@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>