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authorMikulas Patocka <mpatocka@redhat.com>2009-12-10 18:52:30 -0500
committerAlasdair G Kergon <agk@redhat.com>2009-12-10 18:52:30 -0500
commit515ad66cc4c82f210d726340349c8f7c1ec6b125 (patch)
treee6ae5591a7906f3ce9ae0fb0a62419acffcdcbcd /drivers/scsi
parentd698aa4500aa3ca9559142060caf0f79da998744 (diff)
dm snapshot: rework writing to origin
To track the completion of exceptions relating to the same location on the device, the current code selects one exception as primary_pe, links the other exceptions to it and uses reference counting to wait until all the reallocations are complete. It is considered too complicated to extend this code to handle the new snapshot-merge target, where sets of non-overlapping chunks would also need to become linked. Instead, a simpler (but less efficient) approach is taken. Bios are linked to one exception. When it completes, bios are simply retried, and if other related exceptions are still outstanding, they'll get queued again to wait for another one. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/scsi')
0 files changed, 0 insertions, 0 deletions