3.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Josh Durgin <[email protected]> When a snapshot is deleted, the OSD will return ENOENT when reading from it. This is normally interpreted as a hole by rbd, which will return zeroes. To minimize the time in which this can happen, stop requests early when we are notified that our snapshot no longer exists. [[email protected]: updated __rbd_init_snaps_header() logic] Signed-off-by: Josh Durgin <[email protected]> Reviewed-by: Alex Elder <[email protected]> (cherry picked from commit e88a36ec961b8c1899c59c5e4ae35a318c0209d3) Signed-off-by: Greg Kroah-Hartman <[email protected]> Conflicts: drivers/block/rbd.c --- drivers/block/rbd.c | 32 ++++++++++++++++++++++++++++++-- 1 file changed, 30 insertions(+), 2 deletions(-) --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -174,9 +174,13 @@ struct rbd_device { /* protects updating the header */ struct rw_semaphore header_rwsem; + /* name of the snapshot this device reads from */ char snap_name[RBD_MAX_SNAP_NAME_LEN]; + /* id of the snapshot this device reads from */ u64 snap_id; /* current snapshot id */ - int read_only; + /* whether the snap_id this device reads from still exists */ + bool snap_exists; + int read_only; struct list_head node; @@ -590,6 +594,7 @@ static int rbd_header_set_snap(struct rb else snapc->seq = 0; dev->snap_id = CEPH_NOSNAP; + dev->snap_exists = false; dev->read_only = 0; if (size) *size = header->image_size; @@ -598,6 +603,7 @@ static int rbd_header_set_snap(struct rb if (ret < 0) goto done; dev->snap_id = snapc->seq; + dev->snap_exists = true; dev->read_only = 1; } @@ -1466,6 +1472,21 @@ static void rbd_rq_fn(struct request_que spin_unlock_irq(q->queue_lock); + if (rbd_dev->snap_id != CEPH_NOSNAP) { + bool snap_exists; + + down_read(&rbd_dev->header_rwsem); + snap_exists = rbd_dev->snap_exists; + up_read(&rbd_dev->header_rwsem); + + if (!snap_exists) { + dout("request for non-existent snapshot"); + spin_lock_irq(q->queue_lock); + __blk_end_request_all(rq, -ENXIO); + continue; + } + } + dout("%s 0x%x bytes at 0x%llx\n", do_write ? "write" : "read", size, blk_rq_pos(rq) * SECTOR_SIZE); @@ -2069,7 +2090,14 @@ static int __rbd_init_snaps_header(struc cur_id = rbd_dev->header.snapc->snaps[i - 1]; if (!i || old_snap->id < cur_id) { - /* old_snap->id was skipped, thus was removed */ + /* + * old_snap->id was skipped, thus was + * removed. If this rbd_dev is mapped to + * the removed snapshot, record that it no + * longer exists, to prevent further I/O. + */ + if (rbd_dev->snap_id == old_snap->id) + rbd_dev->snap_exists = false; __rbd_remove_snap_dev(rbd_dev, old_snap); continue; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
