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scsi: iscsi: Add support for asynchronous iSCSI session destruction

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iSCSI session destruction can be arbitrarily slow, since it might require
network operations and serialization inside the SCSI layer.  This patch
adds a new user event to trigger the destruction work asynchronously,
releasing the rx_queue_mutex as soon as the operation is queued and before
it is performed.  This change allows other operations to run in other
sessions in the meantime, removing one of the major iSCSI bottlenecks for
us.

To prevent the session from being used after the destruction request, we
remove it immediately from the sesslist. This simplifies the locking
required during the asynchronous removal.

Link: https://lore.kernel.org/r/20200227195945.761719-1-krisman@collabora.com
Co-developed-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Co-developed-by: Khazhismel Kumykov <khazhy@google.com>
Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Frank Mayhar <fmayhar@google.com>
Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Frank Mayhar
2020-02-27 14:59:45 -05:00
committed by Martin K. Petersen
parent bef18d308a
commit cc6b32ee3b
3 changed files with 40 additions and 0 deletions
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1
include/scsi/iscsi_if.h
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@ -60,6 +60,7 @@ enum iscsi_uevent_e {
ISCSI_UEVENT_LOGOUT_FLASHNODE_SID = UEVENT_BASE + 30,
ISCSI_UEVENT_SET_CHAP = UEVENT_BASE + 31,
ISCSI_UEVENT_GET_HOST_STATS = UEVENT_BASE + 32,
ISCSI_UEVENT_DESTROY_SESSION_ASYNC = UEVENT_BASE + 33,
/* up events */
ISCSI_KEVENT_RECV_PDU = KEVENT_BASE + 1,

1
include/scsi/scsi_transport_iscsi.h
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@ -226,6 +226,7 @@ struct iscsi_cls_session {
struct work_struct unblock_work;
struct work_struct scan_work;
struct work_struct unbind_work;
struct work_struct destroy_work;
/* recovery fields */
int recovery_tmo;