Commit 184a09eb authored by Dennis Yang's avatar Dennis Yang Committed by Shaohua Li

md/raid5: preserve STRIPE_ON_UNPLUG_LIST in break_stripe_batch_list

In release_stripe_plug(), if a stripe_head has its STRIPE_ON_UNPLUG_LIST
set, it indicates that this stripe_head is already in the raid5_plug_cb
list and release_stripe() would be called instead to drop a reference
count. Otherwise, the STRIPE_ON_UNPLUG_LIST bit would be set for this
stripe_head and it will get queued into the raid5_plug_cb list.

Since break_stripe_batch_list() did not preserve STRIPE_ON_UNPLUG_LIST,
A stripe could be re-added to plug list while it is still on that list
in the following situation. If stripe_head A is added to another
stripe_head B's batch list, in this case A will have its
batch_head != NULL and be added into the plug list. After that,
stripe_head B gets handled and called break_stripe_batch_list() to
reset all the batched stripe_head(including A which is still on
the plug list)'s state and reset their batch_head to NULL.
Before the plug list gets processed, if there is another write request
comes in and get stripe_head A, A will have its batch_head == NULL
(cleared by calling break_stripe_batch_list() on B) and be added to
plug list once again.
Signed-off-by: default avatarDennis Yang <dennisyang@qnap.com>
Cc: stable@vger.kernel.org (v4.1+)
Signed-off-by: default avatarShaohua Li <shli@fb.com>
parent 3664847d
...@@ -4605,7 +4605,8 @@ static void break_stripe_batch_list(struct stripe_head *head_sh, ...@@ -4605,7 +4605,8 @@ static void break_stripe_batch_list(struct stripe_head *head_sh,
set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS | set_mask_bits(&sh->state, ~(STRIPE_EXPAND_SYNC_FLAGS |
(1 << STRIPE_PREREAD_ACTIVE) | (1 << STRIPE_PREREAD_ACTIVE) |
(1 << STRIPE_DEGRADED)), (1 << STRIPE_DEGRADED) |
(1 << STRIPE_ON_UNPLUG_LIST)),
head_sh->state & (1 << STRIPE_INSYNC)); head_sh->state & (1 << STRIPE_INSYNC));
sh->check_state = head_sh->check_state; sh->check_state = head_sh->check_state;
......
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