diff options
Diffstat (limited to 'drivers/md/raid5.h')
| -rw-r--r-- | drivers/md/raid5.h | 35 |
1 files changed, 16 insertions, 19 deletions
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h index a33001137bf..bb246d9e054 100644 --- a/drivers/md/raid5.h +++ b/drivers/md/raid5.h @@ -6,11 +6,11 @@ /* * - * Each stripe contains one buffer per disc. Each buffer can be in + * Each stripe contains one buffer per device. Each buffer can be in * one of a number of states stored in "flags". Changes between - * these states happen *almost* exclusively under a per-stripe - * spinlock. Some very specific changes can happen in bi_end_io, and - * these are not protected by the spin lock. + * these states happen *almost* exclusively under the protection of the + * STRIPE_ACTIVE flag. Some very specific changes can happen in bi_end_io, and + * these are not protected by STRIPE_ACTIVE. * * The flag bits that are used to represent these states are: * R5_UPTODATE and R5_LOCKED @@ -76,12 +76,10 @@ * block and the cached buffer are successfully written, any buffer on * a written list can be returned with b_end_io. * - * The write list and read list both act as fifos. The read list is - * protected by the device_lock. The write and written lists are - * protected by the stripe lock. The device_lock, which can be - * claimed while the stipe lock is held, is only for list - * manipulations and will only be held for a very short time. It can - * be claimed from interrupts. + * The write list and read list both act as fifos. The read list, + * write list and written list are protected by the device_lock. + * The device_lock is only for list manipulations and will only be + * held for a very short time. It can be claimed from interrupts. * * * Stripes in the stripe cache can be on one of two lists (or on @@ -96,7 +94,6 @@ * * The inactive_list, handle_list and hash bucket lists are all protected by the * device_lock. - * - stripes on the inactive_list never have their stripe_lock held. * - stripes have a reference counter. If count==0, they are on a list. * - If a stripe might need handling, STRIPE_HANDLE is set. * - When refcount reaches zero, then if STRIPE_HANDLE it is put on @@ -116,10 +113,10 @@ * attach a request to an active stripe (add_stripe_bh()) * lockdev attach-buffer unlockdev * handle a stripe (handle_stripe()) - * lockstripe clrSTRIPE_HANDLE ... + * setSTRIPE_ACTIVE, clrSTRIPE_HANDLE ... * (lockdev check-buffers unlockdev) .. * change-state .. - * record io/ops needed unlockstripe schedule io/ops + * record io/ops needed clearSTRIPE_ACTIVE schedule io/ops * release an active stripe (release_stripe()) * lockdev if (!--cnt) { if STRIPE_HANDLE, add to handle_list else add to inactive-list } unlockdev * @@ -128,8 +125,7 @@ * on a cached buffer, and plus one if the stripe is undergoing stripe * operations. * - * Stripe operations are performed outside the stripe lock, - * the stripe operations are: + * The stripe operations are: * -copying data between the stripe cache and user application buffers * -computing blocks to save a disk access, or to recover a missing block * -updating the parity on a write operation (reconstruct write and @@ -159,7 +155,8 @@ */ /* - * Operations state - intermediate states that are visible outside of sh->lock + * Operations state - intermediate states that are visible outside of + * STRIPE_ACTIVE. * In general _idle indicates nothing is running, _run indicates a data * processing operation is active, and _result means the data processing result * is stable and can be acted upon. For simple operations like biofill and @@ -209,7 +206,6 @@ struct stripe_head { short ddf_layout;/* use DDF ordering to calculate Q */ unsigned long state; /* state flags */ atomic_t count; /* nr of active thread/requests */ - spinlock_t lock; int bm_seq; /* sequence number for bitmap flushes */ int disks; /* disks in stripe */ enum check_states check_state; @@ -240,7 +236,7 @@ struct stripe_head { }; /* stripe_head_state - collects and tracks the dynamic state of a stripe_head - * for handle_stripe. It is only valid under spin_lock(sh->lock); + * for handle_stripe. */ struct stripe_head_state { int syncing, expanding, expanded; @@ -290,6 +286,7 @@ struct r6_state { * Stripe state */ enum { + STRIPE_ACTIVE, STRIPE_HANDLE, STRIPE_SYNC_REQUESTED, STRIPE_SYNCING, @@ -339,7 +336,7 @@ enum { * PREREAD_ACTIVE. * In stripe_handle, if we find pre-reading is necessary, we do it if * PREREAD_ACTIVE is set, else we set DELAYED which will send it to the delayed queue. - * HANDLE gets cleared if stripe_handle leave nothing locked. + * HANDLE gets cleared if stripe_handle leaves nothing locked. */ |